Study On Thermal Stability System And Its Influence On Comprehensive Performance Of PVC

As well known,Polyvinyl chloride(PVC)is a kind of widely used general plastic with a great varieties of production.Due to its sources widely,synthesis method simple,and the price desperately reasonable,the development of PVC come out rapidly.PVC has so many good properties,like good process ability and mechanical properties,excellent chemical stability,and good flame retardant performance.PVC was developed since 1835,and during more than one hundred years of time,its comprehensive performance has improved dramatically.However,at present,the structure factors and defects of PVC in our country has lead to its poor thermal stability and light resistance.In the industrial production,the processing temperature of PVC is between 170 to 180?,therefore in this range of temperature PVC is prone to degradation.The product morphology and performance have been greatly affected.In order to improve the thermal stability of PVC,there are two methods.One is to improve the polymerization process,but there are many uncontrollable factors can affect the experimental results.And the other is to add heat stabilizers to protect PVC.In this paper,the research content was studied in the comparison of the kind and quantity of PVC with four main stabilizers,as liquid organ tin,solid organ tin,calcium and zinc complex,and rare earth stabilizer.The experiment was carries out by thermal aging test box method and TGA method in static and by HAAKE processing rheology method in dynamic.The result shows that,the initial thermal stability and the transparency of the solid organ tin are the best,and the long-term stability and mechanical properties of calcium-zinc compound stabilizer are the best.As well,the static and dynamic thermal stability experimental results are of the same conclusion.As an auxiliary stabilizer,LDHs has little effect in the thermal stability of PVC when used alone,but it can improve the stability with other main stabilizers and flame retardancy of PVC.In order to verify the synergistic effect of LDHs and main stabilizers,the experiment was carried out by solid organ tin and calcium-zinc complex,and three different kinds of LDHs.The result shows that the addition of LDHs has the synergistic effect with main stabilizer in improving the thermal stability of PVC,and the circumference of CO32-in LDHs can has the best effect,and the flame retardant property of PVC can be also improved obviously.Compared with PVC,Chlorinated polyvinyl chloride(CPVC)has a higher mechanical property,chemical stability and flame retardant,smoke suppression performance,which can be long-term used at 100?.However compared with PVC,its processing performance is poor,and the processing range is narrow.When the product melts,the melt viscosity increased rapidly which can lead to degree of degradation of products cannot be processed.Therefore,this paper studies the thermal stability and process ability of CPVC and PVC by adjusting the ratio of CPVC and PVC.The two methods of thermal aging test box and TGA test are used to obtain the same conclusion.The formula of 60/40 is of the best thermal stability,and when used in HAAKE test,it has the best liquidity which is more suitable for processing.In order to verify the stabilizer effects in the stability of PVC,the experiment was studied by adding different kinds of heat stabilizers.The result shows that solid organ tin can effectively inhibit the degradation of CPVC/PVC,and the LDHs has a good thermal stability synergistic effect with solid organ tin,and it enhance the mechanics performance,heat resistance and processing performance itself.