Fabrication of Densified Rice Husk by Sequential Hot-Compressed Water Treatment, Blending with Poly(vinyl alcohol), and Hot Pressing

Qianli Wang; Shinji Kudo; Shusaku Asano; Jun-Ichiro Hayashi

doi:10.1021/acsomega.2c03286

Fabrication of Densified Rice Husk by Sequential Hot-Compressed Water Treatment, Blending with Poly(vinyl alcohol), and Hot Pressing

ACS Omega. 2022 Jul 28;7(31):27638-27648. doi: 10.1021/acsomega.2c03286. eCollection 2022 Aug 9.

Authors

Qianli Wang¹, Shinji Kudo^{1

2

3}, Shusaku Asano^{1

2}, Jun-Ichiro Hayashi^{1

2

3}

Affiliations

¹ Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
² Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.
³ Research and Education Center of Green Technologies, Kyushu University, Kasuga, Fukuoka 816-8580, Japan.

Abstract

Processing agricultural wastes into densified materials to partially substitute wooden product production is significant for reducing the consumption of forest resources. This work proposes the fabrication of high-strength rice husk (RH)-based composite materials with poly(vinyl alcohol) (PVA) via densification by hot pressing. RH was pretreated in hot-compressed water (HCW) prior to pulverization and blending with PVA or PVA/glycerol (GL). The incorporation of PVA greatly improved the strength, toughness, and waterproofness of the composite plate, which was discussed with the help of a variety of composite characterizations. The tensile strength, flexural strength, and toughness of a composite of HCW-treated RH, PVA, and GL with a mass ratio of 80:20:2 were 42, 81 MPa, and 5.9 MJ/m³, respectively. The HCW treatment and blending with PVA and GL improved those properties of the hot-pressed original RH plate by factors of 2.5, 2.3, and 6.7, respectively, and reduced the water uptake and swelling ratio in water by 57 and 53%, respectively, despite the hydrophilic nature of PVA and GL. Altogether, this work outlines a valuable and sustainable approach to the efficient utilization of agricultural wastes.