Li Jing, Huang Jindi, Yin Ruiming
School of Energy and Mechanical Engineering, Jiangxi University of Science and Technology Nanchang 330013 P. R. China
School of Metallurgy and Environment, Central South University Changsha 410083 P. R. China.
RSC Adv. 2019 Aug 30;9(47):27305-27317. doi: 10.1039/c9ra04489b. eCollection 2019 Aug 29.
This work aims to develop an effective method for investigating the multistage debinding kinetics and reaction mechanisms of removing ,-dimethylacrylamide/,'-methylenebisacrylamide (DMAA/MBAM) polymer from gelcast ceramic parts. Thermogravimetry (TG) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) experiments were performed to investigate the thermal degradation characteristics and the main compounds produced during the pyrolysis of DMAA/MBAM polymer within green components. A multi-stage parallel reaction model (M-PRM) was proposed to separate the overlapping peaks in the d/d curves. The kinetic parameters (activation energy and pre-exponential factor ) of each substage were calculated using model-free methods (Flynn-Wall-Ozawa, Starink, Friedman and Kissinger-Akahira-Sunose) and an activation energy variable model. In addition, the most appropriate kinetic mechanism function () of each substage was analyzed and discussed Málek's procedure and the Šesták-Berggren (SB) model. The results showed that the DMAA/MBAM polymer burnout in green components can be divided into three substages through a three-stage parallel reaction model (3-PRM). The values of (Friedman method) for substages 1 to 3 were () = 139.862 - 110.481 + 156.161 - 88.714 kJ mol, () = 160.791 + 152.496 - 236.906 + 163.724 kJ mol and () = 72.132 + 452.830 - 669.039 + 507.015 kJ mol, respectively. The average values of showed an increasing tendency from substages 1 to 3, and a kinetic compensation effect was also observed between the and in each substage. The kinetic mechanism analysis revealed that the reaction mechanisms for substages 1 to 3 were () = (1 - ) (-ln(1 - )), () = (1 - ) (-ln(1 - )) and () = (1 - ) (-ln(1 - )), respectively. It is expected that the research results can be extended to investigate the multiplex debinding of binders or polymers for various colloidal molding techniques.
本工作旨在开发一种有效的方法，用于研究从凝胶注模陶瓷部件中去除N,N'-二甲基丙烯酰胺/N,N'-亚甲基双丙烯酰胺（DMAA/MBAM）聚合物的多阶段脱脂动力学及反应机理。进行了热重分析（TG）和热解气相色谱/质谱联用（Py-GC/MS）实验，以研究生坯部件中DMAA/MBAM聚合物热解过程中的热降解特性及产生的主要化合物。提出了一个多阶段平行反应模型（M-PRM）来分离微商热重（d/d）曲线中的重叠峰。使用无模型方法（Flynn-Wall-Ozawa法、Starink法、Friedman法和Kissinger-Akahira-Sunose法）以及活化能变量模型计算了每个子阶段的动力学参数（活化能E和指前因子A）。此外，通过Málek程序和Šesták-Berggren（SB）模型分析和讨论了每个子阶段最合适的动力学机理函数（f(α)）。结果表明，通过三阶段平行反应模型（3-PRM），生坯部件中DMAA/MBAM聚合物的烧除可分为三个子阶段。子阶段1至3的E值（Friedman法）分别为（E1）=(139.862α - 110.481α² + 156.161α³ - 88.714α⁴) kJ mol⁻¹，（E2）=(160.791α + 152.496α² - 236.906α³ + 163.724α⁴) kJ mol⁻¹，（E3）=(72.132α + 452.830α² - 669.039α³ + 507.015α⁴) kJ mol⁻¹。E的平均值从子阶段1到3呈增加趋势，并且在每个子阶段的E和lnA之间也观察到了动力学补偿效应。动力学机理分析表明，子阶段1至3的反应机理分别为f1(α)=(1 - α)⁻¹(-ln(1 - α))，f2(α)=(1 - α)⁻²(-ln(1 - α))，f3(α)=(1 - α)⁻³(-ln(1 - α))。预期该研究结果可推广至研究各种胶体成型技术中粘结剂或聚合物的多重脱脂过程。
