Warm Isostatic Pressing Forming Process and Performance of Ultrahigh Molecular Weight Polyethylene

The ultrahigh molecular weight polyethylene(UHMWPE)parts with a diameter of 120 mm and a height of 105 mm were prepared via soft mold warm isostatic pressing method,and the impacts of pressure on mechanical properties were investigated.By using Scanning Electron Microscope(SEM),X-Ray Diffraction(XRD)and Differential Scanning Calorimetry(DSC),the differences of crystallinity under different molding pressures were studied.Results indicate that high pressure is more conductive to improve the crystallinity.UHMWPE samples crystallized under pressure of 160 MPa are shown to have a melting point of 143.0 ℃,a lamellar thickness of 123 nm and a crystallinity of 69.39%.The increase of stable crystal structure and lamellar thickness may contribute to the increase of melting point.Pressure applied to the UHMWPE powder is the same in all directions during pressing,thus the molding products show great mechanical properties.The UHMWPE molded under pressure of 160 MPa has a tensile strength of36.8 MPa,notched impact strength of 152.3kJ/m^2 and elongation at break of 634%.Feasibility of the warm isostatic pressing method applied on UHMWPE molding indicates a potential application on the industrial preparation of UHMWPE products.