Pirazabol Merkezli İki Kollu Poli(metil metakrilat)’ın Termal Bozunma Kinetiğinin Araştırılması

Year 2016, Volume: 6 Issue: 2, 233 - 251, 27.12.2016

Adnan Kurt , Handan Ayaz Ahmet Gültek

Abstract

Atom transfer radikal polimerizasyon (ATRP) metoduyla 2,6-dibromo pirazabol
başlatıcısı varlığında CuBr/2,2’-bipiridin katalizör sistemi ile katalizlenen metil
metakrilatın 100 oC’de farklı sürelerde sonlandırılan bir seri iki kollu polimeri (PMMA)
sentezlendi. Polimerlerin ortalama molekül ağırlıkları ve molekül ağırlık dağılımları
GPC tekniği ile belirlenerek polimerizasyon kinetiği araştırıldı. 240 dakikalık sürede
polimerleştirilen iki kollu PMMA’ın termal davranışı detaylıca test edildi. TGA metodu
kullanılarak 5, 10, 15, 20 ve 25 oC/dak ısıtma hızlarında termal bozunma kinetiği
araştırıldı. TGA sonuçlarından, ısıtma hızı ile polimerin termal kararlılığı arasında
doğrusal bir ilişki tespit edildi. Polimerin termal bozunma aktivasyon enerjisi FlynnWall-Ozawa
ve Kissinger metotlarından sırasıyla 120,98 kJ/mol ve 112,53 kJ/mol
olarak hesaplandı. Polimerin termal bozunma mekanizmasını belirlemek amacıyla
Coats-Redfern, Tang ve Madhusudanan gibi kinetik metotlar kullanıldı. Elde edilen
kinetik veriler ışığında pirazabol merkezli iki kollu PMMA’ın termal bozunma
mekanizmasının D2 tipi yavaşlama mekanizması üzerinden 5 °C/dak optimum ısıtma
hızında ilerlediği gözlemlendi.

Keywords

Pirazabol, Atom Transfer Radikal Polimerizasyonu (ATRP), Termogravimetrik Analiz, Aktivasyon Enerjisi

Investigation of Thermal Degradation Kinetics of Pyrazabole Centered TwoArmed Poly(methyl methacrylate)

Abstract

A series of two armed polymers of methyl methacrylate (PMMA) was
synthesized by atom transfer radical polymerization (ATRP) method using 2,6-
dibromopyrazabole as initiator and CuBr/2,2’-bipyridine as catalyst system at 100 °C
ended different times. Average number molecular weights and molecular weight
distributions of polymer series were recorded with GPC technique and thus,
polymerization kinetic was determined. Thermal behavior of two-armed PMMA
polymerized at 240 minutes was investigated detailed by TGA method at the heating
rates of 5, 10, 15, 20 and 25 oC/min. From TGA results, a linear correlation was
determined between the heating rate and the thermal stability of the polymer.
Decomposition activation energies of polymer were found to be 120,98 kJ/mol and
112,53 kJ/mol by the Flynn-Wall-Ozawa and Kissinger methods, respectively. Some
kinetic methods such as Coats-Redfern, Tang and Madhusudanan were used to
investigate the thermal degradation mechanisms of polymer. In the light of obtained
kinetic data, it was observed that the thermal decomposition mechanism of the
pyrazabole centered two-armed PMMA was followed by D2 type deceleration
mechanism at 5 °C/min optimum heating rate.

Keywords

Pyrazabole, Atom Transfer Radical Polymerization (ATRP), Thermogravimetric Analysis, Activation Energy

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