Synthesis and characterization of novel natural rubber based cationic waterborne polyurethane—Effect of emulsifier and diol class chain extender

Abstract

ABSTRACT Novel cationic waterborne polyurethanes (cWPU) were synthesized by step‐growth polymerization of hydroxyl telechelic natural rubber, molecular weight of 2800 g mol −1 , toluene‐2,4‐diisocyanate, N ‐methyl diethanolamine (NMDEA) as an emulsifier. The chemical structure of cWPU was confirmed by 1 H‐nuclear magnetic resonance and Fourier transform infrared spectroscopy. The amounts of NMDEA and ethylene glycol under isocyanate (NCO) index of 100 on the properties of cWPU were studied. It was found that cWPU was stable under the concentration of NMDEA more than 1.50 mol and the particle sizes decreased with increasing of NMDEA content. Also, contact angle shows more hydrophilic materials by increasing of NMDEA. Extended cWPU was found in two ranges of nano size. Chain extender has strongly affected cWPU film formation, increasing of mechanical properties, and thermal properties. In addition, stress–strain curve and scanning electron microscopy image shows the change of behavior from soft elastic to ductile plastic by adding ethylene glycol. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45715.