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Abstract  

Differential scanning calorimetry was used to study the influence of an epoxy reactive diluent, vinylcyclohexane dioxide, on the curing reaction of a polymeric system composed of diglycidyl ether of bisphenol A (n=0) and 1,2-diaminecyclohexane (DCH). Heat evolution and glass transition temperature, were measured in terms of the added diluent percentage. Experimental results show that both the curing degree and the glass transition temperature of the polymeric system decrease with an increase in the diluent percentage. Dynamic mechanical analysis of several samples also showed that T g decreases with the increase of diluent percentage, thus corroborating DSC measurements.

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Summary Polymers have a great interest for the study and design of new materials. Among these materials are epoxy resins, that have good properties, such as low shrinkage during cure, good adhesion, high water and chemical resistance, etc. They have also fast and easy cure in a broad range of temperatures. TTT diagrams are very helpful to design new epoxy materials as they allow the search for very important final properties, such as thermal stability, conversion or glass transition temperature of a material cured through a selected curing cycle. In this work the dependence of the thermal stability on the selected curing cycle for a DGEBA/1,2 DCH system was studied.

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Journal of Thermal Analysis and Calorimetry
Authors: Maria Villanueva, I. Fraga, J. Rodríguez-Añón, J. Proupín-Castiñeiras, and J. Martín

Abstract  

The diffusive, calorimetric and thermal degradation behavior of different epoxy-amine systems was investigated during water sorption at different temperatures (23, 40 and 70°C). Experimental results showed that the water absorption at these temperatures fitted well to Fick’s law. Influence of water immersion during different periods of time on the glass transition temperatures was studied by differential scanning calorimetry. Thermal degradation of saturated samples was studied by thermogravimetric analysis. Dependence on the selected curing cycle was also checked.

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Journal of Thermal Analysis and Calorimetry
Authors: L. Núñez-Regueira, M. Villanueva, and I. Fraga-Rivas

Abstract  

The study of the degradation of a polymer is important because it can determine the upper temperature limit, the mechanism of a solid-state process, and the life-time for this system. Since the behavior of thermosets is affected by the selection of the curing cycle, it is important to investigate the changes which take place during the thermal degradation of these materials when a change on the sequence of time and temperature is introduced during the curing reaction. In this work, the thermal degradation of two epoxy systems diglycidyl ether of bisphenol A (BADGE n=0)/1, 2 diamine cyclohexane (DCH) cured through different sequences of time and temperature was studied by thermogravimetric analysis in order to determine the reaction mechanism of the degradation processes, and also to check the influence of the curing cycle on this mechanism. Values obtained using different kinetic methods were compared to the value obtained by Kissinger’s method (differential method which do not require a knowledge of the n-order reaction mechanism), and to that obtained through Flynn–Wall–Ozawa method in a previous work.

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Abstract  

The rheological behaviour of the materials diglycidil ether of bisphenol A (n = 0), 1, 2 diamine-cyclohexane and the epoxy reactive diluent vinylcyclohexane dioxide have been studied both separately and mixed before the beginning of the curing reaction. Different kinds of tests such as: preshear and time sweep, flow curve and stress sweep experiments were carried out. From these experiments, interesting information about: viscosity-shear stress and viscosity-shear rate dependences, storage modulus and the linear viscoelastic region were found out. Relationships between concentration of diluent and the final viscosity of the mixed sample and also between percentage of diluent and storage modulus were studied.

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rheological properties of an epoxy-diamine system . J Therm Anal Calorim 98 : 521 – 525 10.1007/s10973-009-0303-1 . 7. Villanueva , M , Martín-Iglesias , J , Rodríguez-Añón , J , Proupín

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Journal of Thermal Analysis and Calorimetry
Authors: M. V. Alonso, M. Oliet, J. C. Domínguez, E. Rojo, and F. Rodríguez

energies for the thermodegradation process of an epoxy-diamine system . J Therm Anal Calorim . 2006 ; 83 : 3 727 – 733 . 10.1007/s10973-005-6980-5 . 14. Zhang , Z , Gu , A , Liang , G

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-Añón , JA , Proupín-Castiñeiras , J , Martín , JL 2007 Study of the influence of water absorption on different epoxy-diamine systems by DSC . J Therm Anal Cal 87 : 205 – 209 10.1007/s10973-006-7845-2 . 35

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