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Development of polyurethane foam (PUF) containing bio-based components is a complex process that requires extensive studies. This work reports on the production of rigid PUFs from polyol obtained via liquefaction of oil palm empty fruit bunch (EFB) biomass with different isocyanate (NCO) indexes. The effect of the NCO index on the physical, chemical and compressive properties of the liquefied EFB-based PUF (EFBPUF) was evaluated. The EFBPUFs showed a unique set of properties at each NCO index. Foaming properties had affected the apparent density and cellular morphology of the EFBPUFs. Increasing NCO index had increased the crosslink density and dimensional stability of the EFBPUFs via formation of isocyanurates, which had also increased their thermal stability. Combination of both foaming properties and crosslink density of the EFBPUFs had influenced their respective compressive properties. The EFBPUF produced at the NCO index of 120 showed the optimum compressive strength and released the least toxic hydrogen cyanide (HCN) gas under thermal degradation. The normalized compressive strength of the EFBPUF at the NCO index of 120 is also comparable with the strength of the PUF produced using petrochemical polyol.

Optimization of microwave-assisted liquefaction of oil palm empty fruit bunch fiber (EFB) and cellulose (EFBC) in ethylene glycol (EG) was carried out to produce polyols. The liquefaction residues and hydroxyl numbers of the resultant polyols from respective sources were studied and compared. EFB produced a minimum residue of 3.22% at the optimal parameters of 160 °C and 15 min. Meanwhile, optimum liquefaction of EFBC produced 1.03% residue at 175 °C and 40 min. The maximum hydroxyl numbers of both EFB (749.22 mg KOH/g) and EFBC (639.91 mg KOH/g) polyols were obtained at optimum conditions. FTIR analysis revealed the degradation mechanism of cellulose and lignin in EFB at different temperatures. Lignin was found to be liquefied easily at lower temperatures (130 and 145 °C). However, most of the cellulose began to be liquefied at the optimum temperature (160 °C) and severely degraded at higher temperatures (175 and 190 °C).