HEAT-INDUCED SHAPE MEMORY POLYURETHANE WITH INCLUSION OF PALM KERNEL OIL
The performance of the shape memory polyurethane (SMPU) elastomers depends on their chemical composition, crystallinity of soft segment and degree of phase separation. This paper reports the influence of varying the molar ratio of palm kernel oil polyol (PKO) on the tensile and shape memory behaviour of polyurethanes. The SMPUs were synthesized using polycaprolactone diol (PCL) and PKO as soft segments, 4,4 methylene-bis(cyclohexyl isocyanate) (HMDI), isophorone diisocyanate (IPDI) and 1,4-butanediol as the hard segments via two-step bulk polymerization method. The SMPUs were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, tensile and shape memory tests. The results showed that the increase of soft segment crystallinity has enhanced the microphase separation and shape fixity of SMPUs synthesized using the same hard segment content (40%). Also, PU with 20% of PKO molar ratio (PKO20HS40) demonstrated a higher modulus value, tensile strength, elongation at break (EB) and shape fixity. PU prepared using only IPDI as diisocyanate (100 IPDI) showed larger Young’s modulus, EB and shape fixity than PU prepared using HMDI (100 HMDI). PU samples with combination of HMDI and IPDI as diisocyanate showed higher value of Young’s modulus and tensile strength than PU prepared using HMDI and IPDI alone.