Issue 54, 2019

A tough and sustainable fiber-forming material from lignin and waste poly(ethylene terephthalate)

Abstract

In this report we describe repurposing of recycled polyesters as a matrix for lignin-a biorefinery coproduct that is used as a solid fuel and needs to find higher value-to make sustainable high-performance thermoplastic materials. Brittle lignin oligomers, isolated from plant biomass, require a low-melting host polymer matrix to form a rigid and tough renewable material. We demonstrate controlled lignin dispersion and interfacial interactions in softened recycled polyethylene terephthalate (PET) using a simple solvent-free, melt-blending technique. To avoid lignin degradation and devolatilization during melt processing, it was thermally treated. Tall oil fatty acid was used to enable PET processability at low enough temperature to accommodate lignin without charring. Chemical analysis reveals reduction of aliphatic hydroxyl content from 2 mmol g−1 to 1.63 mmol g−1 and an increase of total phenolic hydroxyl moieties from 5.86 to 6.64 mmol g−1 and cleavage of β-O-4 ether linkages due to thermal treatment. Structural transformation of lignin macromolecules during heat treatment was further confirmed by an increase in molar mass and improved thermal stability. Interfacial interactions between lignin and PET were assessed from mechanical properties and thermal analyses. Thermal treatment not only helps to improve the stability of lignin but also slightly reduces the size of the dispersed lignin domains via favored interfacial interactions with the PET matrix. These methods improve mechanical properties of the material. Further, incorporation of lignin in the plasticized PET matrix increases the ductility in the blended products. The method we discuss here utilizes industrial wastes and co-products, and it does not require solvent or toxic chemicals during the reactive extrusion process that yields complete conversion to products.

Graphical abstract: A tough and sustainable fiber-forming material from lignin and waste poly(ethylene terephthalate)

Supplementary files

Article information

Article type
Paper
Submitted
03 Sep 2019
Accepted
18 Sep 2019
First published
01 Oct 2019
This article is Open Access
Creative Commons BY license

RSC Adv., 2019,9, 31202-31211

A tough and sustainable fiber-forming material from lignin and waste poly(ethylene terephthalate)

K. M. Akato, N. A. Nguyen, K. Rajan, D. P. Harper and A. K. Naskar, RSC Adv., 2019, 9, 31202 DOI: 10.1039/C9RA07052D

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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