Fabrication and Nanomechanical Characterization of Thermoplastic Biocomposites Based on Chemically Treated Lignocellulosic Biomass for Surface Engineering Applications

Muhammad Sulaiman,Tanveer Iqbal,Ahmad Shakeel,Hamayoun Mahmood,Saima Yasin

doi:10.3389/fmats.2021.733109

Abstract

Diverse applications of polymeric materials have prompted development of eco-friendly, efficient, and economical materials. These characteristics can be obtained by incorporating appropriate fillers in the polymeric matrix. The objective of this work is to investigate impact of aqueous glycerol (Gly) treated rice husk (RH) on surface mechanical properties of produced biocomposites. RH was treated with aqueous Gly (75 wt%) and compounded with low density polyethylene (LDPE) at different loadings (10, 20, and 30 wt%). The resulting mixture was thermally pressed in molds to fabricate biocomposites. Surface mechanical properties such as elastic modulus, hardness, creep rate, and plasticity of biocomposites reinforced with untreated and treated RH were investigated using nanoindenter. Experimental values depicted that hardness (H) and elastic modulus (Es) of treated biocomposites were higher than untreated ones. Treated biocomposites showed the noticeable improvement in elastic modulus by 24 and 37% compared to untreated biocomposites at 20 wt% loading and neat LDPE, respectively. Reductions in the creep rate by 20 and 14% were observed for untreated and treated biocomposites, respectively, in comparison to the neat LDPE. H/E ratio was increased by 23 and 18% for treated and untreated biocomposites, respectively, as compared to virgin LDPE. Furthermore, mechanical and structural properties of untreated and treated RH are reported based on nanoindentation response and Fourier transform infrared spectroscopy (FTIR) techniques The study indicated that aqueous glycerol pretreatment can partially strip off non-cellulosic constituents from lignocellulose matrix to generate cellulose-rich pulp for engineered composite applications.

Highlights

Polymeric composites reinforced with synthetic fibers such as glass and carbon fibers have been used for various applications including packaging, structural, automobile, construction, and aerospace sectors due to good thermal and mechanical properties (Moha, 2014; Kumar et al, 2010)
Absorption peak was moved to higher wave number from 3,260.2 cm−1 to 3,307.43 cm−1 for pretreated rice husk (RH) that can be indicated the reconstruction of intermolecular hydrogen bonding in cellulose because of reduction in free hydroxyl groups in hemicellulose and lignin
Biocomposites reinforced with treated RH exhibited higher values of hardness and elastic modulus compared to untreated biocomposites due to removal of non-cellulosic impurities (Hf and Biocomposites, 2020)

Summary

Introduction

Polymeric composites reinforced with synthetic fibers such as glass and carbon fibers have been used for various applications including packaging, structural, automobile, construction, and aerospace sectors due to good thermal and mechanical properties (Moha, 2014; Kumar et al, 2010). Depletion of petroleum resources, global warming, environmental pollution, and high cost of the polymeric composites have encouraged the researchers to develop eco-friendly biocomposites (Xu et al, 2018). Biocomposites are fabricated with polymeric material as a matrix phase and lignocellulosic waste (LGW) as a reinforcing phase. Various polymers such as polyester, polypropylene (PP), high density polyethylene, and low density polyethylene (LDPE) are usually used for the composites fabrication (Marzouk et al, 2015). LGW is used as a reinforcing material in polymer matrices because of its good thermal, mechanical, and physical properties (Singh et al, 2002; Kord et al, 2020). LGW has characteristics of renewability, biodegradability, less abrasiveness, non-corrosive, non-toxic, good strength, and low cost (Avérous and Le Digabel, 2006; Lee et al, 2009)

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