Thermal, mechanical, and morphological properties of rigid crude glycerol-based polyurethane foams reinforced with nanoclay and microcrystalline cellulose

Abstract

The enhancement of mechanical and thermal properties of rigid polyurethane foam (RPUF) achieved through a cost-effective and sustainable approach remains an ongoing interest in both industry and academia. In this study, water-blown rigid polyurethane (PU) foams based on crude glycerol (CG) polyol were developed and halloysite nanotubes (HN) and microcrystalline cellulose (MC) with different loadings of 1.0%, 3.0% and 5.0% were incorporated to improve the performance of the foams, respectively. Effects of different loadings of HN or MC on the viscosity of CG polyols and the foaming process were investigated. CG-based polyurethane (CGPU) foams and their foam composites (CG-HN PU foams and CG-MC PU foams) were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results revealed that HN was easier to disperse uniformly in the CG polyol than MC and CGPU foams with 1.0% of HN and MC showed significantly improved performance. Their compressive strength increased by 3.8% and 12.5%, respectively, as the HN and MC loadings increased from 0 to 1.0%. The thermal conductivities of CG PU foams reinforced with 1.0% of HN and MC were 37.79 and 37.94 mW·m^-1·K^-1, which are lower than that (38.24 mW·m^-1·K^-1) of CGPU foams without the addition of fillers. Moreover, compared to CGPU foams, both CG-HN PU foams and CG-MC PU foams showed improved thermal stabilities, and the latter is higher than the former.

Practical applications: Different fillers (HN and MC) were used to reinforce the CG-based polyurethane, and water-blown rigid PU biofoam composites with improved properties were prepared. The use of fillers (HN and MC) has the potential for the production of advanced CG-based rigid PU foams.

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