Effects of Liquid Absorption and Swelling on the Permeability of Natural Fiber Fabrics in Liquid Composite Moulding

Liquid composite moulding (LCM) has been successfully used to manufacture natural fiber reinforced composites. Effects of liquid absorption and swelling on the permeability of natural fiber fabrics in LCM were investigated. It shows that the saturated permeability measured in the corn syrup is 23.1%-69.5% smaller than that in the motor oil because of reduced porosity and flow paths caused by liquid absorption and swelling. Based on traditional models by considering the effects of liquid absorption and swelling of jute fibers, a mathematic model was developed to predict the variable permeability during the mold filling. Experimental results demonstrate excellent agreement with the prediction. The effects of flow rate and fiber volume fraction on permeability were also analyzed. It is found that liquid absorption and swelling may dominate the permeation when the flow rate is low while the flow rate may contribute more when it is large. Furthermore, fiber volume fraction is more sensitive to permeability in the syrup than is the case in the motor oil because of the absorption and swelling of natural fibers. (C) 2015 Society of Plastics Engineer