La(Ⅲ)复合物对LLDPE加工流变性能的影响

LANTHANUM(Ⅲ) COMPOUND ACTS AS PROCESSING AID OF LINEAR LOW DENSITY POLYETHYLENE

用Brabender扭矩塑化仪、HAAKE毛细管流变仪和吹膜机考察了硬脂酸镧与三硬脂酸甘油酯等组成的混和型配合物(LaC)对线型低密度聚乙烯(LLDPE)加工性能的影响。与纯LLDPE相比,加入5%(质量)LaC的体系,在密炼过程最大扭矩减小20.1%,平衡扭矩减小12.5%,塑化能降低17.1%;含该复合物0.25%(质量)的LLDPE仍为假塑性流体,与未含LaC的体系相比,毛细管挤出过程中表观粘度明显降低,非牛顿指数略有增大,在相同剪切速率下粘流活化能轻微减小;相同条件下吹膜时,加入0.25%该复合物,可使主机电流降低达9.2%,又吹膜工艺性能及外观明显改善,对薄膜的力学性能无不良影响。LaC是一种有效的LLDPE加工改性剂。

A mixed complex of trivalent lanthanum stearate with stearin (LaC) was used as a processing aid of linear low density polyethylene (LLDPE) and the efficacy was assessed. Torque rheometry experiments revealed that the incorporation of 5 mass% LaC into LLDPE resulted in 20.1%, 12.5% and 17.1% reduction of maximum torque, equilibrium torque and plasticization energy, respectively. Capillary rheometry examination showed that the LaC considerably improved the rheological properties of LLDPE. The LLDPE whth 0.25 mass% of LaC had a lower apparent viscosity, slightly smaller activation energy for flow than these of LLDPE without LaC had. The blown film extrusion showed that LaC was effective in relieving or eliminating surface roughness and had no harmful effect on the mechanical properties of film. The addition of 0.25% of LaC decreased the extruder current approximately 9.2% under identical extrusion condition. All these improvements demonstrated that LaC is an effective processing aid of LLDPE.