The Effect Of Current Antioxidant On Thermal Oxidation Stability Of PMMA

PMMA resin is a type of thermoplastic, which will be depolymerizated at 200℃. How to improve the thermal oxidative stability of PMMA has became a hot spot. Adding antioxidant is an effective method. Basing on the mechanism, antioxidant can be divided into two categories:first, the main antioxidant, which plays a role to capture radicals. The second, the assistant antioxidant, which can easily slow down the reaction of oxidation chain attributed to decompose the hydroperoxides.The purpose of this paper is to discuss the effect of current antioxidant on thermal oxidation stability of PMMA. In this experiment, PMMA resin was synthesized by continual bulk polymerization, mixed with antioxidant by strong solvent. After that, the actual function of main antioxidant, assistant antioxidant and composite antioxidant were tested by thermogravimetric analysis, which is to comprehensive analysis these functions of antioxidants in views of the initial decomposition temperature, the maximum decomposition temperatures and the aspect of dynamics.It indicated that the addition of antioxidants can effectively improve thermal oxidative stability of PMMA, when independently used, accompanying the added antioxidant capacity to raise, the initial decomposition temperature and maximum decomposition temperatures have a linear increase. While in the case of antioxidants composited, the initial decomposition temperature is affected greatly by the added content of main antioxidants, the content of assistant antioxidants has an effect on the maximum decomposition temperature. The additive amount has the linear relationship with temperature.From the perspective of activation energy, the activation energy of PMMA resin with the antioxidants was increased in evidence, especially the composite antioxidants. With the ratio of decomposition increasing, the activation energy was decreased, which account for the reason that the decomposition of PMMA resin was easy to react. In a different rate of heating-up, the temperature was improved at the same percentage of rate of decomposition, in other words, the influence of diffusion process of MMA from the system could not be neglected at a high heating rate.