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本研究工作在国内外首次把聚合物的熔体连续挤出自增强及熔体在收敛流道内的速度与延伸应变速率的分布规律联系起来进行研究。 采用可视化实验观测与理论分析相结合的方法,揭示了楔形收敛流道内与聚合物熔体挤出自增强紧密相关的流场参数(速度与延伸应变速率)的变化规律。接近收敛流道出口端的很窄范围内,熔体所受的延伸应变速率随流向而迅速增大,因而取向分子链最易于结晶。 在流场研究的基础上,采用普通挤出设备并通过控制挤出压力与熔体温度,成功地实现了熔体的连续挤出自增强,由2种HDPE与1种PP制备了厚度1.5mm、宽度20mm的自增强片材以及直径5mm的自增强棒材。经SEM观察、DSC分析、拉伸测试、摩擦测试、显微硬度测试与透光率测试,结果充分显示了本研究制备的自增强片材具有很高的综合性能,尤其是拉伸强度。40MPa机头压力下制备的自增强HDPE片材与PP片材的拉伸强度最高值分别达229.2MPa与288.11MPa(分别为相应普通试样的8.2与8.1倍),它们已超过被称为超高性能工程塑料的液晶聚合物的拉伸强度,比拉伸强度的最高值比高级合金钢的还要高。与普通片材相比,对40EPa机头压力下制备的自增强HDPE片材,沿其挤出方向的摩擦系数低30.7％、耐磨性能提高2.5倍、显微硬度提高1.2倍,其透光率提高达4.6倍。 本研究表?
The research work at home and abroad for the first time the polymer melt extrusion continuous self-enhancement and the melt in the convergent flow velocity and extension of the relationship between strain rate distribution research. By the combination of visual experimental observation and theoretical analysis, the variation law of the flow field parameters (velocity and extension strain rate) closely related to the self-enhancement of polymer melt extrusion in the wedge-shaped convergent flow channel was revealed. Near the convergent flow channel outlet end of the narrow range, the melt suffered elongation rate increases rapidly with the flow, so the orientation of the molecular chain most likely to crystallize. Based on the study of flow field, the continuous extrusion self-reinforcement of the melt was successfully achieved by using ordinary extrusion equipment and controlling the extrusion pressure and melt temperature. Two kinds of HDPE and one kind of PP were used to prepare a 1.5 mm , A self-reinforcing sheet with a width of 20 mm and a self-reinforcing bar with a diameter of 5 mm. The results of SEM observation, DSC analysis, tensile test, friction test, microhardness test and transmittance test show that the self-reinforced sheet prepared in this study has high comprehensive properties, especially tensile strength. The maximum tensile strength of self-reinforced HDPE sheets and PP sheets prepared under 40MPa head pressure were 229.2MPa and 288.11MPa (8.2 and 8.1 times that of the corresponding normal samples, respectively) The tensile strength of the high-performance engineering plastic liquid crystal polymer is higher than the highest tensile strength than the high-grade alloy steel. Compared with ordinary sheet, self-reinforced HDPE sheet prepared under 40EPa head pressure has a low coefficient of friction along the extrusion direction of 30.7%, wear resistance increased by 2.5 times and microhardness increased by 1.2 times, Rate up to 4.6 times. This study table?