Processing and characterization of a new biodegradable composite made of a PHB/V matrix and regenerated cellulosic fibers

In this study, a biodegradable composite consisting of a degradable continuous cellulosic fiber and a degradable polymer matrix - poly(3-hydroxybutytate)-co-poly(3-hydroxyvaletate (PHB/V with 19% HV) - was developed. The composite was processed by impregnating the cellulosic fibers on-line with PHB/V powder in a fluidization chamber. The impregnated roving was then filament wound on a plate and hot-pressed. The resulting unidirectional composite plates were mechanically tested and optically characterized by SEM. The fiber content was 9.9 ± 0.9 vol% by volumetric determination. The fiber content predicted by the rule of mixture for unidirectional composites was 13.8 ± 1.4 vol%. Optical characterization showed that the fiber distribution was homogeneous and a satisfactory wetting of the fibers by the matrix was achieved. Using a blower to remove excess matrix powder during processing increased the fiber content to 26.5 ± 3.3 vol% (volumetric) or 30.0 ± 0.4 vol% (rule of mixture). The tensile strength of (volumetric) the composite parallel to the fiber direction was 128 ± 12 MPa (10 vol% fiber) up to 278 ± 48 MPa (26.5 vol% fiber), compared to 20 MPa for the PHB/V matrix. The Young's modulus was 5.8 ± 0.5 GPa (10 vol% fiber) and reached 11.4 ± 0.14 GPa (26.5 vol% fiber), versus 1 GPa for the matrix.