This research focused on the dynamic mechanical and thermal properties of woven mat jute/kenaf/jute(J/K/J)and kenaf/jute/kenaf(K/J/K)hybrid composites.Dynamic mechanical analysis(DMA)and Thermo-gravimetric Analysis(TG...This research focused on the dynamic mechanical and thermal properties of woven mat jute/kenaf/jute(J/K/J)and kenaf/jute/kenaf(K/J/K)hybrid composites.Dynamic mechanical analysis(DMA)and Thermo-gravimetric Analysis(TGA)were used to study the effect of layering sequence on the thermal properties of kenaf/jute hybrid composites.The DMA results;it was found that the differences in the stacking sequence between the kenaf/jute composites do not affect their storage modulus,loss modulus and damping factor.From the TGA and DMA results,it has been shown that stacking sequence has given positive effect to the kenaf/jute hybrid composite compared to pure epoxy composite.This is because kenaf and jute fibre has increased the Tg values of the composites,thus affect the thermal degradation.Results showed that the storage modulus for kenaf/jute hybrid composites increased compared with pure epoxy composites with increasing temperature and the values of remained almost the same at glass transition temperature(Tg),the hybrid composite perhaps due to the improved fibre/matrix interface bonding.The preliminary analysis could provide a new direction for the creation of a novel hybrid composite which offers unique properties which cannot be accomplished in a single material system.展开更多
Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysila...Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.展开更多
We investigated the temperature dependency of the dynamic mechanical properties of cement asphalt paste by the dynamic mechanical thermal analysis（DMTA） method. The experimental results show that the dynamic mechani...We investigated the temperature dependency of the dynamic mechanical properties of cement asphalt paste by the dynamic mechanical thermal analysis（DMTA） method. The experimental results show that the dynamic mechanical properties of cement asphalt pastes are sensitive to temperature due to the inclusion of asphalt, and may go through different states within a temperature range of-40 ℃ to 60 ℃, which is different from that of pure cement and asphalt. As the temperature of the cement asphalt paste increases, a considerable change of dynamic mechanical properties, including storage modulus（E＇）, loss modulus（E＇＇） and loss factor（tand） is observed. Moreover, the influence of asphalt to cement（A/C） ratio on the temperature sensitivity of the dynamic mechanical properties of cement asphalt composites was investigated. The temperature dependency of cement asphalt composites is ascribed to the temperature dependency of the asphalt and its interaction with cement paste. A simple fractional model is proposed to describe the viscoelastic behavior of cement asphalt composites.展开更多
1 Results The description of the relaxation properties of polymers is the way to characterizate the influence of the polymer structure on its useful properties: stability and persistence. Synthesis and investigation o...1 Results The description of the relaxation properties of polymers is the way to characterizate the influence of the polymer structure on its useful properties: stability and persistence. Synthesis and investigation of model compounds are needed to perform the physico-chemical characteristics of polymers. Instrumental methods as NMR and dielectric spectroscopy, thermogravimetric analysis and mechanical spectroscopy are used to this goal[1,2]. Dynamic mechanical thermal analysis (DMTA) is one of the most...展开更多
A simple, economic, efficient and eco-friendly nanodiamond （ND） modifying method to reinforce the ND]epoxy composite for the industrialization of the high-performance ND/epoxy composite is always desired. In the pre...A simple, economic, efficient and eco-friendly nanodiamond （ND） modifying method to reinforce the ND]epoxy composite for the industrialization of the high-performance ND/epoxy composite is always desired. In the present work, the ND was successfully modified only using aqueous ammonia through an easy-to-operate method by replacing the hydrogen atoms in the carboxyl group with ammonium ions. Ammonia, which is the only pollutant in the process, could be recycled. The modified ND/epoxy composite showed an overwhelming advantage over the neat epoxy or the ND/epoxy composite in storage modulus in their glassy state without any degradation of tensile strength, hardness and fracture toughness.展开更多
基金This work is supported by UPM under GP-IPS Grant 9486400.
文摘This research focused on the dynamic mechanical and thermal properties of woven mat jute/kenaf/jute(J/K/J)and kenaf/jute/kenaf(K/J/K)hybrid composites.Dynamic mechanical analysis(DMA)and Thermo-gravimetric Analysis(TGA)were used to study the effect of layering sequence on the thermal properties of kenaf/jute hybrid composites.The DMA results;it was found that the differences in the stacking sequence between the kenaf/jute composites do not affect their storage modulus,loss modulus and damping factor.From the TGA and DMA results,it has been shown that stacking sequence has given positive effect to the kenaf/jute hybrid composite compared to pure epoxy composite.This is because kenaf and jute fibre has increased the Tg values of the composites,thus affect the thermal degradation.Results showed that the storage modulus for kenaf/jute hybrid composites increased compared with pure epoxy composites with increasing temperature and the values of remained almost the same at glass transition temperature(Tg),the hybrid composite perhaps due to the improved fibre/matrix interface bonding.The preliminary analysis could provide a new direction for the creation of a novel hybrid composite which offers unique properties which cannot be accomplished in a single material system.
基金Supported by National Natural Science Foundation of China (No.50872101,A3 Foresight Program-50821140308)National Basic Research Program of China (No.2009CB939704)a joint project of National Nature Science Foundation of China and Russian Foundation for Basic Research(No.NSFC-RFBR 51011120252)
文摘Cross-linked polystyrene/glass fiber composites were fabricated using cross-linked polystyrene （CLPS） as matrix and E-glass fiber as the reinforcement. Surfaces of E-glass fibers were modified by vinyl triethoxysilane （VTES）, vinyl trimethoxysilane （VTMS） and γ-methacryloylpropyl trimethoxysilane （MPS）. The treated glass fibers were analyzed by fourier transform infrared spectroscopy （FTIR）. Dynamic mechanical thermal analysis （DMTA） and thermo-gravimetric analysis （TGA） were employed to investigate the effect of glass fibers surface modification on viscoelastic behavior and thermal properties. The morphology of fracture surfaces of various composites was observed by scanning electron microscopy （SEM）. The results revealed that these coupling agents were connected to the surfaces of the fibers by chemical bonding. Dynamic mechanical properties as well as thermal stability of the composites were improved considerablely, but to varying degrees depending on the fiber modification. The diversities of improvement of properties were attributed to the different interfacial adhesion between CLPS matrix and the glass fibers.
基金Funded by the National Natural Science Foundation of China(50878209 and 51208515)the National Basic Research Program of China(“973”Program)(2013CB036201)
文摘We investigated the temperature dependency of the dynamic mechanical properties of cement asphalt paste by the dynamic mechanical thermal analysis（DMTA） method. The experimental results show that the dynamic mechanical properties of cement asphalt pastes are sensitive to temperature due to the inclusion of asphalt, and may go through different states within a temperature range of-40 ℃ to 60 ℃, which is different from that of pure cement and asphalt. As the temperature of the cement asphalt paste increases, a considerable change of dynamic mechanical properties, including storage modulus（E＇）, loss modulus（E＇＇） and loss factor（tand） is observed. Moreover, the influence of asphalt to cement（A/C） ratio on the temperature sensitivity of the dynamic mechanical properties of cement asphalt composites was investigated. The temperature dependency of cement asphalt composites is ascribed to the temperature dependency of the asphalt and its interaction with cement paste. A simple fractional model is proposed to describe the viscoelastic behavior of cement asphalt composites.
文摘1 Results The description of the relaxation properties of polymers is the way to characterizate the influence of the polymer structure on its useful properties: stability and persistence. Synthesis and investigation of model compounds are needed to perform the physico-chemical characteristics of polymers. Instrumental methods as NMR and dielectric spectroscopy, thermogravimetric analysis and mechanical spectroscopy are used to this goal[1,2]. Dynamic mechanical thermal analysis (DMTA) is one of the most...
基金supported by the National Natural Science Foundation of China(Nos.21503241,21473223,51221264,21261160487,91545119 and 91545110)the CAS/SAFEA International Partnership Program for Creative Research Teams
文摘A simple, economic, efficient and eco-friendly nanodiamond （ND） modifying method to reinforce the ND]epoxy composite for the industrialization of the high-performance ND/epoxy composite is always desired. In the present work, the ND was successfully modified only using aqueous ammonia through an easy-to-operate method by replacing the hydrogen atoms in the carboxyl group with ammonium ions. Ammonia, which is the only pollutant in the process, could be recycled. The modified ND/epoxy composite showed an overwhelming advantage over the neat epoxy or the ND/epoxy composite in storage modulus in their glassy state without any degradation of tensile strength, hardness and fracture toughness.
