Thermal-Induced And Thermo-Oxidative Depolymerization Of Natural Rubber And Its Epoxidized Derivatives - Betar, Bashir (2015)
Pemdepolimeran getah asli (NR) dan terbitan terepoksidanya, ENR25 dan ENR50 (NR dengan kandungan epoksi, masing-masing, dalam lingkungan 25% dan 50%) secara teraruh-terma telah dilaksanakan pada 200 oC dalam keadaan: (1) tekanan ambien (760 mm Hg) di mana [O2] ≈ 20.95%, tekanan rendah (85 mm Hg) di mana [O2] ≈ 2.34%, dan tekanan ambien (760 mm Hg) tetapi sampel-sampl dimasukkan dalam bekas-bekas tertutup yang mengandungi [O2] ≈ 100%. Getah-getah permulaan dan yang telah dipemdepolimerkan (diasingkan pada jarak masa 1, 2, 4, 8, 12 dan 16 jam) dipercirikan dengan menggunakan kaedah (i) Kromatografi Penyerapan Gel (GPC), (ii) Penentuan kandungan gel, (iii) Spektroskopi Resonans Magnetik Nukleus Transformasi Fourier Proton (1H FT-NMR), (iv) spektroskopi Inframerah Transformasi Fourier (FT-IR) dan (v) analysis termogravimetri (TGA). Data GPC pemdepolimeran NR berlaku dengan lebih pantas daripada pemdepolimeran ENR25 yang pula berlaku dengan lebih pantas daripada pemdepolimeran ENR50. Thermal-induced depolymerization of natural rubber (NR) and its epoxidized derivatives, ENR25 and ENR50 (NR with epoxy content of approximately 25% and 50%, respectively) was conducted at 200 oC under the following conditions: (1) ambient pressure (760 mm Hg) whereby [O2] ≈ 20.95%, (2) reduced pressure (85 mm Hg) whereby [O2] ≈ 20.95%, and (3) ambient pressure (760 mm Hg) but samples were placed inside sealed containers whereby the initial [O2] ≈ 100%. The starting and depolymerized rubbers (isolated at 1, 2, 4, 8, 12 and 16 hr time intervals) were characterized by means of (i) Gel Permeation Chromatography (GPC), (ii) Gel content determination, (iii) Proton Fourier Transformed Nuclear Magnetic Resonance (1H FT-NMR) spectroscopy, (iv) Fourier Transformed Infrared (FT-IR) spectroscopy and (v) Thermo Gravimetric Analysis (TGA). GPC data reveals that NR depolymerized faster than ENR25 which in turn depolymerized faster than ENR50.