6.1 Processing Aids
6.11 introduction
Processing aids are generally considered to be a class of polymeric additives used in low concentrations to facilitate the melt processing of thermoplastics. Sine processing aids for rigid poly(vinyl chloride)(PVC)were developed in the 1950s, these particular additives allowed far greater use of rigid PVC.Additives are essential topic’s success.PVC without additives is a brittle polymer that will degrade when exposed to heat and longht.PVC degrades at about the same temperature that is requires to process the polymer into useful shapes.Howevere,a real plus for PVC is its ability to accept external modification:thus,an extremely broad spectrum of physical properties can be developed,yielding products ranging from very soft,gel-like products to tough,rigid materials.It is this ability to accept modification that now places PVC just behind polyethylene and polypropylene in total resin production.Just 70 years ago,PVC was an academic curiosity and no apparent practical value until plasticizers were developed in the early 1930s.Plasticizers allowed the PVC resin to be processed at lower temperatures,yielding soft,flexible,rubber-like products.During the 1940s and 1950s,plasticized PVC became a dominant commercial plastic product.The processing improvements of plasticizers without the softening effect on physicalproperties.Many polymer compositions have been patented for this purpose.Hiwevere,over the years,high molecular weigh acrylic polymers,developed in the late 1950s and early 1960s,became Pac’s dominant processing aids[1].

聚氯乙烯无添加剂是一种脆性聚合物降解时会暴露在热和longht.PVC降低大约在同一温度的要求来处理聚合物转化为有用的shapes.Howevere ，一个真正的加聚氯乙烯是能够接受外部修改：因此，一个极其广泛的物理性能可developed ，收益率为产品涵盖范围从非常柔软，凝胶类产品，以坚韧，刚性materials.It这种能力接受改造的地方，现在聚氯乙烯仅次于聚乙烯和聚丙烯树脂production.Just总额70年前，聚氯乙烯是一种学术的好奇心并没有明显的实用价值，直到增塑剂开发在早期1930s.Plasticizers使PVC树脂的加工温度较低，收益率为软的，灵活的，橡胶类products.During 1940年代和1950年代，增塑PVC成为占主导地位的商业塑料product.The处理改善增塑剂没有软化影响physicalproperties.Many聚合物成分已经申请专利的这项purpose.Hiwevere ，多年来，高分子量丙烯酸聚合物，发达国家在20世纪50年代末和60年代初期，成为集团的主要加工助剂[ 1 ] 。

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