Sustainable waterborne polyurethane ionomer reinforced poly(vinyl alcohol) composite films

Poly(vinyl alcohol) (PVA) was successfully reinforced by castor oil based waterborne polyurethane ionomer (PUI) synthesized from castor oil, dimethylolpropionic acid, 4,4′-methylenediphenyl diisocyanate, and triethylamine. The average diameter of PUI determined by dynamic light scattering and transmission electron microscope was around 45 nm. The size of dispersed PUI in PVA/PUI composite was in the ranges of 1.2–3.7 μm with varying PUI content from 1 wt.% to 7 wt.%. The storage modulus of PVA/PUI composite films determined by dynamic mechanical analysis was much higher than that of neat PVA film and increased first and then decreased with the content of PUI. PVA/PUI with 3 wt.% PUI showed the highest storage modulus. The reinforcement effect was also demonstrated by tensile test from the enhancement in Young’s modulus and tensile strength. The UV/vis spectra analysis suggested that the transparency of PVA was seldom influenced by incorporation of PUI.