Print: | ISSN 0256-1115 |
Online: | ISSN 1975-7220 |
Korean Journal of Chemical Engineering,
Vol.32, No.3, 552-562, 2015 Thermal curing and degradation kinetics of terpolymer resins derived from vanillin oxime, formaldehyde and p-chloro-/p-methylacetophenone
A novel class of linear terpolymer resins have been prepared from various macromers formed by vanillin oxime (VO), formaldehyde (F) and p-chloro/p-methylacetophenone in the presence of an acid as catalyst by convenient polycondensation process. The conversion of different macromers into respective terpolymeric resin was studied by DSC analysis from -50 ℃ to 250 ℃. The first thermal transition endotherms ranging from 108-137 ℃ (VOFCA) and 125-150 ℃ (VOFMA) are due to expulsion of water molecules, and the second thermal transition exotherms 177-247 ℃ (VOFCA) and 183.9-249.8 ℃ (VOFMA) are attributed to the formation of methylene linkage between macromers moieties by utilizing methlol groups at terminals. The activation energy required for conversion of methylol into methylene groups for VOFCA and VOFMA was 3.4 and 3.9 kJ/mol, respectively. Structural confirmations were determined through IR, Uv-Vis, 1H NMR spectroscopy and GPC data. The activation energy (Ea) and thermodynamic parameters of the thermal decomposition process were investigated with thermogravimetric analysis (TGA) by isoconversional integral Kissinger-Akahira-Sunose (KAS) and differential Friedman methods. Empirical kinetic models, as well as generalized master plots, were applied to explain the degradation mechanisms of terpolymer resins. The degradation reaction follows Avrami-Erofeev (nucleation and growth) at initial stage to Jander (three-dimensional diffusion) model for PVOMAF and Jander (two-dimensional diffusion) for PVOFCA governed mechanisms. Among all the tested
terpolymers, both resins revealed better activity compared to standard drugs as Gentamycin, Amphicilin, Chloramphenicol, Ciprofloxacin and Noorfloxacin.
Keywords:
Polycondensation; Vanillin Oxime; TG-DTG; Characterization; Isoconversional; Kinetics; Mechanism; Antibacterial Activity
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