Effects of a Hindered Amine Stabilizer (HAS) on radiolytic and thermal stability of poly(methyl methacrylate)

Commercial Poly(methyl methacrylate) (PMMA) containing Tinuvin 622, a Hindered Amine Stabilizer (HAS), in 0.3% (wt/wt) concentration was investigated. The samples were irradiated with gamma radiation (⁶⁰Co) at room temperature in air. The viscosity-average molecular weight (Mv) was analyzed by visco...

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Bibliographic Details
Published in:Journal of applied polymer science 2008-10, Vol.110 (1), p.401-407
Main Authors: Aquino, Katia Aparecida S, Araujo, Elmo S
Format: Article
Language:English
Subjects:
activation energy
additive
Applied sciences
Compounding ingredients
Exact sciences and technology
gamma irradiation
PMMA
Polymer industry, paints, wood
Stabilizers (antioxydants, antiozonants, etc.)
Technology of polymers
thermal degradation
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Summary:Commercial Poly(methyl methacrylate) (PMMA) containing Tinuvin 622, a Hindered Amine Stabilizer (HAS), in 0.3% (wt/wt) concentration was investigated. The samples were irradiated with gamma radiation (⁶⁰Co) at room temperature in air. The viscosity-average molecular weight (Mv) was analyzed by viscosity technique. Both control PMMA (without HAS) and PMMA + 622 (with HAS) showed a decrease in molecular weight with the increase in dose, reflecting the random scissions that occurred in the main chain. The G value (scissions/100 eV of energy transferred to the system) was also obtained by viscosity analysis. G value results showed that the addition of Tinuvin 622 into the PMMA matrix significantly decreased the number of scissions/100 eV at dose range of 0-60 kGy. Analysis of infrared spectra showed a decrease in the carbonyl index (CI) in irradiated samples. However the CI decrease was found lower for PMMA + 622 than for control PMMA sample. Thermogravimetric analysis (TGA) revealed that maximum decomposition temperature of additive PMMA is 42°C higher than control PMMA for unirradiated system. On the other hand this difference is not significant in irradiated systems at 60-kGy irradiation dose. The activation energy of the thermal degradation of PMMA was 165 kJ/mol, this activation energy increased 60 kJ/mol when Tinuvin 622 was added to PMMA matrix. Therefore Tinuvin 622 is a suitable radiostabilizing agent for commercial PMMA in a 0-60 kGy dose interval.
ISSN:0021-8995
1097-4628
DOI:10.1002/app.28465