Morphology and Mechanical Properties of Crosslinked PE/PE Composite Materials

Novel peroxide-crosslinked composite materials based on ultra high molecular weight polyethylene fibers were studied in comparison with their non-crosslinked homologues. Two material types were prepared, either by embedding the fibers in a low-density polyethylene matrix, or by compacting neat fibers. The resulting composites were analyzed by differential scanning calorimetry, focusing on the typical double-melting endotherm of the PE fibers, and by X-ray diffraction, concentrating on the characteristic weak 010 reflection of the triclinic phase in the fiber. Mechanical testing of unidirectional composites showed crosslinking to be highly advantageous, yielding significant property enhancement, e.g., increasing the flexural modulus from 28 to 33 GPa in the compacted fiber composite. The advantage results from the crosslinking mechanism, entailing only partial melting that is confined to the fiber skin, while retaining a significant degree of crystallinity in the fiber.