Pseudo-ductile behavior of poly(vinyl alcohol) fiber-reinforced polypropylene

Composites based on two different polypropylene (PP) grades reinforced with poly (vinyl alcohol) (PVA) fibers were prepared by compounding and injection molding. Very high residual fiber length values of up to 2,500 μm were achieved. The impact performance of a PP homopolymer can be improved dramatically by reinforcement with the PVA fibers, even below the glass transition temperature of the matrix. For a high impact PP heterophasic copolymer, the fiber reinforcement interferes with the elastomer toughening. Scanning electron microscopy and X-ray computer-tomography analysis indicate that the specific composite microstructure has very long, entangled fibers and a low fiber matrix interaction allowing for pseudo-ductility. Analysis of the micromechanical deformations by volume strain and acoustic emission measurements during tensile testing supports this hypothesis. POLYM. COMPOS., 40:4067–4078, 2019.