jlu高分子材料review课件.pptVIP

8. High performance plastics Question: Give an example of high performance plastics that is able to withstand temperature above 350°C and explain why. PEEK: molecular structure, monomer, polymerization type, and property. 分子结构： 单体： 逐步聚合 9. Polymer processing Extrusion: A continuous process to produce thermoplastics in forms of band…. Compression and heat molding Molding is mainly for the processing of thermosets. Liquid or melted materials are poured into a mold and there “hardened’, i.e., polycondensed or polymerized. Phenol and epoxy resins are processed in this manner, as are styrene, acrylate et al. Injection: A reciprocating screw is used to melt a measured volume of feed. And the melt is rammed into a mold under high pressure by a hydraulically driven thrust of the screw (thermosets). Blow molding: A gas is used to expand a hot preform, against the form of a mold cavity to produce a hollow object. Two process are used for blow molding - injection and extrusion (thermoplastics). Calendering: Molten polymer is compressed in the small gap between two heated cylinders rotating in opposite directions to produce sheets. Coating: Solutions, melts or dispersions are applied to a base. The base may be the polymer, itself, or may consist of different materials. It can remain bound to the polymer used after the process, or it may be removed. Spinning: dry-spinning, wet-spinning, electrospinning Question : Which processes are used for fabrication of the following matters: rubber gloves, plastic film, bottle, isolation sheet for cable, man-made leather, polyester fiber, air balloon, computer shell, throw-away cup, car bumper, coating, and nanofibers ? 10. Electrospinning Question: Please decribe the mechanism of the elelctrospinning process. Is it possible to produce nanotubes, nanocables, nanocomposites by electrospinning? How? 在静电纺丝过程中,将聚合物熔体或溶液加上几千至几万伏的高压静电,从而在毛细管和接地的接收装置间产生一个强大的电场力。由于电场力和表面张力共同作用下，液滴将被拉伸成圆锥状（Taylor锥）。当电场力大于表面张力时，聚合物熔体或溶液经过喷丝板的孔眼后，在电场中被拉伸,最终在