Synthesis and characterization of polyurethane and its nanocomposite adhesive derived from biobased isocyanate and polyol

Abstract

In the current research, the vegetable oil based polyurethane nanocomposite (PUNC) adhesive was prepared using transesterified castor oil (CO) based polyol, partially biobased aliphatic isocyanate (PBAI) and organically modified montmorillonite nanoclay (Closite 30B). The transesterified CO was synthesized by reacting CO with ethylene glycol, which was confirmed using proton nuclear magnetic resonance (1HNMR) analysis. Further, the prepared polyurethane (PU) and its nanocomposite adhesive with specific NCO: OH molar ratio 1.3:1 was confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. The increasing of wt% of nanoclay loading level up to 3% into PU matrix increased the lap shear strength of the adhesive systems. Subsequently, the effect of polyurethane nanocomposite adhesives on the bonding strength of wood-to-wood and aluminum-to-aluminum substrate was studied using lap shear strength test. The nanoclay was observed to effectively intercalate into the polymer matrix. Moreover, the phase separation in PU and PUNC adhesive was studied using atomic force microscope (AFM) and differential scanning calorimetry (DSC) analysis.