Moisture- and freeze-thaw-induced deterioration of natural fiber composites with low fiber contents

Abstract

Social, political, and environmental pressures continue to drive the development of sustainable alternatives to petroleum-based materials. Accordingly, natural fiber composites (NFCs) are being developed and used for a range of low- and high- performance applications, such as packaging, automotive parts, and construction materials. As the use of NFCs become more widespread, there is a rising need to investigate the effect of weathering on this emerging class of materials. Previous studies on the moisture and freeze-thaw induced deterioration of NFCs have focused primarily on composites with high fiber contents (>50% by volume). Due to factors, such as low cost, bio-renewability, and enhanced mechanical properties, most commercially available NFCs maximize the content of natural fibers. However, high fiber contents also increase susceptibility to the deleterious effects of environmental aggressors (e.g., moisture and temperature). Since limited data exists on the durability of low-fiber content NFCs, this study investigates the moisture-induced deterioration of NFCs with low fiber content and explicitly analyzes the added effects due to freezing and thawing. Results from a combination of environmental conditioning and X-ray tomography provide and visual evidence of the effect of moisture-induced damage in low-fiber NFCs. Results also show that this deterioration is exacerbated by below-freezing temperatures. Investigating the response of NFCs to such environmental aggressors as demonstrated in this study provides an evidenced-based approach for material design, which ultimately depends on both the intended application and expected environmental conditions.