Name: artificial thermal ageing of polyester reinforced and polyvinyl chloride coated technical fabric
Uploaded: 2020-01-29T15:00:00.000+00:00
Duration: 7 min 48 s
Description: Watch this Scientific Journal Video about Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric at JoVE.com

The publication of this work was supported by the Faculty of Civil and Environmental Engineering at Gdansk University of Technology.

1. Accelerated thermal ageing experiments on technical fabric
<ol>
	<li>Overall preparation
	<ol>
		<li>Prepare a testing machine with proper software (in order to provide constant strain rate tests) and a video extensometer.</li>
		<li>Prepare a thermal chamber providing constant temperature of 80 &#176;C (&#177; 1 &#176;C) and 90 &#176;C (&#177;1 &#176;C) for at least 12 weeks.</li>
	</ol>
	</li>
	<li>Specimen preparation
	<ol>
		<li>Unroll the technical fabric AF9032 bale. Draw the desired shapes (300 mm x 50 mm) with a soft pencil or marker on the fabric surface parallel to the warp or fill direction. 
		NOTE: The distribution of specimens on the fabric surface is given elsewhere17.</li>
		<li>Indicate the warp direction on each specimen with a permanent marker. Cut the specimens with a sharp knife or scissors. Use the ruler if a knife is used for cutting. 
		NOTE: The specimens should be rectangular17. The major load-caring elements of the fabric are threads. In the operational phase, the coating material usually exceeds its yield limit, thus not taking part in the stress distribution. The only elements to carry the load are threads spreading from one grip to another. Therefore, it is not reasonable to use sophisticated shapes of specimens (e.g., a dumbbell shape usually used for metals). On the other hand, such sample shapes result in the need for special grips when the ultimate load is investigated, or the use of an extensometer in order to assess material parameters.</li>
		<li>Measure the specimen&#39;s thickness with a slide caliper and count the number of threads at the short edge of the specimen. 
		NOTE: For each specimen, take three thickness measurements, and compute the average value. Use the magnifying glass to assess the number of threads if necessary.</li>
	</ol>
	</li>
	<li>Turn on the thermal chamber, leaving the door open. Using the buttons and the control display, select the temperature (80 &#176;C). Close the thermal chamber door and observe the increase of temperature on the control panel.</li>
	<li>Specimen warming
	<ol>
		<li>When the temperature is close to 80 &#176;C, open the thermal chamber door. Insert at least 7 sets of specimens with each set consisting of 6 specimens cut in the warp direction and 6 in the fill direction. Close the door as soon as possible in order to avoid a temperature drop. 
		NOTE: The experiments should be conducted for three strain rates. For each strain rate, experiments are performed on two specimens in the warp direction and two in the fill direction. Place excess specimens in the chamber in case the experiments are not successful or the results from both tests are highly divergent.</li>
		<li>After 1 h, don thermal gloves and remove the first set of specimens (the reference set; 6 specimens in the warp direction and 6 in the fill direction). After every 2 weeks, remove a succeeding set of specimens from the thermal chamber. 
		NOTE: The entire warming process will take 12 weeks.</li>
	</ol>
	</li>
	<li>Specimen conditioning
	<ol>
		<li>Leave the specimens at room temperature for one week. Cool the specimens to room temperature (i.e., their properties should be stabilized).</li>
		<li>Before the test, draw two black marks (dots) using a permanent marker with a lengthwise separation of about 50 mm (L0) in the middle of each specimen. 
		NOTE: The dots will be used by the video extensometer.</li>
	</ol>
	</li>
	<li>Testing machine setup
	<ol>
		<li>Install four 60 mm flat inserts into the testing machine, two inserts per one grip. The inserts show a fish scale surface type and are used to avoid slipping the specimens out of the grips.</li>
		<li>Switch on the machine. Start the software (e.g., TestXpert) that controls the machine. Choose the program dedicated to the tensile tests.</li>
		<li>Select the starting position with a 200 mm grip to grip separation in the software. Click the Starting Position button to execute the 200 mm grip to grip separation. This grip position is usually called the starting position for a test. 
		NOTE: The 200 mm distance is required by the ISO standard17.</li>
	</ol>
	</li>
	<li>Video extensometer setup
	<ol>
		<li>Move the camera of the video extensometer along the supporting bar to situate the lens of the camera at the level of the middle part of the specimen. Check whether the lens of the camera provides a clear view of the specimen markers during the whole experiment. 
		NOTE: Perform a similar test before the main test to establish the probable sample elongation range to ensure that the camera will follow the black markers during an entire test.</li>
		<li>Select the proper brightness and focus for the lens using the computer screen and the associated software.</li>
	</ol>
	</li>
	<li>Video extensometer calibration 
	NOTE: The calibration device is the standard equipment of the video extensometer.
	<ol>
		<li>Put the calibration device in the front of the camera and clamp it with the grips.</li>
		<li>Using the video extensometer software (e.g., VideoXtens), select the proper type of markers in the Targets window (usually black and white).</li>
		<li>Select the calibration procedure in the video extensometer software using the Scale option and choose the calibration distance in the Scale window. 
		NOTE: The distance should be similar to the separation of markers on the specimens. The calibration device offers three measuring distances: 10, 15 and 40 mm. Due to the 50 mm marker separation, the 40 mm distance is appropriate.</li>
		<li>After calibration, change the marker type to Pattern in the Targets window. 
		NOTE: This enables the video extensometer to follow the markers indicated on the specimen.</li>
	</ol>
	</li>
	<li>Test performance
	<ol>
		<li>Prepare the test parameters in the TextXpert software. 
		NOTE: The prepared program must enable a test with a selected strain rate in the uniaxial stress case. It must be correlated with the video extensometer. The recorded parameters are the initial distance of the extensometer markers (L0), and result functions of time, grip displacements, current extensometer&#39;s markers distance, and force. The pre-load force of 50 N17 is programmed and the L0 distance is adjusted after preloading.</li>
		<li>Put the specimen along the machine main vertical axis and close the grips using the tubular spanner. 
		NOTE: The specimen must be located symmetrically to the grips in the vertical and horizontal directions.</li>
		<li>Perform the tests with the selected constant strain rate until the specimens break (use 0.005, 0.001, and 0.0001 s-1 strain rates). For each strain rate, test at least two specimens in the warp direction and fill direction. Save the test results. 
		NOTE: The following data are necessary: the initial distance of the extensometer markers (L0), time functions of the extensometer&#39;s marker distance, and the force.</li>
	</ol>
	</li>
	<li>Repeat steps 1.5&#8722;1.9 every two weeks using the other sets of samples (six times, up to 12 weeks).</li>
	<li>Repeat the entire procedure at 90 &#176;C. The total number of specimens does not change. The ageing process lasts 6 weeks. Remove and test subsequent sets of specimens every week.</li>
</ol>
2. Data preparation
<ol>
	<li>Knowing the cross section area of the samples, use graphing software (SigmaPlot18 or similar) to recalculate the registered force and elongation increments according to elementary strength of material equations to the stress-strain relations. Plot a graph of obtained data, separately, for the warp and fill samples and for each of the strain rates.</li>
	<li>Repeat for the 80 &#176;C and 90 &#176;C results.</li>
</ol>
3. Parameter identification of material models
<ol>
	<li>Piecewise linear model for non-linear elastic modeling 
	NOTE: The application of the piecewise linear material model is possible when the stress-strain curve can be split into sections of linear (or approximately linear) shapes. Particular crossing points of the lines at neighboring sections correspond to applicability ranges of the related lines19.
	<ol>
		<li>In the case of every curve obtained in step 2.1, find the strain ranges, detecting the linear or close to linear stress-strain relation.</li>
		<li>Using the fit regression option in the graphing software and the least square method, identify the best-fit line in the chosen region. 
		NOTE: The tangent to this curve corresponds to the stiffness of the material in a particular range.</li>
		<li>Denote the tangent as Eij where the index i corresponds to the current direction of the material (W for the warp direction and F for the fill direction) and the index j is a consecutive number of the identified line.</li>
		<li>Having parameters of all the lines, find the intersection points between the lines; denote them as &#949;k/l, where k and l mark the crossing lines. 
		NOTE: These points (&#949;k/l) constitute the strain ranges to apply the particular longitudinal stiffness values (Eij) (Figure 1).</li>
	</ol>
	</li>
	<li>Bodner&#8211;Partom viscoplastic model 
	NOTE: The Bodner&#8211;Partom constitutive law is used to reflect the elasto-viscoplastic behavior of various materials20,21. The basics and mathematical formulation of the model is given in detail elsewhere20,21,22,23,24,25. The elementary equations are presented in Table 1 only to model the uniaxial stress state. The Bodner&#8211;Partom model parameters are identified by means of the uniaxial tensile tests conducted with at least three different strain rates. The value of the strain rate must be constant at least in the inelastic part of the experiment. The complete Bodner&#8211;Partom model identification procedure modified for technical woven fabrics is widely presented24,25.
	<ol>
		<li>Using the graphing software, identify Bodner&#8211;Partom model parameters following Klosowski et al.24.</li>
	</ol>
	</li>
</ol>
4. Arrhenius extrapolation
NOTE: The Arrhenius law is based on an empirical observation that ambient temperature increase results in acceleration of a number of chemical reactions that may speed up the ageing process as well. The complete mathematical representation of the Arrhenius chemical reaction concept can be found elsewhere11,26. The Arrhenius law in a simplified form is called &#34;the 10 degree rule&#34;27. According to this rule, a surrounding temperature increase of about 10 &#176;C theoretically doubles the rate of the aging process. Hence, the reaction rate f is defined as follows17:
<img alt="Equation 1" src="/files/ftp_upload/60737/60737equ07.jpg" />
where &#916;T = T - Tref is the difference between the ageing temperature T and the service temperature Tref of a material.
<ol>
	<li>Assume the temperature Tref according to the average value based on the results of the local meteorological station (here, Tref = 8 &#176;C28). Assume the thermal chamber temperature T to be used in the ageing test (here, 80 &#176;C and 90 &#176;C). 
	NOTE: The temperature level should be registered for a longer time period, at least one year, and then calculated as the mean value of that period, bringing a time average of this period taken as Tref.</li>
	<li>Calculate the reaction rate constant f from equation 1 and then extrapolate the ageing time (expressed in weeks) to years (Table 2). 
	NOTE: The extrapolation effects of different ageing time periods conducted within the current research are presented in Table 3. For instance, thermal ageing of a specimen in 4 weeks at 90 &#176;C is equal to its ageing in 8 weeks at 80 &#176;C and corresponds to a natural ageing of approximately 23 years.</li>
</ol>
5. Data representation
<ol>
	<li>Present the obtained parameter values in the normalized form of X/X0, where X denotes a current value of the certain parameter and X0 corresponds to the initial value of this parameter, with regard to a specimen aged 1 hour only. 
	NOTE: The time of artificial thermal ageing is set up in hours.</li>
	<li>Plot X/X0 values on the Y axis versus the ageing time plotted on the X axis to show the evolution of the parameters. Prepare plots for the warp and fill directions of the tested material separately.</li>
	<li>Describe the parameter values plotted over time by linear functions (or different best-fit functions) using the least square method and report R2 values.</li>
	<li>To evaluate whether the Arrhenius simplified relation is correct for AF9032 fabric, redraw the results obtained for 90 &#176;C with respect to the ageing time recalculated into &#34;real&#34; time according to the Arrhenius law.</li>
</ol>

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The authors have nothing to disclose.

This article incudes a detailed experimental protocol to simulate the laboratory accelerated experiments on polyester reinforced and PVC coated fabrics for civil engineering applications. The protocol describes the case of artificial thermal ageing only by the means of raising the ambient temperature. This is an obvious simplification of real weather conditions, as UV radiation and water influence play an additional role in material service ageing.
Generally, the conditions of accelerated agei...

Polyester based architectural fabrics are commonly used for construction of hanging roofs1. Being relatively cheap with good mechanical properties, they can be employed in long-term exploitation (e.g., the hanging roof of the Forest Opera in Sopot - Poland). Unfortunately, weather conditions, ultraviolet radiation, biological reasons, and operational purposes (season pre-stressing and loosening2) can affect their mechanical properties. Hanging roofs made of AF9032 are typically seasonal structures subjected to high temperature (especially during sunny days in the summer), regular pre-tensioning and loosening. In order to properly design a hanging roof, fabric parameters must be determined not only at the beginning of exploitation, but also after several years of use.
Ageing analysis measures the ageing indicator and compares the initial and final values of the parameters to assess the impact of ageing. Cash et al.3 proposed one of the simplest methods by comparative analysis of 12 different types of roofing membranes. These membranes were exposed to outdoor weathering for 2 or 4 years. The authors used a rating system of several properties to assess fabric durability. In order to provide an analysis of polymer thermal ageing, the time-temperature superposition principle (TTSP) can be applied4. This principle states that the behavior of a material at low temperature and under low strain level resembles its behavior at high temperature and high strain level. The simple multiplicative factor can be used to relate the current temperature properties with the properties at the reference temperature. Graphically, it corresponds to the curve shift on the log time scale. Regarding the temperature, two methods are proposed to combine the shift factor and the ageing temperature: the Williams-Landel-Ferry (WLF) equations, and the Arrhenius law. Both methods are included in the Swedish standard ISO 113465 to estimate the lifetime and maximum operational temperature for rubber, or vulcanized and thermoplastic, materials. Recently, thermal ageing and Arrhenius methodology have been used in the cable lifetime prediction6,7, heating pipes8, and polymer glue PMMA4. An extension of the Arrhenius law is the Eyring law that takes into account other ageing factors (e.g., voltage, pressure, etc.)9. Alternatively, other studies propose and verify simple linear models for a description of ageing (e.g., biosensor ageing10). Although the Arrhenius method is commonly used, there is discussion on its relevance in the lifetime prediction of every material. Hence, the method must be used with care, especially in terms of initial assumptions and experimental conditions6.
Similar to most polymers, the polyester fabrics used in the current research exhibit two distinct transition phases defined by the melting temperature (Tm) and the glass transition temperature (Tg). The melting temperature (Tm) is the temperature when a material changes from its solid state to the liquid one, and the glass transition temperature (Tg) is the boundary between the glass and rubber states11. According to manufacturer&#39;s data, the AF9032 fabric is made from polyester threads (Tg = 100&#8722;180 &#176;C12, Tm = 250&#8722;290 &#176;C13) and PVC coating (Tg = 80&#8722;87 &#176;C14,15, Tm = 160&#8722;260 &#176;C16). The ageing temperature T&#945; should be selected below Tg. During sunny days, the temperature on the top surface of a hanging roof may even reach 90 &#176;C; thus, two ageing temperatures (80 &#176;C and 90 &#176;C) are tested here. These temperatures are below the thread Tg and close to the coating Tg.
The performance of the accelerated ageing protocol on technical fabrics is presented in the current work. Artificial thermal ageing is used to predict changes of the material properties. The article illustrates appropriate laboratory testing routines and a way to extrapolate relatively short-term experimental results.

<table><tbody><tr><td>AF 9032 technical fabric</td><td>Shelter-Rite Seaman Corporation</td><td></td><td></td></tr><tr><td>knife of scisors</td><td></td><td></td><td></td></tr><tr><td>marker</td><td></td><td></td><td>pernament</td></tr><tr><td>ruler</td><td></td><td></td><td></td></tr><tr><td>Sigma Plot</td><td>Systat Software Inc.</td><td>v. 12.5</td><td></td></tr><tr><td>Testing machine Z020</td><td>Zwick Roell</td><td>BT1-FR020TN.A50</td><td></td></tr><tr><td>TestXpert II program</td><td>Zwick Roell</td><td>v. 3.50</td><td></td></tr><tr><td>Thermal chamber</td><td>Eurotherm Controls</td><td>2408</td><td></td></tr><tr><td>tubular spanner</td><td></td><td></td><td>13 mm</td></tr><tr><td>Video extensometer</td><td>Zwick Roell</td><td>BTC-EXVIDEO.PAC.3.2.EN</td><td>Instead of video extensometer, a mechanical one can be used</td></tr><tr><td>VideoXtens</td><td>Zwick Roell</td><td>5.28.0.0 SP2</td><td></td></tr></tbody></table>

artificial thermal ageing of polyester reinforced and polyvinyl chloride coated technical fabric

Architectural fabric AF9032 has been subjected to artificial thermal ageing to determine changes of the material parameters of the fabric. The proposed method is based on the accelerated ageing approach proposed by Arrhenius. 300 mm x 50 mm samples were cut in the warp and fill directions and placed in a thermal chamber at 80 &#176;C for up to 12 weeks or at 90 &#176;C for up to 6 weeks. Then after one week of conditioning at ambient temperature, the samples were uniaxially tensioned at a constant strain rate. Experimentally, the parameters were determined for the non-linear elastic (linear piecewise) and viscoplastic (Bodner&#8211;Partom) models. Changes in these parameters were studied with respect to the ageing temperature and ageing period. In both cases, the linear approximation function was successfully applied using the simplified methodology of Arrhenius. A correlation was obtained for the fill direction between experimental results and the results from the Arrhenius approach. For the warp direction, the extrapolation results exhibited some differences. Increasing and decreasing tendencies have been observed at both temperatures. The Arrhenius law was confirmed by the experimental results only for the fill direction. The proposed method makes it possible to predict real fabric behavior during long term exploitation, which is a critical issue in the design process.

Figure 2 juxtaposes the stress-strain curves for the warp and fill directions of AF9032 fabric obtained at different ageing times, in the 80 &#176;C temperature level for a strain rate of 0.001 s-1. The difference between the 1 h ageing period (reference test) and the rest of the ageing periods is clear. The ageing time does not seem to substantially affect the material response in the warp direction, as the stress&#8211;strain curves are highly repetitive, showing no important di...

Watch this Scientific Journal Video about Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric at JoVE.com

Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric

Here, we simulate accelerated thermal ageing of technical fabric and see how this ageing process influences the mechanical properties of the fabric.

Architectural fabric AF9032 has been subjected to artificial thermal ageing to determine changes of the material parameters of the fabric. The proposed ...

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6.5K Views.  Gdansk University of Technology. Here, we simulate accelerated thermal ageing of technical fabric and see how this ageing process influences the mechanical properties of the fabric.

Video: Artificial Thermal Ageing of Polyester Reinforced and Polyvinyl Chloride Coated Technical Fabric

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

Fabrication of the Thermoplastic Microfluidic Channels

In our lab, we have successfully isolated nucleic acids directly from microliter and submicroliter volumes of human blood, urine and stool using polymer/nanoparticle composite microscale lysis and solid phase extraction columns. The recovered samples are concentrated, small volume samples that are PCRable, without any additional cleanup. Here, we demonstrate how to fabricate thermoplastic microfluidic chips using hot embossing and heat sealing. Then, we demonstrate how to use in situ light directed surface grafting and polymerization through the sealed chip to form the composite solid phase columns. We demonstrate grafting and polymerization of a carbon nanotube/polymer composite column for bacterial cell lysis. We then show the lysis process followed by solid phase extraction of nucleic acids from the sample on chip using a silica/polymer composite column. The attached protocols contain detailed instructions on how to make both lysis and solid phase extraction columns.

Here we demonstrate how to fabricate thermoplastic microfluidic chips using hot embossing and heat sealing. Then we demonstrate how to use in situ light directed surface grafting and polymerization through the sealed chip to form the composite solid phase columns.

In our lab, we have successfully isolated nucleic acids directly from microliter and submicroliter volumes of human blood, urine and stool using ...

Biology

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

Experimental Implementation of a New Composite Fabrication Method: Exposing Bare Fibers on the Composite Surface by the Soft Layer Method

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional component that should have high electrical conductivity, high mechanical properties, and high productivity.
In this regard, a carbon fiber/epoxy resin composite can be an ideal material to replace the conventional graphite bipolar plate, which often leads to the catastrophic failure of the entire system because of its inherent brittleness. Though the carbon/epoxy composite has high mechanical properties and is easy to manufacture, the electrical conductivity in the through-thickness direction is poor because of the resin-rich layer that forms on its surface. Therefore, an expanded graphite coating was adopted to solve the electrical conductivity issue. However, the expanded graphite coating not only increases the manufacturing costs but also has poor mechanical properties.
In this study, a method to expose fibers on the composite surface is demonstrated. There are currently many methods that can expose fibers by surface treatment after the fabrication of the composite. This new method, however, does not require surface treatment because the fibers are exposed during the manufacture of the composite. By exposing bare carbon fibers on the surface, the electrical conductivity and mechanical strength of the composite are increased drastically.

A protocol to expose bare fibers on the composite surface by eliminating resin rich area is presented. The fibers are exposed during fabrication of the composites, not by the post surface treatment. The exposed carbon composites exhibit high electrical conductivity in the through-thickness direction and high mechanical property.

The bipolar plate is a key component in proton exchange membrane fuel cells (PEMFCs) and vanadium redox flow batteries (VRFBs). It is a multi-functional ...

Deposition of Porous Sorbents on Fabric Supports

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material that can be subsequently treated by dip coating. Dip coating with a sol preparation provides a supported porous layer on the fabric. In this case, the porous layer is a porphyrin functionalized sorbent system based on a powdered material that has been demonstrated previously for the capture and conversion of phosgene. A representative coating is applied to cotton fabric at a loading level of 10 mg/g. This coating has minimal impact on water vapor transport through the fabric (93% of the support fabric rate) while significantly reducing transport of 2-chloroethyl ethyl sulfide (CEES) through the material (7% of support fabric rate). The described approaches are suitable for use with other fabrics providing amine and hydroxyl groups for modification and can be used in combination with other sol preparations to produce varying functionality.

This report details a microwave-initiated approach for deposition of porphyrin functionalized porous organosilicate sorbents on a cotton fabric and demonstrates reduction in 2-chloroethyl ethyl sulfide (CEES) transport through the fabric resulting from this treatment.

A microwave deposition technique for silanes, previously described for production of oleophobic fabrics, is adapted to provide a fabric support material ...

Chemistry

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, where the yarns in each layer are oriented parallel to each other and held in place using binder resins and thin polymer films. The armor is constructed by stacking the unidirectional layers in different orientations. To date, only very preliminary work has been performed to characterize the ageing of the binder resins used in unidirectional laminates and the effects on their performance. For example, during the development of the conditioning protocol used in the National Institute of Justice Standard-0101.06, UD laminates showed visual signs of delamination and reductions in V50, which is the velocity at which half of the projectiles are expected to perforate the armor, after ageing. A better understanding of the material property changes in UD laminates is necessary to comprehend the long-term performance of armors constructed from these materials. There are no current standards recommended for mechanically interrogating unidirectional (UD) laminate materials. This study explores methods and best practices for accurately testing the mechanical properties of these materials and proposes a new test methodology for these materials. Best practices for ageing these materials are also described.

The goal of the study was to develop protocols to prepare consistent specimens for accurate mechanical testing of high-strength aramid or ultra-high-molar-mass polyethylene-based flexible unidirectional composite laminate materials and to describe protocols for performing artificial ageing on these materials.

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...

Fabrication of Carbon-Based Ionic Electromechanically Active Soft Actuators

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, compliant and biomimetic nature of this deformation, actuators made of the laminate have received increasing interest in soft robotics and (bio)medical applications. However, methods to easily fabricate the active material in large (even industrial) quantities and with a high batch-to-batch and within-batch repeatability are needed to transfer the knowledge from laboratory to industry. This protocol describes a simple, industrially scalable and reproducible method for the fabrication of ionic carbon-based electromechanically active capacitive laminates and the preparation of actuators made thereof. The inclusion of a passive and chemically inert (insoluble) middle layer (e.g., a textile-reinforced polymer network or microporous Teflon) distinguishes the method from others. The protocol is divided into five steps: membrane preparation, electrode preparation, current collector attachment, cutting and shaping, and actuation. Following the protocol results in an active material that can, for example, compliantly grasp and hold a randomly shaped object as demonstrated in the article.

This article describes a fast and simple manufacturing process of ionic electromechanically active composite materials for actuators in biomedical, biomimetic and soft robotics applications. The key fabrication steps, their importance for the actuators&#39; final properties, and some of the main characterization techniques are described in detail.

Ionic electromechanically active capacitive laminates are a type of smart material that move in response to electrical stimulation. Due to the soft, ...

A Simple and Scalable Fabrication Method for Organic Electronic Devices on Textiles

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices cannot be worn under everyday conditions. Therefore, textiles are commonly considered the best substrate to accommodate electronic devices in wearable use. In this paper, we describe how to selectively pattern organic electroactive materials on textiles from a solution in an easy and scalable manner. This versatile deposition technique enables the fabrication of wearable organic electronic devices on clothes.

In this paper, we present a protocol to selectively deposit organic materials on textiles, which allows for the direct integration of organic electronic devices with wearables. The fabricated devices can be fully integrated in textiles, respecting their mechanical appearance and enabling sensing capabilities.

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices ...

Bioengineering

Fabrication and Mechanical Property Assessment of Fiber Composite Laminates

Measuring the Mechanical Properties of Glass Fiber Reinforcement Polymer Composite Laminates Obtained by Different Fabrication Processes

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the forming pressure, the mass fraction of fiber is reduced and lots of air bubbles are trapped inside, resulting in low-quality laminates (low stiffness and strength). The wet hand lay-up/vacuum bag (WLVB) process for the fabrication of composite laminates is based on the traditional wet hand lay-up process, using a vacuum bag to remove air bubbles and provide pressure, and then carrying out the heating and curing process. 
Compared with the traditional hand lay-up process, laminates manufactured by the WLVB process show superior mechanical properties, including better strength and stiffness, higher fiber volume fraction, and lower void volume fraction, which are all benefits for composite laminates. This process is completely manual, and it is greatly influenced by the skills of the preparation personnel. Therefore, the products are prone to defects such as voids and uneven thickness, leading to unstable qualities and mechanical properties of the laminate. Hence, it is necessary to finely describe the WLVB process, finely control steps, and quantify material ratios, in order to ensure the mechanical properties of laminates. 
This paper describes the meticulous process of the WLVB process for preparing woven plain patterned glass fiber reinforcement composite laminates (GFRPs). The fiber volume content of laminates was calculated using the formula method, and the calculated results showed that the fiber volume content of WL laminates was 42.04%, while that of WLVB laminates was 57.82%, increasing by 15.78%. The mechanical properties of the laminates were characterized using tensile and impact tests. The experimental results revealed that with the WLVB process, the strength and modulus of the laminates were enhanced by 17.4% and 16.35%, respectively, and the specific absorbed energy was increased by 19.48%.

Author Spotlight: Enhancing Fiber Composite Laminate Quality with the Wet Hand Lay-Up/Vacuum Bag Process 

This paper describes a fabrication process for fiber-reinforced polymer matrix composite laminates obtained using the wet hand lay-up/vacuum bag method.

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the ...