Preparing And Properties Of Thermal Conductive Polypropylene/High Density Polyethylene/Polyolefin Elastomer-based Polymer Composites

The polymer materials has favorable mechanical properties,processing ability and strong plasticity. The conduction ability of polymermaterials could be improved by adding thermal conductive fillers.Firstly, in this paper, analysis had been done on the effect of extruder,high density polyethylene (HDPE) and polyolefin elastomer (POE) on themechanical properties and microstructure of composites. The resultsshowed that the non-twin screw extruder (NTSE) has better distributiveability and dispersive ability, HDPE and POE have a certain synergistictoughening effect on PP. When the weight ratio of PP/HDPE/POE is68/17/15, the blend has the best comprehensive performance.Then, analysis were carried out on the effect of graphite fillingcontent, graphite particle size, surface treatment process of fillers, screwspeed and processing equipment on composites performance. The resultsindicated that the stiffness, strength and thermal stability were graduallyincreased with increasing graphite content，while the toughness andprocessing liquidity were decreased. The composite reaches percolationthreshold value at30%weight ratio of graphite filler, the thermalconduction reaches1.6053W (m K)1at50%graphite content, which wassix times more than the pure plastic materials. The thermal stability ofcomposite was improved with larger graphite particle size, themechanical properties was the best when the particle size was15μm. Thethermal conduction of composite was higher when the graphite particlesize was15μm or greater（150μm）. The mechanical properties andprocessing liquidity of carbon fiber filled composite with silane couplingagents KH-550modification were improved greatly. Moreover, wetprocess modified filler was obviously superior to dry methodmodification. The NTSE has better mixing ability than traditional twinscrew extruder (TSE). From36r·min-1to60r·min-1main screw speed, thefiller dispersive effect and mechanical properties of composite were thebest at48r min-1screw speed in NTSE.Finally, with mechanical properties,MFR,TG,DSC,Vicat SofteningTemperature, morphology and thermal conductivity to characterizematerial properties, this paper further prepared multiple filler composite filling of thermal conductive polymer materials. The results revealthat the thermal stability of composite filler filled composite materialsimproved a lot, but the processing liquidity is reduced. When the weightratio of150μm,30μm and7.5μm graphite was1/1/1, the mechanicalstrength, stiffness of composite materials and processing flowperformance are the best; When particle size ratio is1/1.5/2.5, tensiletoughness and impact toughness of the composite materials is the best;When the carbon fiber filled with150μm,30μm graphite respectively,the impact strength and elongation at break increased greatly. Compositefiller filled composite materials show better mechanical properties andprocessing fluidity in NTSE, its thermal stability performance is alsobetter,the composite filler dispersion is better.