Economically Competitive Biodegradable PBAT/Lignin Composites: Effect of Lignin Methylation and Compatibilizer

Abstract

In the past 70 years, over 8 billion tons of plastics have been produced, the majority of which cannot be fully biodegraded, causing their fragments to be found everywhere in the biosphere, including living organisms. Herein, a group of biodegradable composites were produced by blending poly­(butylene adipate-co-terephthalate) (PBAT) with technical lignin through a twin-screw extrusion method. Two strategies were developed to improve the mechanical properties of PBAT/lignin composites: (1) modifying lignin via methylation to reduce hydrogen bonding between −OH groups and (2) enhancing the intermolecular interactions between PBAT and lignin by adding maleic anhydride-graft-PBAT as a compatibilizer. The composites obtained from the two strategies with 60 wt % lignin contents exhibited ideal tensile performance which could meet the requirement of the Chinese National Standard for packaging. The interactions between different composite components were investigated by morphological and thermal analyses. The results showed that when lignin is used as filler in the composites, the molecular mobility of lignin and the size of its agglomerates remarkably impacted the ductility and mechanical strength of the PBAT/lignin films. A simple cost comparison between neat PBAT film and PBAT/lignin composite films indicated that the latter was economically competitive, and the production costs could significantly reduce by 36%.

Biobased and Eco-Compatible Beauty Films Coated with Chitin Nanofibrils, Nanolignin and Vitamin E

“…Lignin was reported to have a better compatibility with PBAT, because of specific interactions between aromatic groups, than with poly(lactic acid) (PLA), and thus it was used as a compatibilizer in these blends [42]. Lignin was added to PBAT in several works as a reinforcing agent, and this was explained considering the good interactions occurring between PBAT and lignin [43][44][45]. Moreover, more specifically, lignin was reported to favor PBAT crystallization thanks to nucleation induced by its phenolic rings [46].…”

Recent Advances in the Application of Functionalized Lignin in Value-Added Polymeric Materials

“…The SEM micrographs ( Figure 10 b–d) of the PBAT/lignin composites showed large particles formed by lignin self-aggregation. After methylation, the intermolecular interaction between lignin macromolecules was weakened, and lignin agglomerates seemed to disappear in the PBAT/methylated lignin composites even under the circumstance that lignin became the dominate component (60 wt% methylated lignin) in the composite films ( Figure 10 e–g) [ 67 ]. In fact, alkylation was proven to be an effective method to produce lignin-based thermoplastic blends [ 55 , 56 , 68 ].…”

“… SEM micrographs of lignin (L), methylated lignin (ML) and surface morphologies of ( a ) neat PBTA film and PBTA/L ( w / w ) composite films: ( b ) 60/40, ( c ) 50/50, ( d ) 40/60 and PBTA/ML composite films ( w / w ): ( e ) 60/40, ( f ) 50/50, ( g ) 40/60. Reprinted from [ 67 ] with permission from American Chemical Society © 2020. …”

Facile and scalable fabrication of bioderived flame retardant based on adenine for enhancing fire safety of fully biodegradable PLA/PBAT/TPS ternary blends

“…Controlling white pollution and mitigating the oil crisis have become a consensus and an urgent measure for global sustainable development. Certainly, an effective way solving the current environmental problems is to replace petroleum‐based plastics with biodegradable plastics 1,2 …”