Microhardness of extruded high density polyethylene fibers

High-density polyethylene of high tensile modulus has been produced by solid state extrusion using an Instron capillary rheometer. Microhardness measurements on these ultraoriented fibers have been made to assess their perfection from values of the tensile elastic modulus and shear strength. The microhardness tests were measured using a Vickers square diamond. The microhardness increased with the common temperature for crystallization and extrusion, likely due to improvement in the lateral packing of microfibrils. The variation of microhardness with draw ratio is also illustrated.