Thermal stability and mechanical behavior of technical bamboo fibers/bio-based polyamide composites

The objective of this research is to tailor composites with continuous bamboo fibers as reinforcement of a bio-based polyamide (RilsanXD). Using mild chemical and mechanical treatment, technical bamboo fibers were extracted from Phyllostachys viridiglaucescens. They have an average diameter of 397 µm. Their average tensile strength is 323 MPa, and their average Young modulus is 26 GPa. Single ply bamboo fibers/polyamide composites were processed. Gravimetric analyses show that polyamide allows mild processing conditions at 200 °C, therefore permitting to make composites without degrading the fibrous reinforcement. Composites composition was determined from peak analyses of the mass derivative curve associated with bamboo situated at 330 °C. Composites with 60 m % of bamboo fibers were prepared and analyzed. SEM images observation of cryo-cuts shows the absence of voids between technical fibers and polyamide matrix. The cohesion in shear was tested by dynamic mechanical analyses. Comparative data recorded on the bio-based polyamide and the 60/40 bamboo fibers/polyamide composite show a significant improvement of the shear glassy modulus which is multiplied by 1.6 at 20 °C. This result is consistent with the continuity of matter between bamboo fibers and polyamide observed by SEM. This effect may be due to a dense network of static hydrogen bonds.