Preparation Of Toughening Masterbatch And Its Effect On Structure And Properties Of Polypropylene

Polypropylene(PP)is widely used in the fields of automobile,household appliances and daily necessities because of its high stiffness,easy processing,wide source and low price.Homopolymer polypropylene(PPH)has the best degree of regularity and the worst impact resistance compared with that of random polypropylene(PPR)and block polypropylene(PPB).Therefore,the study of PPH strengthening and toughening is of great value.Multi-sequence polypropylene based grafting copolymers(m-PBGC)were prepared by melt grafting of polyolefin elastomer/ high density polyethylene/ homopolypropylene(POE/HDPE/PPH)ternary blends,which can be used as a kind of toughening masterbatch.The impact polypropylene composites were obtained by blending m-PBGC with PPH.POE has a long reactive branching chain,which can be grafted with HDPE and PPH under the initiation of crosslinking agent diisopropyl peroxide and shearing of torque rheometer.There is a weak Van der Waals force or hydrogen bond force between the wafers of PPH spherulites.The toughening agent m-PBGC was blended with PPH in the second step of the torque rheometer.Grafted copolymers can act as a compatibilizer between phases,while POE molecular chains or branched chains of grafted copolymers can insert into PPH lamellar to form the interlocking structures,thus enhancing the molecular force between PPH spherulites.In this paper,the preparation and structure of toughening agent were studied,also the effects of m-PBGC,POE,and HDPE on the properties of PPH were investigated.At the same time,in order to better understand the toughening effect of m-PBGC on structure and properties of PPH,also improve the surface size stability and reduce the cost,the application of PPH/POE/Talc blends and PPH/POE/Talc blends were further discussed.The main contents and results were as follows:m-PBGC is mainly composed of POE,HDPE and PPH.Under the initiation and shearing of DCP,POE and HDPE were successfully grafted onto the PPH molecular skeleton.The results show that polypropylene based grafted copolymers can improve the compatibilization between phases.m-PBGC as dispersed phase distributed in PPH continuous phase,showing typical ductile fracture characteristics,which indicates that m-PBGC has obvious toughening effect on PPH.The impact strength of PPH composites at room and low temperature increased by 132.6% and 161.7%,respectively,and the tensile strength decreased only by 18.7% with 20 wt% content of m-PBGC.Compared with conventional toughening agents POE and HDPE,the toughening effect of m-PBGC at room temperature is higher than that of m-PBGC and HDPE.When the POE content is higher than 15 wt%,the toughening effect is comparable to that of m-PBGC.At low temperature,the toughening effect of m-PBGC is obviously better than that of POE and HDPE.With the increase of m-PBGC content,the toughening effect is more obvious.After adding talcum powder,the overall impact strength of PPH/m-PBGC/Talc blends less than PPH/m-PBGC blends,but the tensile strength finally decreased slightly.The mass fraction of talc powder in the system remained unchanged.When the mass fraction of m-PBGC and POE is 20 wt%,the impact strength of PPH / m-PBGC / Talc blends is comparable to that of PPH/POE/Talc blends at room temperature,but the low temperature impact strength and tensile strength of the former are 46.7% and 12.3% higher than those of the latter,respectively.