The Degradative Effect of Boiling Water on Polyester Fibres in a PVC-Coated Fabric

Abstract

Polyester-fibre fabrics coated with PVC (poly(vinyl chloride)) are commonly used as architectural tension-structure membranes, but they have a limited lifetime of approximately ten years. Fibre and coating embrittlement occurs, par ticularly in hot, moist environments. In order to elucidate fibre-breakdown pro cesses, coated-fabric samples were subjected to accelerated weathering by boiling in distilled water. Tensile stress-strain characteristics show a progressive embrittle ment of the polyester (poly(ethylene terephthalate)) fibres and coating, confirmed by electron micrographs of fracture morphology. A characteristic "stake-and- socket" fracture is observed after five weeks' exposure, which is marked by the ap pearance of two endothermic DSC (differential scanning calorimeter) peaks. It is proposed that boiling initially increases the crystallinity and brittleness of the polyester fibres before hydrolysis/oxidation leads to disruption of the polyester molecules and a reduction in their crystallinity.