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.

Recent Research Progress on Lignin-Derived Resins for Natural Fiber Composite Applications

“…It decreased after that due to the decreasing pore size of the PEO-lignin blend resin. Recently, Ko et al [ 34 ] have prepared the esterified PVA-lignin-maleic acid (EPLM) resin by the mixing of maleic acid (MA) from 0 to 50 wt% with PVA and lignin (1:1 ratios) as shown in Figure 5 c. They optimized the esterified temperature of reaction 180 °C to better mechanical properties and found that the –OH peak at 3490 cm −1 was merged with the –OH peak of PVA-lignin resin. Moreover, the thermal stability of EPLM resin was slightly higher, around 240 °C at 20 wt% of MA, than the PVA-lignin resin (230 °C) [ 35 ], but when the weight ratios of MA increased from 20 to 50 wt%, the thermal stability decreased due to the non-reacting content of MA.…”

“…Bio-based thermoplastic and thermoset polymers are gaining attraction due to their biodegradability and environmental concern that can replace petroleum feedstock-based products [ 32 , 33 ]. Until now, several studies have described the use of lignin in biothermoplastics, including biocomposites due to its modifications possibility, availability, biodegradability, and good mechanical properties [ 6 , 34 , 35 ]. However, much less research progress has been made on the lignin, VN, and DVN-based thermoset resins compared to the thermoplastics.…”

“…However, much less research progress has been made on the lignin, VN, and DVN-based thermoset resins compared to the thermoplastics. In engineering fields, thermoset resins are generally used in electronic components, adhesive, aircraft industry, and automotive because of their high strength, high modulus, good durability, good thermal stability, and chemical resistance [ 34 , 36 ]. Thermoset resins have a wide range of properties that depend on the curing cycle, hardener, and the proportions of hardener used during the preparation of thermoset resins [ 8 ].…”

Modification of the wood‐plastic composite for enhancement of formaldehyde clearance and the 3D printing application

“…Natural fiber materials mainly refer to materials containing cellulose, which is the most abundant form of renewable natural resources 19 . Cellulose is a polysaccharide composed of cellobiose which is linked with each other by β‐1,4‐glycosidic bond to form a long molecular chain 20 .…”

“…The presence of plenty of hydroxyl groups distribute on the surface of cellulose contributes to the adsorption performance, 3 and meanwhile provides the possibility of functional modification reactions, 21 such as esterification, etherification, graft copolymerization, and oxidation. In recent years, the natural fiber composite materials have also emerged and benefit in terms of positive environmental impact, such as recyclability, renewability, and biodegradability 19 . Among them, composite materials prepared by blending natural plant fibers with biodegradable polylactic acid (PLA) have become commonly used 3D printing green materials.…”