Dimensional stability and deformation analysis under mechanical loading of recycled PET-wood laminated composites with digital image correlation

Abstract

The aim of this study is to investigate the dimensional stability, bending strength and modulus of elasticity at bending of recycled polyethylene terephthalate (PET) layers - wood laminated composites bonded with polyurethane (PU) adhesive and to analyze the deformation behavior with digital image correlation (DIC) during the bending test. The waste beverage bottles were collected from a trash bin and granulated with a cutter. PET layers were obtained by molding the granules at 265 °C under a hydraulic pressure. The composites were prepared with three and five layers of wood veneers and PET layers by using a hydraulic press at room temperature (24 °C) for 4 h. The digital image correlation was conducted to detect the deformation behavior of the composites during the bending test. According to the obtained results, water absorption and thickness swelling decreased with the addition of PET layers. Especially, PET layers outside blocked water absorption of the composites and provided higher resistance to water absorption in the composites when the amount of PET layers was raised. The presence of the PET layers decreased the bending strength and modulus of elasticity at bending of the composites, and the decrease in the bending strength and modulus of elasticity at bending was determined to range from 15% to 30%–46% and 50%, respectively. The mechanical simulation results obtained with the DIC were found to be similar to the results determined with the experimental test. The DIC results processed with open-source 2D digital image correlation MatLab software (NCORR) indicated higher deformation area and more densified stress distribution on the surface of the composites with PET layers.