in situ Fibril formation of polyamide-6 （PA6） in isotropic polypropylene （iPP） was first fabricated using a slit die extrusion and hot stretching process. Then the prepared materials were subjected to injection mo...in situ Fibril formation of polyamide-6 （PA6） in isotropic polypropylene （iPP） was first fabricated using a slit die extrusion and hot stretching process. Then the prepared materials were subjected to injection molding in the temperature range higher than the melting temperature of iPP but lower than that of PA6. The obtained injection-molded samples were characterized via scanning electron microscopy （SEM）, differential scanning calorimetry （DSC） and two-dimensional wide- angle X-ray scattering （2D-WAXS）. Mechanical properties were also investigated. The SEM result shows that the optimum fibril formation could be only achieved in the range of 20 wt% to 30 wt% of PA6 content for the studied system. The fibril morphology changes along the sample thickness in the injection-molded bars. The fibril morphology in the skin layer was better than that in the core layer. 2D-WAXS results showed that the orientation of PP decreased with the increase of PA6 content, which indicated that the orientation of PP was confined by PA6 fibrils. Combined consideration of mechanical properties and morphology indicates that only PP/PA6 composites with 20 wt% of PA6 content show better properties because of the better fibril morphology and PP chain orientation.展开更多
A simultaneous increase of both stiffness and extensibility ofpoly（ethylene glycol-co-cyclohexane-1,4-dimethanol terephthalate） （PETG）/polycarbonate （PC） blends prepared through the slit die extrusion-uniaxial c...A simultaneous increase of both stiffness and extensibility ofpoly（ethylene glycol-co-cyclohexane-1,4-dimethanol terephthalate） （PETG）/polycarbonate （PC） blends prepared through the slit die extrusion-uniaxial cold stretching process was observed. The stretched sheets have a unique mechanical character that an increased tensile modulus is accompanied by an increased extensibility with increasing the draw ratio. Especially, a sharp increasing of the extensibility is observed for PETG/PC （70/30 wt%） blends at draw ratios between 8.2 and 20.0, where a nine times increase of extensibility is achieved. The mechanism of stretching-induced superior extensibility is investigated via micrograph observation, rheometry and calorimetric analysis. The observed superior extensibility could be tentatively explained by the bridging effect of the PC microfibrils on the crack development during tensile failure.展开更多
基金This work was supported by the National Natural Science Foundation of China(Nos.50533050,20490220,20404008,and50373030)This work was subsidized by the Special Funds for Major State Basic Research Projects of China(No.2003CB615600)by the Ministry of Education of China(No.20050610030).
文摘in situ Fibril formation of polyamide-6 （PA6） in isotropic polypropylene （iPP） was first fabricated using a slit die extrusion and hot stretching process. Then the prepared materials were subjected to injection molding in the temperature range higher than the melting temperature of iPP but lower than that of PA6. The obtained injection-molded samples were characterized via scanning electron microscopy （SEM）, differential scanning calorimetry （DSC） and two-dimensional wide- angle X-ray scattering （2D-WAXS）. Mechanical properties were also investigated. The SEM result shows that the optimum fibril formation could be only achieved in the range of 20 wt% to 30 wt% of PA6 content for the studied system. The fibril morphology changes along the sample thickness in the injection-molded bars. The fibril morphology in the skin layer was better than that in the core layer. 2D-WAXS results showed that the orientation of PP decreased with the increase of PA6 content, which indicated that the orientation of PP was confined by PA6 fibrils. Combined consideration of mechanical properties and morphology indicates that only PP/PA6 composites with 20 wt% of PA6 content show better properties because of the better fibril morphology and PP chain orientation.
基金supported by the National Natural Science Foundation of China(Nos.50533050,20874064 and 50873063)
文摘A simultaneous increase of both stiffness and extensibility ofpoly（ethylene glycol-co-cyclohexane-1,4-dimethanol terephthalate） （PETG）/polycarbonate （PC） blends prepared through the slit die extrusion-uniaxial cold stretching process was observed. The stretched sheets have a unique mechanical character that an increased tensile modulus is accompanied by an increased extensibility with increasing the draw ratio. Especially, a sharp increasing of the extensibility is observed for PETG/PC （70/30 wt%） blends at draw ratios between 8.2 and 20.0, where a nine times increase of extensibility is achieved. The mechanism of stretching-induced superior extensibility is investigated via micrograph observation, rheometry and calorimetric analysis. The observed superior extensibility could be tentatively explained by the bridging effect of the PC microfibrils on the crack development during tensile failure.
