Formulation designs and characterisations of whey‐protein based API adhesives

Abstract

Purpose

The purpose of this paper is to investigate the effects of the components of whey‐protein based aqueous polymer‐isocyanate (API) adhesives on the bond strength.

Design/methodology/approach

The bond test (according to the JIS K6806‐2003 standard), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterise the whey‐protein based API adhesives with various formulations and processing technologies.

Findings

The good bond strength of the optimised whey‐protein based API adhesive was attributed to the formation of strong chemical bonds in the bondline and to the additions of polyisocyanate, polyvinyl alcohol (PVA) and nano‐CaCO₃ powder that improved adhesive cohesive strength by either chemical crosslinks or mechanical interlocking. The blending procedures of whey protein, PVA, polyvinyl acetate (PVAc) and p‐p‐MDI had great impacts on the performances of the whey‐protein based API adhesives.

Research limitations/implications

SEM micrographs showed that the effects of blending processes on the bond strength, pot life and colour might be attributed to the particle size of hydrophobic p‐MDI droplet and p‐MDI distribution in the protein‐PVA matrix.

Practical implications

The study lays the foundations of the formulation design and the processing technology for preparing whey‐protein based API adhesives.

Originality/value

The effects of the components of whey‐protein based API adhesives and the effects of blending processes on the bond strength were investigated by means bond strength evaluation, FTIR and SEM analyses; whey protein is utilised successfully to prepare novel API adhesives for structural uses.

Citation

Zhao, Z., Gao, Z., Wang, W. and Guo, M. (2011), "Formulation designs and characterisations of whey‐protein based API adhesives", Pigment & Resin Technology, Vol. 40 No. 6, pp. 410-417. https://doi.org/10.1108/03699421111180563