Preparation and Properties of Bio-based Polyurethane Containing Polycaprolactone and Natural Rubber

Abstract

Novel polyurethanes were successfully synthesized by a one-shot polymerization. They contained poly(e-caprolactone) diol (PCL diol) and hydroxyl telechelic natural rubber (HTNR) as the soft segment. The effect of the NCO:OH molar ratio (0.75:1.00–2.25:1.00), chain extender and PCL:HTNR molar ratio (1:1, 0.7:0.3 and 0.3:0.7) on the thermal and mechanical properties of the resulting polyurethane were investigated. FTIR analysis showed the presence of urethane linkages and crosslinking or chain branching. The derived polyurethanes demonstrated excellent mechanical properties, which depended on their chemical composition. Their tensile behavior seemed to have typical elastomeric characteristics. Polyurethanes became amorphous and showed a phase separation between the PCL diol and HTNR segments. The phase separation between the soft and the hard segments was observed by the DMTA technique whereas DSC results showed only the glass transition temperatures of the soft segment. The longer and more flexible chain and non-polarity of HTNR was responsible of a decrease in the mechanical properties and transition temperatures.