In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die rela...In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter. The extrudate was drawn at a drawing ratio of 3.1, and then quickly cooled in cold water. The specimens were obtained by injection molding at processing temperatures less than 190℃, far below the melting temperature of PET (265℃) and PA (230℃), which can maintain the solid state of PET and PA microfiber phase in the composites. Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0~20 wt pct PET or PA), and especially, PET and PA were almost deformed into fibers at the concentration of 15 wt pct. Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test results. The most noticeable improvement of the tensile properties occurred at 15 wt pct of PET in PET/PE system, corresponding to the highest microfiber content, where the tensile strength reached 32.5 MPa, whereas only 19.5 MPa for the pure PE.展开更多
5052 Al and carbon fiber-reinforced polyamide 6 composite(CF-PA6)were jointed via ultrasonic welding with the assistance of temperature compensation device.The effects of the ultrasonic welding time and temperature co...5052 Al and carbon fiber-reinforced polyamide 6 composite(CF-PA6)were jointed via ultrasonic welding with the assistance of temperature compensation device.The effects of the ultrasonic welding time and temperature compensation on the microstructure and mechanical properties of the joints were investigated.Through analysis of the wettability and fluidity of the molten carbon fiber-reinforced thermoplastic composites(CFRTP),the bonding mechanism and failure path of Al/CFRTP were clarified.The results show that under the conditions of temperature compensation of 220°C and welding time of 1500 ms,the joint strength of the two components reaches 2480.4 N,which is 813.6%higher than that of Al/CFRTP components obtained at room temperature.Overall,temperature compensation prolonged the wetting time of molten CFRTP on the aluminum alloy surface.When the fluidity and wettability were coordinated with each other,a high-quality joint was formed.In addition,the ultrasonic welding process of Al/CFRTP mainly relies on“physical adsorption,”“diffusion effect,”and“mechanical locking effect”to achieve sufficient bonding,and the effect of hydrogen bonding is weak.展开更多
基金Thanks are kindly given to the Scientific and Technological Committee of Sichuan for financial supportWe are also grate-ful for project subsidizing by the Special Funds for Major Basic Research (Contract No. G1999064805) the National Natural Science
文摘In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA), and continuous polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter. The extrudate was drawn at a drawing ratio of 3.1, and then quickly cooled in cold water. The specimens were obtained by injection molding at processing temperatures less than 190℃, far below the melting temperature of PET (265℃) and PA (230℃), which can maintain the solid state of PET and PA microfiber phase in the composites. Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0~20 wt pct PET or PA), and especially, PET and PA were almost deformed into fibers at the concentration of 15 wt pct. Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test results. The most noticeable improvement of the tensile properties occurred at 15 wt pct of PET in PET/PE system, corresponding to the highest microfiber content, where the tensile strength reached 32.5 MPa, whereas only 19.5 MPa for the pure PE.
基金supported by the National Natural Science Foundation of China(Grant Nos.52275360 and 52075360).
文摘5052 Al and carbon fiber-reinforced polyamide 6 composite(CF-PA6)were jointed via ultrasonic welding with the assistance of temperature compensation device.The effects of the ultrasonic welding time and temperature compensation on the microstructure and mechanical properties of the joints were investigated.Through analysis of the wettability and fluidity of the molten carbon fiber-reinforced thermoplastic composites(CFRTP),the bonding mechanism and failure path of Al/CFRTP were clarified.The results show that under the conditions of temperature compensation of 220°C and welding time of 1500 ms,the joint strength of the two components reaches 2480.4 N,which is 813.6%higher than that of Al/CFRTP components obtained at room temperature.Overall,temperature compensation prolonged the wetting time of molten CFRTP on the aluminum alloy surface.When the fluidity and wettability were coordinated with each other,a high-quality joint was formed.In addition,the ultrasonic welding process of Al/CFRTP mainly relies on“physical adsorption,”“diffusion effect,”and“mechanical locking effect”to achieve sufficient bonding,and the effect of hydrogen bonding is weak.
