Study On Structure And Property Of PP/Compatibilizers/PE Blended System

Polypropylene (PP) and polyethylene (PE) are two important and general resins. PP has asmall specific gravity, abrasion resistance and resistance to stress cracking projecting, goodheat resistance and chemical stability etc. advantages, but it has poor impact resistance in alow temperature. PE has many characteristics of excellent electrical insulation, chemicalresistance, low temperature resistance and good processing mobility etc., but poor heatresistance and ease stress cracking etc. shortcomings are quite prominent. Although themethod by melt blending with the PP and PE can improve the impact resistance of PP andlow-temperature brittleness of PE, because of poor compatibility between PP and PE, thestiffness and strength of the composite material are decreased. So it has a important practicalsignificance for getting good performance of PP/PE composites by further study thecompatibility of PP/PE composite materials.Three different types PE (HDPE, LDPE and LLDPE) are selected to melt and blend withPP. PP/10%LLDPE composite is selected as a compatibilizer substrate by testing andanalysing the prepared samples，and the compatibility of PP/10%LLDPE composite materialis also analyzed and studied with three different type compatibilizers of organicmontmorillonite (OMMT), nano-silica (SiO2) and dicumyl peroxide (DCP).Adding different types and levels of PE can improve flowability and impact properties ofPP in a certain degree, HDPE has good effect to improve the flowability than LDPE andLLDPE, and in terms of impact properties,LLDPE is good than LDPE and HDPE. Vicatsoftening point of PP/HDPE blends has been presented downward trend, while for the PP/LDPE and PP/LLDPE the two blends, the trend showes the first rise and after fall, and atlevels of5%, the two are all has a maximum value. By polarized crystal ball to see: LDPE andLLDPE can improve spherulitic morphology of PP, but HDPEcan not. DSC analysis showesthat: the molecular chains of LLDPE and PP in PP/10%LLDPEcomposite are entangled,make the crystallinity increases. Taking into account the relationship between structure andproperties, select PP/10%LLDPE blends as compatibilizers experimental matrix.For the PP/10%LLDPE/OMMT composite: when the OMMT amount of5%, thecomposite material have a best crystallinity degree and intercalation effect, PP/10%LLDPEand OMMT achieve a optimum compatibility, and the degree of spherulite is best，and theimpact properties of the composites is best in normal temperature reached5.5877KJ/m2in thismoment.But in the low temperature，the impact properties preferably for4.6455KJ/m2in anamount of4%OMMT. However, the amount of OMMT between3%~5%, OMMT has littleeffect on the low-temperature impact performance. And OMMT has little effect on the tensileproperties and heat distortion temperature of the composites. For PP/10%LLDPE/SiO2composite: When the SiO2content of1%, the nano-SiO2relatively uniform disperses in matrix, it greatly improve the crystal morphology andspherulite morphology of the composite material, and the PP βcrystalline formation isinduced by adding a small amount of nano-SiO2.The toughness and heat resistance of thecomposite are improved, impact resistance at room temperature is5.6683KJ/m2, and thebearing temperature achieves at144.3℃. When the amount of SiO2is2%, the tensile strengthand low temperature impact strength reaches maximum at32.84MPa and3.3375KJ/m2respectively. However, considering macroscopic properties and microstructure structure of thecomposite: When SiO2amount of1%, the matrix of PP and LLDPE Capacity best.The results of the reactive compatibilization show that: when the DCP content is0.02%,the degree of crystallinity and spherulite of the composite material is preferably, and the PP βcrystalline formation is induced by adding a small amount of DCP,improving the toughnessof the composite. At room temperature and low temperature, the impact properties ofcomposite materials are best, respectively7.292KJ/m2and2.592KJ/m2. But DCP does notcontribute to the tensile strength and heat distortion temperature of the composite, instead，itcauses a decrease in the tensile properties of the composite.