Esterified PVA-lignin resin by maleic acid applicable for natural fiber reinforced composites

This article reports an esterified polyvinyl alcohol (PVA)-lignin resin that is applicable for natural fiber reinforced polymer composites. To meet the requirement for the composites, a biopolymer-based resin is necessary, which should well interact with the natural fiber with good waterproof behavior. By mimicking the relationship between cellulose, lignin and hemicellulose in wood, the esterified PVA-lignin resin with maleic acid is provided. The preparation and characterization of the environment-friendly resin are illustrated in this article. 180 °C of esterification reaction temperature and 40% of maleic acid contents are shown to be an optimum condition for the preparation of the resin. The esterified PVA-lignin resin exhibits 13, 31, and 55% increase of its tensile strength, toughness, and failure strength, respectively. The water contact angle of the esterified PVA-lignin resin is improved from 0 to 57°. The prepared resin is originally thermoplastic composite and it turned to be a thermoset resin by the esterification reaction at 180 °C, which is beneficial for composite processing. The developed resin is applicable for environment-friendly and high strength-natural fiber reinforced polymer composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48836.