Realizing simultaneous toughening and reinforcement in polypropylene blends via solid die-drawing

Abstract

High orientation structure in die-drawing products ensures excellent tensile strength and stiffness along the drawing direction but extremely poor toughness and ductility. Poly (ethylene-co-octene) (POE) was used to toughen orientated polypropylene (PP) prepared by die-drawing. However, the enhancement of toughness is at the expense of stiffness of matrix. To efficiently reserve the stiffness of PP matrix, high density polyethylene (HDPE) as auxiliary modifier, together with network structure through crosslinking and highly orientated structure through die-drawing process were applied. Specially, two different crosslinking strategies namely one-step and two-step crosslinking were compared. The results revealed that the combination of HDPE, POE and crosslinking reaction could realize simultaneous toughening and reinforcement of die-drawing PP blends. The tensile strength, modulus and impact strength of two-step crosslinking PP/POE/HDPE were 88.0 MPa, 1.7 GPa and 42.9 kJ/m2 respectively after die-drawing, nearly three times in strength and even ten times higher in impact strength than raw PP.