Tensile properties of fibrous materials in vacuum

Abstract

The changes in tensile properties of nylon, Dacron, Nomex, PBI (polybenzimidazole), X-101 (aromatic polyamide), PRD-14 (polyimide), and glass yarns in vacuum (∼1 × 10 −6 torr) at 70°F after seven to ten day and forty-five day vacuum exposures are presented. The changes in tensile properties of fabrics woven from nylon, Dacron, Nomex, PBI, glass and metal yarns in vacuum at 70°F after vacuum exposures of one to sixty-four hours, and the changes in tensile strengths of 9 16 in wide nylon, Dacron and Nomex tapes in vacuum after seven-day exposures are also given. With several notable exceptions, long-term vacuum exposures generally do not have a considerable effect on the tensile properties of polymeric yarns. The tensile modulus of nylon and X-101 yarn, the rupture elongation of Nomex yarn, and the modulus and rupture elongation of Dacron and PRD-14 yarn in vacuum differ by 10 to 25 per cent from their properties in 14-7 psia, 10°F, 65 per cent RH air. The other tensile properties of these yarns and the properties of PBI yarn in vacuum differ from their properties in air by less than 10 per cent and, in most instances, by less than 5 per cent. The tensile strength of glass yarn in vacuum is as much as 39 per cen t greater and the rupture elongation, 25 per cent greater than in air. Vacuum exposures of one to sixty-four hours also appear to have only a slight effect on the tensile properties of polymeric fabrics. However, glass fabric exhibits up to 45 per cent greater tensile strength in vacuum than in air. The rupture load of 9 16 in wide nylon, Dacron and Nomex tapes is 2 to 7 1 2 per cent greater in vacuum than in air.