The work investigated the effect of organic biogenic lignocellulosic filler obtained from coffee production waste on the adhesive properties and residual stresses of epoxy composites. The relevance of this study stems from the growing interest in utilizing renewable secondary raw materials as functional additives for the development of polymeric materials. The adhesive strength at separation and residual stresses were determined using the ASTM separation method, and the mechanism of interfacial interaction was analyzed based on morphological analysis of the fracture surfaces. The polyfunctional nature of the filler was established by the method of IR spectroscopy, due to the presence of hydroxyl –OH (ν = 3425 cm–1), carbonyl C=O (ν = 1655 cm⁻¹) and ether (ν = 1057 cm–1) C–O–C groups, which form a high density of polar centers. It has been established that the introduction of a filler in the amount of 0.50…1.00 wt.% into the epoxy binder ED-20 provides a synergistic effect of the interaction of the ingredients (hydrogen and dipole-dipole interactions), which leads to the transition of the failure mechanism from adhesive to cohesive. At the optimal filler content (0.50…1.00 wt.%), the adhesive strength increases from 24.4 MPa to 34.2 MPa, and the residual stresses decrease by half.
Сапронова et al. (Thu,) studied this question.