| Due to the excellent comprehensive performance,poly(vinyl chloride)(PVC)is one of the five most commonly used plastics and widely used in building materials,light industry,agriculture field and so on.However,it is prone to degrade and hard to fuse during processing.Hence,the thermal stabilizers and processing aids are necessities especially for the rigid PVC products.Acrylate processing aids(ACR)having a good compatibility with PVC are usually used to promote fusion of PVC in almost all rigid formula and many flexible ones.In this study,Styrene-butyl acrylate-methyl methacrylate copolymer(SACR)as PVC processing aid was prepared by emulsion polymerization.A new SACR ionomer was synthesized with purpose to combine the fusion otion function of ACR with a good compatibility to PVC and the stabilization function of rare earth compounds.At present although the effects of fusion on the rheological properties of PVC melts have been studied,systematic studies have been few and unifying views have not yet been proposed.The influence of entanglement density on the processing properties and rheological behavior was studied in detail by using HAAKE Torque Rheometer and Rotary Rheometer.It was found that the entanglement density of PVC/SACR blends increased with increasing of SACR content.When the entanglement density of the matrix was low as 1.479×1023 m3,PVC resin trended to plastify slowly and the equilibrium time reached more than 5 min,and the entanglement density was high as 2.32×1023 m3,resin particle rupture,primary particle melt to domain particle and molecular chain entanglement with each other took place simultaneously.On further increasing the entanglement density,the fusion disappeared and only equilibrium torque of the matrix was observed.The viscosity slightly increased as the milling temperature and time increased,and hence,G’ increased.The flow activation energy showed a minimum at a shear rate around 100 s-1 and increased with increasing the addition of SACR.The change in these rheological properties with increasing the addition of SACR was caused by a transition from particle flow to uniform molecular chain flow in the mixtirx,leading to higher plasticizing capacity. |
