Session: 03-05-01 Design, Material Processing, and Applications of Polymer Composites

Paper Number: 98985

98985 - Frontal Polymerization of Short-Fiber-Reinforced Polymer Matrix Composites 

Thermoset polymer matrix composite materials are used in many engineering applications due to their excellent mechanical properties and environmental resistance. An innovative and energy-efficient method based on the frontal polymerization of the resin has been developed to replace traditional curing methods which take place in large autoclave or heated molds, are based on bulk polymerization, and involve high energy demand, long processing times, as well as high CO2 emissions. The curing energy needed in the frontal polymerization process uses the polymerization enthalpy of the monomer used instead of being supplied externally, thereby achieving substantial (by multiple orders of magnitude) saving in energy cost.

In this study, the manufacturing of short-fiber-reinforced carbon/dicyclopentadiene (DCPD) composite materials by frontal polymerization is investigated numerically and analytically. The numerical and theoretical analyses are based on a homogenized thermo-chemical model which incorporates the thermal properties, shape, and orientation of the fibers embedded in the DCPD resin. The coupled homogenized reaction-diffusion equations are written in terms of the degree-of-cure and temperature fields. The effects of fiber aspect ratio, volume fraction, and orientation angle on the front location, speed, temperature, and inclination angle are first investigated using the Multiphysics Object-Oriented Simulation Environment (MOOSE) taking advantage of the robust mesh adaptivity needed to capture the very sharp thermal and degree-of-cure gradients in the vicinity of the advancing polymerization front. In addition to the results of the multiphysics, nonlinear, transient, coupled finite element analysis, we present closed-form estimates of the dependence of the front speed and orientation of the volume fraction and orientation of the short carbon fibers, showing excellent with the values obtained numerically in the steady-state regime of front propagation. These results show that the impact of fiber orientation angle on the front angle increases with the fiber volume fraction, and that the front velocity decreases with increasing fiber orientation angle and fiber volume fraction.

Finally, we present the results of frontal polymerization in a carbon/DCPD specimen for which the fiber orientation is spatially dependent across the specimen thickness and is taken from a separate experimental study of fiber orientation in composite panels made through injection molding. The results of that numerical study indicate that the steady-state front has a straight profile angled towards the propagation direction after the simulation reaches a steady-state regime. Due to the low difference in fiber orientation angles across the thickness of the specimen, a relatively small change in front speed and front shape is predicted.

Presenting Author: Philippe H Geubelle University of Illinois at Urbana Champaign

Presenting Author Biography: Originally from Belgium, Philippe Geubelle got his B.Sc. in mechanical engineering at the Catholic University of Louvain in 1988, and his M.Sc. and Ph.D. in aeronautics at the California Institute of Technology in 1989 and 1993, respectively. After a year as Postdoctoral Research Associate at Harvard, he joined the University of Illinois at Urbana-Champaign in January 1995, where he is currently Bliss Professor in the Department of Aerospace Engineering, with joint appointments in Mechanical Science and Engineering and at the Beckman Institute for Advanced Science and Technology. He served as the Head of the AE Department from 2011 to 2018 and was appointed as the Executive Associate Dean of the Grainger College of Engineering in January 2019. His research interests pertain to the theoretical and numerical treatment of complex problems in solid mechanics and materials with emphasis on composite manufacturing, multiscale analysis and design of materials, fracture mechanics, and biomimetic multifunctional materials.

Authors:

Tolga Topkaya Batman University
Yuan Gao University of Illinois at Urbana Champaign
Philippe H Geubelle University of Illinois at Urbana Champaign