Study of the Degree of Cure through Thermal Analysis and Raman Spectroscopy in Composite-Forming Processes.

Juan A García-Manrique,Amparo Ribes-Greus,Llúcia Monreal,Roberto Teruel,Bernabé Marí,Juan A Sans,Llanos Gascón,Julia Marí-Guaita

doi:10.3390/ma12233991

Juan A García-Manrique, Amparo Ribes-Greus + Show 6 more

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https://doi.org/10.3390/ma12233991

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Abstract

The curing of composite materials is one of the parameters that most affects their mechanical behavior. The inspection methods used do not always allow a correct characterization of the curing state of the thermosetting resins. In this work, Raman spectroscopy technology is used for measuring the degree of cure. The results are compared with conventional thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscope (SEM). Carbon fiber specimens manufactured with technologies out of autoclave (OoA) have been used, with an epoxy system Prepreg System, SE 84LV. The results obtained with Raman technology show that it is possible to verify the degree of polymerization, and the information is complementary from classical thermal characterization techniques such as TGA and DSC; thus, it is possible to have greater control in curing and improving the quality of the manufactured parts.

Highlights

There is currently a great demand from the aerospace, wind, nautical and automobile industries for the development of new high-performance composites
Thethe degree cureresults is directly related towith an increase in temperature peaks, as shown in Derivative Thermogravimetric (DTG) studies, which results in a rise of the crystalline order
The degree of cure is directly related to an increase in temperature peaks, as shown in DTG studies, which results in a rise of the crystalline order

Summary

Introduction

There is currently a great demand from the aerospace, wind, nautical and automobile industries for the development of new high-performance composites. The cure characterization of the parts affects both the forming processes and the repair–maintenance processes. Cure time is generally calculated very conservatively to ensure complete curing of the part before removing it from the mold. This practice greatly slows manufacturing times, and in some cases, it damages the part. Control techniques of the mold filling and cure monitoring provide enough information to reduce the injection and curing times. Biomedical applications are used to increase the thickness of the part’s fillers; a high degree of cure could be difficult to achieve, reducing its mechanical properties and the biocompatibility [1]

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