Wood fibre reinforced polyhydroxyalkanoate (PHA) composites have attracted significant interest as promising new sustainable biocomposites. However, their manufacture can be challenging due to PHA's relatively low thermal stability and melt viscosity. There is currently a lack of understanding of the effect of extrusion processing parameters on the molecular weight of the PHA matrix and, ultimately, on the mechanical properties of the composites. In this study, we show that commercially-relevant mechanical properties of a wood-poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) composite can be achieved through extrusion processing, even at temperatures as high as 190 °C, by adjusting screw speed and feeding rate, and consequently the induced shear rate and residence time. Moreover, the mechanical properties of 40 wt% wood-PHBV were found to be superior to properties previously reported in the literature. Relative to neat PHBV, a 73% increase in modulus and 80% retention of tensile strength was achieved. A Taguchi approach to experimental design was adopted to systematically investigate the effect of extrusion parameters (temperature profile, screw speed, feeding rate, and fibre mixing) on the processing of neat PHBV biopolymer and wood-PHBV composites with wood contents of 10, 20, 30, and 40 wt%. Evaluation of the mechanical performance was conducted through testing of tensile strength, tensile modulus and strain at maximum load. Changes in molecular weight were analysed via gel permeation chromatography (GPC). For both neat PHBV and wood-PHBV composites, molecular weight M_w was found to decrease under high shear stress and long residence time from 550-650 kDa to 350–550 kDa. However, M_w reductions were not enough to result in a decrease of mechanical performance. This discovery is significant for industrial-scale production as it shows that the processing window for wood-PHBV composites is not as narrow as expected, because thermal degradation can be limited by optimising a combination of processing parameters.

木纤维增强的聚羟基链烷酸酯（PHA）复合材料作为有前途的新型可持续生物复合材料引起了广泛的关注。但是，由于PHA的相对较低的热稳定性和熔体粘度，其制造可能具有挑战性。当前缺乏对挤出加工参数对PHA基质的分子量以及最终对复合材料的机械性能的影响的理解。在这项研究中，我们表明木材-聚（羟基丁酸酯-钴羟基戊酸酯）（PHBV）复合材料可以通过挤出加工来实现，即使在高达190°C的温度下，也可以通过调节螺杆速度和进料速率，从而调节剪切速率和停留时间来实现。此外，发现40重量％的木材-PHBV的机械性能优于先前在文献中报道的性能。相对于纯净的PHBV，模量增加了73％，拉伸强度保持了80％。采用Taguchi进行实验设计的方法，系统地研究了挤出参数（温度曲线，螺杆速度，进料速率和纤维混合）对纯净PHBV生物聚合物和木材含量为10、20， 30和40重量％。机械性能的评估是通过测试拉伸强度来进行的，最大负载下的拉伸模量和应变。通过凝胶渗透色谱法（GPC）分析分子量的变化。对于纯PHBV和木质PHBV复合材料，分子量在高剪切应力和较长的停留时间下，M _w从550-650 kDa下降到350-550 kDa。但是，M _w的降低不足以导致机械性能的降低。这一发现对于工业规模生产而言意义重大，因为它表明，木质-PHBV复合材料的加工窗口没有预期的那么窄，因为可以通过优化加工参数的组合来限制热降解。