Polymer degradation mechanisms

B. Rimez, H. Rahier, G. Van Assche, T. Arttoos, M. Biesemans, and B. Van Mele, The thermal degradation of poly(vinyl acetate) and poly(ethylene-co-vinyl acetate), Part I Experimental study of the degradation mechanism, Polym. Degrad. Stab., 93, 800-810 (2008). 

Camino, G. Costa, L. Luda, M. P. Overview of fire retardant mechanism, Polymer Degradation and Stability, 1991, 33(2), 131-154. 

Camino G, Costa L, Luda di Cortemiglia MP. Overview of fire retardant mechanisms. Polym. Degrad. Stab. 1991 33 131-154. 

D. M. Bate and R. S. Lehrle, Kinetic measnrements by pyrolysis-gas chromatography, and examples of their nse in deducing mechanisms. Polymer Degradation and Stability, 53, 39-44 (1996). 

C. McMeill and A. Ricon, Thermal degradation of polycarbonates reaction conditions and reaction mechanisms, Polym. Degrad. Stab., 39, 13-19 (1993). 

S.P. Fairgrieve and J.R. Mac Callum, Hindered amine light stabilizers aproposed photostabilization mechanism, Polym. Degrad. Stab. 1984, 8, 107-121. 

Romao W, Franco MF, Corilo YE, Eberlin MN, Spinace MAS, De Paoli MA. Poly (ethylene terephthalate) thermo-mechanical and thermo-oxidative degradation mechanisms. Polym Degrad Stab 2009 94 (10) 1849-1859. 

Brehme Sven, Schartel Bernhard, Goebbels JUrgen, et al. Phosphorus polyester versus aluminium phosphinate in poly(butylene terephthalate) (PBT) Flame retardancy performance and mechanisms. Polym. Degrad. Stab. 96 no. 5 (2011) 875-884. 

Malajati Y, Therias S, Gardette J (2011) Influence of water on the photooxidation of KHJ phenoxy resins, 1. Mechanisms. Polym Degrad Stab 96 144-150... 

Fairgrieve SP, Mac CaUum JR. Hindered-amine light stabiUzers a proposed photostabilization mechanism. Polym Degrad Stab 1984 8 107-21. 

Other aspects of stabilization of acetal resins are briefly discussed under processing and fabrication. Reference 15 provides a more detailed discussion of the mechanism of polymer degradation. 

J. E. Rabek, Polymer Degradation Mechanisms and Experimental Methods, Chapman and HaU, London, 1995, pp. 296—306. 

Fig. 3. Mechanisms for polymer degradation. The illustration is a schematic representation of three degradation mechanisms I, cleavage of cross-links II, hydrolysis, ionisa tion, or protonation of pendent groups III, backbone cleavage. Actual biodegradation may be a combination of these mechanisms.

The principal mechanism of polymer degradation during aging is the acid-catalyzed cleavage of the ether linkage in the backbone. The acid acceptor. 

K. Schwetlick, Mechanisms of Polymer Degradation and Stabilization (G. Scott, ed.), Elsevier Science Publishers, New York, Chap. 2, (1990). 

There have been many studies on the thermal and thermo-oxidative degradation of PMMA.23 24 It is well established that the polymer formed by radical polymerization can be substantially less stable than predicted by consideration of the idealized structure and that the kinetics of polymer degradation are dependent on the conditions used for its preparation. There is still some controversy surrounding the details of thermal degradation mechanisms and, in particular, the initiation of degradation.31... 

Well before the advent of modern analytical instruments, it was demonstrated by chemical techniques that shear-induced polymer degradation occurred by homoly-tic bond scission. The presence of free radicals was detected photometrically after chemical reaction with a strong UV-absorbing radical scavenger like DPPH, or by analysis of the stable products formed from subsequent reactions of the generated radicals. The apparition of time-resolved ESR spectroscopy in the 1950s permitted identification of the structure of the macroradicals and elucidation of the kinetics and mechanisms of its formation and decay [15]. 

This article highlights the growing problem of plastics waste disposal and then investigates modes of polymer degradation - thermal, chemical, mechanical, photodegradation, bio-degradation, solvolysis andglycerolysis. 4 refs. 

Al-Malaika, S. and Amir, E.J., Thermoplastic elastomers Part III—Ageing and mechanical properties of natural rubber-reclaimed rubber/polypropylene systems and their role as solid phase dispersants in polypropylene/polyethylene blends, Polym. Degrad. Stab., 26, 31, 1989. 

Meyer, M., Muhlbach, R., and Harzer, D. (2005). Solubilisation of cattle hide collagen by thermo-mechanical treatment. Polym. Degrad. Stab. 87,137-142. 

Scheme II.1 Mechanism of antioxidant action. After Grassie and Scott [1]. From N. Grassie and G. Scott, Polymer Degradation and Stabilisation, Cambridge University Press, Cambridge (1988). Reproduced by permission of Cambridge University Press...

One of the more important protective mechanisms is probably the ability of these substances to interact not only with various oxygen-centered radicals but also with hydroperoxides. This ability is supplemented by the formation of associates between the amine light stabilizer and species responsible for polymer degradation. 

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