Polyurethane nano-coatings were prepared by adding nano-concentrates with nanometer zinc oxide (nano-ZnO) to polyurethane coating. The dispersion state of nanoparticles was observed by TEM images. SEM observation and ...Polyurethane nano-coatings were prepared by adding nano-concentrates with nanometer zinc oxide (nano-ZnO) to polyurethane coating. The dispersion state of nanoparticles was observed by TEM images. SEM observation and FT-IR analysis indicate that the nano-coating with 1% ZnO nanoparticles can retain better morphological structure than the nano-coating with 5% ZnO nanoparticles after 500 h accelerated aging. It is known from XPS analysis that the anti-oxidation properties of polyurethane coating are enhanced by 1% ZnO nanoparticles through the nano-network and destroyed by 5% ZnO nanoparticles due to the strong light catalysis. A small change in capacitances of nano-coatings with 1% ZnO nanoparticles before and after accelerated aging indicates that 1% ZnO nanoparticles improve the corrosion resistance of coating, while a large increase in capacitances of nano-coating with 5% ZnO nanoparticles before and after accelerated aging demonstrates that 5% ZnO nanoparticles damage the corrosion resistance of coating.展开更多
Utilization of biochar in plastic based blends offers a sustainable way to renewable materials as well as value-added use of wood waste.To investigate the interfacial compatibility and weatherability properties of bio...Utilization of biochar in plastic based blends offers a sustainable way to renewable materials as well as value-added use of wood waste.To investigate the interfacial compatibility and weatherability properties of biochar composites,four types of Wood-Plastic Composites(WPC)were prepared by an extrusion process.The mechanical properties,water absorptions,thermal and viscoelastic properties,and rheological behavior of the composites were also evaluated.The decolorizing carbon(NA)composite melts showed the higher modulus and viscosity,indicating better melt strength.The NA composites performed the best in tensile properties(strength of 2&6 MPa and modulus of 3.4 GPa)and had strong interfacial interaction between particles and the matrix.The degree of HDPE crystallinity in the biochar and carbon composites decreased relative to Douglas-fir(DF)composites,while the thermal properties of the composites improved compared with DF composites.For the water resistance,the DF composites displayed the highest water absorption(3.7%)and thickness swell(2.9%).During accelerated weathering tests,longer exposure time increased the color change and lightness,especially for DF composite.NA and biochar composites resulted in improved photostability.This study opens up a pathway to utilize effectively the renewable biochar as reinforcing filler in WPC in outdoor applications.展开更多
A new kind of renewable biocomposite was prepared by compounding bio-based poly（butylene succinate） （PBS） with teakwood sawdust which sieved sawdust were used as received or treated with 3-aminopropyltriethoxy sil...A new kind of renewable biocomposite was prepared by compounding bio-based poly（butylene succinate） （PBS） with teakwood sawdust which sieved sawdust were used as received or treated with 3-aminopropyltriethoxy silane （APS）. The PBS/teakwood composites were compounded in the weight ratio of 90/10 wt%, 80/20 wt%, 70/30 wt% and 60/40 wt%. Thermal properties and morphology of the composites were investigated. The accelerated weathering testing was carried out for 60 h under water spraying and cycle of UV ex- posure at 60 ~C. Tensile and flexural properties before and after the accelerated weathering condition were analyzed. It was found that teakwood sawdust did not effect on the melting temperatures of PBS but reduced the degree of crystallinity. The composites showed lower thermal stability due to the degradation ofhemicellulose and silane. Interfacial adhesion between PBS and APS-treated teakwood sawdust was achieved showing less pull-out of sawdust. Tensile and flexural modulus of composites increased with respect to sawdust content, in which the APS-treated composites had higher modulus. After passing the accelerated weathering condition, tensile modulus of the composites slightly increased while flexural properties decreased in the composites added sawdust content higher than 20 wt%. Loss of flexural properties was more pronounced than tensile properties due to the hydrolytic degradation introduced by hydrophilicity of lignocellulosic fillers.展开更多
Predicting the lifetime of polymeric insulators is one of the most important research topics in studying the life cycle of high voltage insulators in the power transmission and distribution networks. HTV （high temper...Predicting the lifetime of polymeric insulators is one of the most important research topics in studying the life cycle of high voltage insulators in the power transmission and distribution networks. HTV （high temperature vulcanized） silicone rubber is a high performance dielectric material used within electrical power equipment, in particular transmission and distribution insulators. In this paper, we proposed a new approach using the Newton＇s method and Lagrange method to predict the aging of HTV silicone rubber that are subjected to multiple stress conditions. Concentration of chemical elements such as carbon, oxygen, silicon and aluminum were obtained and evaluated using a SEM （scanning electron microscope） with EDS （energy dispersive X-ray spectroscopy）. Curve fitting using the Newton＇s and Lagrange interpolation methods yield useful linear interpolation equations that describe the aging characteristic of the specimens under study. This approach can be applied to predict the change in chemical concentration of polymeric insulators over the life cycle with good accuracy.展开更多
LDPE （low-density polyethylene） photo degraded through various accelerated weathering tests has the molecular weight distribution curves unlike that through outdoor exposure. The authors therefore developed new weat...LDPE （low-density polyethylene） photo degraded through various accelerated weathering tests has the molecular weight distribution curves unlike that through outdoor exposure. The authors therefore developed new weathering test condition based on the existing accelerated weathering test using a xenon arc lamp. Samples of LDPE were photo degraded using various accelerated weathering test conditions and outdoor exposure. The physical properties and chemical structures of the photo degraded samples were studied through a tensile test, infrared spectroscopy, and gel chromatography. The authors found that the molecular weight distribution curve of a sample photo degraded using a xenon lamp at a higher BPT （black panel temperature） （73 ~C） was more similar to that of an outdoor-exposed sample than that of a sample photo degraded at the standard BPT （63 ~C）. It is considered that higher temperature accelerates radical recombination, consequently recreating molecular enlargement similar to the outdoor-exposed sample. Multiple regression analysis using newly introduced Mp （peak-top molecular weight） and Mw （weight-average molecular weight） as explanatory variables was conducted, which successfully enabled the authors to provide a simple explanation for the decrease in polymer tensile strength.展开更多
基金Supported by the National Key Technology R & D Program (Grant No. 2007BAB27B02-02)
文摘Polyurethane nano-coatings were prepared by adding nano-concentrates with nanometer zinc oxide (nano-ZnO) to polyurethane coating. The dispersion state of nanoparticles was observed by TEM images. SEM observation and FT-IR analysis indicate that the nano-coating with 1% ZnO nanoparticles can retain better morphological structure than the nano-coating with 5% ZnO nanoparticles after 500 h accelerated aging. It is known from XPS analysis that the anti-oxidation properties of polyurethane coating are enhanced by 1% ZnO nanoparticles through the nano-network and destroyed by 5% ZnO nanoparticles due to the strong light catalysis. A small change in capacitances of nano-coatings with 1% ZnO nanoparticles before and after accelerated aging indicates that 1% ZnO nanoparticles improve the corrosion resistance of coating, while a large increase in capacitances of nano-coating with 5% ZnO nanoparticles before and after accelerated aging demonstrates that 5% ZnO nanoparticles damage the corrosion resistance of coating.
文摘Utilization of biochar in plastic based blends offers a sustainable way to renewable materials as well as value-added use of wood waste.To investigate the interfacial compatibility and weatherability properties of biochar composites,four types of Wood-Plastic Composites(WPC)were prepared by an extrusion process.The mechanical properties,water absorptions,thermal and viscoelastic properties,and rheological behavior of the composites were also evaluated.The decolorizing carbon(NA)composite melts showed the higher modulus and viscosity,indicating better melt strength.The NA composites performed the best in tensile properties(strength of 2&6 MPa and modulus of 3.4 GPa)and had strong interfacial interaction between particles and the matrix.The degree of HDPE crystallinity in the biochar and carbon composites decreased relative to Douglas-fir(DF)composites,while the thermal properties of the composites improved compared with DF composites.For the water resistance,the DF composites displayed the highest water absorption(3.7%)and thickness swell(2.9%).During accelerated weathering tests,longer exposure time increased the color change and lightness,especially for DF composite.NA and biochar composites resulted in improved photostability.This study opens up a pathway to utilize effectively the renewable biochar as reinforcing filler in WPC in outdoor applications.
文摘A new kind of renewable biocomposite was prepared by compounding bio-based poly（butylene succinate） （PBS） with teakwood sawdust which sieved sawdust were used as received or treated with 3-aminopropyltriethoxy silane （APS）. The PBS/teakwood composites were compounded in the weight ratio of 90/10 wt%, 80/20 wt%, 70/30 wt% and 60/40 wt%. Thermal properties and morphology of the composites were investigated. The accelerated weathering testing was carried out for 60 h under water spraying and cycle of UV ex- posure at 60 ~C. Tensile and flexural properties before and after the accelerated weathering condition were analyzed. It was found that teakwood sawdust did not effect on the melting temperatures of PBS but reduced the degree of crystallinity. The composites showed lower thermal stability due to the degradation ofhemicellulose and silane. Interfacial adhesion between PBS and APS-treated teakwood sawdust was achieved showing less pull-out of sawdust. Tensile and flexural modulus of composites increased with respect to sawdust content, in which the APS-treated composites had higher modulus. After passing the accelerated weathering condition, tensile modulus of the composites slightly increased while flexural properties decreased in the composites added sawdust content higher than 20 wt%. Loss of flexural properties was more pronounced than tensile properties due to the hydrolytic degradation introduced by hydrophilicity of lignocellulosic fillers.
文摘Predicting the lifetime of polymeric insulators is one of the most important research topics in studying the life cycle of high voltage insulators in the power transmission and distribution networks. HTV （high temperature vulcanized） silicone rubber is a high performance dielectric material used within electrical power equipment, in particular transmission and distribution insulators. In this paper, we proposed a new approach using the Newton＇s method and Lagrange method to predict the aging of HTV silicone rubber that are subjected to multiple stress conditions. Concentration of chemical elements such as carbon, oxygen, silicon and aluminum were obtained and evaluated using a SEM （scanning electron microscope） with EDS （energy dispersive X-ray spectroscopy）. Curve fitting using the Newton＇s and Lagrange interpolation methods yield useful linear interpolation equations that describe the aging characteristic of the specimens under study. This approach can be applied to predict the change in chemical concentration of polymeric insulators over the life cycle with good accuracy.
文摘LDPE （low-density polyethylene） photo degraded through various accelerated weathering tests has the molecular weight distribution curves unlike that through outdoor exposure. The authors therefore developed new weathering test condition based on the existing accelerated weathering test using a xenon arc lamp. Samples of LDPE were photo degraded using various accelerated weathering test conditions and outdoor exposure. The physical properties and chemical structures of the photo degraded samples were studied through a tensile test, infrared spectroscopy, and gel chromatography. The authors found that the molecular weight distribution curve of a sample photo degraded using a xenon lamp at a higher BPT （black panel temperature） （73 ~C） was more similar to that of an outdoor-exposed sample than that of a sample photo degraded at the standard BPT （63 ~C）. It is considered that higher temperature accelerates radical recombination, consequently recreating molecular enlargement similar to the outdoor-exposed sample. Multiple regression analysis using newly introduced Mp （peak-top molecular weight） and Mw （weight-average molecular weight） as explanatory variables was conducted, which successfully enabled the authors to provide a simple explanation for the decrease in polymer tensile strength.
