Characterization of dimensional stability in flax fiber reinforced polypropylene composites

Abstract

Flax fibers are a sustainable and high performance reinforcement for polymer composites. Molding polymers and polymer composites nearly always results in warpage or compromised “dimensional stability” of the part. However, there are very few reports on the quantitative analysis of dimensional stability, especially for natural fiber reinforced polymer composites. A systematic study of the dimensional stability of flax fiber reinforced polypropylene (PP) composites is undertaken by measuring the shrinkage of the composites after molding. Shrinkage is directly related to dimensional stability. Using flax fibers decreases part shrinkage or increases dimensional stability. Shrinkage in the molding flow direction is less than shrinkage perpendicular to it, which is shown to be a result of fiber orientation in that direction. Using maleic anhydride modified PP as a coupling agent further decreases the shrinkage. It is found that less shrinkage occurs in composites of higher modulus. POLYM. COMPOS., 40:132–140, 2019. © 2017 Society of Plastics Engineers.