According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (...According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (UFPR) were introduced,which were prepared through irradiating common rubber lattices and spray drying them. Epoxies toughened with UFPRshowed a much better toughening effect than those with CTBN, and the heat resistance of epoxy was unexpectedly elevated.For polypropylene toughening, UFPR can improve the toughness, stiffness and heat resistance of PP simultaneously. Thesespecial toughening effects overcome the deficiencies in rubber toughening technology and are worth further investigating.展开更多
In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential ...In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential scanning calorimetry（DSC）, wide-angle X-ray diffraction（WAXD）, dynamic mechanical analysis（DMA） and scanning electron microscopy（SEM）. Interestingly, the impact strength of β-PPR/20 EPDM blend annealed at 120 ℃ is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing.展开更多
SiO2 nano particle, through surface modification by silicane coupling agent KH-570, was successfully applied to make nano SiO2/PP composite material by the melt-out blending process with twin-screw extruder. Effects o...SiO2 nano particle, through surface modification by silicane coupling agent KH-570, was successfully applied to make nano SiO2/PP composite material by the melt-out blending process with twin-screw extruder. Effects of nano SiO2on the reinforcing and toughening of PP were studied by analyzing the material impact broken fracture, the crystal structure and the diameter of SiO2nano particle using SEM, XRD and TEM, respectively. Results showed that the impact strength and the tensile strength of nano SiO2/PP composite material were improved apparently; the impact strength of PP was fracture was increased to 67% when the nano SiO2 content was 4%; while the nano SiO2 particle upon surface treatment will impose obvious heterogeneous nucleation function over PP crystal.展开更多
A series of polypropylene（PP）/poly（ethylene-co-propylene） in-reactor alloys with different ethylene contents was prepared through a two-stage polymerization process using a MgCl2/TiCl4/diisobutyl phthalate/phospha...A series of polypropylene（PP）/poly（ethylene-co-propylene） in-reactor alloys with different ethylene contents was prepared through a two-stage polymerization process using a MgCl2/TiCl4/diisobutyl phthalate/phosphate tris-methylphenyl ester catalyst system. The ethylene content, particle shape, fractured surface, and glass-transition temperature（Tg） of the obtained PP in-reactor alloys were characterized by means of nuclear magnetic resonance, scanning electron microscopy（SEM）, and dynamic mechamcal analysis（DMA）. The ethylene content of the PP alloys increased from 2.34% to 26.69% when the propylene/ethylene feed ratio was increased from 66/34 to 54/46（molar ratio）. Morevoer, the increment in ethylene content increased the notched Izod impact strength of the resulting PP alloys. The impact strength of the PP alloy with an ethylene content of 26.69% was 55.8 kJ/m^2, which is 12.7 times that of isotactic polypropylene. The results of DMA and SEM analysis reveal that ethylene-propylene random copolymer（EPR） in the PP alloy has a low Tg of ca. -50℃ and a high interface compatibility with the PP matrix. The excellent impact performance of the PP alloy can be attributed to the uniform dispersal of EPR in the alloy particles and PP matrix.展开更多
基金This work was financially supported by the Special Funds for Major State Basic Research Projects of China (No. G1999064800).
文摘According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (UFPR) were introduced,which were prepared through irradiating common rubber lattices and spray drying them. Epoxies toughened with UFPRshowed a much better toughening effect than those with CTBN, and the heat resistance of epoxy was unexpectedly elevated.For polypropylene toughening, UFPR can improve the toughness, stiffness and heat resistance of PP simultaneously. Thesespecial toughening effects overcome the deficiencies in rubber toughening technology and are worth further investigating.
基金financially supported by the Human Resources and Social Security Department of Hebei ProvinceGuangdong Winner Functional Materials Co.Ltd.the oversea training project for outstanding experts of Hebei Province
文摘In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer（PPR） and ethylene-propylene-diene terpolymer（EPDM） blends was investigated by differential scanning calorimetry（DSC）, wide-angle X-ray diffraction（WAXD）, dynamic mechanical analysis（DMA） and scanning electron microscopy（SEM）. Interestingly, the impact strength of β-PPR/20 EPDM blend annealed at 120 ℃ is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing.
文摘SiO2 nano particle, through surface modification by silicane coupling agent KH-570, was successfully applied to make nano SiO2/PP composite material by the melt-out blending process with twin-screw extruder. Effects of nano SiO2on the reinforcing and toughening of PP were studied by analyzing the material impact broken fracture, the crystal structure and the diameter of SiO2nano particle using SEM, XRD and TEM, respectively. Results showed that the impact strength and the tensile strength of nano SiO2/PP composite material were improved apparently; the impact strength of PP was fracture was increased to 67% when the nano SiO2 content was 4%; while the nano SiO2 particle upon surface treatment will impose obvious heterogeneous nucleation function over PP crystal.
基金Supported by the National Natural Science Foundation of China（No.U1462124）.
文摘A series of polypropylene（PP）/poly（ethylene-co-propylene） in-reactor alloys with different ethylene contents was prepared through a two-stage polymerization process using a MgCl2/TiCl4/diisobutyl phthalate/phosphate tris-methylphenyl ester catalyst system. The ethylene content, particle shape, fractured surface, and glass-transition temperature（Tg） of the obtained PP in-reactor alloys were characterized by means of nuclear magnetic resonance, scanning electron microscopy（SEM）, and dynamic mechamcal analysis（DMA）. The ethylene content of the PP alloys increased from 2.34% to 26.69% when the propylene/ethylene feed ratio was increased from 66/34 to 54/46（molar ratio）. Morevoer, the increment in ethylene content increased the notched Izod impact strength of the resulting PP alloys. The impact strength of the PP alloy with an ethylene content of 26.69% was 55.8 kJ/m^2, which is 12.7 times that of isotactic polypropylene. The results of DMA and SEM analysis reveal that ethylene-propylene random copolymer（EPR） in the PP alloy has a low Tg of ca. -50℃ and a high interface compatibility with the PP matrix. The excellent impact performance of the PP alloy can be attributed to the uniform dispersal of EPR in the alloy particles and PP matrix.
