MICROINDENTATION TESTING OF INHOMOGENEOUS MICROSTRUCTURES IN WELDED POLYETHYLENE

A microcomputer controlled microindenter with a flat cylindrical micro indenter face has been used to measure the variation of storage modulu s and loss factor that results from differences in microstructure in h igh density polyethylene (HDPE). The microstructural variations have b een produced by butt welding the polyethylene and varying the thermal histories of the weld. The dynamic mechanical thermal analysis data fr om the microindenter have been compared to similar tests on uniform bu lk material run in bending using a commercial analyzer. The normalizat ion procedure used on the microindenter data was justified by examinin g the calculated stress fields under the indenter tip. The quantities measured using the microindenter are consistent viiith the measured ch anges in crystallinity.