Synthesis and characterization of rigid polyurethane-palm oil based polyol/diaminopropane-montmorillonite nanocomposite foam

Abstract

Issues on environmental impact and sustainability have driven the development of rigid polyurethane (PU)-palm oil based polyol (POP) /diaminopropane (DAP)-montmorillonite (MMT) nanocomposite foam. PU rigid foam derived from POP and polymeric 4,4-diphenylmethane diisocyanate (p-MDI), was successfully prepared via two steps-direct mixing method. Firstly, POP and DAP-MMT were mixed in a flask and stirred at 1500 rpm for 2 minutes to form a homogenous solution. Then, silicone surfactant and distilled water were added and further stirred for 2 minutes to form a pre-mixture. Later, p-MDI was added into the pre-mixture under high speed stirring at 1500 rpm for 45 seconds before charged into a mould. Fourier transform infrared energy peaks at 1533 cm-1, 1218 cm-1 and 1731 cm-1 of N-H, C-N and C=O groups confirmed the formation of urethane linkages. PU foam was prepared at 1:1 diisocyanate: polyol (NCO:OH) ratio exhibited a comparable compressive strength (4969 kPa) with the control PU (4999 kPa). Meanwhile the amount of silicone surfactant as a foam stabilizer at 2 part per hundred polyol (pphp) showed the highest compressive strength (8452 kPa) with uniform and finer cell size. The X-ray diffraction (XRD) test showed that samples with DAP-MMT contents at 2 wt % and 4 wt. % exhibited exfoliated structure while the scanning electron microscopy (SEM) micrographs showed the reduction of cell size of each sample. This morphology effect was clearly manifested on the sample with 4 wt. % MMT loading that had the highest compression strength and density which were 19648 kPa and 0.13 gcm-3. Results from water absorption test revealed that samples with 6 wt. % MMT loadings had about 31% reduction of water uptake against that of pure PU foam.