KINETIC CHARACTERIZATION BY DIFFERENTIAL ENTHALPY ANALYSIS OF LIGNOSULFONATE-BASED PHENOL-FORMALDEHYDE RESINS

Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to characterize various types of lignin and phenol-formadehyde resin (PF), as well as lignin-based phenolic resins (LPF) as mixtures with 20, 30 and 40% PF replacement by lignin. These studies have allowed comparison of thermal stability of the lignins and characterization of the curing reaction of LPF mixtures. The thermal properties as determined by TG have shown that lignin can be used as a copolymer in phenolic adhesives. The kinetic parameters (the activation energy, the heat of reaction and the degree of polymer conversion) obtained by DSC, as well as the isotherms calculated with these parameters, are effective in the accurate representation of the role of lignin in lignin-based phenolic resin formulations.