The Curing And Phase Separation Study On Reactive Plasticizer In Polyvinyl Chloride Matrix

Because of its low price, wide variety of sources of raw materials, a wear-resistant, flame retardant, electrical insulation properties, good chemical resistance and mechanical strength advantages, Polyvinyl chloride (PVC) resin is widely used. However, the processing temperature and decomposition temperature of PVC is very close, and then the thermal decomposition occurs in the process. The diallyl phthalate (DAOP) as a reactive plasticizer of PVC to improve to the processing of PVC, for the initiator of diallyl phthalate (DAOP), taking into account the molding temperature (160℃～190℃) of thermoplastic resin. Therefore, based on the curing reaction and cure kinetics of DAOP/dicumyl peroxide (DCP) system, this paper discussed the rheological properties, mechanical properties, curing reaction and phase separation of the PVC/DAOP/DCP blends system.The studies of DAOP/DCP curing system have shown that, DCP can trigger the free radical polymerization of DAOP monomer in the range of 150℃～180℃, and the dosage of initiator at 3% and the curing temperature at 160℃is appropriate. The DSC method is used to determin the curing process and curing kinetic parameters of DAOP/DCP (3%) system.Using a Huck rheometer, the rheological properties of PVC/DAOP system is studied; the addition of DAOP effectively reduces the processing temperature of PVC and enhances the mobility of system in processing, at the same time, the thermal decomposition of PVC can be effectively prevented. When the DCP exists, the DCP in PVC/DAOP/DCP system is split into two free radicals by heat, that cause the monomer polymerization of DAOP, the tensile strength, flexural strength and Thermal stability are enhanced in varying degrees with the DAOP monomer of system being cured by heating. In the process, the presence of DCP can influence the rheological behavior of system, and there is a certain link between this impact and the content of DAOP.The dynamic mechanical analysis results show that, in the early stage of blending, the PVC/DAOP/DCP system is a homogeneous system, there is only one glass transition temperature and the glass transition temperature is slightly lower than the glass transition temperature of pure PVC system. By polarizing microscope observation, along with the increasing of heat cure time, the same as curing degree rising of DAOP monomer in system, the size of DAOP dispersed particle trends evenly; the aggregation phenomenon of DAOP is also gradually disappeared, and finally, the DAOP particals form uniform small particles which disperse in the matrix phase. The DAOP of system separated from the homogeneous system with the improvement of curing, and this change process is relatively slow.