Rheological properties of konjac glucomannan chitosan PVA laminating adhesive

In order to develop environment-friendly wood adhesive, the thermosetting process and the rheological properties of the blending adhesive consisted of konjac glucomannan (KGM), chitosan (CA) and polyvinyl alcohol (PVA) were investigated by DSC and rheometer. The results show that the rheological behavior of adhesives is significantly nonlinear. The relationship between the viscosity and the shear rate fit the Cross model well, while the dependence of the viscosity on the temperature can meet the Arrhenius equation well in which the pre-exponential factor is 1.25×10^-6Pa·s and the flow activation enthalpy is 54.24kJ/mol. The fourth order polynomials can be used to fit the frequency curves which show that average molecular mass of adhesive decreases gradually with the temperature increase while wider molecular mass distribution of adhesive reverse. The gelling temperature, gel time, glass transition temperature and heating temperature are 110.4℃, 20.1min, 87.4℃ and 130℃ respectively according to the temperature and time curves.