Thermo-mechanical characterisation of a nanosized particle filled underfill
This paper describes work carried out as part of a larger project aimed at the development of nanosized particle filled underfill material. Several characterisation experiments have been applied to study the influence of these particles on the curing behaviour and the thermomechanical properties such as the coefficient of thermal expansion, geltime, glass transition temperature, and modulus. Constitutive models are assessed for their ability to describe the observed behaviour
Determination of gel and vitrification times of thermoset curing process by means of TMA, DMTA and DSC techniques
In the present work, gelation and vitrification experimental data are obtained by TMA and DMTA techniques using the same thermoset based on an epoxy-amine system. The results show that the times obtained are not equivalent and depend on the technique used. An attempt has been made to compare both determinations using the degree of cure obtained by means of DSC technique. The principal conclusion that we want to emphasize is that it is the conversion degree and not the time of the phenomenological changes that take place during cure, that is the link to connect and interrelate the results obtained with different techniques. A method is also described for constructing the TTT diagram with only DSC and TMA or DMTA data.
Theory of glass transition: chemical equilibria approach
Abstract The main principles of a chemical approach to the analysis of glass-forming melt structure and its change with temperature are formulated. It is shown that such an approach leads to the concept of the existence of chemical groupings in melts. The use of the basic equations of chemical thermodynamics provides conclusions about the temperature dependences of structural changes in glass-forming melts. Taking into account the highly probable dependence of the activation energies of structural relaxation on temperature and the distribution of relaxation times values which is inevitable for any amorphous substance, one can develop an algorithm to obtain a good fit between the calculated and experimental dependences of properties. In principle, this algorithm nearly coincides with that for the phenomenological Tool-Narayanaswamy model. Thus the approach described can be considered as a theoretical foundation for this model.