Effect of Exogenous Carboxyl and Hydroxyl Groups on Pyrolysis Reaction of High Molecular Weight Poly(L-Lactide) under the Catalysis of Tin
Tóm tắt
The effect of exogenous hydroxyl, carboxyl groups and/or Sn2+ on pyrolysis reactions of poly(L-lactide) (PLLA) was investigated by thermogravimetric analysis (TGA). The activation energy (Ea) of pyrolysis reactions was estimated by the Kissinger-Akahira-Sunose method. The kinetic models were also explored by the Malek method, and the random degradation behavior was determined by comparing the plots of In{-In[1 - (1 - w)0.5]} versus 1/T for experimental data from TGA with model reactions. The pyrolysis reaction rate of PLLA was affected slightly by exogenous hydroxyl and carboxyl groups at lower levels of Sn with 65–70 mg·kg-1 but increased appreciably in the presence of extraneous Sn2+, -COOH/Sn2+, or -OH/Sn2+. The Ea values for the pyrolysis reactions of the PLLAs that provided lactide were different under the catalysis of Sn2+ in different chemical environments because Sn2+ can form the new Sn-carboxylate and Sn-alkoxide with exogenous carboxyl and hydroxyl groups, which were different in steric hindrance for the formation of activated complex between Sn2+ and PLLA. Under the catalysis of Sn2+, a lactide molecule can be directly eliminated selectively at a random position of PLLA molecular chains, and the molecular chain of PLLA cannot change two PLLA fragments at the elimination site of lactide. However, it was regenerated into a new PLLA molecule with the molecular weight reduced by 144 g·mol-1.
Tài liệu tham khảo
Witzke, D. R.; Narayan, R.; Kolstad, J. J. Reversible kinetics and thermodynamics of the homopolymerization of L-lactide with 2-ethylhexanoic acid Tin(II) salt. Macromolecules 1997, 30, 7075–7085.
Kopinke, F. D.; Mackenzie, K. Mechanistic aspects of the thermal degradation of poly(lactic acid) and poly(β-hydroxybutyric acid). J. Anal. Appl. Pyrol. 1997, 40–41, 43–53.
Kopinke, F. D.; Remmler, M.; Mackenzie, K.; Moder, M.; Wachsen, O. Thermal decomposition of biodegradable polyesters—II. Poly(lactic acid). Polym. Degrad. Stabil. 1996, 53, 329–342.
McNeill, I. C.; Leiper, H. A. Degradation studies of some polyesters and polycarbonates. 2. Polylactide—degradation under isothermal conditions, thermal-degradation mechanism and photolysis of the polymer. Polym. Degrad. Stabil. 1985, 11, 309–326.
Lv, S. S.; Zhang, Y. H.; Tan, H. Y. Thermal and thermo-oxidative degradation kinetics and characteristics of poly (lactic acid) and its composites. Waste Management 2019, 87, 335–344.
Södergård, A.; Näsman, J. H. Melt stability study of various types of poly(L-lactide). Ind. Eng. Chem. Res. 1996, 35, 732–735.
Arrieta, M. P.; Parres, F.; López, J.; Jiménez, A. Development of a novel pyrolysis gas chromatography/mass spectrometry method for the analysis of poly(lactic acid) thermal degradation products. J. Anal. Appl. Pyrol. 2013, 101, 150–155.
Aoyagi, Y.; Yamashita, K.; Doi, Y. Thermal degradation of poly[(R)-3-hydroxybutyrate], poly[ε-caprolactone], and poly[(S)-lactide]. Polym. Degrad. Stabil. 2002, 76, 53–59.
Yang, L. X.; Chen, X. S.; Jing, X. B. Stabilization of poly(lactic acid) by polycarbodiimide. Polym. Degrad. Stabil. 2008, 93, 1923–1929.
Drumright, R. E.; Gruber, P. R.; Henton, D. E. Polylactic acid technology. Adv. Mater. 2000, 12, 1841–1846.
Wang, H.; Sun, X.; Seib, P. Mechanical properties of poly(lactic acid) and wheat starch blends with methylenediphenyl diisocyanate. J. Appl. Polym. Sci. 2000, 84, 1257–1262.
Kylma, J.; Harkonen, M.; Seppala, J. V. The modification of lactic acid based poly(ester-urethane) by copolymerization. J. Appl. Polym. Sci. 1999, 63, 1865–1872.
Dorgan, J. R.; Lehermeier, H. J.; Palade, L. I.; Cicero, J. Polylactides: properties and prospects of an environmentally benign plastic from renewable resources. Macromol. Symp. 2001, 175, 55–66.
Dec, S. F.; Knauss, D. M. Phosphite stabilization effects on two-step melt-spun fibers of polylactide. Polym. Degrad. Stabil. 2002, 78, 95–105.
Feng, L. D.; Bian, X. C.; Cui, Y.; Chen, Z. M.; Li, G.; Chen, X. S. Flexibility improvement of poly(L-lactide) by reactive blending with poly(ether urethane) containing poly(ethylene glycol) blocks. Macromol. Chem. Phys. 2013, 214, 824–834.
Schmack, G.; Jehnichen, D.; Vogel, R.; Tadler, B.; Beyreuther, R.; Jacobsen, S.; Fritz, H. G. Biodegradable fibres spun from poly(lactide) generated by reactive extrusion. J. Biotechnol. 2001, 86, 151–160.
Abe, H.; Takahashi, N.; Kim, K. J.; Mochizuki, M.; Doi, Y. Thermal degradation processes of end-capped poly(L-lactide)s in the presence and absence of residual zinc catalyst. Biomacromolecules 2004, 5, 1606–1614.
Zou, H. T.; Yi, C. H.; Wang, L. X.; Liu, H. T.; Xu, W. L. Thermal degradation of poly(L-lactic acid) measured by thermogravimetry coupled to Fourier transform infrared spectroscopy. J. Therm. Anal. Calorim. 2009, 97, 929–935.
Huang, G. J.; Zou, Y. N.; Xiao, M.; Wang, S. J.; Luo, W. K.; Han, D. M.; Meng, Y. Z. Thermal degradation of poly(lactife-co-propylene carbonate) measured by TG/FTIR and Py-GC/MS. Polym. Degrad. Stabil. 2015, 117, 16–21.
Khabbaz, F.; Karlsson, S.; Albertsson, A. C. Py-GC/MS an effective technique to characterizing of degradation mechanism of poly(L-lactide) in the different environment. J. Appl. Polym. Sci. 2000, 78, 2369–2378.
Jamshidi, K.; Hyon, S. H.; Ikada, Y. Thermal characterization of polylactides. Polymer 1998, 29, 2229–2234.
Feng, L. D.; Feng, S. Y.; Bian, X. C.; Li, G.; Chen, X. S. Pyrolysis mechanism of poly(lactic acid) for giving lactide under the catalysis of tin. Polym. Degrad. Stabil. 2018, 157, 212–223.
Nishida, H.; Mori, T.; Hoshihara, S.; Fan, Y. J.; Shirai, Y.; Endo, T. Effect of tin on poly(L-lactic acid) pyrolysis. Polym. Degrad. Stabil. 2003, 81, 515–523.
Cam, D.; Marucci, M. Influence of residual monomers and metals on poly(L-lactide) thermal stability. Polymer 1997, 38, 1879–1884.
Wachsen, O.; Platkowski, K.; Reichert, K. H. Thermal degradation of poly-L-lactide—studies on kinetics, modelling and melt stabilization. Polym. Degrad. Stabil. 1999, 57, 87–94.
Yu, H. X.; Huang, N. X.; Wang, C. S.; Tang, Z. L. Modeling of poly(L-lactide) thermal degradation: theoretical prediction of molecular weight and polydispersity index. J. Appl. Polym. Sci. 2003, 88, 2557–2562.
Kissinger, H. E. Reaction kinetics in differential thermal analysis. Anal. Chem. 1957, 29, 1702–1706.
Fatemi, N. S.; Whitehead, R.; Price, D.; Dollimore, D. Determination of activation-energy value from the maximum rate of reaction points obtained from non-isothermal experiments. Thermochim. Acta 1984, 78, 437–440.
Malek, J.; Smrcka, V. The kinetic-analysis of the crystallization processes in glasses. Thermochim. Acta 1991, 186, 153–169.
Gotor, F. J.; Criado, J. M.; Malek, J.; Koga, N. Kinetic analysis of solid-state reactions: the universality of master plots for analyzing isothermal and nonisothermal experiments. J. Phys. Chem. A 2000, 104, 10777–10782.
Malek, J.; Criado, J. M. A simple method of kinetic-model discrimination. Part 1. Analysis of differential nonisothermal data. Thermochim. Acta 1994, 236, 187–197.
Sestak, J.; Malek, J. Diagnostic limits of phenomenological models of heterogeneous reactions and thermal analysis kinetics. Solid State Ionics 1993, 63–65, 245–254.
Huang, L.; Chen, Y. C.; Liu, G.; Li, S. N.; Liu, Y.; Gao, X. Nonisothermal pyrolysis characteristics of giant reed (Arundo donax L.) using thermogravimetric analysis. Energy 2015, 87, 31–40.
Malek, J. The kinetic-analysis of nonisothermal data. Thermochim. Acta 1992, 200, 257–269.
Fan, Y. J.; Nishida, H.; Shirai, Y.; Endo, T. Thermal stability of poly(L-lactide): influence of end protection by acetyl group. Polym. Degrad. Stabil. 2004, 84, 143–149.
Babanalbandi, A.; Hill, D. J. T.; Hunter, D. S.; Kettle, L. Thermal stability of poly(lactic acid) before and after γ-radiolysis. Polym. Int. 1999, 48, 980–984.
Ignazio, B. End-life prediction of commercial PLA used for food packaging through short term TGA experiments: real chance or low reliability?. Chinese J. Polym. Sci. 2014, 32, 681–689.
Yang, M. H.; Lin, Y. H. Measurement and simulation of thermal stability of poly(lactic acid) by thermogravimetric analysis. J. Test. Eval. 2009, 37, 364–370.
Nishida, H.; Yamashita, M.; Endo, T. Analysis of the initial process in pyrolysis of poly(p-dioxanone). Polym. Degrad. Stabil. 2002, 78, 129–135.