Authors:J. M. Morancho, A. Cadenato, X. Ramis, X. Fernández-Francos, M. Flores, and J. M. Salla
HBP in an epoxy resin without adding a hardener [ 20 – 23 ]. The authors have previously studied the influence of some HBPs in the thermalcuring and in the photocuring of Diglycidyl ether of bisphenol A (DGEBA). Concretely, in [ 22 ], the authors have
Authors:Jiang Jinxue, Yang Yonglin, Li Cheng, and Li Jianzhang
effects of three boron compound FR chemicals on thermalcuring behaviors of the UF resin, using non-isothermal method of DTA. The main findings drawn from this study can be summarized as follows.
All of the three kinds of boron compound FRs changed
Authors:Arunjunai Raj Mahendran, Günter Wuzella, Andreas Kandelbauer, and Nicolai Aust
The thermal cure kinetics of an epoxidized linseed oil with methyl nadic anhydride as curing agent and 1-methyl imidazole as catalyst was studied by differential scanning calorimetry (DSC). The curing process was evaluated by non-isothermal DSC measurements; three iso-conversional methods for kinetic analysis of the original thermo-chemical data were applied to calculate the changes in apparent activation energy in dependence of conversion during the cross-linking reaction. All three iso-conversional methods provided consistent activation energy versus time profiles for the complex curing process. The accuracy and predictive power of the kinetic methods were evaluated by isothermal DSC measurements performed at temperatures above the glass transition temperature of the completely cured mixture (Tg∞). It was found that the predictions obtained from the iso-conversional method by Vyazovkin yielded the best agreement with the experimental values. The corresponding activation energy (Ea) regime showed an increase in Ea at the beginning of the curing which was followed by a continuous decrease as the cross-linking proceeded. This decrease in Ea is explained by a diffusion controlled reaction kinetics which is caused by two phenomena, gelation and vitrification. Gelation during curing of the epoxidized linseed/methyl nadic anhydride system was characterized by rheological measurements using a plate/plate rheometer and vitrification of the system was confirmed experimentally by detecting a significant decrease in complex heat capacity using alternating differential scanning calorimetry (ADSC) measurements.
Authors:A. Cadenato, J. Morancho, X. Fernández-Francos, J. Salla, and X. Ramis
The thermal polymerization kinetics of dimethacrylate monomers was studied by differential calorimetry using non-isothermal
experiments. The kinetic analysis compared the following procedures: isoconversional method (model-free method), reduced master
curves, the isokinetic relationship (IKR), the invariant kinetic parameters (IKP) method, the Coats-Redfern method and composite
integral method I. Although the study focused on the integral methods, we compared them to differential methods. We saw that
even relatively complex processes (in which the variations in the kinetic parameters were only slight) can be described reasonably
well using a single kinetic model, so long as the mean value of the activation energy is known (E). It is also shown the usefulness of isoconversional kinetic methods, which provide with reliable kinetic information suitable
for adequately choosing the kinetic model which best describes the curing process. For the system studied, we obtained the
following kinetic triplet: f(α)=α0.6(1−α)2.4, E=120.9 kJ mol−1 and lnA=38.28 min−1.
Authors:P. Tabaddor, C. Aloisio, H. Bair, C. Plagianis, and C. Taylor
DSC, TGA and DMA thermal analysis techniques are used to characterize a complex adhesive blend. The chemical and thermomechanical property development shown to follow a two-stage process. Beneficial synergy between these analysis tools is demonstrated in this study.
Authors:Chinnaswamy Thangavel Vijayakumar, Rajendran Surender, Kumaraswamy Rajakumar, and Sarfaraz Alam
crosslinking density. Micheal addition of primary or secondary diamines to bismaleimides was used to effect chain extension through thermalcuring to reduce the high crosslinking density and brittleness of the polymers [ 5 , 6 ].
Various processes have
Authors:María González González, Juan Carlos Cabanelas, Javier Pozuelo, and Juan Baselga
thermalcuring [ 19 ] have been studied for the neat resin as well as for modified systems with dendritic-toughening additives [ 17 ] and with surface-modified SiO 2 particles [ 24 ].
In view of the alleged lack of reactivity against amines, no
polyesters with styrene initiated by BPO was indicated. It can be attributed to the thermalcuring of epoxy groups to the hydroxyl or carboxyl groups in polyester resulting in forming ether or ester linkages [ 20 , 21 ]. The broad asymmetric exothermic peak
Authors:J. Morancho, A. Cadenato, X. Fernández-Francos, J. Salla, and X. Ramis
The purpose of this work is to analyse certain kinetic features related to thermoinduced and photoinduced isothermal curing
in the 25/75 mass% bis-GMA/TEGDMA system. The kinetic parameters associated with photo and thermal curing were determined and compared using an
isoconversional procedure and the kinetic model was obtained by means of a reduced master plot. In photocuring, the kinetic
results obtained by means of this phenomenological methodology were compared with those obtained on the basis of mechanistic
considerations. In this case, we estimated the propagation and termination constants associated with photocuring at different
conversions. When the phenomenological procedure is performed, the rate constant decreases slightly during the curing process
and the autoacceleration effect of the process is demonstrated in the kinetic model, which is autocatalytic. However, in the
mechanistic model, this same effect is noted through an increase in the rate constants, while it is assumed that the kinetic
model is in the order of n with n=1.