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Thermal degradation behavior and kinetic analysis
of poly(L-lactide) in nitrogen and air atmosphere |
| Ming-Tao RUN,Xin LI,Chen-Guang YAO, |
| Key Laboratory of Medicinal
Chemistry and Molecular Diagnosis (Ministry of Education), College
of Chemistry and Environmental Science, Hebei University, Baoding
071002, China; |
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Abstract The non-isothermal and isothermal degradation behaviors and kinetics of poly(L-lactide) (PLLA) were studied by using thermogravimetry analysis (TGA) in nitrogen and air atmosphere, respectively. At lower heating rate ((5–10)°C/min), PLLA starts to decompose in air at lower temperature than those in nitrogen atmosphere; however, at higher heating rate ((20–40)°C/min), the starting decomposition temperature in air are similar to those in nitrogen atmosphere, not only showing that PLLA has better thermal stability in nitrogen than in air atmosphere, but also suggesting that the faster heating rate will decrease the decomposition of PLLA in thermal processing. Whether in air or in nitrogen atmosphere, the decomposition of PLLA has only one-stage degradation with a first-order decomposed reaction, suggesting that the molecular chains of PLLA have the similar decomposed kinetics. The average apparent activation energy of non-isothermal thermal degradation (Ēnon) calculated by Ozawa theory are 231.7kJ·mol−1 in air and 181.6kJ·mol−1 in nitrogen; while the average apparent activation energy of isothermal degradation (Ēiso) calculated by Flynn method are 144.0kJ·mol−1 in air and 129.2kJ·mol−1 in nitrogen, also suggesting that PLLA is easier to decompose in air than in nitrogen. Moreover, the decomposed products of PLLA are also investigated by using thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS). In air atmosphere the volatilization products are more complex than those in nitrogen because the oxidation reaction occurring produces some oxides groups.
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| Keywords
poly(L-lactide) (PLLA)
degradation
kinetics
TG
apparent activation energy
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Issue Date: 05 March 2010
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Li Y, Shimizu H. Improvement in toughnessof poly(L-lactide) (PLLA) through reactive blending with acrylonitrile-butadiene-styrenecopolymer (ABS): Morphology and properties. European Polymer Journal, 2009, 45(3): 738―746
doi: 10.1016/j.eurpolymj.2008.12.010
|
|
Li X-G, Huang M-R. Thermal decomposition kineticsof thermotropic poly(oxybenzoate-co-oxynaphthoate) Vectra copolyester. PolymerDegradation and Stability, 1999, 64(1): 81―90
doi: 10.1016/S0141-3910(98)00175-X
|
|
Lee J W, Jeong E D, Cho E J, et al. Surface-phase separation of PEO-containing biodegradablePLLA blends and block copolymers. AppliedSurface Science, 2008, 255(5): 2360―2364
doi: 10.1016/j.apsusc.2008.07.121
|
|
Xu H, Teng C, Yu M. Improvements of thermal property and crystallizationbehavior of PLLA based multiblock copolymer by forming stereocomplexwith PDLA oligomer. Polymer, 2006, 47(11): 3922―3928
doi: 10.1016/j.polymer.2006.03.090
|
|
Milicevic D, Trifunovic S, Galovic S, et al. Thermal and crystallization behaviour of gammairradiated PLLA. Radiation Physics andChemistry, 2007, 76(8―9): 1376―1380
doi: 10.1016/j.radphyschem.2007.02.035
|
|
Loo J S C, Ooi C P, Boey F Y C. Degradation of poly(lactide-co-glycolide) (PLGA) and poly(L-lactide) (PLLA) by electron beam radiation. Biomaterials, 2005, 26(12): 1359―1367
doi: 10.1016/j.biomaterials.2004.05.001
|
|
Renouf-Glauser A C, Rose J, Farrar D, et al. A degradation study of PLLA containing lauricacid. Biomaterials, 2005, 26(15): 2415―2422
doi: 10.1016/j.biomaterials.2004.07.067
|
|
Cam D, Hyon S H, Ikada Y. Degradation of high molecular weight poly(L-lactide)in alkaline medium. Biomaterials, 1995, 16(11): 833―843
doi: 10.1016/0142-9612(95)94144-A
|
|
Proikakis C S, Mamouzelos N J, Tarantili P A, et al. Swelling and hydrolytic degradation of poly(D,L-lacticacid) in aqueous solutions. Polymer Degradationand Stability, 2006, 91(3): 614―619
doi: 10.1016/j.polymdegradstab.2005.01.060
|
|
Tsuji H, Echizen Y, Nishimura Y. Photodegradation of biodegradable polyesters: A comprehensivestudy on poly(L-lactide) and poly(ϵ-caprolactone). Polymer Degradation and Stability, 2006, 91(5): 1128―1137
doi: 10.1016/j.polymdegradstab.2005.07.007
|
|
Chen J H, Li C R. Thermal Analysis and ItsApplication. Beijing: Science Press, 1985 (in Chinese)
|
|
Coats A W, Redfern J P. Kinetic parameters from thermogravimetricdata. Nature, 1964, 201: 68―69
doi: 10.1038/201068a0
|
|
Ozawa T. A new method of analyzing thermogravimetric data. Bulletin of the Chemical Society of Japan, 1965, 38: 1881―1886
doi: 10.1246/bcsj.38.1881
|
|
Nam J-D, Seferis J C. Generalized composite degradationkinetics for polymeric systems under isothermal and nonisothermalconditions. Journal of Polymer SciencePart B: Polymer Physics, 1992, 30(5): 455―463
doi: 10.1002/polb.1992.090300505
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