Compatibilization Of Linear Low Density Polyethylene/Polystyrene/Poly (Ethylene Terephthalate) Ternary Blends And Researchs Of Its Carbon Black Stuffing Conductivity

Linear low density polyethylene（LLDPE）,Polystyrene（PS）,Polyethylene terephthalate（PET）are three kinds of polymers with high dosage.On account of differences of thermodynamic performances,they are incompatible systems.Researchs on compatibilization of them is not only beneficial for recycling of mixed plastics waste,but also useful for establishing of related theories and exploitation of functional composites.In this article,compatibilized master batch with LLDPE-g-PS was prepared by Friedel-Crafts alkylation reaction between LLDPE and PS.Then,the master batch was melt-grafted with glycidyl methacrylate（GMA）for preparing GMA grafted modified compatibilized master batch（hereinafter referred to as GMA modified master batch）,investigating the optimum grafting conditions and composition of GMA modified master batch and its influences on structures and performances of LLDPE/PS/PET（60/20/20,mass ratio,the same below）ternary blends.Furthermore,utilizing the peculiarity of carbon black selectivity dispersing in multi-components systems,carbon black was added into LLDPE/PS/PET（60/20/20）blends,exploring the feature of dispersion of carbon black,influences of GMA modified master batch and mixing methods on conductive performances and mechanical performances of blends.These studies mentioned above are of great significances for compatibilization of multi-components blending systems and preparation of conductive materials composed of multi-components blending systems with low percolation threshold.The specific research results are as follows:1、Under the catalysis of anhydrous aluminum chloride（AlCl₃）,LLDPE and PS can occur grafting reaction and generate LLDPE/PS compatibilized master batch containing LLDPE-g-PS.The best grafting condition was:50phr LLDPE,50phr PS and 0.4phr AlCl₃ was mixed in an internal mixer under 140℃and 60r/min for 4 minutes.The grafting ratio of PS reached 30.7%.2、GMA modified master batch with high GMA relative grafting ratio was be obtained via 0.3phr dicumyl peroxide（DCP）,3phr GMA and 100phr compatibilized master batch mixed in an internal mixer under 180℃and60r/min for 8 minutes.Results of extraction and separation of composition indicated that GMA modified master batch was mainly composed by PS,LLDPE-g-GMA and（LLDPE-g-PS）-g-GMA.3、After adding GMA modified master batch into LLDPE/PS/PET（60/20/20）blends,with the increase of amount of GMA modified master batch,mechanical performances of blends improve evidently,melt flow rate decrease,storage modulus（G’）,loss modulus（G"）and complex viscosity（η*）increase.After extracting and separating of composition,results of infrared analysis showed that（LLDPE-g-PS）-g-PET is produced in compatibilized blends,producing fine compatibilizing effects.Observation of micro-structures showed that particle sizes of minor phase lessen obviously and interfaces between each phase become indistinct in compatibilized blends.4、With the improvement of fluidity of GMA modified master batch,mechanical performances of blends heighten gradually.In high frequency regions,with the rise of fluidity of GMA modified master batch,G’,G"andη*of blends ascend gradually.Photographs of scanning electron microscopy（SEM）showed that particle sizes of dispersed phases lessen significantly and interfaces become indistinct gradually when the fluidity of GMA modified master batch improves.5、Results of solution extraction showed that carbon black selectivity disperses in LLDPE phase.After adding GMA modified master batch into blends,sizes of dispersed phases reduce,generating heterogeneous nucleation effects on LLDPE,enhancing the crystallinity of LLDPE,making for carbon black concentrating in amorphous regions and forming conductive network under low concentration,thus decreasing percolation threshold.Using“two-step mixing”methods to prepare blends is beneficial for GMA modified master batch contacting with PET and reacting,producing more（LLDPE-g-PS）-g-PET,further enhancing heterogeneous nucleation of LLDPE,consequently reducing percolation threshold and strengthening mechanical performances of materials.