Preparation And Properties Of Toughened PVC Electrical Bushing Composites

As an electrical casing material,polyvinyl chloride（PVC）has the advantages of good electrical insulation,good flame retardancy and high strength,but it also has disadvantages such as high brittleness and poor toughness.Therefore,a kind of PVC with good toughness and low cost is developed for electrical casing.became the primary goal of this study.Firstly,acrylate rubber（ACM）and chlorinated polyethylene（CPE）were used to modify PVC respectively,and the most cost-effective formula was selected as the basic formula A;Then,on the basis of formula A,rigid body nano calcium carbonate（nano-CaCO₃）and elastomer butyl acrylate/methyl methacrylate/butadiene terpolymer（AMB）were added for modification respectively;The toughening agent is compounded,and the formula with the best comprehensive performance is obtained through the orthogonal experiment.In this study,the impact properties,tensile properties,processing rheology,dynamic thermomechanical properties（DMA）,etc.of the samples were characterized,and the microscopic cross-sectional morphologies of the samples were observed by scanning electron microscopy（SEM）.（1）First,the toughening agents ACM and CPE are used to modify PVC respectively.The results show that the toughness of ACM to PVC is greatly improved.When the amount of ACM is 12phr,the impact strength at room temperature is 13.14KJ/m²,which is2.4 times higher than that of pure PVC;the dosage is At 10phr,the low temperature impact strength is 8.19KJ/m²,which is 2.3 times higher than that of pure PVC.The processing rheology results show that the toughener can promote the melt plasticization of PVC.The SEM results showed that the fracture surface of the toughened material was rougher,and the toughening agent had good compatibility with the matrix.The DMA results show that ACM can lower the glass transition temperature of the system more.After comprehensive comparison,it is found that the system has the highest cost performance when ACM is added to 10phr,so the formula when ACM is 10phr is used as the basic formula A in the following two chapters.（2）On the basis of formula A,nano-CaCO₃was modified as a variable.When nano-CaCO₃was added with 2phr,the impact strength at room temperature reached15.06KJ/m²,which was 2.7 times higher than that of pure PVC and 16%higher than that of formula a;The impact strength at low temperature reaches 8.64KJ/m²,which is 2.5times higher than that of pure PVC and 5%higher than that of formula a.The results of processing rheology showed that nano-CaCO₃could promote the melting and plasticization of PVC.DMA results showed that nano-CaCO₃could slightly increase the glass transition temperature of formula A.（3）On the basis of formula A,modified with AMB as variable,When the amount of AMB was 9 phr,the impact strength at room temperature reached 23.42KJ/m²,which was4.2 times higher than that of pure PVC and 1.8 times higher than that of formula a;The low-temperature impact strength is 14.47KJ/m²,4 times higher than that of pure PVC and1.8 times higher than that of formula a.The results of processing rheology showed that AMB could promote the melting and plasticization of PVC.SEM results show that PVC,ACM and AMB have good compatibility,and there are ductile fracture characteristics at the impact section.DMA results showed that AMB could reduce the glass transition temperature of formula A.（4）Finally,three factors and five levels of ACM,nano-CaCO₃,and AMB were set to conduct orthogonal experiments,and PVC/ACM/nano-CaCO₃/AMB composites were prepared,and the range analysis of the impact strength of the samples was carried out.The formula with the best impact strength at room temperature and low temperature is:PVC/ACM/nano-CaCO₃/AMB=100/10/3/9.In order to verify this result,a series of formulas were designed with ACM and nano-CaCO₃as the quantitative and AMB as the variable.When the amount of AMB was 9 phr,the impact strength at room temperature was 27.64KJ/m²,which was 5 times higher than that of pure PVC;the impact strength at low temperature was It is 14.91KJ/m²,which is 4.1 times higher than that of pure PVC.DMA results show that adding AMB can lower the glass transition temperature of the system.