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

ABSTRACT 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.