Blister appearance in thermoplastic composites

Abstract

Blisters were observed in thermoplastic composite materials after a thermal shock during the manufacturing process of electronic parts. The aim of this paper is to describe the blister appearance and its mechanism. First, an experimental study is presented about the environmental conditions and the evolution of blister appearance on the specimen, then the mechanism of their formation and propagation in the material is suggested, and finally an attempt is made to explain the origin of the phenomenon. Experiments show that the water content of the material, the time and the temperature of the thermal shock play an important role. Observations made by SEM show the blister progression in the core of the material. A crack is initiated and then propagates on the interface fiber-matrix. After a crack reaches a sufficient length, the internal stress field opens it and a blister appears.