Water uptake and mechanical evolution behavior of carbon fiber reinforced plastic under saline and acidic environments

Abstract

Understanding the mechanical evolution behavior of carbon fiber reinforced plastic (CFRP) under the service environments is necessary for using safety. This paper investigates the water uptake and interlaminar shear strength behavior of CFRP laminates after ageing. Distilled water, 1.0% saline solution and pH ≈ 4.0 ± 0.2 acidic solution were prepared to treat the samples for 12 weeks. Analytical balance was used to investigate the water uptake behavior, and scanning electron microscope (SEM) was used to analyze the environmental damage. Short beam shear tests were performed to evaluate the interlaminar shear strength (ILSS). The experimental results show that saline and acidic solution can reduce the water uptake capacity of CFRP laminate compared with distilled water. Delamination in layer and between layers and fiber-matrix interface debonding were the main environmental damages. After 12 weeks ageing, the ILSS reduction of specimens aged in acidic solution had the largest reduction (21.52%), followed by saline solution (15.65%), and distilled water had the smallest reduction (10.59%). However, there was an increase in ILSS at the early acidic and saline ageing, while a stable in distilled water ageing, which may be a new way to strengthen the CFRP in future. It was also found that the ILSS degraded nonlinearly with the increasing of water uptake of matrix. The results would guide the application of CFRP in engineering filed.