Browsing by Author "Yang, Kai"
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- 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.
- ItemElectrical Heating Properties of Carbon Fabric/Green Epoxy Composites Filled with Fly Ash(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Wang, Yuan-Feng; Karthik, Daniel; Yang, Kai; Yang, Tao; Xiong, Xiao-Man; Baheti, Vijay; Militký, JiříThis paper investigates the joule heating behavior and electrical property of the carbon fabric/green epoxy composite laminates filled with various concentrations of unmilled fly ash and milled fly ash. The infrared camera was used to record the change in surface temperature of composites over a period of time (i.e. from 0 to 240 sec) by varying the voltage from 0 to 10 V. The results show that the composite containing 0.5% fly ash exhibited the maximum temperature under different applied voltages. The maximum temperatures of epoxy/carbon composites could be finely tuned by controlling the concentrations of fly ash fillers as well as the applied voltage. When a certain voltage was applied to the composite, the surface composite temperature reached the maximum and became stable at a time shorter than 120s. In addition, the milled fly ash filled epoxy/carbon composites were found to reveal improvement in electrical heating performance and structural stability over the unmilled fly ash filled composites.
- ItemInfluence of EMI Shielding on Silane-coated Conductive Fabric(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Periyasamy, Aravin Prince; Yang, Kai; Xiong, Xiaoman; Venkatraman, Mohanapriya; Militký, Jiří; Mishra, Rajesh; Křemenáková, DanaElectromagnetic interference (EMI) takes place due to an increase in the complexity of electronic devices/systems in the form of higher packing density for a quick response. To overcome its adverse effects, the effective shielding of components is abundantly needed. This leads to an increase in the undesirable influence of electromagnetic signals and troublesome charges against which the protection of human beings is required. A textile-based structure with electromagnetic shielding ability is a promising replacement for conventional materials due to its flexibility, air permeability and comfort properties. In this work, a Cu-coated fabric was silanized with different types of silane to stabilize the Cu deposition fabric. Three different silanes were used in the silanization treatment in order to stabilize the Cu deposition. The results showed improved electromagnetic shielding properties.
- ItemNumerical Modelling of the Acoustic Properties of Polyester Non-woven(TEXTILE BIOENGINEERING & INFORMATICS SOCIETY LTD, TBIS 2010 SECRETARIAT MN104, HONG KONG POLYTECHNIC UNIV, HONG KONG SAR, 0000, PEOPLES R CHINA, 2019) Yang, Tao; Saati, Ferina; Xiong, Xiao-Man; Wang, Yuan-Feng; Yang, Kai; Mishra, Rajesh; Militký, Jiří; Petrů, MichalThis paper investigates the acoustical properties of polyester non-woven by using practical and numerical methods. Several types of non-woven samples made from staple, hollow and bi-component polyester fibres were chosen to carry out this study. The AFD300 Acoustic Flow device was used to measure airflow resistivity. The 45 mm Materiacustica two-microphone impedance tube was used to measure the surface impedance and sound absorption coefficient. Widely used impedance models, such as the Delany-Bazley, Miki, Garai-Pompoli and Komatsu models, were applied to predict acoustical properties. A comparison between measured and predicted values has been performed to derive the most accurate model. The Johnson-Champoux-Allard-Lafarge (JCAL) model was applied to obtain some non-acoustical properties based on the inverse method. It is found that the Delany-Bazley and Miki models can accurately predict the surface impedance of polyester non-woven. The results indicate that the Miki model is the most acceptable method for predicting the sound absorption coefficient, with an 8.39% mean error for all of the samples. The values are 8.92%, 12.58% and 69.67% for the Delany-Bazley, Garai-Pompoli and Komatsu models, respectively. Several difficult-to-obtain parameters have been investigated.
- 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.
- ItemStudy on the sound absorption behavior of multi-component polyester nonwovens: experimental and numerical methods(2019-08) Yang, Tao; Saati, Ferina; Horoshenkov, Kirill V.; Xiong, Xiaoman; Yang, Kai; Mishra, Rajesh; Marburg, Steffen; Militký, JiříThis study presents an investigation of the acoustical properties of multi-component polyester nonwovens with experimental and numerical methods. Fifteen types of nonwoven samples made with staple, hollow and bi-component polyester fibers were chosen to carry out this study. The AFD300 AcoustiFlow device was employed to measure airflow resistivity. Several models were grouped in theoretical and empirical model categories and used to predict the airflow resistivity. A simple empirical model based on fiber diameter and fabric bulk density was obtained through the power-fitting method. The difference between measured and predicted airflow resistivity was analyzed. The surface impedance and sound absorption coefficient were determined by using a 45 mm Materiacustica impedance tube. Some widely used impedance models were used to predict the acoustical properties. A comparison between measured and predicted values was carried out to determine the most accurate model for multi-component polyester nonwovens. The results show that one of the Tarnow model provides the closest prediction to the measured value, with an error of 12%. The proposed power-fitted empirical model exhibits a very small error of 6.8%. It is shown that the Delany-Bazley and Miki models can accurately predict surface impedance of multi-component polyester nonwovens, but the Komatsu model is less accurate, especially at the low-frequency range. The results indicate that the Miki model is the most accurate method to predict the sound absorption coefficient, with a mean error of 8.39%.
- 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.