抄録
Effect of preparation conditions of polytetrafluoroethylene-coated glass fiber fabric (PTFE-glass mem-brane) on their structures and durabilities were studied. The observation of PTFE surfaces by a scanning electron microscopy (SEM) revealed that the quenched specimen was smooth while the slowly cooled (at about 1°C/min) specimen had sheaf-like bands and spaces between these banded structures. The crystallinity of PTFE was determined by the differential scanning calorimetry (DSC) and the density gradient method. Results showed that the crystallinity of the quenched specimen was about 30% and that of the slowly cooled specimen was 65%. Tensile strength of the PTFE-glass membrane was independent of the crystallinity of PTFE. However, the retained tensile strength for the slowly cooled specimen with high degree of crystallinity decreased after being immersed in water at 90°C for 14 days. This was because water was easily infiltrated into the surface layer of the slowly cooled specimen as confirmed by measuring the water vapor transmission rate. It was also found that the weight loss of the abraded PTFE-glass membrane increased as the degree of crystallinity of PTFE increased.
