THE EFFECT OF CHAIN LENGTH OF POLYETHYLENE GLYCOL ON PROPERTIES OF CASTOR OIL BASED POLYURETHANE ELASTOMERS

Abstract

ABSTRACT Polyurethane (PU) elastomers from castor oil based polyol, polyethylene glycol (PEG) of various molecular weight (200, 400, and 600) and toluene diisocyanate were prepared in the form of transparent sheets. The sorption, mechanical and thermal properties have been studied. The solubility parameter, molecular weight between two crosslinks and degree of crosslinking of PU samples were calculated from equilibrium swelling experiments. The kinetic study of swelling revealed that sorption is anomalous in nature in all the samples. Diffusion coefficient (D) and sorption coefficient (S) were found to decrease with an increase in chain length of PEG. The stress-strain data showed that the elastomers obtained using PEG-200 gave the best mechanical properties. The thermal degradation of all elastomers starts at ∼250°C, regardless of the PEG chain length. The values of activation energy of degradation were in the range of 60–72 kJ/mole.