Fabrication and characterization of soybean straw and polylactide acid-based hybrid bio-board

Abstract

Biodegradable bio-board is held together by the self-bonding ability of natural fibre rather than by the synthetic resin adhesives used in traditional fibreboard. This provides a promising way to reduce the use and release of toxic substances. However, the hydrophilic characteristic of natural fibres gives bio-board poor water resistance compared to conventional fibreboards. Therefore, the objective of this study was to fabricate a hybrid bio-board in a wet forming process using soybean straw fibre with polylactic acid (PLA) added as a binder at different mass percentages. The effects of applied pressure during fabrication on the mechanical properties, water resistance properties, and wettability of hybrid bio-board were investigated. The thermal stability, spectroscopic characteristics, and morphological properties were also analysed. The addition of PLA weakened the bending strength and tensile strength of the hybrid bio-board made at each of three applied pressure levels. Fortunately, the hybrid bio-board with 10 and 30% PLA contents could maintain a considerable bending strength higher than 35 MPa when made with 8 MPa of applied pressure. The addition of PLA greatly improves the water-resistant performance of the board. Even with only 10% PLA, the water absorption and thickness swelling rates were reduced by more than half. We argue that PLA could be utilized as a latent natural binder to make hybrid bio-board using agricultural straw fibre; however, an environmentally friendly coupling agent is needed to improve the mechanical properties.

Keywords:

• Soybean straw
• hybrid bio-board
• polylactic acid
• wet-forming process
• mechanical properties
• water-resistant performance

Acknowledgments

The authors also acknowledge the support from the EUEL Laboratory of Mie University.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was supported by the Doctor Foundation of Inner Mongolia University of Technology (BS2021031) and the Program for Innovative Research Team in Universities of Inner Mongolia Autonomous Region (NMGIRT2213).