Fire-resistant composites based on acrylic-functionalized lignin and polyester resin obtained from waste poly(ethylene terephthalate)

Abstract

This paper investigates the using potential of acryl-functionalized kraft lignin (AKL) in reducing theflammability of polymer composites based on recycled unsaturated polyester resins (UPR). Acryl functionalization ofkraft lignin was performed by direct esterification of free polyphenolic groups with acryloyl chloride, after what, theAKL was blended in UPR resin synthesized from the polyols obtained by catalytic depolymerization of wastepoly(ethylene terephthalate). The AKL was homogenized in UPR resin in different weight ratios: 2.5, 5.0, 7.5, and 12.5wt.%. Structural and dynamic-mechanical characteristics of acryl-functionalized kraft lignin and composites weredetermined using FTIR spectroscopy, dynamic-mechanical analysis (DMA), and tensile tests. The influence offunctionalization and mass fraction of AKL on tensile and thermal properties of UPR resin was studied. The thermalproperties of the composite were tested according to the standard UL-94 method, based on which the highest categoryof heat-resistant materials is a composite with 12.5 wt.% acyl-functionalized lignin.