Welding of Plastics (II)

Thermal Effects Studied by the Optical Method

Abstract

In the previous paper, authors described on the advisable conditions of plastic welding. In this paper, authors reported mainly on the heat effects of plastic welding investigated by the optical method and the mechanical test.
Polyvinylchloride specimens as recieved and annealed were previously observed by the photoelasticity test in advance to the charnv impact test at the room temnerature.
The above mentioned tests were also applied to the heat affected zone of welded plastics. According to the results of the experiments, stress relief heat treatment taken place under the sui-table period of time and temperature for polyvinylchloride was effective to relief the weldingstress and the initial stress. Nevertheless, because of the dissolution in the structure ofpolyvinylchloride, the stress reliefed specimens have been shown brittlenees.