A micro-Raman study of Cu-particulate-filled epoxy matrix composites
S. Tognana, W. Salgueiro, M. B. Valcarce
eXPRESS Polymer Letters
Epoxy resins are used in structural applications ranging from high-performance composites for aerospace applications to encapsulants for the microelectronics industry because of their high thermal resistance, high tensile strength and modulus, and good chemical resistance. It is well known that the most important factors that influence their performance are the molecular architecture, the ratio between the epoxide and the hardener, and the cure conditions, frequently at a high temperature,
... determine the final properties of the material. The influence of the filler particles on the curing is still a subject of study and clearly depends on the nature of the particles      . Epoxy matrix composites find new appli-cations every day in several areas of engineering and technology. For example, copper-filled composites have a high possibility of being used in microelectronics because the high thermal conductivity of copper allows the composite to be a good heat dissipator, which serves as protection to electronic devices [6, 7]. The matrix-particle interphases also play an important role. The physical properties of the polymeric composites can be significantly influenced by their thermal history; in fact, internal stresses are developed during the fabrication process and further thermal treatments. Microtechniques such as microcalorimetry , micro-Raman spectroscopy , and atomic-force microscopy have been used to study 312 Abstract. A micro-Raman study is carried out to investigate the influence of the filler on the curing process of bisphenol A diglycidyl ether (DGEBA)-based epoxy matrix composites. The composites are cured (14 h at 393 K) with an anhydride (methyl tetrahydro phthalic anhydride, MTHPA, 100:90 pbw), catalyzed with a tertiary amine (0.7 pbw) and filled with a 30% volume of Cu particles of approximately 75 !m in diameter. The experimental results are compared with those obtained for the same epoxy resin unfilled and for the same composite with Cu filler but not catalyzed. The micro-Raman experimental technique is used to search for information on the curing process in different regions of the matrix, near to and far from the copper filler, taking into account the results of differential-scanning-calorimetry measurements performed on the same composites. The results provide information on the influence of the copper filler on the curing process of the epoxy matrix. Differences were observed in the peaks associated with the epoxy ring and the ester group as a function of the distance to the nearest copper particle, but no differences were observed between the different composites.