Novel silk/poly(butylene succinate) biocomposites: the effect of short fibre content on their mechanical and thermal properties

In the present study, novel short silk fibre (Bombix mori) reinforced poly(butylene succinate) biocomposites have been fabricated with varying fibre contents by a compression molding method and their mechanical and thermal properties have been studied in terms of tensile and flexural properties, thermal stability, thermal expansion, dynamic mechanical properties, and microscopic observations. The results demonstrate that chopped silk fibres play an important role as reinforcement for improving the mechanical properties of PBS in the present system although raw silk fibres are used without any surface modification normally done to enhance the interfacial adhesion between the natural fibre and the matrix. The tensile and flexural properties of PBS matrix resin are markedly improved with increasing the short fibre content in the composites, showing a maximum value at a fibre loading of 50 wt%. Also, the thermomechanical stability of PBS resin is greatly improved by incorporating reinforcing short silk fibres in the composite matrix, showing much lower linear coefficient of thermal expansion and higher storage modulus than PBS control, respectively. The thermal stability of silk/PBS biocomposites is likely to be intermediate between the PBS matrix and the silk fibre depending on the short fibre content. This work also suggests that use of animal-based natural silk fibres as reinforcement in a natural fibre composite system may be potential for effectively improving the properties and performances of biodegradable polymer matrix resins.