Thermal and Mechanical Properties of Esterified Lignin in Various Polymer Blends

Abstract

Lignin is an abundant polymeric renewable material and thus a promising candidate for incorporation in various commercial thermoplastic polymers. One challenge is to increase the dispersibility of amphiphilic lignin in lipophilic thermoplastic polymers We altered Kraft lignin using widely available and renewable fatty acids, such as oleic acid, yielding more than 8 kg of lignin ester as a light brown powder. SEC showed a molecular weight of 5.8 kDa with a PDI = 3.80, while the Tg of the lignin ester was concluded to 70 °C. Furthermore, the lignin ester was incorporated (20%) into PLA, HDPE, and PP to establish the thermal and mechanical behavior of the blends. DSC and rheological measurements suggest that the lignin ester blends consist of a phase-separated system. The results demonstrate how esterification of lignin allows dispersion in all the evaluated thermoplastic polymers maintaining, to a large extent, the tensile properties of the original material. The impact strength of HDPE and PLA blends show substantial loss upon the addition of the lignin ester. Reconverting the acetic acid side stream into acetic anhydride and reusing the catalyst, the presented methodology can be scaled up to produce a lignin-based substitute to fossil materials.

Thermal, Physical and Mechanical Properties of Poly(Butylene Succinate)/Kenaf Core Fibers Composites Reinforced with Esterified Lignin

“…Pure PBS has the lowest density of 1.26 g/cm 3 among all of the composites produced in this study. After the addition of lignin and KCF, all of the composites displayed a higher density compared to pure PBS, where the highest density of 1.43 g/cm 3 was recorded in the PBS70/L30 sample.…”

“…As one of the main components in lignocellulosic biomasses, lignin is a cheap, readily available and natural substance that has huge potential to be used in bio-based material production [2]. Kraft lignin is mainly found in black liquor, a by-product generated excessively during the paper pulping process and delignification process of both softwoods and hardwoods [3]. Annually, an estimated of 1 million tons of spent pulping liquor were generated by the relevant industries all over the world.…”

A New Family of Renewable Thermosets: Kraft Lignin Poly‐adipates

“…Gioia et al reported the synthesis of an epoxy resinbased on fractionated and subsequently epoxidated KL crosslinked with a polyetheramine. [10] Jawerth et al have investigated the allylation of fractionated KL that allows the reaction with a set of poly-thiols-based crosslinkers to yield materials with tunable mechanical properties. [11] Different esterification strategies to yield thermosets have also been investigated in the production of thermosetting polymers.…”

“…The solid nature of lignin and its poor solubility hinders the direct generation of a prepolymer, that is, an important intermediate for the production of a thermoset. A cross‐linking mixture (CLM) is generally not able to disperse KL sufficiently where usually one or more pretreatment steps are required, for example, KL fractionation, KL pre‐functionalization, use of dispersants such as PEG or solvents [10–18] . Consequently, a synthetic strategy that allows the direct mixing of KL and a CLM to yield a uniform liquid prepolymer would be beneficial.…”

“…A cross-linking mixture (CLM) is generally not able to disperse KL sufficiently where usually one or more pretreatment steps are required, for example, KL fractionation, KL pre-functionalization, use of dispersants such as PEG or solvents. [10][11][12][13][14][15][16][17][18] Consequently, a synthetic strategy that allows the direct mixing of KL and a CLM to yield a uniform liquid prepolymer would be beneficial. The free hydroxyl moieties are the main functional groups on the Kraft lignin chain (approx.…”