Abstract: Through a shearing-drawing two-dimensional stress field applied in a pipe-extrusion die developed by this group, two-dimensional self-reinforcement high density polyethylene (PE-HD) pipe was prepared. The tensile strength, molecule orientation and crystallinity of the pipe were studied. It showed that the two-dimensional stress field improved the molecule orientation and crystallinity, the circular and axial tensile strengths of the pipe were improved simultenously. The best circular and axial tensile strength were 24.52 MPa and 25.82 MPa, increased by 13 % and 14.8%, respectively, based on regular pipe. The crystallinity was increased to 71.95 % and the improvement was 8.2 %. A shish kebab structure was observed.

Key words: high density polyethylene, shearing-drawing two-dimensional compound stress field, two-dimensional self-reinforcement, orientation, crystallinity