Sludge Fiber Waste and Kraft Lignin Powder as Fillers in Polylactic Acid Biocomposites: Physical, Mechanical, and Thermal Properties.

Thiago Souza Da Rosa,Rosilani Trianoski,Franck Michaud,Fábio Yamashita,Setsuo Iwakiri

doi:10.3390/polym13050672

Abstract

In this investigation, sludge fibre waste (SFW) and Kraft lignin powder (KLP) are introduced into polylactic acid (PLA) matrix biocomposites. These alternative materials allow for both the reuse of fibre waste from paper mill sludge and a reduction in the amount of high-cost biopolymer used in the same volume. Proportions from 10 to 40 wt.% of SFW with the addition of 2.5% and 5% of KLP are incorporated in PLA by extrusion and injection moulding. The thermogravimetric properties, water absorption, tensile and flexural properties, and morphology of the fabricated biocomposites were investigated. According to the results, KLP contributes to thermically stabilising the loss resulting from the incorporation of SFW. Flexural and tensile tests reveal a more pronounced decrease in strength with an SFW ratio above 10%. The modulus of elasticity increases significantly with an SFW ratio above 20%. The strength properties are stabilised with the addition of 5% KLP. The addition of KLP presents a tendency to reduce water absorption obtained by the incorporation of SFW into biocomposites. Scanning electron micrographs evidence that KLP improves the interfacial adhesion by reducing the voids between fibres and PLA.

Highlights

IntroductionAround 25% of waste from paper mills stored in sludges is intended for landfilling, land spreading, and composting [2,3,4]
The generation of solid waste from paper mill sludge is increasing and it is estimated that the global waste production ranges between 0.5 and 1.3 million tons per year [1].Around 25% of waste from paper mills stored in sludges is intended for landfilling, land spreading, and composting [2,3,4]
Different types of composite materials are being generated by fibers from sludge fiber waste (SFW), which are lightweight, durable, non-abrasive, renewable, biodegradable, and recyclable products, allowing competition with products, mainly crude-oil derivative-based with less availability or environmental disadvantages [9]

Summary

Introduction

Around 25% of waste from paper mills stored in sludges is intended for landfilling, land spreading, and composting [2,3,4]. Sludge wastes are considered non-hazardous wastes that show high alkalinity and are basically composed of organic matter, mainly cellulose fibers, and inorganic compounds, such as kaolin, talc, and calcium carbonate [3,5,6]. With regards to safety and the environment, the sludge waste from paper mills can be reused with the generation of new higher value-added products, which reduces landfill disposal [7]. Different types of composite materials are being generated by fibers from sludge fiber waste (SFW), which are lightweight, durable, non-abrasive, renewable, biodegradable, and recyclable products, allowing competition with products, mainly crude-oil derivative-based with less availability or environmental disadvantages [9]

Methods

Results

Conclusion