Workshop: Characterizing Construction Materials using Vapor Sorption Techniques

Okay, maybe I think we should start now and then we can wait for people to come in. As I start introducing myself. Good morning everyone. I hope you can all hear me. My name is Nachal Subramanian and I will be your host for this workshop. First of all, I would like to welcome you all for the workshop on characterization of construction materials using Vapor Sorption techniques. This is a collaborative workshop partnership between Surface Measurement Systems and the University of Luxembourg. I would like to thank Professor Stefan maas and his PhD student Sebastian for being helpful supportive in conducting this workshop. I would also like to give a little bit of an introduction to Surface Measurement systems. Who we are, what we do. We are a UK based company based in London. We are the world leaders of sorption science. The company has been around for more than 30 years now and we develop and engineer innovative experimental techniques and instrumentation for physical chemical characterization of complex solids. We specialize in mainly two techniques, Dynamic deposition DVS and Inverse Gas Chromatography igc. Today you'll learn all about these two techniques for the characterization of building materials. Now I think it's time to start the actual program. Let me just remind you all of you, house rules since this is a virtual workshop. But I'm sure you've all been used to this for the past year or so due to Covid restricting us to doing virtual meetings and conferences and such. But let me just remind you all, you'll be muted during the whole presentation just to avoid any background noise. And at the end of each presentation we'll have some time for Q and A. We want to make this session as interactive as possible. So please do ask any questions you have. At the end of each presentation I will unmute you. You can raise your hand if you have a question by clicking the little hand button on the top and I will unmute you. You can go ahead and ask the question yourself or you can also feel free to type in your question anytime during the presentation in the questions panel and I will pick it up at the end of the presentation for the speaker to answer. I will also be sending you copies of the presentations from today and you can get in touch with us to do a free couple of samples you could send in for this free demonstration analysis. So the agenda for today we have two presentations. One on DVS technology, the other one on inverse gas chromatography technology. And I have Professor Darrell Williams with us today. So he's the founder and managing director of Surface Measurement Systems. Usually he's really busy, but today I have my other Colleagues, application scientists, they had other appointments, conferences, and so on. So Daryl kindly stepped in and I'm really glad to have him as a speaker in my workshop today. So a little bit of an introduction to Daryl. So Professor Daryl Williams. He graduated with a BSc in Physical Chemistry from University of Melbourne, Australia and an MSc in Polymer Science from Lehigh University, USA. Then he got his PhD from Imperial College London. He's the founder and Managing Director of Surface Measurement Systems and also the professor of Particle Science in the Department of Chemical Engineering at Imperial College London. Darrell has published over 100 papers in referee journals. He's been granted many international patents as well. His research interests mainly include surface and bulk characterization of complex organic solids, including biopharmaceutics, foods, pharmaceuticals, polymers and many other areas. In 1991, he invented the DVS technology. He led the commercialization of two standard techniques for materials characterization, namely DVS and IGC methods via surface measurement systems. So here we go with that short introduction. I would like to welcome Daryl to start off with our presentation of the day. Thank you.

Thank you very much, Natal for your introduction. Very kind of you. And let me start to share my screen. Let me just see if we can see that. Okay, I just checking. Can you see my screen? Yes, that's clear. Is it?

Yes, it's very clear.

Great. Okay. And you can hear me. That's great. Well, so welcome to this morning's seminar webinar and I'm going to speak to you for probably about 40 minutes around characterization of materials that are very much in the wood and building materials domain. As Nichelle said, I've been involved in materials characterization for a very long time. Although to be candid with you, wood and building materials probably aren't the materials I know the most about. But I have some knowledge. But in terms of water absorption behavior, I've been studying water sorption behavior in materials for probably about 30 years now. So we have seen a lot of interesting materials over the years. But today's presentation will introduce you to a technique that some you won't have come across, but you may have read about. But if you're interested in how moisture interacts with the materials, this is potentially an important technique for you. So really, why might you be interested in this? Well, the reality is that we live in a world where water is ubiquitous. In the room that you're currently sitting at the moment, probably about 1% of the molecules in the room you are are probably water molecules. But importantly, unlike the nitrogen molecules and the oxygen molecules in the room, the water molecules Actually would prefer to be in a liqu so they are intrinsically very sticky molecules. And what that means is that in any environment where there are water molecules, the performance, storage, processing, and indeed formulation of materials can be strongly dependent on the way water interacts with them. And changes in both the humidity and the temperature can cause many chemical changes, dimensional changes, or mechanical changes in materials. And we're going to discuss some of the things that water can do to materials today. One of the critical questions which sort of underlies why we're talking to you today and why you might have some interest in today's presentation, is really understanding how water interacts with solid state materials. And when I mean solids, it could be the materials that your chair is made out of, you're sitting on, it could be the clothes that you're wearing, could be your hair, could be the food you had for breakfast, or water interacts with all sorts of materials. Indeed, there's hardly a material that water doesn't interact with. And therefore, when water interacts with solid state materials, we are led to a number of important questions. And sometimes they're very simple questions like how much water is in the coffee powder in my powdered coffee in the kitchen? And then we say, well, actually there's 7%. Well, how active or labor or reactive is it? Is it going to transfer to other components in a formulation? Then we get to the question, how fast does the water go into my materials? They'll get into kinetics. Then there's a critical question. Where is the water? Is it on the surface of the particles? Has it dissolved inside my solid state material, or is it inside pores? And if I change the humidity and the temperature, how is the stability of my material affected or not? Also we then get into questions around the morphology of the material. Is it solid? Is a solid crystalline? Is it semi crystalline? Is it crystalline? So what's the form? And then of course, if there are pores involved, what size pores, micro meso macros, and how much water is in each of those pores. Or indeed, maybe the water's reacted chemically and formed a hydrate. So these are all critical questions that relate to performance, stability, manufacture, products, and sometimes we need to answer those questions to move forward and our understanding of stability of many materials. So if I do a water vapor sorption experiment, and I'll tell you all about how we do that very, very soon, obviously I can talk to you about stability at different concentrations or different humidities at different temperatures, and we'll spend quite a bit of time talking about what are called water absorption isomed. And I'll explain what they are in a few minutes time. But in terms of some of the chemical and physical properties we can get from the experiments I'm about to describe, some of the properties are very simple and really quite fundamental. I can measure the surface area of my powder or my granulated material. I can sometimes measure the amorphous content, pore size, pore volume. If it's a hydrate. What sort of hydrate? Semi hydrate, Dihydrate, trihydrates. If the materials amorphous, I can measure the glass transition temperature. And again, that can be quite important to understand how stable it is. If I'm concerned about transport, I'm probably concerned about diffusion and permeability. I can measure those rates. If the material is unstable and is crystalline, maybe I can measure at deliquescens point. If it's amorphous, maybe it collapses to certain humidities. If it's very hydrophobic, I can measure the hydro vision or I can measure the water activity, which is something people in the food industry like to measure. So there's a range of physiochemical properties I can measure as well as or linked to the measurement of adsorption isotherm, which is what we'll discuss in a few minutes. So we'll spend a few moments just talking about how the technique compares to other characterization techniques. And let's be clear, if you're a material scientist or you're researching materials, you have lots of techniques to choose from. Why would this technique be any more useful than any of the techniques you currently use? And we'll talk about that a little bit. And we'll talk about what sort of absorption process can occur, then we'll talk a bit about the technology, how we do these experiments. And finally we have, I think, five or six examples of measurements that you can do on some problems that are related to wood and building materials. And hopefully that will help you a little bit in seeing how it might relate to sort of problems that you're concerned about in your research work or studies. So first we just want to talk about, broadly speaking, the sort of techniques we have out there. So as a material scientist and I spend most of my life characterizing materials, I really have a range of different techniques at my disposal, but they can broadly be classified into two types. There are techniques where I'm going to use effectively energy or changes in energy as the way of interrogating the material. So this I'm thinking about spectroscopic techniques I might Use light, X rays, lasers. So this technique could be infrared spectroscopy, could be scanning electron microscopy, could be x ray diffraction. And those techniques will typically give me analytical information or structural information. You know, what's the percent crystallinity? Oh, there are hydroxyl groups present in my material. So a lot of what material and where is it material. And if we're using calorimetry, where I'm basically using heat, so sort of thermal radiation, if you wish, I can then probe thermodynamic states. But it turns out that there are lots of problems where actually the best way of probing a material is to use another molecule. So I'm going to talk today really around sorption techniques where essentially we're using matter, water molecules predominantly today to probe the materials. And when we're interested in properties where molecular interactions are important, that actually makes sense. So if I'm interested in understanding how does my solid dissolve in water or how do my powder particles stick to another powder particle, then actually that's all about intermolecular forces. So actually if I'm interested in those sorts of things, using the molecule to get the information actually doesn't seem a bad idea. So as I said, if I'm using radiation as a probe, techniques, xrd, xps, nmr, ftr, all the sorts of optical microscopy, SEM, they're all useful bits of information, but tends to be sort of what's present, where is it? It doesn't always gives information around molecular physics, you know, intermolecular forces, things of that sort, difficult to get from that. If I'm doing dsc, I can get information or tga, get information around thermal events and that can be very helpful. But that tells you about the way molecules interact with themselves. That can be quite helpful. But if interest in understanding how my solid interacts with water or with a solvent, that doesn't always help me. But the techniques I'm going to talk about today are really around using vapor phase molecules. We're mainly going to talk about water molecules today, but it could be alkanes, could be hexane molecules, could be ethanol molecules. Really any molecules that you choose can potentially be used in the experiments that I'm going to describe today. Those molecules go into my material. Some of the molecules will adsorb on the surface, so we'll talk about adsorption. Some will go inside the material. They might dissolve in the material, they might go inside pores, but they'll go inside the material. And we'll sometimes use the term absorb for that. And eventually the molecules will desorb from the system. So the molecules are going to interrogate the material and then they're going to leave the material of interest. And of course, in the process of doing that, we're looking effectively at adsorption process, so physisorption and chemisorption. And we're also looking at, if you like, two different sorts of bulk absorption. We're looking at dissolution, where the molecules dissolve inside of another material or sometimes they can be incorporated into the lattice, I.e. form a crystalline hydrate. But essential, by doing an adsorption experiment, we are learning about the way molecules interact at quite a fundamental level with the material we have of interest. Now, people have been studying the way water interacts with solids for many, many years. And these jar or desiccator methods have been around a very long time. And when we first invented the DVS in The very early 90s, we were working with Pfizer pharmaceutical company in the UK and they used to have rooms full of these desiccators. They'd have hundreds of desiccators. In every desiccator they have a little dish. The dish would have a gram of sample and every desiccated would have a saturated salt solution in it. And once a day the technician would come in, take out the, take out the little sample boat, weigh it and put it back in. And this would carry on for months. This was a standard technique at the time. And effectively the new technology that we developed at the time called dynamic vapor absorption, really automated that. Now I'll describe the technique in a moment. It is a gravimetric technique, in short, so it. The closest technique that you might currently be familiar with, indeed you may use that's similar, is basically TGA thermo gravimetric analysis. There's also a gravimetric approach. The differences are in a tga, you change the temperature of the sample and look at mass changes in the dvs, you change the humidity around a sample and look at the actual change in mass. So humidity is a variable, not so much a temperature. And of course, if we look at a static method, they typically use fairly large samples, typically means many grams. But for these DVS methods we typically only use maybe 10mg, although we can use a lot more if we want. However, the larger samples always take a little bit longer to get equilibrium, so we tend to use smaller samples wherever it is sensible. In the static methods, the desiccators are sealed, there's no gas flow or any air motion. So the equilibrium can be rather Slow. We're depending entirely on Brownian motion of the gases. Whereas in the DBS techniques, we are continuously flowing carrier gas containing water molecules over the sample. So it's a dynamic equilibrium. The sample is exposed to a continuous flow humidity. So we have very good and very fast mass equilibrium. And these static methods, though they were successful in their own way, they could take many weeks or months for a single data point. And of course, we can do the whole experiment in typically a day, sometimes two days, depends on the sample. And of course, there's no need to intervene, there's no need to take your tweezers, take the sample out, wipe it back in, with all the complications it has. This is a continuous measurement where there's no time taken for the user to actually get involved in touching the sample. So it's a continuous measurement with minimal, if any, operator intervention. So let me just sort of briefly describe the schematics of this approach and let me just see. Okay, so I. Can you see my mouse here at the moment? Nichelle?

Yes. Yes, you're fine.

So basically this is a thermogravimetric technique. So the first thing is that it has a microbalance. And this micro balance can measure very small mass changes. And we will resolve 0.1 microgram. So even if we got a 10 milligram sample, we can actually measure one part in a hundred thousand in terms of mass changes. So the small sample will go here and typically it's 10 to 50 milligrams, can be smaller if you want. And this is all maintained inside a constant temperature thermal environment. So the experiments are almost always done isothermally, unlike tga. So isothermal experiments, very small masses measuring mass changes. And the important part is that we are feeding, flowing over the sample, a continuous stream, typically of dry nitrogen or dry air if you want to, which we have added a known amount of water molecules. We are measuring the humidity of the gas going through the sample. So effectively we have full measurement of the system temperature, humidity and mass. And those are the primary things we're measuring for the samples that we're studying. So just explain a little bit more what goes on. So essentially we are measuring the sample. So the sample goes in here, where you're flowing humidified air. So when the water molecules interact with the solid, they will increase the sample mass, as you would expect. So what happens is as over time, I typically will increase the humidity in steps you can see here. And as the concentration of water molecule rises, I.e. the relative humidity rises, not surprisingly, the mass of the sample will rise as more and more water molecules are associated with the solid. So increasing humidity results in increase in mass. That's what we're going to be doing. So what happens is we do this experiment at different humidities for the same sample. Over time, we increase the humidity, as you can see in the blue steps. And the red step reflects the way the sample behaves. So at the start of the experiment, it's quite common to dry the sample to 0% humidity. When I dry the sample, there is a mass decrease. So the weight which is shown on the Y axis, decreases here. And as humidity goes up, so does the sample mass, as you would expect. And at the end of the experiment, I then would go down in humidity back to my starting point by looking at the mass, and particularly at the end of each step, the mass becomes constant, and then I step on to the next humidity. I can construct what we really want, which is the adsorption isotherm. And remember, the isotherm is simply a plot. Humidity on the x axis and sample mass on the Y axis. And it's taken from the data points from the isotherms. And I can do anywhere between 5 and typically 100 steps if I really want. So I can look at very small changes in humidity, or I can look at large ones, depending on the level of detail I want. So when I get the isotherm, I will typically get a part of the isomer which goes up in humidity, another part which comes down as a gap between the two, which is not uncommon, indeed is quite common, and that's called hysteresis isotherm hysteresis or adsorption disorption hysteresis, many materials will exhibit that. And that tells a bit more about the chemical state the water is in. So if there are pores or other complex structures, these hysteresis is a sign about that sort of material behavior. So this is sort of introduction to the watersorption technology we're going to be using. So let's have a look at some data. So the first thing I want to show you, we start looking at some information on some materials. So we're going to look at a range of materials. And the first example I've got you, I'm just showing the adsorption isotherms. I'm not showing the kinetics. We'll see some kinetics in a moment. This is what you get after you analyze the experiment versus time. So what you can see here on the actual X axis is the P of a pinhole, which is basically in Our case, the humidity. This is an experiment with water vapor done at 25 degrees on a solid piece of wood. So someone's cut a piece of sample just over about half a gram. We've run an experiment for a few days and then we measured the isotherm points and what you can see is this experiment went to 80% humidity, which is what the customer wanted. And at 80% humidity we had about, just under about 11% moisture content. So in other words, the mass of the sample when it was dry increased by 11% by the time that it went to 80% humidity. And then when I went to go down, it returns pretty well to zero. And you can see here there is some histories. There's a bit of difference between the adsorption and the desorption cycles. And that's probably a reflection of some of the porosity of the wooden material. So this is a solid chunk of wood, small cube if you like. And we were able to measure the adsorption isotherm for that material. So that's a typical piece of wood. We'll see in a moment that there are a few bits of information we can get from these experiments. Where is it? Okay, fine. So we'll see that the, there are some effects of particle size. If we would look at smaller particles, we get slightly faster equilibrium. We can get the isotherms and also the hysteresis shape will depend a little bit on the actual particle size that we use in our experiments. But just to show you that measuring properties of something like wood is quite an easy thing for us to do. So some other wood related products we'll have a look at now, some wheat straw. Okay. And that's a biomaterial used for a lot of applications these days. It's sometimes used as a bioadsorbent for wastewater treatment. It's sometimes used as a low cost reinforcement material for composites, and sometimes it's used as a biofuel derived from wheat. And one of the crucial steps in producing the bioethanol from wheat straw is the pre treatment. And that pretreatment is partially related to breaking up the crystalline domains inside the actual raw product, which in the end facilitate the conversion into biodiesel. As in many cellulosic products, crystalline domains, which are quite commonly present, are quite difficult to dissolve. If we can find a chemical way of breaking up the crystalline domains, we get more amorphous cellulosic products and they are easier to react with and form bioproducts from. So in this particular research project, the people we're working with were interested in doing a pre treatment which was to increase the chemical sites available for following bioreaction. And they're also interested in the fiber surface area and the hydrophilicity and the amorphous content. And remember, in this case, amorphous content means removing crystallinity. And that means better economic feasibility by being able to dissolve more and more material. So here's the first. Let's look at some experimental data. And this is the behavior of some raw wheat straw samples. Okay. And what you can see here, this experiment ran for about three days. The blue line you can see here, that's just the increases in humidity up to about 90% in this case. And the red lines relate to the mass increase. As you can see, this particular material took up about just over 25% water at 25 degrees. Okay? So, you know, it takes up quite a bit of water. So this is our sort of as received material. And from that data there, I can then determine my isotherm. This is the isotherm for the as received material. About 25% uptake. And there's some hysteresis in here as well, which is due to do with the the pore size or the actual crystallinity of the sample. So now we'll look at some other materials. These are type 2, type 3 isotherms. A low initial uptake and some higher uptake at high humidities. And later on, we'll talk about measuring BET surface areas of materials, which we can also do. If you don't know much about BET measurements, Just a little refresher here. When you're looking at adsorption isotherms on the surfaces, and I do distinguish between adsorption on the surface and adsorption where it dissolves. Historically, most adsorption science is focused on surface absorption. And if you're doing nitrogen, for example, which is a common way to measure surface area and sometimes porosity, then surface absorption is indeed what we have. And if we have surface absorption, we have these five classic isotherm types. And the type 2 isotherm is a particularly important one. Was we can then use the BET theory to actually work out the surface area, but only for surface absorption. For the some of the materials that we're looking at here, you can notice here how slow the kinetics are. This experiment took a few days. So what this tells us, because there are slow kinetics, this is not water molecules on the surface of the straw particles or fibers. Slow kinetic. These slow kinetics mean the water molecules are dissolving into the molecular structure, into the polymeric or biopolymer fibers here. So this is around diffusion into some semi crystalline structures, which is why we get these slow kinetics, so that the kinetics in their slow nature tells us this is a dissolution process, not a surface absorption process. Just to talk about BET just for a moment. If we do have experiments, and we do from time to time using other molecules, not always water, sometimes we use a molecules such as octane or nonane. These molecules often only absorb on the surface. We can then use the BET equation that you see here. And just to remind you, the PET model allows us to take an isotherm of the type that we see here on this type 2, and we can actually calculate the equivalent area of the material by knowing the monolayer equivalence point, which is basically a sub m here. Okay. And of course, if we want to measure BET using octane, for example, we can actually measure the surface area, particularly of low surface area materials. This is a pharmaceutical material which has quite a low surface area, typically less than a meter squared per gram. So if we're interested in surface areas for materials, these devious techniques can get us to that as well. Right, Let me get me back to our straw stuff. Okay. So we've looked at different straw materials, and some of them have two different pre treatments. Okay. One of them was extruded at 100 rpm with a 4% sodium hydroxide wash. And the other one had a pre washing and then a extrusion. So it's a washing and extrusion or an extrusion and we've got some raw samples. Okay. And if we want to know which it is, the W at the end means it had a pre wash. Okay. So here are the experimental data sets. Okay. And what we can see here is that the data effectively clumps into two sorts. We've got the sets down the bottom here, which represents two materials. The material that is washed, okay, the brown one is down here and actually our starting material is down here. So those materials have lower uptake, and lower uptake also corresponds to higher crystallinity. The ones that's interesting here is this one here, which is the pink and the green. That's the one that's had the. Didn't have a pre wash, but it did have the sodium hydroxide treatment. And you can see here how much higher the moisture content is. It's typically heading on towards three times higher. And what that tells us is that that material must have much higher amorphous content, that is less crystallinity so if we want to convert this material into biodiesel, where the crystalline domains will stop our process of dissolution, this is potentially quite important. So the pre treated sample had a much higher uptake, so that means it's got a higher amorphous content, therefore it's going to be more reactive. So decrease sea of crystallinity and more amorphous regions. This sample does not show the hysteresis. This is due to some swelling effects in the materials. So we can learn some interesting physiochemical problems can help us understand what's going on in our materials. So one question we sometimes get is rates and diffusion and permeability. And I'm just going to briefly introduce you to some things we can do around diffusion and permeability. So if we've got a film, in this case I'm talking about a polyamide film, we can take that film, we can directly hang it in the machine and we can do experiments where we increase the humidity. In this case we've increased the humidity from 0 to 20% and of course we get an increase in mass. And if we plot the mass at time infinity of the mass at time t and the square root of time, we get a very standard sort of diffusion analysis which allows us from the slope of this line to measure the diffusion constant. So if you're into diffusion in materials, in this case in thin films, if we know the thickness of the film, there's a very simple way we can determine the diffusion constants. And here are some diffusion constants at 20, 40 and 60% humidity for some polyamide films. And we can measure these, these are traditional units. And you can see here the diffusion constants. As we are going up here, the diffusion constants are changing with different humidities. The other thing we can do is sometimes that's when diffusion is, if you like, two sided. There are some cases where we don't want to do the experiment that way. We actually want to measure it in a slightly different fashion. And this is a effectively a single diffusion experiment. This is a slightly more accurate measurement in my experience. What we're going to do is we're going to take a small piece of polymer film and we're going to trap it between 2o rings here and underneath the sample. Inside here we're going to have a zeolite or an activated carbon that's going to act as a drying agent. So up here we're going to introduce some humidity. We've got our test specimen here and we're going to get water Vapor coming through the sample into here. And we're going to measure that in our machine. So this gets attached to the DVS machine and we can measure the diffusion rate through this film in quite a nice little experiment. So, okay, I think it's the next overhead, isn't it? Where is it? Yeah. So essentially we can measure diffusion rates through single film in a single film way or in a two film way. So lots of good ways that we can measure the diffusion constant into polymer films. If you're interested in polymeric materials, we can also do blister packs. Again, we can put a zeolite tablet inside the actual blister film. And in different humidities we can from the slopes of these lines here, we can determine diffusion constants, which again, for packaging or some other applications is quite important. So let me move for the next final 15 minutes. Let me move back to building materials. So obviously an important class of materials are cements. Cement are well known for their hydration reaction in terms of the way water reacts with these materials. And you can study the hydration reaction inside of dvs. You take some cement powder, you introduce some water vapor to that via the DVS. In this case, we're doing the experiment at 95% humidity. You can see these two different types of cements have very different kinetics and that relates to different chemistry of the hydration reactions. Two different classes of cements. So if you're developing cementous materials and you understand the hydration chemistry, devious can tell you about the kinetics and also how much water is taken up in your cements when you're actually forming them in their initial phase of production. So this is the second last topic I'm going to talk about really is a restoration project. This is some work done on a property where they're interested in understanding the materials in this building in terms of some flood damage they'd had. And they wanted to work out what sort of material to replace the materials in the original building. And they particularly understanding how much water would be taking up by the original bricks in this building versus other brick materials that they were looking. So it was a compatibility thing. We're replacing bricks in this property. What sort of bricks should we have that would be similar to the bricks that we're taking out? Because you want to make sure if you've got buildings that materials expand, contract in the same way and humidity is one of the driving forces for that. So we're looking at here basically some brick materials. Now, of course, you won't be surprised to discover that inorganic materials like bricks don't take up 30 or 40% water or not. Ideally their water uptake is much lower. So here is some of the original material. I don't know what the form it was, it might have been a brick powder, I'm not sure. But what you can see here is that this initial material took up about 1.2% water vapor. In other words, at 90% humidity, the brick material in the original building took up about 1.2%. The new material that they were planning to use for this refurbishment actually took up more water. You can see here it takes up 1.6%. And that, you know, that is by brick standards, that is still a much higher uptake and something that you might need to be careful about when you're designing your materials. So here you can see the isotherms. So the bricks used in the 18th century reconstruction, which is part of a 12th century structure, and the brick used 19th century for repair, have quite different watersorbing behaviors. And you need to keep an eye on that. That might have some implications for if you are putting those bricks together. That might be something. You have to keep an eye on that. But again, even for materials that have low uptake, the devious technique can be quite sensitive. The next application we've got here is a hemp straw. And the customer interested was also interested in looking at some of the materials used to bind hemp straw. And these include hemp lime. I'm not expert in these materials, but there was work published a few years ago using devious to characterize these sorts of biomaterials. And here we've got some basic adsorption isotherms for both the hemp itself, that's the blue curve. And you can see the hemp takes up to maybe 30% water vapor very slowly. So the kinetics imply the water is dissolving inside the hemp and the hemp, the lime based binder, which is called hemp lime, it binds together the fibers. And if by changing the amount of lime and hemp, you can vary the watersorption of the hemp lime, you can see this particular formulation of hemp lime actually absorbs quite a bit less water, about half the water that the actual hemp itself absorbs. So again, if you're trying to match compatibility these materials, understanding how much the hemp and the hemp lime was or the hemp credence caught here measures is quite important from the design of your materials perspective. And you can see here from the kinetics we saw in the previous graph we can measure the isotherms for both the hemp and also the hemp line very, very easily. So I'm drawing to a close now, and it's only been a very quick survey, but I have allowed a bit of time for you to ask questions. But essentially for really any sort of material, including building materials, we're able to determine watersorption properties of those materials. And that can tell us about hydrate formation, stability, morphology, manufacture, and aging. And there are many examples where understanding the performance of building materials, or indeed many materials, is important. And these properties can be measured quite easily and very quickly, relatively speaking, using these dynamic vapor sorbet instruments, which are a new tool which you can add to your armory of research tools when you're trying to understand how materials behave with their environment. So I think, you know, we've probably heard enough from me for today. I'll stop and I'll be happy to answer any questions you might have. And I thank you for your time and for your attention.

Thank you, Daryl. That was a great presentation. I've always enjoyed your presentations. Very clear, very informative. I hope your audience did, too. And I would like to open up for some questions. Now, if anybody has a question would like to ask yourself, please raise your hands and I can unmute you or.

Type it in the chat if you wish.

Yes.

Or if you want to contact us offline after the presentation, maybe it's not a question you want to share with your colleagues for a range of reasons. Be free to email Natal, who can contact me, and we'll be happy to talk to you offline if you turned out. If it turns out you prefer that. And as I said, we have studied over the years thousands of materials. So if you're wondering if we've studied the material, you've got ask us the chance that we probably have. Whether we know all about it, I don't know, but we've almost. We've characterized so many materials, I've nearly lost track. But we're happy to answer any questions around water interacting with materials.

Yeah, I can start with a question, darl, because usually this question gets asked in almost all our workshops. So the BET surface area is measured by dvs. Are they comparable with the nitrogen fibsoption technique?

Yeah, I mean. So let's talk about the BET measurements. There are a lot of people interested in BET analysis. As a general rule, we don't do BET analysis. BET analysis with water vapor, it's not a good molecule for that, but there are many molecules. We do. BET analysis was Most commonly methanol is quite popular and probably octane or cyclohexane. So if you use those sorts of molecules and you compare your results with nitrogen, you get very good comparison. I think the main benefit of the devious technique is our ability to do low surface area materials when you get to. And a lot of materials have low surface area. So if you've got very fine powders, nitrogen BT is really quite good. But once particles get above 10 microns and certainly about 50 microns, they tend to have very low surface area. So nitrogen BT actually for meter squares of less than 1 or 2 is not very accurate. Our experience at gravimetric techniques such as dvs as well as volumetric as well as chromatographic techniques such as IGC are much, much more accuracy. So for example, with igc, which you may hear about later on, we can measure surface areas down to 0.1 meters square per gram and less really easily and quite readily. And certainly comparability, the data is very, very comparable. If you take a reference material, such as a reference alumina sample under 1 meter squared, you'll get results within typically about 10%, which is probably as good as you get for any repeatability. And do remember of course that there are the reason the BET analysis is interesting using methanol octane is that that experiment is done at room temperature and room pressure. And actually that's what I would describe a much more realistic surface area. So it's all very nice to measure the surface area of your material 78 kelvin with nitrogen, but actually in the real world it's not a 78 Kelvin and in the real world it's not nitrogen, it's interacting with material. So doing the experiment at room temperature with an organic molecule, that's maybe more relevant to the process you're understanding just makes better sense. So you get in my view more realistic answers and they're very comparable with nitrogen results.

Great, thanks, Daryl. I have a question from Sebastian Gotts. Sebastian, would you like to. I'm just going to unmute you and you could ask the question yourself if you would like.

Go ahead, Sebastian. Hello, can you hear me? Yep, you're good to go. Okay, well, thank you for the presentation. It was very interesting. I was wondering if the equipment would have any possibility to combine with for example Raman or just microscopy to visualize what's happening. You've asked for my second lecture. If you've got another hour, I'll give you that. But the short answer is yes. We do a whole lot of work on hyphenation, the most popular one, the most popular things we do are microscopy. So as well as taking the mass measurements, we measure the samples using a microscopic video camera that has a. It's not like a high quality optical micro, but the field of view, it's more like a stereo micro. The field of view is typically 2 or 3 millimeters and we take pictures of the materials at that scale and we can look at swelling or color changes or cracking. So we do that regularly. We also can do near IR and Raman spectroscopy concurrently. And we have a lot of customers, often in the pharmaceutical industry who will take Raman and video and Devious simultaneously on the material. So in short, we do that regularly. And what we can do. I'll ask Natal to send you a specific presentation on that that you can have a look at offline. That would be great. Thank you. By the way, Sebastian, what sort of materials are you working on? Well, I'm now looking at salts, but that related to building materials. Salts in building materials. So as an effervescence and stuff like that? Yes.

Yeah.

I'm looking at the growth rates and blue ribbon sort of stuff. Excellent. Oh well, you could, you could. So potentially you could image the, the rate at which these materials recrystallize out in, in normally real time. So for what you want to do, potentially ideal. Okay, great. Thank you. Sure. Thank you.

Okay. Okay. So we don't have any more questions. Maybe we will get them later on. Please feel free to send us any questions later on if you have any question. If you want any application notes, any, please go to our website as well. You'll find loads of application notes and videos on YouTube. So please do get in touch if you have questions later on. I would like to thank Daryl again.

Thank you.

Contact if you have any questions. And I'll try and hang around later on, but I'll turn my camera, my mic off for the moment. Thank you.

Thank you. Thank you. Okay, so now I think we'll move on to our next presentation. The next presentation is going to be inverse gas chromatography for construction material applications. So our speaker is Maishan Goh Meihan is an application engineer. She obtained her master's degree in chemical engineering from Imperial College London. She joined SMS in 2018 and since the. And she has been working on surface characterization of solid state materials using both DVS and IGC techniques. So with that I would like to pass it over to Maishan for a presentation on IGC SDA technology.

Thank you Nacho for the introduction. I'M just going to share my screen. I hope you can see it. Yes, okay, perfect. So, hello everyone, I'm Mei Xian. And in my presentation I will talk about another vapor sorption technique also using molecules as a probe for the material characterization which is the inverse gas chromatography surface energy analyzer, the IGCSEA technique. So here's the outline of my presentation. We will first have a brief introduction about the principles and the instrument with the IGC measurement as well as some kind of common properties. We will use IGC to mirror and then we can go in details about the applications, especially in the building industries based different material, for example the fibers, the minerals and the polymers. So the principle of IGC was developed over 50 years ago to study the surface and bulk properties of particulate of fibrous material. However, until recently, most of the IGC studies were carried out based a home built system which is converted directly from the traditional GC instrument. And this will have a limitation in case of the reproducibility and accuracy. And the first commercial system using the IGC technique was developed by SMS over 10 years ago. And this is specially designed for the surface energy as well as the surface energy heterogeneity. And we can also measure some other physical chemistry properties like the heat absorption, glass transition solubility parameters and so on. And the principle of IGC technique is rather simple, just being opposite of the traditional gas chromatography. So for example, in the conventional GC experiment we will have a certain kind of solid as the stationary phase and then we will inject an unknown mixture of the gas compound through this solid phase and there will be different peaks showing up here and from the peak width and height. We can then get the quality and quantity information of the injected compound at very beginning here and in case of inverse gas chromatography. So this time we will pack the sample of interest into the column and there will be a single organic vapor through this column and only one peak will showing up as the result. And from the retention time and retention volume, we can then determine the physical chemical property of the solid compound solid sample inside the column here. So, some basic procedure to perform the IGC measurement. So we first need to pack a column with sample of interest. We need to select different probes for different interactions. The nonpolar probe for the dispersive surface energy and the polar probes for the specific interactions. We can then inject all the probe molecules at different concentrations. And from the detecting signal we can then calculate the solid properties, the surface property of the solid inside the column. And here is our IGC system with the instrument. So all the solvent inside the system will be injected directly from the gas phase. And we can totally put 12 solvent at the same time inside the reservoir, which is six on each side in this case. And the carry gas for the system could be helium or nitrogen. And in the front here, the blue item here is the column oven. And there will be two sample positions inside the system. That means we can load two samples at one time. And it will run the experiment in sequence. The temperature for the column oven is from 20 to 150 degree. And the detector for the system is the FID detector, which is very sensitive for the organic vapors. And the system is also equivalent with hydrogen or organic vapor leak detector, which means it's very safe for the operation during the experiment, if there is any leak, it will stop automatically. And the system can also be equipped with some background humidity controller which allow you to run the experiment with the humidity background. And this will allow you to study the impact of humidity on the surface property, like for example, the surface area or the surface energy. How does the water will compete with the size on the surface. And here are some of the sample we measured before with our IGC system. So we can measure some powder sample, like pharmaceutical powder or active carbon. Or we can also measure some fiber sample, like high fiber, cotton fiber or carbon fiber. And we also have another accessory which is an external accessory to put on the bench outside this instrument, which is a film cell. Allow you to put some film or the plate sample in the middle of the film cell. And one side of the film will be exposed to the vapor molecule. So in this case you can start either coating on this plate or the surface property of the film sample itself. But in case of the film cell, it's not controlled by the oven in the system. So the temperature for the film or the experiments will be the room temperature or the temperature in the lab. And for the sample preparation for the experiment, it's rather simple. Here is our column. We just need to put the sample simply into the column. For the fiber sample, we just put it straight in the column. And for the powder sample, we can use some glass wool to stop the powder inside the column. And we also have a YouTube video just showing how easy to preparation the sample before the experiment. Typically just use about five minutes for sample preparation. And we have different size of column for different samples. For example, we can use the powder sample with the 2 or 3 millimeter column. And we can put the fiber sample inside the 4 millimeter column. And the larger column is especially designed for some for example, the tablet with some coating. And we want to study the coating of the tablet, we don't want to break the sample. Then we just need to put the tablet in our 10 millimeter column and we can study the coating effect or the surface property of the coating with the sample itself. And here are some of the property can be measured with the IGC technique. For example, we can use different polar molecules and non polar molecule. Then we can determine different components of the surface energy as well as different levels of the size on the surface energy. The heterogeneity mapping on surface. We can also calculate the assay base property with the polar molecules giving the K and KB values. And with the organic vapors we can determine the sorption isotherm. And from the isotherm we can also determine the BET surface area of the solid material. And with the surface energy we can also calculate the work of cohesion and adhesion, which is rather important in the formulation development that you can determine the affinity between each other or how does the sample will blend in with other materials. And two of the most common parameters we can measure with IGC is the surface area and surface energy. Then first for the surface area we have different methods for the BET determination. For example, the most common method can be the volumetric method with nitrogen sorption, which is quite accurate for the POWASS material. But it will have a kind of limitation. In case of some low surface area material, the measurement will have a large variation in the result. An IGCD technique is especially accurate in case of the low surface area material. And we can measure as low as 0.1 square meter per gram. Still with very good reproducibility. And the most difference between two methods, the volumetric one and the IGC technique is the condition of performing the experiment. So with the volumetric method we need to use nitrogen at liquid nitrogen temperature and also degassing the sample at vacuum condition. And in this case some of the sample may already change the structure, especially for some free gel or citizen material, it will lose the hydration water along with the sample at the dry condition as well as it will collapse in case of the extreme conditions. And with the IGC method we will perform the experiment at room temperature as well as ambient pressure, which keeps the original nature of the sample without any net damage. So the merit value from the IGC technique is more accurate in this case compared to the volumetric technique. And another limitation for the nitrogen absorption is with the small surface area material, it will give a very large variation. In this case, we need to use Kraton as the probe molecule rather than the nitrogen. And with the IGC method we will perform with the organic vapors and we can determine as low as 0.1. Still with 1% RSD values. That means IGC is more accurate, especially for the low surface area materials. And here's an example with a kind of pharmaceutical powder, the paracetamol. We did 10 different rounds of BET measurement on the same column, and we get the values between 0.27 to 0.28 square meter per gram. Still with the RSV less than 2%, just showing the excellent reproducibility of the IGC measurement. We also performed some other measurements with the commercial samples, the CRM170, which has a reported value about 1.05 square meter per gram. And the IGC measurement we get about 1.01 square meter per gram, just showing a very good consistent with the commercial samples. And as I mentioned, we can also equip the background humidity controller inside the system, which means we can study the impact of humidity on the surface property. So, for example, here the sample is the Alpha Alumina 171 sample. The surface area at dry condition is reported as 2.95 square meter per gram. And then we perform the same experiment at different humidity. And as you can see, at 90% RH, the surface area of this sample is only 1.5 square meter per gram. It's dropping to half of the value at the dry condition, which is because the water molecule will compete the size on surface and also blocking the surface for the organic vapors. So that means in the real application of the product, maybe at the humidity condition, the surface area of the product is not the same as the dry condition that you measured with the volumetric technique. And IGC in this case can give you an idea about what the surface area will change with the humidity conditions outside in the applications. So that's all about the surface area. And the next important parameter is the surface energy. Surface energy is a kind of property for the solid material, very similar to the surface tension of the liquid material. It will quantify the surface to react compared to the bulk of the material. And according to Falk's theory, there are two different components of surface energy. The dispersive components only for the wonder waltz interaction and the specific component called for the other chemical interaction, like the hydrogen bonding dipole dipole interactions. And with the IGC technique, we can perform the different Components of surface energy by different solar polar molecules and non polar molecules. For example, we can use the N alkanes, at least three of them, like heptane, hexane, octane, nonin, for the dispersive component on the surface energy. And then we can use two monofunctional polar solvents for the specific component. For example, the dichromethane, ethyl acetate, toluene, chloroform. And the sum of two components gives the total surface energy of the solid material. And there are many different parameters are related to surface energy. For example, the sample with higher surface energy is easier to get wet. Or the powder with higher surface energy has a higher tendency to aggregate because it's more active and it will react with itself. And if you create more effect size on the surface, the surface energy will go higher as well, as the heterogeneity on the surface will go broader as well. And if the sample has higher surface energy, it's also considered as better affinity with other sample as well. So with the surface energy, we can easily predict those kind of different properties of the solid material, how it will interact with each other, or it will interact with other components. So the application, the first one is for the surface treatment, as I mentioned, surface energy is related to other properties. Then we can change the surface energy by the surface treatment for a higher or a lower value. And the first start is on our demanito, which is a kind of pharmaceutical expense. And we also use the demonitor as our reference material for the system calibration. And here we have the untreated dementor. And we also did the salinization process on the D magnitude. We measured the surface energy of both two different magnitude samples. And here shows the blue line is for the surface energy of the untreated demagnetode. And as you can see, the surface energy on the red axle is changing as a function of the surface coverage. That means on the untreated D manacle there are different levels of energy size. On the surface. It has both high energy size as well as low energy size. The sample is a very heterogeneous sample on the surfaces. And in case of the selenized D manito, which is the right line here. So this time, as you can see, the energy on the surface is almost the same level of energy. So all the sides on the selenized D manitole becomes the same level of energy because of the same functional group on the surface. That means after salinization, the surface energy becomes lower compared to the untreated Magnitude as well as the sample becomes more homogeneous and more uniform with the selenization process. And this is the surface energy profile for both of the material. We can also do the point by point integration of the surface energy profile. And this will give us the distribution profile for the surface energy. So on the x axis of the distribution gives the surface energy values. And to interpret the distribution, the wider on the x axis, the wider gap for the peaks, that means the sample is more heterogeneous. And in this case, the untreated D mantle is much wider compared to the selenized D mantle, which is much uniform or more homogeneous compared to the untreated one. So the untreated Manito is much more heterogeneous compared to the selenized one. And the surface of selenized Manito is the same level of energy. Also indicating that the coating of the magneto is a complete precise that all the surface is coated with the same functional group. And this can also indicate the completion of the coating process on the sample or the surface treatment on the sample. And the next example with some carbon fibers that we have the size carbon fiber and unsized carbon fiber here. So the sizing is just the same kind of coating per size. In case of the fiber industry and igc here we can measure the surface energy heterogeneity of these fibers to determine the effect of the surface treatment as well as the conditioning temperature on those fiber samples. So here's the result of four different carbon fibers. And as you can see, the red line and the pink line for the unsized carbon fiber is much higher in the surface energy as well as it's very much with the coverage of surface, it has both high energy site and low energy size. That means the unsized carbon fiber is very heterogeneous in the nature. And in case of size carbon fiber, after applying the sizing agent, the surface energy for both of the carbon fiber, which is the yellow and the blue line here is passivated surface with the sizing agent as well as the sample becomes more homogeneous that the surface energy on the samples are almost the same level of energy. So the size carbon fiber are more homogeneous compared to the unsized carbon fiber. And in case of the conditioning temperature, the higher temperature, which is the right line here for 120 degree compared to the pink line here for 30 degree. So higher temperature will activate the size on the surface and remove all the contaminants on the surface that result in a higher surface energy compared to the lower temperature. The pink one Here and in case of the size carbon fiber, the two temperature plots are almost the same with each other just overlapping on the plot here. That means this kind of sizing agent is behaving as a kind of protection layer that will protect the temperature effect on this carbon fiber. And here just show you IGC can be used to determine those kind of siding effect as well as the temperature effect on the carbon fibers. And we also have another kind of case study also related to carbon fiber. And this time we apply the oxidization agent as well as the sizing agent. We want to compare the assay based property of those carbon fibers. So we use different polar molecules to determine the KAKB value on the surface. So the last column here is for the unsized carbon fiber. And as you can see, the KB value is much higher than the K value. That means the sample is more basic in the nature. There is more electron donating group on the surface. And after the oxidization, which is the 1 and 2 column here, the K value becomes higher than the KB value. That means the sample is changing to acidic nature. After the oxidization there are more electron accepting group on the surface. And the middle column is after sizing with oxidization. So the sizing agent just reduce this kind of acidity on the surface. With the cytoin agent and with the assay based properties, we can easily predict the chemical the surface chemistry on the surface with the K and KB values. And this is also something we can do with the IGC measurement. The next example we have the nitrous and synthesized fibers. And we want to measure the BET surface area of different kind of fibers. So here we have three different fibers. The synthesized cellulose fiber, the biomete sample. And we also have two fast fiber, the Kinect fiber and the flax fiber. And here we have the SEM images of all three fibers. And as you can see, the biomid sample and the kinep sample are quite neat and clean on the surface. It's very smooth on the surface. But for the flex fiber, there are some small fragments of the cuticles on the surface which make the surface of the flex fiber more rough. It's not very smooth as the others. And then we pack the fibers inside our column and we measure the surface area based the same column repeating for three different times. So here shows the standard deviation of all three different times is less than 5%. Just means the experiment to experiment reproducibility for the IGC measurement is quite excellent. And the surface area for the first two fiber, the BioMed fiber and kidnapped fiber is about 0.5 square meter per gram. And the surface area for the flex fiber is three times larger than the previous two. And this large surface area compared to the previous can be related to the surface roughness as we seen in the previous SEM image, it has more cuticles on the surface and it's not as clean as neat as the others. And this is the result within the same column. We can then pack different columns with the same sample. And we want to measure the surface area of different batches. So here shows the two natural fiber, the flax fiber and kinnaf fiber have much higher batch to batch variation compared to the biomete fiber which is a kind of synthesized fiber. And this is expected as the natural fiber have irregular structures as well as the heterogeneous properties on the surface, while the synthesized fiber are more uniform and homogeneous in the nature. So this study just demonstrates the potential of IGC for the characterization of nitrofibers. And also we can narrow the batch to batch variation because IGC has a very high sensitivity. And this study is published by Dr. Lagras and Dr. Kwonda. And here's the reference paper. You can have a look in detail later if you are interested. So the previous application are all related to surface treatment. We can also use IGC for deformulation study of different multi component system. So in case of the multi component system, for example the x pin and the drug, or the polymer and the matrix, the polymer matrix and the filler, the interaction between different components is very important to the quality of this composite material. And with the IGES technique we can measure the surface energy individually for different components. And then we can calculate the work of cohesion and work of adhesion between different material with the surface energy dispersive one and specific component of different materials. So the work of adhesion is between different components is the affinity of different components between each other. And the work of cohesion is within the same material, the aggregation or the sticky of the one component to itself. So the higher work of cohesion that means the higher tendency to aggregate for the sample inside the composite material. And the first story we have here is about the minerals in the asphalt. That aspect is a kind of building material consisting of the minerals and the binder. And the quality of this aspect depends on the interaction between the minerals and the binder. And in practice it's observed that different minerals will give different affinities with the same binder. So we can use IGC here to study this kind of affinity between different minerals and the binder to improve the formulation design for the final aspect material. And here we have four different materials, the pure coarse sample and the coarse sand sample. The calcite sand sample and potassium feldspar sample. And here we find the sample. The two mineral in the middle here has very good affinity with the binder. And the pure coarse sample has the worst affinity with the binder. Then we perform the same IGC experiment for all four different samples at 50 degree, with the preconditioning at 150 degree to remove the moisture for two hours. And first for the result of the dispersive surface energy. So we find the surface energy of the two samples in the middle here with the best affinity with the BENDER has the strongest dispersive surface energy compared to the other two samples. And this suggests that the dispersive surface energy is a very good indicator for the affinity. And this affinity is related to the adhesion between mineral and the binder and further evolving to the quality of the aspect. So we can see the sample with higher surface energy may give a better quality in the final aspect material. And in case of the specific free energy, which is the interaction between the polar molecules. So all the mineral material have a very strong interaction with ethyl acetate and one butanol. And this indicates the hydrophilic character of all the mineral samples. And in case of the calcification calcite sand sample and 5 spar sample, it has the strongest interaction with the 1 butanol, which is a kind of Lewis acid solvent. That means those two samples has a basic character compared to the other minerals. And in case of the coarse sand sample, it has the strongest interaction with the Lewis base solvent, which is the ethyl acetate. That means this kind of sample shows slightly acidic character compared to the other solvent. So with this result we can then calculate the acid base constant of the solid material, the KEKB value as we shown for the carbon fiber sample. And this will tell us about the surface chemistry of the mineral. And we can also choose which mineral has the best affinity with the binder, leading to the final product, the best quality of the final product. And the last case study I'd like to show here is about the nano fillers with the polymer matrix, which is related to the adhesion study. So here we have four different kind of fillers. The untreated nanotube, the treated nanotube, the untreated nanoclay and the treated nanoclay. And the polyurethane is using as the polymer matrix to get the best filler among four of them. Which two has the best affinity with the polymer matrix. So we use the IGC method to measure the surface energy of all five different components. And here shows the untreated nanoclay sample and the treated nanotube sample has the highest dispersive surface energy compared to the other samples. And then we can use the dispersive and the specific surface energy to calculate the work of cohesion and adhesion with those two equations. And here shows that the adhesion to cohesion ratio, the untreated nanotube sample has the highest work of adhesion to cohesion ratio as well as the treated nano clay sample. So from the IGC result we can easily predict that we think the untreated nanotube sample and the treated nanoplate sample may have a better affinity with the final polymer matrix in the final composite material. So these are just our prediction before we finally making the composite. It's kind of pre formulation stage that we make the consumption with the IDC result. And here is the final products. And we merrill some other kind of property like tensile strength with some other technique. And we find that the untreated nano tube sample and the treated nano clay sample has the better mechanical performance compared to the other fillers. It just have a very good consistent with our prediction that we also think the untreated nanotube and the treated nanoclay will have a better adhesion with the polymer matrix. So that means we can use IGC to predict those kind of mechanical performance in the formulation design to choose which kind of filler has the best affinity with the matrix sample. So that's all for my presentation. And IGC is just a very sensitive and versatile tool to determine those kind of surface properties. And apart from surface area and surface energy, it can also determine the hands and solubility parameter, the glass transition, humidity and temperature, as well as some other properties. And I hope you will find IGC useful in your future research. And that's all for my presentation. Here's the reference list. Just thank you for listening and let me know if you have any questions. Thank you.

Thank you, Meishan. Another great presentation. I'm going to open up for questions now, so anybody with any questions, please do type in or raise your hand. A quick question for you. So can we also measure semi solid samples, like you know, like viscous samples, sars for example.

Sorry, Nacho, could you repeat that?

Can we also using this technique, measure semi solid, semi solid samples, viscous samples maybe?

Yeah, of course, no problem. We measure Some kind of viscous sample, like some binder, as well as some viscous oil sample. We just simply to put some glass wool in the column to stop the liquid flowing inside the system. Or we can use some glass beads to dip inside the liquid sample and then put it in the column. We did some kind of measurement before, so there's no problem to measure those kind of samples.

Thank you. I'm just going to wait for a few more minutes. If any questions, wait for that. And I think we do have time. So we have a few demo videos prepared to show. It will be more of a practical overview of what TVS looks like, how you can put samples and how you can analyze the data. Similarly, for igc, we do have a video showing how you can start an external experiment. I think that's more important than theory, than, you know, really how it looks like, what you can do, really, with the systems. So we do have those videos. So please do wait. I'll just give a couple of more moments for anybody to ask any questions and then we can go to the videos.

I'm happy if anybody thought of a DVS question they want to ask now before I leave, I'd be happy to answer them. Otherwise, thank you, everyone for attending. And to follow up if you have any questions or maybe you've got samples you think might value from some DBs or IGC investigations.

Thank you. Thank you, Daryl, for your time today.

No problem. Happy to help out. In which case I don't put their hand up, that I can tell, which probably means I might go to my next meeting. Okay, thanks, everybody, and thanks for participating in today's webinar. Take care. Bye.

Bye.

Thank you. Thank you. Okay, I think. Thank you, Mason. I would like to thank you again. And we'll move to our last part of the session. We'll just, you know, have some videos. And I would just like to let you know, in case you cannot hear the sound from the video, please do remove your headphones if you're using them. Because for some reason I've tried with the headphones on the Gotowebinar play the sound from the video. So if you're having trouble listening to it, please do remove the headphones and try. So we'll go with a first video on dvs. John, do we have the video ready or should we wait a couple more minutes?

We should be ready. It's just loading now.

Great.

Thank you, John. Thank you for that. So, yes, so we're at the end of the workshop today. We're a little bit early, but but I think it's good. So if you have any questions, please do get in touch. I will be sending you the presentations from today, and also a few application notes that would be relevant. And if you have if you have any samples that you would like to test, do a demonstration, please feel free to get in touch with me and we can arrange testing, sample testing. And if you need any other application notes, publications, please do visit our website. We do run webinars and workshops very often, so please go to the website if you need anything you can download for yourself, or you can let me know and I can send you the documents. That's all for today. Thank you everyone for attending the workshop. I hope it was useful in some way, and thank you very much. Bye and take care. Stay safe.