Rigid polyurethane foam from palm oil polyol-polyethylene glycol blend

Abstract

Renewable palm oil polyol (POP) was blended with commercial polyethylene glycol (PEG) at 1.5:1 wt% ratio prior to reacting with polymeric 4, 4-diphenylmethane diisocyanate (p-MDI) to form rigid polyurethane foam (PU). PEG with different molecular weight i. e. PEG600 and PEG 1000 were utilized. Effects of the POP-PEG blend on thermal stability and morphological property were investigated. As a comparison, pure POP PU foam was used as a control sample. Fourier transform infrared (FTIR) analysis confirmed the formation of urethane linkages at the wavebands of 1507 cnr1-1509 crrr1 in all samples. Thermal stabilities of blended polyols (332°C) were higher than the control PU foam (298°C) as shown by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) images showed the control PU and PU-PEG1000 foams had comparable closed cell sizes with uniform cell shapes, while PU-PEG600 showed the distorted cell shapes and smaller cell sizes. The later was thought related with the foam shrinkage due to lacks of foam's stability. Therefore, the amounts of silicone surfactants as foam stabilizer were varied at 2.0 wt. %, 2.5wt.% and 3.0wt.% in the PU-PEG600 formulation. The thermal profiles of all samples did not show significant changes compared with the control PU. However, beyond 426 °C, sample with 2.5wt.% surfactant showed the slowest degradation rate with the formation of more closed cell in the sample. Higher silicone content at3.0wt% led to over-stabilize the system, thus producing a sample with bigger cell size, closed cell, and low thermal stability.