Prepare Of Transparent PP And Study Of Its Crystallization Behavior

The influences of basic resin, nucleating agents and its content, other agents, extrusion temperature and rotating velocity on the transparency of PP are studied by lab experiment. It is found that the transparency of random polypropylene-ethylene copolymer(RCPP) is better than homopolymer, and the improving of the ethylene content contributes to the transparency. Effect of nucleating agent content of A on the transparency is better than Millida3988. With increasing of nucleating agent content, the haze of PP/A decreases. The transparency is improved by the addition of suspending agent, and it decreased with CaSt. The technologies and batch formula of transparent PP are confirmed. Pilotscale experiment proves that the results of lab experiment have good repeatability. Commercial process of kt/a is carried out.The crystallizing and melting processes, crystal cell arrangement and its transformation, micromorphologies are studied in detail.DSC studies of PP show that both α and β nucleating agent improve crystallization temperature and rate, α-nucleating agent has no effect of melting process and equilibrium melting point. However, P nucleating agent decreases melting point of PP about 10℃.Crystal cell arrangement of PP with nucleating agent is studied by means of WAXS and DSC. It is found that P -PP is formed by addition P -nucleating agent, at the same time crystallization temperature, heating rate, melting temperature and time have great effect on P-α phase conversion of PP during the melting process. The addition of α -nucleating agent contributes to formation of Y phase, and Y phase content improves with the increase of crystallization temperature, nucleating agent content, ethylene content of PP and MFI. Essentially the schematic phase stability diagram of PP explains the effects of crystallization temperature, nucleating agent and the content of ethylene monomer in random copolymer of propylene on crystallization morphology of PP, and the influence of ethylene content on PP crystallization morphology is also proved by the crystallization kinetics.The micromorphology and optical properties of PP with nucleating agent are investigated by means of PLM and haze instrument. It is found that α -nucleating agent make spherulite size of homo-PP and co-PP homogeneous, make haze decrease greatly, and can't change spherulite size of block PP. However, P -nucleating agent make spherulite size of three kinds of PP homogeneous, but haze of PP increases.