Long-term properties of polymers

Albertsson A-C, R nby B (1979) IUPAC International symposium on long-term properties of polymer materials. Stockholm, Sweden. Appl Polym Symp 35 423... 

Long-term properties of polymers are severely affected and the service-life is reduced due to the migration of additives. There is also the possibility that some of the additives accumulate in the environment and affect our health and the environment. SPME has been applied for the extraction of several common polymer additives. Since additives often have rather low volatility, a significant advantage with SPME and HS-SPME compared to HS-GC-MS is the ability to extract even semi-volatile compounds [9,13]. 

It should be summarized that quinone methides, though they may discolour a polymer, do not exhibit entirely negative action from the standpoint of long-term properties of polymers because they contribute to the chain-breaking effect of antioxidants, from which they were derived, by retardation of thermal oxidation and quenching the singlet oxygen. 

Former data about properties of cyclohexadienones are reviewed in42 43 This chapter deals only with derivatives containing a peroxide function in the molecule, because they have a specific importance for the long-term properties of polymers. Compounds derived from phenolic antioxidants have the structure of 4-alkylperoxy-4-substituted 2,6-di-tert-butyl-2,5-cyclohexadiene-l-ones XXXVI (in Scheme 5) or 2-alkylperoxy-2-substituted 4,6-di-tert-butyl-3,5-cyclohexadiene-l-onesLXXIV, where R1 may be alkyl, substituted alkyl, or the residue of a molecule of multi-nuclear phenolic antioxidant and R is the residue derived from the oxidized substrate. 

Hydroxycyclohexadienones of the type CX take part in photoinduced reactions which yield a mixture of compounds containing 4-6 membered rings174 17S). According to our present knowledge, this process does not significantly influence the long-term properties of polymers. 

Kagiya, V., Takemoto, K., Hagiwara, M. lUPAC Macromol. Symp. Long-Term Properties of Polymer and Polymeric Materials. Stockholm, September, October, 1976... 

In order to fully characterize the long-term properties of polymers a variety of techniques must be used. Several of them may give similar results but often they complement each other. The most important thing is to relate the observations obtained by analysis with postulated degradation mechanisms, whereby it should be possible to describe the possible failure of the new materials. The interaction of the polymers with the environment will give valuable information concerning the use of plastics, e.g. in the human body or the possibility to compost them. 

The scientific development of new polymeric materials was earlier directed at obtaining the most stable plastics possible. Modern technologies demand instead that polymers be easily adapted to today s strict requirements established for the protection and preservation of our environment. The long-term properties of polymers should be predictable polymers should stable if needed, or there should be a way to eontrol the degradation time of polymerie materials. 

J. F. Jansson, B. Terselius lUPAC Symposium on Long-Term Properties of Polymers, Stockholm, Sweden 30. 8. - 1. 9. 1976. 

Product design with plastics, A practical manual , Joseph B. Dyn Industrial Press Inc. (1983) ISBN 0831111410. A classic, applied, practical plastic design book. Topics covered include (1) introduction to the application of plastics, (2) description and derivation of short term and long term properties, (3) polymer formation, variation, and characteristics, (4) product design features, (5) designing the plastic product, (6) joining... 

K. Jacobsson, P. Eriksson, T. Reitberger, B. Stenberg, Chemiluminescence as a tool for polyolefin oxidation studies, In A.C. Albertsson (Ed.), Long Term Properties of Polyolefins, Advances in Polymer Science, Springer, 2004, Vol. 169, p. 151. 

In actual long term applications of polymers, however, it is well known that chemical reactions occur which actually change the viscoelastic properties of the material while it is in use. In addition, environmental factors such as exposure to solvents or even water, while not always chemically modifying a material, can have a profound influence on its viscoelastic properties in much the same way as a true chemical transformation. If predictions based exclusively on time-temperature correspondence were to be successful, the rates of all of these processes would have to vary with temperature in exactly the same m inner as does the viscoelastic spectrum. While this might be approximately true in certain special cases, it is usually not so. Thus, a more general theoretical framework is necessary to predict the properties of simultaneously chemically reacting and physically relaxing networks. 

Gedde, U.W., Mattozzi, A., Polyethylene morphology, long-term properties of polyolefins, Adv. Polym. Sci. 2004,169 29-73. 

Desai SM, Singh RP (2004) Long-term properties of polyolefins (Advances in Polymer Science), vol 169. Springer, Berlin Heidelberg New York, p 231... 

Long Term Properties of Degradation of Hot Water Polyolefin Pipes, Polymer Engineering and Science, 34 (1994) 24, p. 1773 -1787... 

However, at low doses (0-60 kGy), irradiation is used both for the improvement of long-term properties of some polymers (crosslinking of PE pipes, cables, etc.) and for medical applications. For example, in the sterilization of medical items, a dose of 25 kGy of Co y-radiation has been used to destroy bacteria, fungi, and spores [44-46]. 

---