Cure characterization of the ring‐opening metathesis polymerization of linseed oil‐based thermosetting resins

BACKGROUND: Bio‐based polymers from vegetable oils are excellent alternatives to petroleum‐based resins for both environmental and economic reasons. A detailed understanding of the cure behavior of bio‐based polymers is essential to optimize cure schedules and the final properties of the polymers. In this work, the cure of newly developed linseed oil‐based thermosetting resins, synthesized using Grubbs' first‐generation catalyst and a bis‐norbornadiene cross‐linking agent by ring‐opening metathesis polymerization, is characterized using differential scanning calorimetry (DSC) and parallel plate oscillatory rheometry. RESULTS: Experimental results reveal that the rate of cure increases and the gel time decreases with increasing cross‐linker loading; however, the activation energy of the cure does not vary systematically with cross‐linker loading. Phenomenological reaction models are used to describe the dynamic DSC measurements and to determine the kinetic parameters which facilitate cure predictions under isothermal conditions. CONCLUSION: This work demonstrates that the cure kinetics of a linseed oil‐based thermosetting resin can be controlled by varying the cross‐linker loading. Furthermore, the kinetic parameters and cure rates at any cross‐linker loading for this system can be described by a simple autocatalytic reaction model which facilitates development of cure schedules. Copyright © 2009 Society of Chemical Industry