Lateral Compression Behavior of High-Strength and High-Elastic-Modulus Fibers and Influence of Environment

Abstract

In this paper, we describe the quasi-static lateral compression tests of high-strength, high-elastic-modulus fibers. The fibers examined were γ-alumina fiber (Altex) by Sumitomo Chemical Co., Ltd., two types of carbon fibers by Mitsubishi Rayon Co., Ltd., and four types of aramid fibers by Du Pont and Teijin Ltd. Special attention was paid to environmental influences such as water absorption and electron or ultraviolet radiation on the lateral compression behavior of aramid fibers. A specially designed testing machine (load range:0.1mN-5N, accuracy:0.02mN) that enables mechanical testing, including fatigue of microelements, was employed. Using the testing machine, lateral compression of fibers whose diameter ranged from 7 to 17 μm was achieved with sufficient precision. The transverse compression behavior of carbon fibers and alumina fiber exhibited brittle nature:most of the load-displacement curve followed the elastic deformation, with a final catastrophic fracture into small pieces. However, that of the aramid fibers showed a more ductile nature:the very early stage of the load-displacement curve was elastic, and the rest was plastic. The final catastrophic fracture observed in ceramic and carbon fibers did not occur with a large amount of plastic deformation. The influence of electron radiation on the transverse elastic modulus of aramid fibers was not observed. However, water absorption or ultraviolet radiation lowered the transverse elastic modulus. The fiber surface was closely examined using an atomic force microscope, and the influence of environment on surface degradation and deformation behavior is discussed.