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. 2024 Mar 8;9(11):13100-13111.
doi: 10.1021/acsomega.3c09583. eCollection 2024 Mar 19.

Valorization of Agricultural Rice Straw as a Sustainable Feedstock for Rigid Polyurethane/Polyisocyanurate Foam Production

Roger G Dingcong Jr  1 , Mary Ann N Ahalajal  2 , Leanne Christie C Mendija  3 , Rosal Jane G Ruda-Bayor  3 , Felrose P Maravillas  2   4 , Applegen I Cavero  2   5 , Evalyn Joy C Cea  2 , Kaye Junelle M Pantaleon  3 , Kassandra Jayza Gift D Tejas  1 , Edison A Limbaga  3 , Gerard G Dumancas  6 , Roberto M Malaluan  1   7 , Arnold A Lubguban  1   7
Affiliations

Valorization of Agricultural Rice Straw as a Sustainable Feedstock for Rigid Polyurethane/Polyisocyanurate Foam Production

Roger G Dingcong Jr et al. ACS Omega. .

Abstract

Agricultural rice straw (RS), often discarded as waste in farmlands, represents a vast and underutilized resource. This study explores the valorization of RS as a potential feedstock for rigid polyurethane/polyisocyanurate foam (RPUF) production. The process begins with the liquefaction of RS to create an RS-based polyol, which is then used in a modified foam formulation to prepare RPUFs. The resulting RPUF samples were comprehensively characterized according to their physical, mechanical, and thermal properties. The results demonstrated that up to 50% by weight of petroleum-based polyol can be substituted with RS-based polyol to produce a highly functional RPUF. The obtained foams exhibited a notably low apparent density of 18-24 kg/m3, exceptional thermal conductivity ranging from 0.031-0.041 W/m-K, and a high compressive strength exceeding 250 kPa. This study underlines the potential of the undervalued agricultural RS as a green alternative to petroleum-based feedstocks to produce a high-value RPUF. Additionally, the findings contribute to the sustainable utilization of abundant agricultural waste while offering an eco-friendly option for various applications, including construction materials and insulation.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
Major components of lignocellulosic biomasses include (a) cellulose, (b) hemicellulose, and (c) lignin.
Figure 2
Figure 2
General polyurethane formation mechanism via the reaction of polyol and polyisocyanate.
Figure 3
Figure 3
General reaction mechanism for an acid-catalyzed liquefaction of lignocellulosic biomass; (a) cellulose, (b) hemicellulose, and (c) lignin in polyhydric glycerol.
Figure 4
Figure 4
FTIR analysis of RS-biomass, RS-based polyol, and petrochemical polyol (Voranol 490).
Figure 5
Figure 5
1H NMR spectra of RS-based polyol reveal its chemical features.
Figure 6
Figure 6
FTIR analysis of the prepared RPUFs at different RS-based polyol weight percent replacement (e.g., 0%, 10%, 20%, 30%, and 50%); (a) FTIR spectra from 4000 to 2500 cm–1 and (b) FTIR spectra from 2000 to 1550 cm–1.
Figure 7
Figure 7
Morphological images and cell size distribution analysis of RPUFs at different RS-based polyol replacements; (a–c) RS-0%, (d–f) RS-10%, (g–i) RS-20%, (j–l) RS-30%, and (m–o) RS-50%.
Figure 8
Figure 8
DSC plot of RPUF’s glass transition temperature (Tg) corresponding to the effect of different levels of RS-based polyol replacement.
Figure 9
Figure 9
TGA/DTG curves RPUFs at different RS-based polyol replacement; (a) RS-0%, (b) RS-10%, (c) RS-20%, (d) RS-30%, and (e) RS-50%.
See this image and copyright information in PMC

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