聚烯烃挤塑用新型加工助剂

市场上可以买到的基于二异氰酸酯和多元醇嵌段共聚物（即TPUEs）的热塑性弹性体（TPEs），在线性低密度聚乙烯（LLDPE）的挤塑过程中用来延迟鲨皮斑和粘滑不稳定性。在LLDPE中加入少量TPUE，TPUE在挤塑过程中会在塑模面沉积，将鲨皮斑不稳定性的开始推迟到12-20倍高的挤塑速率。鲨皮斑的推迟也可以在TPUE涂布模头里熔融PE没有滑动的条件下实现。不稳定性延迟的效率取决于加工温度下TPUE的弹性。TPUE是聚乙烯挤塑、吹塑和注塑加工过程中象加工助剂、润滑剂和脱模剂之类的氟化聚合物的低成本的替代物。

Commercially available thermoplastic elastomers （TPEs） based on block copolymers of diisocyanates and polyols （i. e. , TPUEs ） were used to delay sharkskin and stick- slip instabilities in the extrusion of linear low density polyethylene （LLDPE）. When TPUE is added in a small mass fraction to LLDPE,it deposits at the die surface during extursion and may postpone the onset of sharkskin instability to a 12- 20 times higher rate of extrusion. Substantial delay of sharkskon was also achieved under conditions without slip of molten PE inside the die coated by TPUEs. Efficiency to delay the instabilities depends on elasticity of TPUE at processing temperature. The TPUEs could be a cost- effective substitution of fluorinated polymers such as processing aid ,lubricant and release agent in the processing of polyethylene by extrusion ,blow molding ,and injection molding.