Accelerated Aging of Polymer Materials

PhotoDSC has also been used to study the kinetics of acrylates with functionality of 1 to 6 [52], The author suggested an autocatalytic or autoaccelerated reaction. 

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Very often, thermoplastics contain minute amounts of metallic compounds which originate from polymerization catalysts, contaminated fillers, polymerization or processing equipment, or metal contact (wire and cable insulators) during the use of the polymer. The interactions between the polymer and metallic substances are complex, but generally result in the accelerated aging of the material. Most metal deactivators are bifunctional stabilizers with phenolic and nitrogen, or phenohc sulfide and phosphite, moieties in their structure, and act by a chelating action which reduces the harmful effects of the metal ions. 

M Otsubo, Y Shimono, T Hikami, C Honda, K Ito. Influence of the humidity on leakage current under accelerated ageing of polymer insulating materials. Proceedings of IEEE International Symposium on Electrical Insulation, Montreal, 1966, pp. 267-270. 

UV treatment of surfaces was also used [17-20] in order to accelerate aging of polymeric materials (in this way the polymers become more environmentally friendly materials). 

Grabmayer, K., Wallner, G.M., BeiBmann, S., et al. Accelerated aging of polyethylene materials at high oxygen pressure characterized by photoluminescence spectroscopy and established aging characterization methods. Polym. Degrad. Stab. 109, 40-49 (2014)... 

The results presented in this chapter suggest that the accelerated aging of ultra-thin films of gas separation membrane materials is caused by an enhanced mobility near the film surface that allows the polymer to relax towards an equilibrium state more rapidly than bulk samples. This deviation from thick film behavior is also strongly dependent on the polymer structure, complicating efforts to predict thin film behavior from bulk properties. Although some modeling efforts capture thickness dependent properties, estimating thin film behavior from bulk measurements only provides a first-order approximation. 

As a consequence, it becomes mandatory to assess quickly the effidency of additives with respect to technical and environmental conditions to which they are likdy to be subjeaed. Since examination of changes of polymer materials at ambient conditions often requires long time periods, several methods have been devdoped which allow an accelerated degradation. Neverthdess, it has to be ensured that accelerated aging... 

Photo-DSC on the other hand, is a much more recent technique which has been developed thanks to technological developments in thermal analysis and coupled techniques. Until very recently, it has been used mainly to study photopolymerization or photocuring reactions by measuring the heat of reaction. We proposed the use of this powerful technique to study polymer photo-aging, using the photo-DSC as an accelerated aging device and coupled in situ analysis of the modification of the morphology of the materials. In this case, the crystallizability of the polymer is used as an indicator of the structural modifications. 

Stress Is an Important parameter In the service environment of loadbearing polymeric materials (1). The accelerating effect of stress on polymer-aging reactions Is recognized however, no experimental methods exist for direct determination of the effect of stress on the rates of real-time aging reactions. Cheoilluml-nescence offers potential for direct determination of the rates of polymer aging reactions. 

The 19 compounds were re-mixed in 1999-2000 in order that accelerated ageing tests could be carried out for direct comparison with the results from natural ageing. A total of 20 new compounds were also mixed to represent polymers not available in 1958 and to reflect changes in compounding practice. Ten of these materials were formulations directly nominated by industry covering materials of current interest to particular companies. 

Dao B, Hodgkin J, Krstina J, Mardel J, Tian W. Accelerated aging versus realistic aging in aerospace composite materials II. Chemistry of thermal aging in a structural composite. J Appl Polym Sci 2006 102 3221-32. http //dx.doi.org/10.1002/app.24573. 

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