The Study On Polypropylene Materials With High Transparency And High Toughness

The matrix resins used in this study are two different grades of polypropylene(T30s,EPD60R).Under the action of twin-screw extruder,the matrix resins are mixed with ethylene-octene copolymer(POE),styrene-ethylene-butylene-styrene block copolymer(SEBS),ethylene-vinyl acetate copolymer(EVA)and low density.Degree polyethylene(LDPE)polymer materials were treated to complete the melt blending operation.The specific results are as follows:(1)According to the results of orthogonal design,the following processing conditions are optimum:injection temperature must reach 205,225,235,and 215 degrees;injection pressure must conform to 25MPa,15MPa,10MPa;injection time must conform to 10s;cooling time must conform to 20s;and packing pressure should conform to 25MPa,15MPa,10MPa.Compliance with 25MPa,45MPa,45MPa;Pressure holding time should not be less than 35s;Injection rate of 35%,25%and 20%,is the best processing method.(2)T30s grade PP was selected as the matrix resin.The results showed that the transparency and mechanical properties of PP/POE,PP/LDPE and PP/EVA blends were better when the contents of POE,LDPE and EVA reached 10phr,5phr and 10phr.(3)For T30s,SEBS can significantly reduce the crystallinity and crystallization temperature of PP/POE,PP/LDPE and PP/EVA materials;SEBS can reduce the grain size and hinder the crystallization of polypropylene;when the content of SEBS reaches the standard of 12phr,it can be judged as the optimum proportion of PP/POE/SEBS(100/10/12)The elongation at break of the blend is high,even up to 420.2%.The tensile strength can reach 21.5MPa,the impact strength at low temperature can reach 22.2kJ/m2,the transmittance is relatively high,and the mist can reach 89.7%and 26.2%.The results show that the mechanical properties of the blend are stronger and the transparency is excellent.(4)For EPD60R PP,the results show that SEBS can reduce the crystallinity and crystallization temperature of the polymer obviously,and reduce the grain size;when the content of SEBS reaches the standard of 80phr,the prepared PP/SEBS has better properties,and the transparency and mechanical properties are relatively good;during this period,the system breaks elongation.The elongation increased to 642.6%and the tensile strength decreased to 14.2MPa,the transmittance increased to 90.2%,the mist decreased to 14.5%,the hardness decreased to 36HD,the impact strength at low temperature increased to 27.2kJ/m2,and the properties of the soft PVC material with 90A hardness were basically similar.