Thermosetting Behavior and Adhesive Application of Lac Terpene Acid under Solvent-Free Conditions
Abstract
Lac terpene acid (LTA) is frequently discarded as industrial waste due to the significant challenges associated with its high-value utilization. In this work, the waste liquid from shellac saponification to obtain the LTA was investigated, and then the thermal property of LTA was investigated, and its application was developed. It was confirmed that LTA hydroxyl groups oxidize at 150 °C to form aldehydes/ketones, while its solidification at 225 °C primarily results from self-polymerization through esterification, yielding polymeric materials. Therefore, LTA as a high-performance thermosetting adhesive, capable of bonding a wide range of materials, is including metals, glass, wood, and paper. Notably, LTA achieves 12.25 MPa shear strength on metal substrates and demonstrates exceptional stability in harsh environments after heat curing. The study offers a theoretical and practical basis for the development and high-value utilization of LTA also provides a new reference for the study of terpene compounds.