Study On Performance Of Wollastonite/Linear Low Density Polyethylene And Polypropylene Composite

As a thermoplastic synthetic resin with excellent properties,Polypropylene（PP）has been widely used in production and life.However,the toughness of PP is poor,and the disadvantage of low temperature brittleness severely limits the application range of PP which its toughness is poor.PP-g-MAH wrap wollastonite/linear low density polyethylene（LLDPE）/polypropylene（PP）composites were prepared by melt blending in order to improve PP toughness while improving other properties.The main research work is as follows:（1）LLDPE and PP were melt-blended to prepare LLDPE/PP plastic alloys.The effects of various conditions including changes of LLDPE content in LLDPE/PP system,the difference in particle size between LLDPE and PP,the rotation speed of the host and feeder of the twin-screw extruder and temperature of liquation were investigated for the mechanical properties of LLDPE/PP plastic alloys.In addition,XRD,melt flow rate and Vicat softening point characterization were used to assist in explaining the changes in the mechanical properties of LLDPE/PP.The results show that when LLDPE and PP are similar in size,the LLDPE/PP plastic alloy contains 20 wt%of LLDPE,the ratio of the speed of the main machine to the feeder is 12:6,the head temperature during melt extrusion is 190℃,the temperature at the zone to zone five is:190℃,220℃,220℃,225℃,220℃,and the room temperature impact strength increased to 12.59 kJ·m^-2,its low temperature impact strength can increase to 5.2 kJ·m^-2,its bending strength can drop to 24 MPa,and its tensile strength can decrease to 21.55 MPa.（2）The inorganic rigid particle wollastonite was selected as the filler.The effect of wollastonite in wollastonite/LLDPE/PP system on the properties of wollastonite/LLDPE/PP composites was investigated.By the test of mechanical properties and SEM,the results of characterization analysis show that when the wollastonite/LLDPE/PP mass ratio is 30/20/80,the room temperature impact strength of the modified product rises to 18.55 kJ·m^-2and the low temperature impact strength increases to 7.59 kJ·m.^-2.Meanwhile,the bending strength was increased to 49 MPa and the tensile strength was 23.28 MPa.（3）The compatibility of wollastonite/LLDPE/PP composites was explored using two methods:wrought-out wollastonite/LLDPE/PP composites and wollastonite/LLDPE/PP composites with compatibilizers.Measured by mechanical properties,SEM,polarized light microscope,melt flow rate,water contact angle,XRD,DSC,TG,film expansion ratio and other methods,the results show that the method of secondary extrusion of wollastonite/LLDPE/PP composite material not only fails to solve the compatibility problem of wollastonite/LLDPE/PP composite material,but also causes its original excellent mechanical properties to decline,even other performance is also severely impaired.So this method cannot be used to improve the internal compatibility of wollastonite/LLDPE/PP composites;when wollastonite coated with a compatibilizer PP-g-MAH is added and the ratio of PP-g-MAH/wollastonite is 0.4,the internal compatibility and high-temperature thermal stability of wollastonite/LLDPE/PP composites are well adjusted,and the room temperature impact strength reaches the level of PP.5.46 times,the impact strength at low temperature reached 14.44 times that of PP,the bending strength increased by 16 MPa compared with PP,and the tensile strength was almost the same as that of PP,which proved that this method is extremely beneficial to improve the comprehensive performance of composite materials.Especially in the case of improved low-temperature performance,the high-temperature resistance also rises significantly,which greatly broadens the application space of the material.