Thermal degradation of epoxy/silica composites monitored via dynamic mechanical thermal analysis
ABSTRACT A dynamic mechanical thermal analyzer (DMTA) was used to monitor changes of dynamic mechanical properties during thermal degradation of two types of epoxy/silica composites, both of which are used as electrical insulation in power apparatus. It was found that the peak value of the dynamic loss factor (tan δ), glass transition temperature (Tg), and dynamic storage modulus (E′) above Tg changed considerably with increasing thermal degradation, while E′ at the glassy state only underwent a moderate change with increased thermal degradation. It is concluded that the DMTA technique is very sensitive to the structural changes in the investigated epoxy composites due to the thermal degradation. It is also confirmed by DMTA tests that further cross-linking and loss of dangling chains are occurring slowly during the stage prior to the onset of the severe degradation. © 1992 John Wiley & Sons, Inc.
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ABSTRACT: Mechanical behaviour play an important role in the election of an epoxidic formulation of well determined properties as it has a marked influence on both structural and external factors. Temperature and time strongly act on polymers properties owing to their viscoelastic nature. Knowledge of the dynamic moduli and properties of polymeric materials is indispensable for the design of this materials. At the same time, the influence of the temperature on polymers behaviour may be studied once the activation energy is known. In this paper the different dynamic moduli and activation energy are measured using a Perkin Elmer DMA 7. The relationships between the dynamic mechanical properties and the molecular weight of the polymers make possible the calculation of the molecular weight. Results reasonably agree with literature values.Journal of Thermal Analysis and Calorimetry 01/1994; 41(6):1543-1550. · 1.98 Impact Factor
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ABSTRACT: A high-purity silica was obtained from thermal decomposition of molding resin used as electronic packaging materials. The reaction was performed at high temperature and in oxidizing atmosphere. The product was suitable for reuse as inorganic filler in the production of semiconductor devices, as well as the starting materials in the manufacture of silicon materials. Thermal decomposition kinetics of the electronic packaging material were investigated under various reaction parameters including gas flow rate, sample loading, grain size, oxygen concentration and heating rate by using a thermogravimetric analysis (TGA) technique. The results indicated that thermal degradation of electronic packaging material consisted of two distinct reaction stages. The corresponding kinetic parameters including the activation energy, pre-exponential factor, and reaction order in the chemical reaction-controlled region are presented. A mechanism of thermal decomposition was proposed, which is in good agreement with the experimental results.Chemical Engineering Journal - CHEM ENG J. 01/2004; 98(1):39-51.
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ABSTRACT: A new phosphorous containing coupling agent namely, diethylenetriamino-diethylphosphate (DTDP) was synthesized. The structure was confirmed by means of FT-IR, 1H-NMR, 13C-NMR spectra, and mass spectral analysis. The coupling ability of DTDP was investigated by blending it with DGEBA and PDMS, and thus obtained blends have reflected in an increase in the modulus, glass transition temperature and adhesion strength property between the metal-to-metal interface. The high thermal stability, IPDT temperature and flame retardant properties (LOI) were attributed to the presence of phosphorous atom in the coupling agent.Polymer-Plastics Technology and Engineering 02/2011; 50(3):266-275. · 1.48 Impact Factor