Preparation Of PVC/Graphite/MgO Thermal Conductive Composite Panels By Mechanical Ball Milling And Performance Research

PVC is applied widely in many fields such as chemical production,equipment manufacturing,electronic products,etc.It has a lot of advantages as production quantity is large and comprehensive performance is advantageous.But its thermal conductivity performance is poor.If the thermal conductivity of PVC is improved,it could be used to replace some precious metal and other thermal materials in many fields.Its industrial value is very considerable.The method of this subject is milling PVC and additives(Graphite,MgO)by the mechanical ball milling.Then the flat vulcanizing machine is used to press raw material into shape under a certain hot-pressing temperature and time.Finally the coefficient of thermal conductivity of composite panel is measured by thermal conductivity instrument.The main researches are as follows.(1)As for PVC/MgO panels,the optimized process conditions-MgO is 30%wt,milling time is 50 min,milling speed is 150 r·min-1,hot-pressing temperature is 160?,hot-pressing time is 10 min,hot-pressing pressure is 5 MPa-are found after the orthogonal experiments which are on the basis of single factor experiments.The thermal conductivity of composite panel on the optimized process conditions is 0.7416 W·m-1·K-1 which is almost 5.30 times of pure PVC,and 2.65 times of non-milling composite panel.(2)As for PVC/Graphite panels,the optimized process conditions-graphite is 35%wt,milling time is 80 min,milling speed is 150 r·min-1,hot-pressing temperature is 165?,hot-pressing time is 15 min,hot-pressing pressure is 5 MPa-are found after the orthogonal experiments which are on the basis of single factor experiments.The thermal conductivity of composite panel on the optimized process conditions is 0.8502 W·m-1·K-1 which is 6.07 times of pure PVC,and 2.82 times of non-milling composite panel.(3)As for PVC/Graphite/MgO panels,the optimized process conditions-graphite is 20%wt,MgO is 15%wt,milling time is 80 min,milling speed is 150 r·min'I,hot-pressing temperature is 155?,hot-pressing time is 20 min,hot-pressing pressure is 5 MPa-are found after the orthogonal experiments which are on the basis of single factor experiments.The thermal conductivity of composite panel on the optimized process conditions is 0.8889 W·m-1·K-1 which is 6.34 times of pure PVC,and almost 3 times of non-milling composite panel.In the three methods of preparation of conductive composite panels,the PVC/Graphite/MgO composite panels are the best.(4)The SEM shows that mechanical ball milling can make the effect of packaging PVC and reforming conductive chains evident.And it can improve the quantity of the heat conductive net for improving the thermal conductivity of composite panels remarkably.(5)The test of mechanical properties shows that PVC/MgO composite panels'tensile strength is 48.73 MPa and bend strength is 49.80 MPa.PVC/Graphite composite panels'tensile strength is 39.21 MPa and bend strength is 53.21 MPa.P V C/Graphite/MgO composite panels,tensile strength is 47.39 MPa which is 8MPa more than PVC/Graphite composite panels'and its bend strength is 51.98 MPa which is 2 MPa more than PVC/MgO composite panels'.In the three methods of preparation of conductive composite panels,the mechanical properties of PVC/Graphite/MgO are the best.(6)By mechanical ball milling,the so:ttening point of PVC shrinks from 82.81? to 80.73? and deeomposition temperature shrinks from 287.61? to 281.4?.The softening point and decomposition temperature of the composites have many improvements.PVC/Graphite/MgO panels are the best.The softening point is 88.60? which is 6? higher than PVC's.The decomposition temperature is 305.59? which is 18?higher than PVC's.The results show that as the composite panels have good heat resistance,it broadens the use of PVC materials in industry.