Abstract

Differential Scanning Calorimetry (DSC) was used to analyse the thermal properties and curing behaviour of a structural acrylic adhesive at heating rates of 5, 10, and 15 °C/min. The study focused on the curing kinetics, glass transition temperature (Tg), specific rate (k), and activation energy (Ea) of the polymerization reaction. The material is tested according to ASTM 3418 standards. Results showed that increasing the heating rate shifted the endothermic curing occurred at lower temperatures, consistent with kinetic control of the reaction. It was interpreted that higher heating rates delay the curing reaction to higher temperatures due to kinetic control resulting less time for molecular rearrangement. The heat flow in the sample is negative. The Tg exhibited a heating rate dependence, increasing at higher rates due to thermal lag. The transition temperature is clustered between 82 °C to 89 °C . The activation energy, determined using Ozawa-Flynn method, was found to be 57.81 KJ/mol, indicating the energy barrier for the curing process. These findings highlighted the trade-off between heating rate and curing quality: slower rates ensure thorough crosslinking but prolong processing, while faster rates save time but risk residual stresses or incomplete curing. The outcome provides critical insights into the thermal behaviour of structural acrylics, aiding in the optimization of curing conditions for industrial applications

Keyword: DSC, structural acrylic, heating rate, curing kinetics, activation energy, specific heat capacity, glass transition temperature

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