Sulfate Lignin Research Articles

Viscosity of lignin-modified polypropylene determined by capillary viscometry

The properties of polypropylene containing 2, 5, 10, and 15% alkali sulfate lignin have been studied by the method of capillary viscometry at temperatures of 190, 230, and 250°C. It has been shown that introducing lignin, irrespective of the concentration, leads to an increase in the Newtonian viscosity of the melt and to an increase in the weighted-mean molecular weight. An analysis of the apparent relative activation energy of viscous flow shows that the greatest effect is obtained by introducing from 2 to 5% lignin. The results obtained permit a hypothetical conclusion concerning the mechanism of the crosslinking process (possible "ladder" structure).

Mechanical properties of polypropylene modified by decomposition products of alkali sulfate lignin

During processing of polypropylene and alkali sulfate lignin at a temperature of 180° C, a reaction occurs resulting in the formation of a polymer which appears to have a three-dimensional structure. The observed cross-linking is accompanied by an increase in reversible deformation, a decrease in irreversible deformation, a transition from solubility to limited swelling in solvents, an increase in tensile strength, and an increase in freeze resistance. This is achieved by also adding a plasticizer to the polymer.