Adnan KURT, Murat KOCA

Pirazol Temelli Yeni Bir Kopolimerin [poli(1,3-difenil-1H-pirazol-5-il metakrilat-ko-stiren)] Termal Bozunma Kinetiği

Mevcut çalışmada, pirazol sübstitüe gruplu 1,3-difenil-1H-pirazol-5-il metakrilat (DPMA) ve stiren (St) birimlerini içeren yeni bir kopolimer [poli(DPMA-ko-St)] sentezlenmiş ve kopolimer sisteminin termal bozunma kinetiği termogravimetrik analiz (TGA) tekniği ile detaylıca araştırılmıştır. Isıtma hızındaki değişime bağlı olarak (5 °C/dak – 20 °C/dak) kopolimerin termal stabilitesinde 252,02 °C'den 274,89 °C'ye bir artış gözlemlenmiştir. Kopolimerin termal bozunma aktivasyon enerjileri, %9 - %21 dönüşüm aralığında, Kissinger ve Flynn-Wall-Ozawa yöntemleri ile sırasıyla 149,37 kJ/mol ve 140,99 kJ/mol olarak sonuçlanmıştır. Coats-Redfern, Tang, Madhusudanan ve Van Krevelen gibi farklı kinetik metotlar ışığında kopolimerin termal bozunma mekanizması incelenmiştir. Elde edilen sonuçlar kopolimerin termal bozunma mekanizmasının özellikle Coats-Redfern metoduna göre 20 °C/dak optimum ısıtma hızında tek boyutlu difüzyon tipi bir yavaşlama mekanizması yani D1 mekanizması üzerinden ilerlediğini göstermiştir.

Thermal Degradation Kinetics of a Novel Pyrazole Based Copolymer [poly(1,3-diphenyl-1H-pyrazol-5-yl methacrylate-co-styrene)]

In the present study, a new copolymer containing pyrazole substituted 1,3-diphenyl-1H-pyrazol-5-yl methacrylate (DPMA) and styrene (St) units, [poly(DPMA-co-St)], was synthesized. Thermal degradation kinetics of the copolymer system was investigated in detail with the thermogravimetric analysis (TGA) technique. An increase in the thermal stability of the copolymer from 252.02 °C to 274.89 °C was observed depending on the change in heating rate (5 °C/min – 20 °C/min). The thermal degradation activation energies of the copolymer were 149.37 kJ/mol and 140.99 kJ/mol, respectively, with the Kissinger and Flynn-Wall-Ozawa methods in the conversion range of 9% - 21%. The thermal degradation mechanism of the copolymer was investigated in the light of different kinetic methods such as Coats-Redfern, Tang, Madhusudanan, Van-Krevelen and Horowitz-Metzger. The results showed that the thermal decomposition mechanism of the copolymer proceeds through a one-dimensional diffusion-type deceleration mechanism, namely the D1 mechanism, at the optimum heating rate of 20 °C/min, especially according to the Coats-Redfern method.

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