Sustainable panels design based on modified cassava starch bioadhesives and wood processing byproducts

Abstract

This work was focused on the development of ecofriendly adhesives from cassava starch modified by polycarboxylic acids evaluating their performance in the design of sustainable panels using wood by-products. Additionally, a deep insight on the adhesive-substrate interactions was carried out through ATR-FTIR studies. Bioadhesives were formulated with cassava starch suspensions (5% w/w) modified with the addition of 0?80% (polycarboxylic acid weight /100 g starch) citric acid (CA) or 1,2,3,4 butane-tetracarboxylic acid (BTCA) and loaded with native starch at 5% (w/w) as filler. Formulated adhesives presented a pseudoplastic behavior. Panels were obtained from blends of wood processing byproducts (medium-density fiberboard -MDF) and the formulated bioadhesive by thermo-compression, optimizing the processing conditions. ATR-FTIR and SEM studies revealed the substrate-adhesive interactions and the affinity between the components. The stress values increased with BTCA concentration being 19 MPa for 80%, demonstrating the better cross-linking capacity of this acid compared to CA (11 MPa). Crosslinking and plasticizing effects were occurring in panels containing CA, depending on its concentration, as was confirmed by both puncture assays and contact angle. Thus, it was possible to obtain sustainable panels based on an eco-compatible adhesive, with distinguishable characteristics by tailoring both, the formulations and the processing conditions.