Study On Improving The Thermal Reversible Crossling Density Of PVC And Its Properties

Polyvinyl chloride resin(PVC)is an important polymer raw material with excellent physical and mechanical properties and chemical resistance.However,due to its structural characteristics,PVC hard products have poor impact resistance,and the soft products have low rebound rate and are easily deformed.In order to improve the mechanical and mechanical properties of PVC materials,polyvinyl chloride is often modified by chemical crosslinking.The chemically crosslinked PVC has good mechanical properties,but loses high temperature thermoplasticity and introduces heat reversible.The network can impart good mechanical properties to PVC and retain thermoplastic processing properties.The study of the reaction of dicyclopentadiene dicarboxylate as a crosslinking agent with PVC can form a crosslinked network with thermal reversibility.However,due to the low active chlorine content in the molecular chain of commercial PVC resin,the density of the crosslinked network is low.Material performance improvement is not obvious.Therefore,this research uses acrylate rubber(ACM)as a co-crosslinking component,introduces more active chlorine as a crosslinking reaction site,and forms a co-crosslinked network by esterification with dicyclopentadienoate,in order to improve the performance of the material.The main research work is as follows:(1)The activity of cross-linking reaction between DCPD(COONa)2?DCPD(COO)2Zn cross-linking agent and two soap cross-linked acrylate rubbers was studied.The hot pressing time and hot pressing temperature were studied.The effect of crosslink density.The crosslink density was characterized by gel content and swelling degree.The results showed that the cross-linking activity of acrylate rubber and two dicyclopentadienoate was higher.The appropriate reaction conditions were 180? hot pressing for 30 min.(2)Using acrylate rubber as a co-crosslinking component,DCPD(COO)2Zn or DCPD(COONa)2 was added as a crosslinking agent to polyvinyl chloride to obtain a co-crosslinked PVC material.The composition of the crosslinked network was analyzed by DSC and FTIR,and the formation of the co-crosslinked network was determined.Compared with the PVC without acrylate,the crosslink density of the co-crosslinked PVC increased,and the elongation at break of the material was significantly increased from 20%to 120%,imply that the fracture toughness is significantly improved.(3)The shape memory properties of co-crosslinked PVC materials were studied by classical methods.The results show that the co-crosslinked PVC has excellent shape fixing ability,shape recovery ability and repetitive memory ability;when the recovery temperature is 70?,the recovery time is 300s,the spline recovery rate can reach 95%;The effect of DOP dosage on shape memory performance was investigated.It was found that the shape memory performance of the material was superior when the DOP dosage was 10-15 parts.(4)A spiral spline was proposed to characterize the shape memory recovery of shape memory polymers.For the co-crosslinked PVC shape memory material,the spline is heated to the decrosslinking temperature(180?),plasticized and then wound into a spiral shape,and then cooled and cross-linked to realize the material memory shape from a straight strip shape to a spiral shape.The thermal reversible cross-linking properties of the materials were further verified.The shape memory performance of the spiral spline after secondary molding was investigated.The comparison of the recovery angles of the straight segments by the spiral spline shows that the co-crosslinked PVC has excellent secondary forming properties compared with the reference sample without commercial ACM and the commercial splint material,and the spiral spline produced by the secondary molding has excellent performance.Shape recovery ability.