The Preparation And Resistivity- Temperature Performance Of Polylactic Acid/Conductive Particles Composites

A series of conductive composites with polylactic acid(PLA)as the polymer matrix and graphene and carbon black(CB)as the conductive fillers were prepared in this thesis.We focused on the preparation and performance study of PLA/different conductive particles composites,the detailed works were as follows:1.The crystal structure and phase transition behavior of PLLA/Graphene/AmimCl composites prepared by solution precipitation method were investigated.The results showed that the crystal structure of PLLA/Graphene/AmimCl composites was the α′ phase of PLLA.And PLLA/Graphene/AmimCl composites suffered from α′-α phase transition during the heating process.The addition of Graphene/AmimCl could improve the activity ability and crystallization rate of PLLA,which could be used as nucleating agent and plasticizer simultaneously.2.PLLA/Graphene composites with PLLA as polymer matrix and graphene prapared by ball milling as conductive filler were prepared by solution casting method,focusing on various performance studies of PLLA/Graphene composites.The results indicated that graphene could be uesd as a heterogeneous nucleating agent which improved the crystallization behavior of PLLA effectively.The tensile strength and young’s modulus of PLLA/graphene composites increased with the increasing amount of graphene,while the elongation at break of PLLA/graphene composites first increased then showed a downward trend with the increase of graphene.The reason was that the graphene dispersed in PLLA exists a critical value.The thermal stability and electric properties of PLLA/graphene composites improved with the increase of graphene content.3.PLLA/CB conductive composites with PLLA as polymer matrix and CB as conductive filler were prepared by melt-compounding,focusing on the resistivitytemperature performance study of PLLA/CB conductive composites.The results indicated that the resistivity-temperature performance of PLLA/CB composites showed a positive temperature coefficient(PTC)effect,namely the resistivity ofPLLA/CB composites increased as the temperature rised.However,the PTC intensity of PLLA/CB composites was small.To solve the problem of low PTC intensity of PLLA/CB composites,we introduced the nucleating agent of PLLA(sebacate benzoyl hydrazine,TMC-300),and discussed the effects of TMC-300 on the resistivitytemperature performance of polylactic acid based PTC composites.The results showed that the addtion of TMC-300 could improve the PTC intensity of polylactic acid based PTC composites effectively.