Evolution of network topology of bifunctional epoxy thermosets during cure and its relationship to thermo-mechanical properties: A molecular dynamics study

摘要

Thermoset polymers are used for a wide range of application from large airframes to microelectronics and fundamental understanding of the development of their 3D network during cure and its relationship to thermo-mechanical properties is of fundamental and applied interest. Experimental characterization of network properties, such as the density of crosslinked chains, involves the use of approximate models with uncertain parameters leading, consequently, to uncertainties in resulting properties. We use molecular dynamics to simulate the cure of two thermoset epoxy systems, characterize the evolution of its network topology and establish relationships to the stiffness, yield stress and glass transition temperature. Relating the predicted crosslink density with experimental measurements of rubber elasticity indicates that these polymers behave somewhere between an affine and phantom networks; the proportionality constant extracted between rubber modulus and crosslink density can be used for similar systems to experimentally extract network characteristics. (C) 2015 Elsevier Ltd. All rights reserved.