Method for in situ analysis of volatiles generated during cure of composites. (August 2019)

• Record Type: Journal Article
• Authors: Lo, Jonathan; Nutt, Steven
• Is Part Of: Composites. Volume 123(2019)
• Page Start: 141
• Page End: 148
• Publication Date: 2019-08
• Subjects: Processing monitoring -- Cure behavior -- Chemical analysis -- Porosity; Composite materials -- Periodicals; Manufacturing processes -- Periodicals; Composite materials; Manufacturing processes; Periodicals; 620.11805
• DOI: 10.1016/j.compositesa.2019.05.013
• Languages: English
• ISSNs: 1359-835X

Abstract

Abstract: Conventional epoxies used in composites are formulated to release minimal amounts of volatiles during cure, aside from moisture, which is a perpetual concern. However, a variety of polymers are used in production of composite parts, including adhesives, prepregs, and non-epoxy polymers, and sources of volatilization during processing can be both difficult to determine and problematic. Here we demonstrate a general method for in situ analysis of volatile release during cure. The method improves upon traditional characterization techniques of TGA/MS and TGA/FTIR (thermogravimetric analysis, mass spectroscopy, and Fourier transform infra-red spectroscopy). We characterize a commercial epoxy prepreg typical of those used in aerospace, a benzoxazine/epoxy blended liquid resin intended for high-temperature service, and finally, a high-temperature polyimide. By understanding the identity, origin, and kinetics of volatile release in these three materials, we can prescribe additional pre-treatments and define process windows to minimize and even eliminate volatile-induced porosity. Finally, we demonstrate the utility of the reaction cell/FTIR approach for characterizing cure-induced volatiles and mitigating final part porosity.