Toward the controlled production of oligoesters by microwave-assisted degradation of poly(3-hydroxyalkanoate)s |
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Authors: | Julien RamierDaniel Grande Valérie LangloisEstelle Renard |
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Institution: | Equipe “Systèmes Polymères Complexes”, Institut de Chimie et des Matériaux Paris-Est, UMR 7182 CNRS - Université Paris-Est Créteil, 2 rue Henri Dunant, 94320 Thiais, France |
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Abstract: | The degradation of poly(3-hydroxyalkanoate)s (PHAs) could be performed in a rapid, inexpensive and straightforward way via microwave irradiation with good potential for further scale-up. One such degradation was compared to that induced by conventional heating at 190 °C. The experimental results showed that PHA oligomers with varying molar masses, characterized by a terminal crotonic double bond and a carboxyl group on the other chain end, could be effectively obtained from native PHAs in the bulk by both degradation approaches. The kinetics of PHA oligomer production was monitored by size exclusion chromatography and 1H NMR. The influence of temperature as well as microwave irradiation time and power was investigated, and the optimal conditions of degradation are described. It turned out that this treatment was much more efficient than a conventional thermally-induced degradation, as oligomers with similar molar masses were formed with an about 100 times faster rate corresponding to very short irradiation times (maximum 15 min). Two microwave-assisted procedures could be advantageously used: an irradiation with constant temperature was appropriate to afford PHA oligomers with molar masses lower than 1000 g.mol−1 and high yields, while irradiation under constant power was more convenient to provide oligoesters with higher molar masses. |
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Keywords: | Poly(3-hydroxyalkanoate)s Conventional thermal degradation Microwave-assisted degradation PHA oligomers |
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