Evalutation of In-Plane and Transverse Permeability of Flax Fiber Preforms for Biocomposite Materials

Natural bast fibers, such as flax, hemp, ramie, kenaf, and jute have been investigated as environmentally friendly alternatives to the use of glass fibers as reinforcement in engineered composites over the past couple decades. In general, bast fibers exhibit good mechanical properties, low density, and present less concern with health and safety during handling, but various challenges still remain which prohibits their wide range acceptance for structural composite applications. In this study, a flax fiber preform manufactured using North American oilseed flax crop was analyzed and evaluated for permeability using a newly accepted, analytical approach and compared against known values of permeability for traditional fiberglass preforms. In addition, the relaxation behavior of the flax fiber preforms under pressure was characterized and reported. The in-plane flow front behavior measured in the flax fiber preform was not as uniform or consistent as for the traditional fiberglass preforms. However, based on the permeability values determined, liquid flow through the flax fiber preforms studied was found similar to that of traditional fiberglass preforms. Therefore, the potential exists to use current liquid molding techniques and process simulation software developed for glass fiber composites to manufacture flax fiber reinforced composites.