Renewable resources polyol as chain extenders for waterborne polyurethane dispersion

Abstract

Waterborne polyurethane dispersion (PUD) was synthesized by using inverse dispersion prepolymer technique. A prepolymer mixture of isophorone diisocyanate and polypropylene glycol was extended with five types of chain extenders. The first two types are from the amine based chain extenders which are ethylene diamine and hydrazine; the other three are diol based chain extenders, one from a petroleum based diol which is ethylene glycol and the other two from renewable resources which are castor oil (CO) and palm oil based-polyols (POP). In attempt to reduce the toxicity by replacing the toxic amine based chain extender with diols. Furthermore, renewable resources chain extenders were used to decrease dependency on petroleum which is an expensive and depletable resources. Fourier Transform Infrared Spectroscopy analysis showed that all samples have been successfully synthesized into PUDs, based on the absorption peaks at 1537-1539 cm-1 and 1718-1725 cm-1 which corresponded to the NH and carbonyl peaks of urethane respectively and also the absence of -NCO peak at 2275 cm-1. Palm oil-based PUD has the highest viscosity of 5.4 cP, particle size of 1.738 micron but low solid content of 31 wt%. The oil based chain extended polyurethane exhibited better thermal stability than the rest of the samples. This is assumed due to the hydroxyl group of the triglycerides which may react with isocyanate at high temperature to produce crosslink polyurethane. However, the oil based chain extended samples were sticky upon drying and has potential to be used as adhesives.