Micron-sized poly (methyl methacrylate) (PMMA) with high flammability is widely applied in industries, constructions and transportations. Study on the thermal degradation behaviors of micron-sized PMMA in oxygenous atmosphere, which receives scarce attention to date, can provide valuable guidance for the prevention and mitigation of injuries and damages arising from the micron-sized PMMA dust explosions and fires. In the present study, the thermal degradation characteristics of micron-sized PMMA in air were investigated by thermogravimetry. Deconvolution method using Gauss function coupled with model-free and model-fitting methods was employed to conduct the kinetic modeling. The values of thermodynamic parameters (ΔH, ΔG and ΔS) were estimated. The results indicated that one peak and one shoulder occurred in the mass loss rate (MLR) variations of the micron-sized PMMA degradation in air. The values of MLR at peak and shoulder both decreased with heating rate. Besides, the average value of the MLR varied little with heating rate. The values of MLR at the peak and the average MLR of micron-sized PMMA degradation in air were both less than those of the traditional-sized PMMA degradation in air. The calculated kinetic parameters can be used to well predict the thermal degradation behaviors of micron-sized PMMA in air. Additionally, the micron-sized PMMA in air was easier to decompose than the traditional-sized PMMA in air. Non-spontaneous reactions were involved in the thermo-oxidative degradation of micron-sized PMMA. Besides, with the progressing of thermo-oxidative degradation, less energy was required and pyrolytic products with well-ordered structures may be generated.

具有高易燃性的微米级聚甲基丙烯酸甲酯（PMMA）广泛用于工业，建筑和运输。迄今为止，对含氧大气中微米级PMMA的热降解行为的研究很少受到关注，它可以为预防和减轻微米级PMMA粉尘爆炸和火灾造成的伤害和损害提供有价值的指导。在本研究中，通过热重分析法研究了微米级PMMA在空气中的热降解特性。利用高斯函数的反卷积方法结合无模型和模型拟合方法进行动力学建模。热力学参数（ΔH，ΔG和ΔS）的值）进行了估算。结果表明，在空气中微米级PMMA降解的质量损失率（MLR）变化中出现一个峰和一个肩峰。峰值和肩峰处的MLR值均随加热速率而降低。此外，MLR的平均值随加热速率变化很小。空气中微米级PMMA降解的峰值MLR值和平均MLR均小于空气中传统尺寸PMMA降解的MLR值。计算出的动力学参数可用于很好地预测微米级PMMA在空气中的热降解行为。此外，空气中的微米级PMMA比传统的空气中PMMA更容易分解。非自发反应参与了微米级PMMA的热氧化降解。除了，