Measurement of crystallinity in polyethylene welds and helical content in polypropylene welds using FTIR-microspectrometry

At the current time there have been few studies on the fundamental changes in polymer chemistry which occur when a thermoplastic undergoes a welding cycle. The techniques described in this paper have been developed to study such changes. The experimental metho4s, using the bands at l894cm and 13O3cm for polyethylene and 998cm and 973cm for polypropylene, have been evaluated using parent materials, and were found to be sufficiently reproducible and accurate to distinguish small changes in crystallinity (polyethylene) and helical content (polypropylene) in weld areas.