Effect of UV irradiation on mechanical properties and structure of poly(1,3,4-oxadiazole) fibers

The accelerated ultraviolet aging behavior of poly(1,3,4-oxadiazole) fibers (POD fibers) exposed to artificial environment for different durations were studied. The influence of ultraviolet light on the intrinsic viscosity, structure, appearance and morphology, mechanical properties of POD fibers were investigated during aging by ATR-FTIR and UV-spectra, XPS, WXRD, SEM and tensile strength tester. The results revealed that the structure and properties of POD fibers were affected by UV light. Tensile strength and breaking elongation of POD fibers were severely decreased after 48 h UV light irradiation, and the change of intrinsic viscosity indicated that only degradation but not crosslink occurred. Disruption of oxadiazole rings and formation of carbonyl and amide were observed. UV aging process in nitrogen atmosphere suggested that the oxygen was indispensable and the essence of POD UV aging was photo-oxidation process. POD was amorphous and the recrystallization on surface was present after UV aging due to degradation. Morphology of POD fiber surface was damaged after UV aging. (C) 2010 Elsevier Ltd. All rights reserved.