223 Recent advances in the radiation curing of high performance composite materials
Xavier Coqueret1, Brigitte Defoort2, Mickael Krzeminski1 and Philippe Ponsaud2
1 Institut de Chimie Moléculaire de Reims, CNRS UMR 6229, Université de Reims Champagne Ardenne, BP 1039, 51687 Reims Cedex 2, France
2EADS Astrium, BP 11, 33165 Saint Medard en Jalles Cedex, France
E-mail: xavier.coqueret@univ-reims.fr
Abstract
Cross-linking polymerization initiated by high energy radiation is a highly attractive technique for the fabrication of high performance composite materials. The method offers many advantages compared to conventional energy- and time-consuming thermal curing processes. Free radical and cationic polyaddition chemistries have been investigated in some details by various research groups along the last years. A high degree of control over curing kinetics and material properties can be exerted by adjusting the composition of matrix precursors as well as by acting on process parameters.
However, the comparison with state-of-the-art thermally cured composites revealed the lower transverse mechanical properties of radiation-cured composites and the higher brittleness of the radiation cured matrix. Improving fiber-matrix adhesion and toughening the polymer network are thus two major challenges in this area. We have investigated several points related to these issues, and particularly the reduction of the matrix shrinkage on curing, the wettability of carbon fibers, the design of fiber-matrix interface and the use of thermoplastic toughening agents. Significant improvements were achieved on transverse strain at break by applying original surface treatments on the fibers so as to induce covalent coupling with the matrix. A drastic enhancement of the KIC value exceeding 2 MPa.m1/2 was also obtained for acrylate-based matrices toughened with high Tg thermoplastics.
Similarly, in some related approaches conducted by other groups (selected posters to be presented at IMRP 2008), radiation-cured composites with advanced properties were obtained by using carbon nanotubes, by impregnating wood by monomer blends or by using X-ray activation in the perspective of the mass production of high-performance materials.
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