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首页> 外文期刊>Journal of Macromolecular Science. Physics >Non-isothermal Thermogravimetric Degradation Kinetics, Reaction Models and Thermodynamic Parameters of Vinylidene Fluoride Based Fluorinated Polymers
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Non-isothermal Thermogravimetric Degradation Kinetics, Reaction Models and Thermodynamic Parameters of Vinylidene Fluoride Based Fluorinated Polymers

机译：非等温热重度降解动力学，反应模型和偏二氟乙烯基氟化聚合物的热力学参数

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摘要

Commercial fluororubber SKF 32, fluoroplastic F-32L, fluoroelastomer Kel-F, fluoroplastic FK 800 (labeled as SKF 32, F-32L, Kel-F and FK 800) and an in-house prepared poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM) copolymer were investigated in terms of their thermal degradation kinetics, reaction models and corresponding thermodynamic parameters. All samples underwent a single step thermal degradation using thermogravimetric analysis (TGA) at different heating rates under nitrogen atmosphere. The kinetic parameters were determined through the Kissinger method and three isoconversional methods; viz. the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira- Sunose (KAS) and Starink. The activation energies of the SKF 32, F- 32L, Kel-F, FK 800 and FKM obtained using the Kissinger method were 206, 200, 185, 221 and 243 kJ mol~(-1), respectively. The activation energy values for the degradation obtained using the KAS method were: 180-225 kJ mol~(-1) for SKF 32, 192-209 kJ mol~(-1) for F-32L, 163-185 kJ mol~(-1) for Kel-F, 213-227 kJ mol~(-1) for FK 800 and 187-269 kJ mol~(-1) for FKM with the extents of conversion (α) = 0.1-0.9. These values of the activation energies obtained from the KAS method were in good agreement with those obtained using the FWO and Starink methods. In addition, the appropriate degradation reaction models were determined by means of the Coats-Redfern and Criado methods. The thermodynamic parameters, such as activation Gibb free energy, ΔG*, activation enthalpy, ΔH*, and activation entropy, ΔS*, for formation of the activated complexes during the thermal degradation were also determined and discussed. The positive values of the Ea, ΔG*, ΔH*, and ΔS* for SKF 32, F-32L, FK 800 and FKM indicated a non-spontaneous process, while the positive values of the E_a, ΔG* and ΔH*, and negative value of ΔS* for Kel-F meant that the formation of the activated complex was accompanied by a smaller decrease of entropy than for the other polymers.
机译：商用氟橡胶SKF 32，氟塑料F-32L，氟塑料kel-F，氟塑料FK 800（标记为SKF 32，F-32L，KEL-F和FK 800）和内部制备的聚（偏二氟乙烯 - 氯三氟乙烯）（FKM在其热降解动力学，反应模型和相应的热力学参数方面研究了共聚物。所有样品均在氮气氛下在不同加热速率下使用热重分析（TGA）进行单一步骤热劣化。通过基辛格方法和三种异组方法测定动力学参数; viz。 Flynn-Wall-Ozawa（FWO），基辛格 - Akahira- Sunose（KAS）和明星。使用基辛方法获得的SKF 32，F-32L，KEL-F，FK 800和FKM的激活能量分别为206,200,185,221和243kJMol〜（-1）。使用KAS方法获得的降解的激活能量值为：用于SKF 32,192-209 kJ mol〜（-1）的180-225 kJ mol〜（-1），用于f-32l，163-185 kj mol〜（ -1）对于FK 800和187-269 kJ mol〜（-1）的Kel-F，213-227 kJ mol〜（-1），用于转化率（α）= 0.1-0.9的范围。从KAS方法获得的这些激活能量的值与使用FWO和饥饿方法获得的值良好。此外，通过涂层和CRIADO方法测定适当的降解反应模型。还确定并讨论了热力学参数，例如激活Gibb自由能，ΔG*，活化焓，ΔHα和活化熵，ΔS*，用于形成活性复合物的形成。 SKF 32，F-32L，FK 800和FKM的EA，ΔG*，ΔH*和ΔS*的正值表示非自发性过程，而E_A，ΔG*和ΔH*的正值，以及对于kel-f的Δs*的负值意味着活化复合物的形成伴随着熵的较小降低而不是其他聚合物。

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