Investigation of Thermal Degradation Kinetics of Poly(Ɛ-caprolactone) Grafted onto PEMA-co-PHEMA

Abstract

Poly(ethyl methacrylate)-co-poly(2-hydroxyethyl methacrylate), PEMA-co-PHEMA, which containing 5% 2-hydroxyethyl methacrylate (HEMA) was synthesized by the free radical polymerization. ɛ-caprolactone was grafted -OH side group of PEMA-co-PHEMA via ring opening polymerization method. A newly synthesized PEMA-co-PHEMA-g-PCL which grafted onto PEMA-co-PHEMA were characterized by experimental measurements such as FTIR, 1 H NMR and TGA techniques. The reaction mechanism of degradation process and the kinetic parameters of the polycaprolactone grafted onto PEMA-co-PHEMA in nitrogen environment were investigated by thermogravimetric analysis (TGA) at different heating rates. The evident activation energies of thermal degradation for polycaprolactone, as defined by the Kissinger’s, Flynn–Wall–Ozawa and Tang methods, which does not necessary knowledge of the reaction mechanism (RM), were 108.58, 113.88 and 108.35 kJ/mol, respectively. These values were compared using different integral and differential methods. An analysis of the experimental results proposed that the reaction mechanism was an R3 deceleration type in the conversion range (2- 40%) studied.

Serbest radikal polimerizasyonuyla sentezlenen %5 oranında 2-hidroksietilmetakrilat (HEMA) içeren poli(etilmetakrilat)-ko-poli(2-hidroksi etilmetakrilat), PEMA-ko-PHEMA, kopolimerinin –OH ucuna, Ɛ-kaprolakton halka açılması polimerizasyonu metoduyla aşılandı. Sentezlenen polimerler FTIR ve 1 H-NMR teknikleriyle karakterize edildi. PEMA-ko-PHEMA-a-PCL aşı kopolimerinin termal degradasyon kinetiği farklı ısıtma hızlarında termogravimetrik analizle araştırıldı. Aktivasyon enerjisi Kissinger, Flynn–Wall–Ozawa ve Tang metotlarıyla, reaksiyon mekanizması bilinmeden, sırasıyla 108.58, 113.88 ve 108.35 kJ/mol olarak hesaplandı. Farklı integral ve diferansiyel metotlar kullanılarak bu değerler karşılaştırıldı. Deneysel sonuçların analiziyle, çalışılan dönüşüm aralığında (%2-40) reaksiyon mekanizması R3 olarak belirlendi.