Browsing by Author "Venkataraman, Mohanapriya"
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- ItemA novel method for producing bi-component thermo-regulating alginate fiber from phase change material microemulsion(SAGE PUBLICATIONS LTD, 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND, 2019-11) Wang, Yan; Yao, Juming; Zhu, Guocheng; Militký, Jiří; Marek, Jaromír; Venkataraman, Mohanapriya; Zhang, GuoqingA novel method for fabricating thermo-regulating alginate fiber by wet spinning from phase change material (PCM) microemulsions was proposed and carried out. In order to synthesize the PCM microemulsion successfully, different emulsifiers (alkylphenol polyoxyethylene ether (OP-10), sodium dodecyl sulfate (SDS) and their mixture) were added into the stock solution system. The solution systems with emulsifiers were observed under optical microscope and evaluated by using a differential scanning calorimeter (DSC); the results showed that only the solution system with the mixture of OP-10 and SDS transformed into PCM microemulsion, corresponding to the success of fiber formation by wet spinning. In addition, the microemulsion had a stable thermal property based on the DSC result, in which the latent heat capacity remained at 97.3% after 100 cycles of heating and cooling. The thermo-regulating alginate fiber was evaluated in terms of morphology, thermogravimetric (TG) analysis and differential scanning calorimetry. The results showed that the fiber had a smooth surface and porous structure in the cross-section, the bimodal TG curve of alginate fiber indicated that the PCM was successfully embedded into fiber and the DSC results demonstrated that the thermo-regulating alginate fiber had a comfortable phase change temperature of 25-35celcius, and an acceptable phase change enthalpy of about 20 J/g.
- ItemAn experimental evaluation of convective heat transfer in multi-layered fibrous materials composed by different middle layer structures(SAGE PUBLICATIONS INC, 2455 TELLER RD, THOUSAND OAKS, CA 91320 USA, 2019-10) Xiong, Xiaoman; Venkataraman, Mohanapriya; Jašíková, Darina; Yang, Tao; Mishra, Rajesh; Militký, Jiří; Petrů, MichalIn this work, three types of multi-layered fibrous materials with different middle layer structures, including Struto nonwoven, Struto nonwoven with air pockets and Struto nonwoven with air pockets filled by aerogel particles, were prepared based on laser engraving technique and laminating method. A custom-built new device was fabricated to evaluate convective thermal behaviour of the multi-layered materials in cross flow. It was found that in cross flow the heat transfer coefficient of the multi-layered material with encapsulated aerogels is directly proportional to Reynolds number. There are considerable variances in heat transfer rates of the three structures at low airflow velocity (less than 10 m/s), but the values are very close at high airflow velocity. It is concluded that the air pockets and aerogels present in the multi-layered fibrous material have significant effect on convective thermal behaviour of the overall structure in cross flow. The finding is a new contribution to the field of aerogel-based fibrous materials as thermal insulators in building and industrial facilities.
- ItemCo-solvent free interfacial polycondensation and properties of polyurea PCM microcapsules with dodecanol dodecanoate as core(Elsevier Ltd, 2020-03) Cai, Changwei; Ouyang, Xu; Zhou, Lan; Liu, Guojin; Wang, Yan; Zhu, Guocheng; Yao, Juming; Militký, Jiří; Venkataraman, Mohanapriya; Zhang, GuoqingA kind of eco-friendly micro-encapsulated phase change materials (MEPCM) with dodecanol dodecanoate as core material were synthesized via the interfacial polymerization of toluene-2, 4-diisocyanate (TDI) and diethylenetriamine (DETA). During the preparation, a facile solvent free synthesis route was developed owing to the good compatibility of TDI and dodecanol dodecanoate. The synthesized MEPCM were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Particle Size Distribution (PSD) analyzer, Differential Scanning Calorimetry (DSC), Thermogravimetric/Infrared spectrometry (TG-IR) and thermal constants analyzer. It is found that the resultant MEPCM in nearly spherical shape are in the size scope from 10.0 to 40.0 μm, have the average latent heat in the range of 103.4–140.3 J/g, and exhibit high temperature resistance with an onset evaporation temperature at 234.0 °C. Moreover, the MEPCM possess good thermal conductivity from 0.17 W/m K to 0.21 W/m K. Therefore, it is confirmed that the prepared MEPCM can be regarded as a promising thermal energy storage material appropriate to the thermo-regulating fields such as renewable solar heating system.
- ItemEffect of silanization on copper coated milife fabric with improved EMI shielding effectiveness(Elsevier Ltd, 2020) Periyasamy, Aravin Prince; Yang, Kai; Xiong, Xiaoman; Venkataraman, Mohanapriya; Militký, Jiří; Mishra, Rajesh; Křemenáková, DanaElectromagnetic interference takes place due to the increase in complexity of electronic devices/systems in the form of higher packing density for quick response. To overcome its adverse effects, the effective shielding of components is needed abundantly. This leads to an increase of undesirable influence of electromagnetic signals and troublesome charges against which protection of human beings is required. Textile based structure with electromagnetic shielding ability has promising replacement of conventional materials due to its flexibility, air permeability and comfort properties. In this work, a copper coated fabric was silanized with different types of silane to stabilize the copper deposition on the fabric. Three different silanes were used for the silanization treatment to stabilize the copper deposition. The results showed excellent electromagnetic shielding properties. In addition to that, electrical and physical properties of the fabrics were evaluated before and after silanization treatment.
- ItemExceptional Electromagnetic Shielding Properties of Lightweight and Porous Multifunctional Layers(AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA, 2020-04-28) Militký, Jiří; Křemenáková, Dana; Venkataraman, Mohanapriya; Večerník, JosefThe preparation of functional fabrics with enhanced electrical properties requires suitable selection of surface modification and particulate systems as fillers. The best choice would be to use materials with low fiber diameters, good shape stability, and comfort-related properties. In this study, a composite nonwoven fabric "Milife" with surface covering by a particulate-based copper layer was investigated. Electromagnetic, electrical, and transport characteristics of the prepared materials were evaluated. The results showed extremely high total electromagnetic shielding effectiveness accompanied by very good air permeability and moderate bending modulus, indicating comfort behavior. The copper-coated Milife exhibited good potential to be used in protective textile clothing where a combination of electromagnetic interference shielding and antimicrobial effect is required.
- ItemInfluence of Nanoparticles on Thermal and Electrical Conductivity of Composites(MDPI, 2020-03-27) Coetzee, Divan; Venkataraman, Mohanapriya; Militký, Jiří; Petrů, MichalThis review analyzes thermal and electrically conductive properties of composites and how they can be influenced by the addition of special nanoparticles. Composite functional characteristics—such as thermal and electrical conductivity, phase changes, dimensional stability, magnetization, and modulus increase—are tuned by selecting suitable nanoparticle filler material. The conductivity of composites can be related to the formation of conductive pathways as nanofiller materials form connections in the bulk of a composite matrix. With increasing use of nanomaterial containing composites and relatively little understanding of the toxicological effects thereof, adequate disposal and recyclability have become an increasing environmental concern.
- ItemInvestigation on sound absorption properties of aerogel/polymer nonwovens(2019-02-01) Yang, Tao; Xiong, Xiaoman; Venkataraman, Mohanapriya; Mishra, Rajesh; Novák, Jan; Militký, JiříThis paper presents an investigation on sound absorption performance of aerogel/polymer nonwoven fabrics. Polyester/polyethylene nonwovens embedded with hydrophobic amorphous silica aerogel were chosen for sound absorption measurements. The sound absorption coefficient (SAC) of single and laminated layers of aerogel nonwovens blankets was tested by Bruel and Kj AE r impedance tube, the noise reduction coefficient (NRC) was used for numerical analysis. A sound absorption index was developed to analyze the effect of aerogel content on sound absorption ability. The effect of air-back cavities on SAC of single-layer aerogel/polymer nonwoven fabrics was investigated. The results show that there is a decrease in SAC with the increase of aerogel content. It is observed that the NRC linearly increased with the increase of layers for all the samples. It was also found that the air-back cavities result in resonance phenomenon, as the increase in thickness of air-back cavities the peak values of SAC shift toward lower frequencies.
- ItemPerformance of Electrospun Polyvinylidene Fluoride Nanofibrous Membrane in Air Filtration(2019) Xiao, Yuanxiang; Wen, Enlong; Sakib, Nazmus; Yue, Zhonghua; Wang, Yan; Cheng, Si; Militký, Jiří; Venkataraman, Mohanapriya; Zhu, GuochengPolyvinylidene fluoride (PVDF) fibrous membranes with fiber diameter from nanoscale to microscale were prepared by electrospinning. The structural parameters of PVDF fibrous membrane in terms of fiber diameter, pore size and its distribution, porosity or packing density, thickness, and areal weight were tested. The relationship between solution concentration and structural parameters of fibrous membrane was analyzed. The filtration performance of PVDF fibrous membrane in terms of air permeability and filtration efficiency was evaluated. The results demonstrated that the higher solution concentration led to a larger fiber diameter and higher areal weight of fibrous membrane. However, no regular change was found in thickness, porosity, or pore size of fibrous membrane under different solution concentrations. The air permeability and filtration efficiency of fibrous membrane had positive correlations with pore size. The experimental results of filtration efficiency were compared with the predicted values from current theoretical models based on single fiber filtration efficiency. However, the predicted values did not have a good agreement with experimental results since the fiber diameter was in nanoscale and the ratio of particle size to fiber diameter was much larger than the value that the theoretical model requires.
- ItemPreparation and evaluation of thermo-regulating bamboo fabric treated by microencapsulated phase change materials(2019-08) Zhang, Guoqing; Cai, Changwei; Wang, Yilai; Liu, Guojin; Zhou, Lan; Yao, Juming; Militký, Jiří; Marek, Jaromír; Venkataraman, Mohanapriya; Zhu, GuochengTwo types of microencapsulated phase change materials (ENPCMs) were synthesized by polymerization. The core material of ENPCM was n-octadecane and the shell materials were polymethyl methacrylate-butyl acrylate and polymethyl methacrylate-butyl acrylate-hydroxyethyl methacrylate. Subsequently, the synthesized ENPCMs were applied onto bamboo fabric by the dip and dry method. The properties of ENPCMs were analyzed in terms of surface morphology, size distribution and latent heat; the treated bamboo fabrics were evaluated in terms of surface morphology, hydrophilicity, washing fastness and heat storage capacity. The results showed that polymethyl methacrylate-butyl acrylate/n-octadecane (PMBO) microcapsules had an irregular shape, while polymethyl methacrylate-butyl acrylate-hydroxyethyl methacrylate/n-octadecane (PMBHO) microcapsules were spherical, and the mean diameters of both microcapsules were less than 1 mu m. The latent heat of phase change material (PCM) microcapsules was almost the same at a thermal storage capacity of 110 J/g. There were many more and more even PMBHO microcapsules deposited on bamboo fabric than that of PMBO microcapsules deposited on bamboo fabric. Bamboo fabrics treated by both microcapsules were hydrophilic, and the hydrophilicity of fabric treated by PMBHO microcapsules was even better. The ratio of PCM microcapsules to bamboo fabric was about 1:4, and the latent heat of treated bamboo fabrics was about 20 J/g. Moreover, the treated bamboo fabrics exhibited excellent washing fastness due to the strong binding strength between the highly hydrophilic microcapsules and bamboo fibers. Approximately 72% of PCM microcapsules were retained on the fabric after 15 washing cycles.
- ItemPREPARATION OF ELECTROSPRAYED MICROPOROUS MEMBRANES(IOP PUBLISHING LTD, DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND, 2018) Venkataraman, Mohanapriya; Mishra, Rajesh; Yang, Kai; Militký, Jiří; Křemenáková, Dana; Zhu, Guocheng; Yao, JumingPolytetrafluoroethylene (PTFE) which is also called as "TEFLON" is a synthetic fluoropolymer of tetrafluoroethylene that has wide applications due to its differentiating properties. In this study, different PTFE dispersions for preparation of polytetrafluoroethylene mesoporous active membranes doped by basalt and carbon particles which were created in high voltage electrostatic field has been studied. The adjusting of process parameters of common electrospinning system (Nanospider) for preparation of membranes with tunable porosity created by nanofibrous assembly (electrospinning) and interconnected particles (electrospraying) has also been investigated. The nanoparticles based on milled basalt and carbon was used for activation and achieving of special effects. Superhydrophobic Polytetrafluoroethylene (PTFE) microporous membranes with different surface structures were obtained by controlling operating parameters in the electrospinning process. The diameters and microstructure of the PTFE microporous membrane were characterized by scanning electron microscopy. The contact angles on the microporous membranes were evaluated by static micro-drop observation, and a modified Yang equation was applied to analyze the contact angles. The superhydrophobic PTFE microporous membranes were also tested for thermal properties. As a result of this study, optimized PTFE blend solutions were identified. The results also revealed that the specific surface area was the key factor affecting the contact angles. The thermal properties revealed that thermal conductivity was higher and thermal resistance was lower for carbon and basalt doped membranes.
- ItemPreparation of Electrosprayed, Microporous Particle Filled Layers(MDPI, 2020-06-15) Venkataraman, Mohanapriya; Yang, Kai; Xiong, Xiaoman; Militký, Jiří; Křemenáková, Dana; Zhu, Guocheng; Yao, Juming; Wang, Yan; Zhang, GuoqingPolytetrafluoroethylene (PTFE) is a synthetic fluoropolymer known for its excellent hydrophobic properties. In this work, samples from PTFE dispersions with different combinations of water and carbon microparticles were prepared using an electrospraying method. The morphologies and sizes of carbon particles were investigated and the properties of layers including roughness, hydrophobicity and electrical resistivity were investigated. The non-conductive carbon microparticles were selected as a model particle to check the compatibility and electrospraying ability, and it had no effect on the hydrophobic and electrical properties. Carbon microparticles in polymer solution increased the degree of ionization and was found to be beneficial for the shape control of materials. The results showed that PTFE dispersion with the composition of water and carbon microparticles produced fine sphere particles and the layer fabricated with increased roughness. It was also found that the electrical resistivity and hydrophobicity of all the layers comparatively increased. The fabricated microporous layers can be used in various applications like interlining layer in multilayer textile sandwiches.
- ItemPreparation of Hybrid Tapes for Fabrication of Composites(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2018) Venkataraman, Mohanapriya; Militký Jiří; Baheti, Vijay; Mishra, Rajesh; Pulíček, Roman; Novotná, Jana; Samková, Alžběta; Voleská, Karolína; Srb, PavelTechnical fabrics, especially glass tows, are increasingly used for reinforcement of composites, due to its good mechanical properties. In this paper, glass fiber-based tapes containing special types of resins (in pre-condensate form) were prepared. This could be used for the preparation of composites using precise winding technique. The tensile properties of the tapes made from glass were investigated. Measurements were focused on the breaking force, deformation at break and initial modulus. It was also found that the durability of the tapes was sufficient for long term storing. The major benefit was the avoidance of resin penetration in the winded structure. This was achieved by the tight arrangements of fibrous phase which is very complicated. Also, the resins were loaded by suitable types of nanoparticles to enhance mechanical properties. The results showed a significant difference between the samples.
- ItemProgress in Sol-Gel Technology for the Coatings of Fabrics(MDPI, 2020-03-18) Periyasamy, Aravin Prince; Venkataraman, Mohanapriya; Křemenáková, Dana; Militký, Jiří; Zhao, YanThe commercial availability of inorganic/organic precursors for sol-gel formulations is very high and increases day by day. In textile applications, the precursor-synthesized sol-gels along with functional chemicals can be deposited onto textile fabrics in one step by rolling, padding, dip-coating, spraying or spin coating. By using this technology, it is possible to provide fabrics with functional/multi-functional characteristics including flame retardant, anti-mosquito, water- repellent, oil-repellent, anti-bacterial, anti-wrinkle, ultraviolet (UV) protection and self-cleaning properties. These surface properties are discussed, describing the history, basic chemistry, factors affecting the sol-gel synthesis, progress in sol-gel technology along with various parameters controlling sol-gel technology. Additionally, this review deals with the recent progress of sol-gel technology in textiles in addressing fabric finishing, water repellent textiles, oil/water separation, flame retardant, UV protection and self-cleaning, self-sterilizing, wrinkle resistance, heat storage, photochromic and thermochromic color changes and the improvement of the durability and wear resistance properties.
- ItemSelected Topics in Fibrous Materials Science(2022-09-05) Militký, Jiří; Venkataraman, MohanapriyaTato kniha je již šestou částí seriálu odborných publikací o vybraných výsledcích aktivit skupiny pracovníků TUL zaměřených v širším kontextu na problematiku materiálového inženýrství vlákenných materiálů. Jsou zahrnuty současné trendy zpracování, mikrostruktury a vlastností materiálů ve vláknité formě s širokým uplatněním pro textilně orientované a technicky orientované výrobky. Důraz je kladen na popis fyzikální a chemické podstaty dějů popisujících chování a vlastnosti zkoumaných materiálů. V kapitolách popisujících stav a očekávané trendy ve vybraných oblastech jsou sumarizovány nejen publikované práce ale také vlastní výsledky a kritické zhodnocení a zobecnění základních poznatků. Většina kapitol obsahuje původní výsledky získané touto skupinou v posledních letech. Kromě přípravy materiálů s novými efekty je pozornost zaměřena na vývoj nových testovacích principů, konstrukci přístrojů metrologické poznatky. Výzkumné aktivity se týkají všech druhů vláken se zřetelným posunem k syntetickým a speciálním vláknům pro jiné než oděvní aplikace. To odpovídá současnému trendu rozvoje v oblasti vysoce výkonných vláken, hlavně pro použití jako výztuže v různých kompozitních materiálech a funkčních vláknech pro smart textilie. Oblast vlákenných materiálů zahrnutá v této knize je skutečně velmi rozsáhlá. Komprimovat základní dostupné informace na přiměřeném prostoru byl tedy obtížný úkol. Cílem při psaní této knihy bylo poskytnout široké pokrytí této oblasti, aby byla kniha vhodná pro každého, kdo se obecně zajímá o vláknité materiály a jejich aplikace pro různé účely. Autoři poskytli dostatek kritických odkazů na původní literaturu a přehledové články, aby nasměrovali čtenáře se zvláštním zájmem o jakoukoli konkrétní oblast. Vláknité materiály jsou pro současnou společnost a společnost budoucnosti velmi důležité, protože nabízejí efektivní řešení řady praktických problémů pomocí odlehčených, porézních a flexibilních materiálů. Příklady zahrnují elektrickou vodivost, EMI stínění, optickou propustnost, pevnost a houževnatost, nehořlavost atd. Všechny tyto funkční soft materiály souvisejí s vnitřní strukturou a makro strukturou vláknitých materiálů. Strukturní vlastnosti materiálů zahrnují jejich chemické složení, lokální konfigurace polymerních řetězců a jejich uspořádání do mikrostruktur. Nauka o vláknitých materiálech je tedy široký vědecky zaměřený obor a lze jej považovat za interdisciplinární oblast. Zahrnuje studium struktury a vlastností vláknitého materiálu, vytváření nových typů materiálů a návrh vlastností materiálu tak, aby vyhovovaly potřebám konkrétních aplikací. Základem metodologie vývoje funkčních vláknitých materiálů je kombinace vláken a jejich povrchových modifikací, úprav a případně kombinace různých fází ve vícesložkovém vláknitém systému pro docílení požadovaných efektů. Důležitou součástí jsou fyzikální vlastnosti vláknitých materiálů, které obvykle hrají důležitou roli při výběru materiálu pro konkrétní aplikaci. Jsou zahrnuty také metody návrhu, modelování, simulace, predikce, hodnocení, zpracování a výroby. Výzkum v této oblasti využívá řady pokročilých metod charakterizace materiálů jako jsou speciální mikroskopie, dynamické mechanické analýzy, optoelektronická měření, termogravimetrické analýzy, FTIR atd. Přispěvatelé kapitol v této knize mají řadu speciálních znalostí v rámci pokročilého využití vláknitých materiálech. Proto je tato kniha částečně interdisciplinárně zaměřena také na unikátní zvláštnosti textilních materiálů. Tato kniha je určena zejména pro čtenáře se zkušenostmi z materiálových věd, aplikovaných věd a produktového inženýrství obecně a speciálně textilního oboru. Autoři a editoři věří, že kniha bude zajímavá také pro vysokoškolské studenty, učitele a výzkumníky, kteří se zajímají o oblasti vědy o vláknitých materiálech, inženýrství a technologie a konkrétně o pokročilé materiály, polymerní kompozity, nanomateriály, biomateriály a funkční materiály. Vzhledem k tomu, že se zabývá mnoha základními pojmy, které jsou předmětem zájmu v příslušných oblastech, lze tuto knihu použít také jako základ pro studium materiálových věd a inženýrství. Kniha se skládá ze tří hlavních částí orientovaných na technické vláknité materiály, funkční vláknité materiály a kompozita. Autoři jednotlivých kapitol jsou výzkumníci, doktorandi převážně z katedry materiálového inženýrství Fakulty textilní Technické univerzity v Liberci. Témata zahrnutá v knize popisují nejnovější širší nebo obecné poznatky ve specifických oblastech souvisejících s využitím vláknitých materiálů. Zároveň existuje dostatek podkladů o předchozím výzkumu v této oblasti jinými výzkumníky z celého světa. Primární zaměření se týká navrhování materiálů na molekulární úrovni pro dosažení žádoucích vlastností a aplikací na makroskopické úrovni. S tímto širokým zaměřením se výzkum pohybuje od základního vědeckého zkoumání interakcí, vlastností a sestavování takových molekulárních složek až po aplikované inženýrské úsilí, které převádí tyto základní informace do futuristického technologického pokroku. Velká část výsledků výzkumu je vysoce interdisciplinární a je určena pro různé specialisty v chemii, biochemii, materiálových vědách, strojírenství, biologii a medicíně.
- ItemStudy on the Relationship between Structure Parameters and Filtration Performance of Polypropylene Meltblown Nonwovens(Sciendo, 2019) Xiao, Yuanxiang; Sakib, Nazmus; Yue, Zhonghua; Wang, Yan; Cheng, Si; You, Jianmin; Militký, Jiří; Venkataraman, Mohanapriya; Zhu, GuochengIn this study, polypropylene meltblown nonwoven fabrics with different structure parameters such as fiber diameter, pore size, and areal density were prepared by the industrial production line. The morphology of meltblown nonwoven fibers was evaluated by using scanning electron microscope, and the diameter of fibers was analyzed by using image-pro plus software from at least 200 measurements. The pore size of nonwoven fabric was characterized by a CFP-1500AE type pore size analyzer. The filtration efficiency and pressure drop were evaluated by TSI8130 automatic filter. The results showed that the pressure drop of nonwoven fabrics decreased with the increase in pore size; the filtration efficiency and the pressure drop had a positive correlation with the areal density. However, when the areal density is in the range of 27-29 g/m2, both filtration efficiency and pressure drop decreased with the increase of areal density; when the areal density was kept constant, the filtration efficiency decreased as the pore size decreased; when the pore size of the meltblown nonwoven fabric is less than 17 μm, the filtration efficiency increased as the pore diameter decreased; when the pore diameter of the nonwoven fabric is larger than 17 μm. In a wide range, the pressure drop decreased as the fiber diameter decreased.
- ItemThermal Behaviour of Multi-layer Composite Containing PEG and Laponite as PCM(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Yang, Kai; Venkataraman, Mohanapriya; Wang, Yuan-Feng; Xiong, Xiao-Man; Yang, Tao; Wiener, Jakub; Militký, Jiří; Mishra, Rajesh; Marek, Jaromír; Zhu, Guo-Cheng; Yao, Ju-MingPolyethylene glycol (PEG) and laponite were prepared together as PCM and a multi-layer composite containing this PCM was developed, consisting of a PCM loaded layer, a nano barrier layer and a protective layer. SEM was used to observe the structure of multi-layer composites containing PCM, with better adhesion observed between the PCM loaded layer, the nano barrier layer and the protective layer. DSC revealed the melting temperature, the cooling temperature and the enthalpy of PEG and laponite as PCM. The multi-layer composite containing PCM was obtained. Laponite functionalized as a nucleating agent to accelerate the crystallization of PEG and 15wt% LP in PCM resulted in a disordered PEG molecular. The composites with more laponite had the higher thermal insulation.
- ItemThermal Performance of Kevlar Woven Fabrics Coated with Silica Aerogel(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Venkataraman, Mohanapriya; Xiong, Xiao-Man; Yang, Tao; Yang, Kai; Wang, Yuan-Feng; Mishra, Rajesh; Militký, JiříKevlar woven fabrics coated with aerogel particles were fabricated via blade coating. Fly ash nanoparticles were incorporated to investigate their effect on thermal performance. Thermal behavior of the prepared fabrics was evaluated and compared by using different techniques. It is found that the aerogels combined with a Kevlar fabric resulted in reduced thermal conductivity and higher thermal resistance. The fly ash coating brought a rapid rise in thermal absorptivity of the overall structure. Under laser radiation with high temperature, the aerogel content played a vital role on the surface temperature of the fabrics. At laser radiations with pixel time 330 mu s, the surface temperatures of the aerogel coated Kevlar fabrics were 400-440 degrees C lower than the uncoated fabric. The results also indicate that the fabric temperature is directly proportional to pixel time. It can be concluded that the Kevlar fabrics coated with silica aerogel provides better thermal protection under high temperature.
- ItemTransport Properties of Electro-Sprayed Polytetrafluoroethylene Fibrous Layer Filled with Aerogels/Phase Change Materials(MDPI, 2020) Xiong, Xiaoman; Venkataraman, Mohanapriya; Yang, Tao; Kučerová, Klára; Militký, Jiří; Yang, Kai; Zhu, Guocheng; Yao, JumingThis work is the first attempt to prepare microporous polytetrafluoroethylene (PTFE) fibrous layers embedded with aerogels/phase change materials. For preparation of this layer, the needle-less electrospray technology of water dispersion of individual components is used. Microstructure characteristics, including surface morphology and particle size distribution, and various properties of the prepared materials were investigated and explained. Transport performance of the fibrous layers embedded with aerogels/phase change materials, such as the transmission of heat, air, and water vapor was evaluated and discussed in details. It was found that the electro-sprayed materials composed by spherical particles with rough surface had compact disordered stacking structure. Aerogels and phase change materials (PCMs) play different roles in determining structural parameters and transport properties of the materials. Those parameters and properties could be flexibly adjusted by optimizing the spinning parameters, changing the content or proportion of the fillers to meet specific requirements.