Effect of gas diffusion on creep behavior of polycarbonate

Biaxial tension‐tension creep experiments were performed to study the effect of gas diffusion on creep behavior of polycarbonate. Experiments were conducted on a thin‐walled tubular specimen by applying both gas pressure and axial tension at room temperature, and measuring axial strain and gas absorption. Experiments were performed with helium, nitrogen, air, carbon dioxide and Freon‐22 Registered trademark, E. I. duPont de Nemours Co., Inc. . It was found that the creep deformation was highly affected by the solubility controlled gases, carbon dioxide and Freon. The absorption measurements showed that the gas absorption behavior was clearly affected by the creep deformation of the material. Also an anomalous diffusion‐type behavior appeared even in permanent gas‐polymer systems under creep conditions. The modified superposition principle satisfactorily predicted the recovery following creep. The axial creep for the biaxial tension‐tension experiments was also computed from data previously reported for creep under combined tension and torsion of a different sample of polycarbonate.