STUDY OF PRECIPITATION KINETICS OF AN AL-MG-SI ALLOY USING DIFFERENTIAL SCANNING CALORIMETRY

<p class="AMSmaintext">This work has been carried out by differential scanning calorimetric (DSC) to study the precipitation kinetics in quenched and natural aging Al-Mg-Si alloy. DSC curves showed exothermic and endothermic peaks corresponding to the precipitation and the dissolution processes. The activation energy of the precipitation process has been calculated using Kissinger model. The results obtained showed a change in the activation energy values, the activation energy for the β″ and β determined for natural aging alloy were higher than that in the quenched alloy. </p>

The Natural Aging Effect on the Activation Energy of the Precipitation Processes in the Al-Mg-Si Alloy

The precipitation sequence of an Al-Mg-Si alloy depends on many parameters. In this study the natural aging effect on the activation energy of the precipitation sequence in the Al-Mg-Si alloy have been investigated by differential scanning calorimetry (DSC). The precipitation sequence of an Al-Mg-Si alloy has been established. The activation energy of the precipitation process was calculated using Kissinger model. The results obtained using this method showed a change in the activation energy for all precipitated phases. The activation energy of the metastable phases (β″ and β′) and the stable phase β formation in the Al-Mg-Si alloy aged at room temperature have been determined.

Pyrolysis kinetics of recycled polyesters

Purpose – The purpose of this paper is to study the non-isothermal degradation kinetics of recycled polybutylene terephthalate, polytrimethylene terephthalate and polyethylene terephthalate using thermogravimetric analysis (TGA) in a nitrogen atmosphere. Design/methodology/approach – To achieve this goal, the author utilized standard kinetic models, such as Coats-Redfern and Kissinger equations, for analysis of the TGA data. Findings – When applied to the TGA data, the Kissinger model resulted in a coefficient of determination (R2) value greater than 0.99. Originality/value – This study describes the maiden application of the Kissinger model to obtain the pre-exponential factor (A) and activation energy (E) for different polyester systems used in the textile industry.

Thermal Degradation Kinetics of Polyurethane/polybenzoxazine Alloys

Recently, the alloys of polyurethane (PU)/polybenzoxazine (PBA-a) have been studied due to many interesting properties; however, the thermal degradation kinetics of the system has not been mentioned before. In this study, the degradation temperatures of the obtained alloys were determined using Thermogravimetric Analyzer (TGA) with various heating rate of 10, 20, 25oC/min. The polyurethane /polybenzoxazine alloys at the weight ratios of 30/70 were prepared for determination due to its highest degradation temperature. The first derivative curves of the thermograms (DTG) were deconvoluted with Peak-fit program. The results reveal three main sub-stages of degradation. According to Arrhenius Eq., the activation energies (Ea) of each degradation sub-stage were determined using Kissinger model and Fynn-Wall Ozawa model.