Ultrafine full-vulcanized polybutadiene rubber（UFBR） with particle sizes of ca.50―100 nm were used for modifying mechanical and processing performances of polypropylene（PP） with PP-g-maleic anhydride（PP-g-MA） a...Ultrafine full-vulcanized polybutadiene rubber（UFBR） with particle sizes of ca.50―100 nm were used for modifying mechanical and processing performances of polypropylene（PP） with PP-g-maleic anhydride（PP-g-MA） as a compatibilizer for enhancing the interfacial adhesion between the two components.The morphology,dynamical rheology response and mechanical properties of the blends were characterized by means of SEM,rheometer and tensile test,respectively.The results show that the ternary PP/UFBR blends compatibilized with PP-g-MA possess rheological behaviors like highly branched PP,while no obvious strain hardening is observed in its control binary PP/UFBR blends,a low level of PP-g-MA in PP/UFBR blends can even endow the material with rheological characteristics of high melt strength materials like highly branched PP.The enhancement interfacial interaction between the UFBR particles and PP matrix accounting for the rheological behavior of compatibilized blends and effectiveness of PP-g-MA were proposed and proved.展开更多
Foamable high melt strength polypropylene （HMSPP） was prepared by grafting styrene （St） onto polypropylene （PP） and simultaneously introducing poly- dimethylsiloxane （PDMS） through a one-step melt extru- sion ...Foamable high melt strength polypropylene （HMSPP） was prepared by grafting styrene （St） onto polypropylene （PP） and simultaneously introducing poly- dimethylsiloxane （PDMS） through a one-step melt extru- sion process. The effect of PDMS viscosity on the foaming behavior of HMSPP was systematically investigated using supercritical CO2 as the foaming agent. The results show that the addition of PDMS has little effect on the grafting reaction of St and HMSPP exhibits enhanced elastic response and obvious strain hardening effect. Though the CO2 solubility of HMSPP with PDMS （PDMS-HMSPP） is lower than that of HMSPP without PDMS, especially for PDMS with low viscosity, the PDMS-HMSPP foams exhibit narrow cell size distribution and high cell density. The fracture morphology of PDMS-HMSPP shows that PDMS with low viscosity disperses more easily and uniformly in HMSPP matrix, leading to form small domains during the extrusion process. These small domains act as bubble nucleation sites and thus may be responsible for the improved foaming performance of HMSPP.展开更多
As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves...As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves the ductility and the toughness simultaneously under high strength is the miniature of the casting microstructure. In this paper, the Nb which affects the austenite grain miniature is added by 0.00%, 0.03% and 0.06% in this steel and the ingot is manufactured in a vacuum induction melting furnace （VIM）. The casting microstructure and the mechanical property of the maraging steel according to Nb contents are analyzed by conducting the solution annealing and the age hardening after hot rolling. In this result, a specimen containing 0.03% Nb is most miniature. When it does the long time age hardening, the precipitation estimated as the carbide is appeared. The mechanical properties are excellent if a specimen containing 0.06% Nb does the age hardening during 8 h in 482℃.展开更多
基金Supported by the National High Technology Research and Development Program of China(No.2002AA333040)the Special Funds of Science and Technology Bureau of Harbin for Hi-Tech Research,China(No.2007AA4BG140)
文摘Ultrafine full-vulcanized polybutadiene rubber（UFBR） with particle sizes of ca.50―100 nm were used for modifying mechanical and processing performances of polypropylene（PP） with PP-g-maleic anhydride（PP-g-MA） as a compatibilizer for enhancing the interfacial adhesion between the two components.The morphology,dynamical rheology response and mechanical properties of the blends were characterized by means of SEM,rheometer and tensile test,respectively.The results show that the ternary PP/UFBR blends compatibilized with PP-g-MA possess rheological behaviors like highly branched PP,while no obvious strain hardening is observed in its control binary PP/UFBR blends,a low level of PP-g-MA in PP/UFBR blends can even endow the material with rheological characteristics of high melt strength materials like highly branched PP.The enhancement interfacial interaction between the UFBR particles and PP matrix accounting for the rheological behavior of compatibilized blends and effectiveness of PP-g-MA were proposed and proved.
基金Acknowledgements This work was financially supported by National Natural Science Foundation of China （Grant Nos. 21476085 and 21306047）, Fundamental Research Funds for the Central Universities of China （22A201514016 222201314051）.
文摘Foamable high melt strength polypropylene （HMSPP） was prepared by grafting styrene （St） onto polypropylene （PP） and simultaneously introducing poly- dimethylsiloxane （PDMS） through a one-step melt extru- sion process. The effect of PDMS viscosity on the foaming behavior of HMSPP was systematically investigated using supercritical CO2 as the foaming agent. The results show that the addition of PDMS has little effect on the grafting reaction of St and HMSPP exhibits enhanced elastic response and obvious strain hardening effect. Though the CO2 solubility of HMSPP with PDMS （PDMS-HMSPP） is lower than that of HMSPP without PDMS, especially for PDMS with low viscosity, the PDMS-HMSPP foams exhibit narrow cell size distribution and high cell density. The fracture morphology of PDMS-HMSPP shows that PDMS with low viscosity disperses more easily and uniformly in HMSPP matrix, leading to form small domains during the extrusion process. These small domains act as bubble nucleation sites and thus may be responsible for the improved foaming performance of HMSPP.
基金supported by Research Funds from Chosun University,2007.
文摘As the aircraft and aerospace industry and the automobile industry are developed, the demand of reliable materials with high strength and high toughness is steadily increased. The grain miniature method which improves the ductility and the toughness simultaneously under high strength is the miniature of the casting microstructure. In this paper, the Nb which affects the austenite grain miniature is added by 0.00%, 0.03% and 0.06% in this steel and the ingot is manufactured in a vacuum induction melting furnace （VIM）. The casting microstructure and the mechanical property of the maraging steel according to Nb contents are analyzed by conducting the solution annealing and the age hardening after hot rolling. In this result, a specimen containing 0.03% Nb is most miniature. When it does the long time age hardening, the precipitation estimated as the carbide is appeared. The mechanical properties are excellent if a specimen containing 0.06% Nb does the age hardening during 8 h in 482℃.
