Influence of the structure on thermoset cure kinetics

Abstract

The influence of molecular structure on cure kinetics was studied using a new approach for characterizing the cure kinetics of thermosets in the glass transition region. Reactions in or near the glassy state are controlled by chain mobility, where the whole structural unit undergoes small‐angle oscillation motions around the network link. All structural features affecting the mobility such as stiffness, bulky structures, substitution, symmetry effects, and functionality lead to high segment activation energies and slow final curing. The influence of the segment activation energy on the kinetic curves is also discussed. © 1993 John Wiley & Sons, Inc.

Kinetic analysis of isothermal cures performed below the limiting glass transition temperature

“…The effect has been explained 5) by a transition from kinetic to diffusion control caused by vitrification. The observed decrease is also consistent with the recent experimental findings 10,11) that cures in the glass transition region have a very small activation energy.…”

A sustainable, eugenol-derived epoxy resin with high biobased content, modulus, hardness and low flammability: Synthesis, curing kinetics and structure–property relationship

“…Specially, the p-xylene ether bonds of DEU-EP/DDM will facilitate the diffusion of epoxy groups to effectively collide with reactive amine groups to react with each other, since these bonds are relatively easy to rotation with much lower activation energy, in analogy to the other thermosetting curing reactions [43]. Therefore, we observe the decrease in Eα at the final stage of the isothermal cure.…”

Lifetime assessment of epoxies by the kinetics of thermal degradation

“…Although degradation was performed here in the vicinity of the glass transition, a clear first‐order kinetics was observed. This shows clearly, that in contrast to cure kinetics,16, 17 the degradation reaction is not related to chain mobility (and therefore not dependent on the difference between annealing temperature and actual glass temperature), but controlled only by the absolute temperature. Obviously the bond breakage in a polymer is only dependent on the thermal activation of the bond and independent of segmental mobility.…”