Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mec...Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mechanical properties of the composites before and after UV accelerated weathering. HDPE, wood fibers, pigments and other processing additives were dry-mixed in a high-speed mixer. The mixtures were extruded by two-step extrusion process with a self-designed twin-screw/single-screw extruder system. Color of the samples was determined according to CIE 1976 L^＊a^＊b^＊ system by a spec- trophotometer and the bending properties were tested to evaluate the mechanical properties before and after accelerated UV weathering. The result shows that the modulus of elasticity of WF/HDPE did not obvi- ously changed after incorporating with the pigments, but the bending strength increased. After accelerated aging for 2000 h, both color and mechanical properties significantly changed. Iron oxide red and black performed better than the other two pigments, and the pigments dosage of 2.28% in the composites is favourable.展开更多
The natural attapulgite(NAPT)was disaggregated by high-pressure homogenization technology combined with extrusion process to prepare the attapulgite with disaggregated rod crystal bundles(DAPT)and large specific surfa...The natural attapulgite(NAPT)was disaggregated by high-pressure homogenization technology combined with extrusion process to prepare the attapulgite with disaggregated rod crystal bundles(DAPT)and large specific surface area of 133.7 m^(2)/g.NAPT and DAPT were incorporated into the silicone rubber to obtain the composite NAPTSR and DAPT-SR by mechanical blending method,respectively.After thermal oxidative ageing at 300℃ for 0.5 h,temperature for the 5%weight loss increased greatly from 385℃ of the neat silicone rubber to 396-399℃ with addition of NAPT and DAPT.NAPT and DAPT enhanced the interaction between the filler nanoparticles and rubber matrix thus inhibited the nanoparticle agglomeration.The conservation rate of the side methyl group in NAPT-SR and DAPT-SR was greatly improved after ageing.Therefore,the thermal oxidative degradation and ageing performance of the silicone rubber composites was significantly reinforced.Moreover,DAPT could greatly restrain the growth of nanoparticles after ageing.Therefore,DAPT-SR showed the better retention of tensile strength(40.6%),elongation at break(34.9%)and tear strength(30.1%)compared with the corresponding mechanical properties of the neat silicone rubber(10.6%,7.4%,and 5.0%)after ageing.展开更多
The main focus of this paper is to investigate the influence of hygrothermal aging on tensile strength of epoxy resin matrix composites.Firstly,tests of water absorption and moisture induced tensile strength degradati...The main focus of this paper is to investigate the influence of hygrothermal aging on tensile strength of epoxy resin matrix composites.Firstly,tests of water absorption and moisture induced tensile strength degradation of glass fiber reinforced polymer(GFRP)are conducted.Results show that the moisture absorption behavior of the GFRP follows the Fick’s law,and its tensile strength retention decreases notably in the early hygrothermal aging stage and then gradually approaches a constant.Then,microscale longitudinal and transverse strength prediction models for unidirectional fiber reinforced composites are proposed.They are moisture concentration dependent and reflect the inherent probability of failures of fiber and matrix(or fiber/matrix interface).The moisture diffusing analysis demostrates that the proposed models can predict degradation of tensile strength of epoxy resin matrix composites undergoing different hygrothermal durations.The proposed models are validated by the experiments of hygrothermal residual strength of the GFRP mentioned above.展开更多
In recent years,natural fiber reinforced composites have been widely applied to various industrial products for their excellent environmental-friendly performance.It is essential to understand the mechanical propertie...In recent years,natural fiber reinforced composites have been widely applied to various industrial products for their excellent environmental-friendly performance.It is essential to understand the mechanical properties of natural fiber reinforced composites under their in-service environment.Compared with synthetic fibers,the hydrophilicity of natural fibers could result in a much larger quantity of water absorption from the moisture atmosphere,which would have adverse consequences for the durability of natural fiber reinforced composites[1].The environmental temperature would affect the展开更多
基金supported by the National Natural Science Foundation of China (30671644, 30771680)
文摘Four kinds of iron oxide pigments were added into wood-fiber/high-density-polyethylene composites （WF/HDPE） at three different concentrations, to determine the effects of pigments on the changes in the color and mechanical properties of the composites before and after UV accelerated weathering. HDPE, wood fibers, pigments and other processing additives were dry-mixed in a high-speed mixer. The mixtures were extruded by two-step extrusion process with a self-designed twin-screw/single-screw extruder system. Color of the samples was determined according to CIE 1976 L^＊a^＊b^＊ system by a spec- trophotometer and the bending properties were tested to evaluate the mechanical properties before and after accelerated UV weathering. The result shows that the modulus of elasticity of WF/HDPE did not obvi- ously changed after incorporating with the pigments, but the bending strength increased. After accelerated aging for 2000 h, both color and mechanical properties significantly changed. Iron oxide red and black performed better than the other two pigments, and the pigments dosage of 2.28% in the composites is favourable.
基金supported by the Key Special Program on the S&T for the Pollution Control and Treatment of Water Bodies (No.2017ZX07603-003)。
文摘The natural attapulgite(NAPT)was disaggregated by high-pressure homogenization technology combined with extrusion process to prepare the attapulgite with disaggregated rod crystal bundles(DAPT)and large specific surface area of 133.7 m^(2)/g.NAPT and DAPT were incorporated into the silicone rubber to obtain the composite NAPTSR and DAPT-SR by mechanical blending method,respectively.After thermal oxidative ageing at 300℃ for 0.5 h,temperature for the 5%weight loss increased greatly from 385℃ of the neat silicone rubber to 396-399℃ with addition of NAPT and DAPT.NAPT and DAPT enhanced the interaction between the filler nanoparticles and rubber matrix thus inhibited the nanoparticle agglomeration.The conservation rate of the side methyl group in NAPT-SR and DAPT-SR was greatly improved after ageing.Therefore,the thermal oxidative degradation and ageing performance of the silicone rubber composites was significantly reinforced.Moreover,DAPT could greatly restrain the growth of nanoparticles after ageing.Therefore,DAPT-SR showed the better retention of tensile strength(40.6%),elongation at break(34.9%)and tear strength(30.1%)compared with the corresponding mechanical properties of the neat silicone rubber(10.6%,7.4%,and 5.0%)after ageing.
基金the National Natural Science Foundation of China(No.11872205)the State Key Laboratory Open Fund(No.MCMS-E-0221Y02)the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The main focus of this paper is to investigate the influence of hygrothermal aging on tensile strength of epoxy resin matrix composites.Firstly,tests of water absorption and moisture induced tensile strength degradation of glass fiber reinforced polymer(GFRP)are conducted.Results show that the moisture absorption behavior of the GFRP follows the Fick’s law,and its tensile strength retention decreases notably in the early hygrothermal aging stage and then gradually approaches a constant.Then,microscale longitudinal and transverse strength prediction models for unidirectional fiber reinforced composites are proposed.They are moisture concentration dependent and reflect the inherent probability of failures of fiber and matrix(or fiber/matrix interface).The moisture diffusing analysis demostrates that the proposed models can predict degradation of tensile strength of epoxy resin matrix composites undergoing different hygrothermal durations.The proposed models are validated by the experiments of hygrothermal residual strength of the GFRP mentioned above.
基金supported by the Shenzhen Municipal Government through the Fundamental Research Project(Grant No.JCYJ20170307151049286)the National Natural Science Foundation of China(Grant No.11572227)
文摘In recent years,natural fiber reinforced composites have been widely applied to various industrial products for their excellent environmental-friendly performance.It is essential to understand the mechanical properties of natural fiber reinforced composites under their in-service environment.Compared with synthetic fibers,the hydrophilicity of natural fibers could result in a much larger quantity of water absorption from the moisture atmosphere,which would have adverse consequences for the durability of natural fiber reinforced composites[1].The environmental temperature would affect the
