Abstract: [Objective] To improve the performance and reduce the costs, the poly(3-hydroxybutyrate-co-4-hydroxybutyrate)(P34HB)was reinforced with wood flour. The optimum ratio of wood flour was determined by experimental research.[Method] Using Chinese white poplar(Populus tomentosa)flours and P34HB as raw materials, the biodegradability composites were prepared by hot pressing method. The structure and properties of the biodegradability composites were characterized by scanning electron microscopy(SEM), differential scanning calorimetry(DSC), thermal gravimetric analysis(TGA), Fourier transform infrared spectroscopy(FTIR),dynamic mechanical analysis(DMA)and mechanical property analysis.[Result] Results show that the tensile strength, breaking elongation and flexural strength of the composite increase firstly and then decrease with the increasing of wood flour, but the impact strength decreases continuously. The tensile strength, elastic modulus and Young's modulus of the composites increase by 89%, 59% and 103%, respectively. The storage modulus E' of the composites is continual increasing with the wood flour content, while the tanδ is decreasing initially and then increasing. The dynamic stiffness of the composite is better than static stiffness,for the higher frequency modulus is greater than the lowerone.Compared with P34HB, the composites show the wider thermal decomposition range, the slower pyrolysis rate and the higher pyrolysis residual mass.[Conclusion] With the increase of wood flour content, the structure of the composites is further dense. The storage modulus and brittleness of the composites increase because of hindering the movement of the molecular chain of bioplastics P34HB by wood flour. At the same time, the transcrystallinity of P34HB with high crystallinity and developed layer structure is developed bywood fibers as nucleating agents,strengthening the interfacial bonding strength between wood flour and P34HB, and obviously improving the mechanical properties and thermal stability of the composites. It is also found that the optimum wood flour content of P34HB/wood flour composite is 50%.

Key words: P34HB, Populus tomentosa wood flour, biocomposite, mechanical properties, thermal performance