Cathy D. Stewart
Chemist
Intertape Group Polymer

Measuring Adhesive Cure using Pyrolysis GC-MS

Abstract: The primary pyrolysis products of the poly(isoprene) in natural rubber are well defined: the isoprene monomer and the two dimers 1,4-dimethyl-4-vinylcyclohexene and d-limonene. When natural rubber is cross-linked, it affects the pyrolysis pattern resulting in an increase in the isoprene monomer relative to the dimers. An experiment was run using pyrolysis GC-MS to measure the degree of cure in a natural rubber adhesive. In theory, the higher the cure of the adhesive, the higher the amount of monomer and the lower amount of dimer that should form. Samples with different amounts of cure were analyzed using Pyrolysis GC-MS, Gel Content and Solvent Cure to determine the degree of cure. The results of all three tests were comparable. Using pyrolysis GC-MS has some advantages since, as it is based on peak height ratios, it is more sensitive to small variations in cure. A second experiment was run to show how this methodology is also applicable to cured acrylic adhesives as well.