Use of epoxy-phenolic lacquers in food can coatings: Characterization of lacquers and cured films

Liquid and cured epoxy-phenolic lacquers used as can coatings were characterized. Tinplate was used as the base material, which was coated with lacquers of different epoxy to phenolic ratios (EPRs) from a commercial source. Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were used together to obtain helpful information about the degree of curing and the composition of the lacquers. From FTIR analysis, we were able to infer that the lacquers were composed of a high-molecular-weight diglycidyl ether of bisphenol A type epoxy resin and a resol-type phenolic resin. In addition, from FTIR spectra, we estimated the EPRs of lacquers applied on the tinplate and detected if they had been overcured. The EPRs of the applied lacquers were estimated also from DSC analysis. From TGA, we detected undercuring in the applied lacquers. © 2005 Wiley Periodicals, Inc.Fil: Manfredi, Liliana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ginés, M. J. L.. Centro de Investigacion Industrial; ArgentinaFil: Benftez, G. J.. Centro de Investigacion Industrial; ArgentinaFil: Egli, Walter Alfredo. SIDERAR; ArgentinaFil: Rissone, H.. SIDERAR; ArgentinaFil: Vázquez, Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Photopolymerization kinetics of an epoxy based resin for stereolithography

Curing reactions of photoactivated epoxy resins are assuming an increasing relevance in many industrial applications, such as coatings, printing, and adhesives. Besides these processes, stereolithography (SL) makes use of photoactivated resins in a laser-induced polymerization for 3D building. The kinetic behavior of photocuring is a key point for full comprehension of the cure conditions occurring in the small zone irradiated by the laser beam during the building process. Furthermore, the kinetic analysis is very important to determine the cure time needed for part building in a stereolithographic equipment. The mechanisms involved in a cationic photopolymerization are complex compared with radical photopolymerization. In this paper the photoinitiated polymerization of a commercially available epoxy-based resin for stereolithography (SL5170) was studied by means of differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Substantial information about the SL5170 chemical composition and curing mechanism was determined through FTIR analysis. The polymerization rate and the maximum degree of reaction were determined directly from experimental DSC curves. Kinetic characterization of epoxy photopolymerization was carried out as a function of the temperature and irradiation intensity and experimental results were compared with an original mathematical model

Consistent model predictions for isothermal cure kinetics investigation of high performance epoxy prepregs

An accurate kinetics model is essential for understanding the curing mechanism and predicting the end properties of polymer materials. Graphite/epoxy AS4/ 8552 prepreg is a recent high-performance thermosetting composite modified with thermoplastic, which is being used in the manufacture of aircraft and military structures. The isothermal cures of this system along with another thermoplastic toughened high-performance prepreg, the T800H/3900-2 system, were investigated by real-time Fourier transform infrared (FTIR) spectroscopy. The cure rate was quantitatively analyzed based on the concentration profiles of both the epoxy and primary amine groups. Three autocatalytic models were used to determine kinetics parameters for both composite systems. The model which utilizes an empirical term, the final relative conversion (at different isothermal curing temperatures), describes the experimental data of both systems more satisfactorily than the model which applies a diffusion factor. The modeling results suggest that the curing of epoxy within both prepregs can be assumed to be a second order process.<br /