Polymers exposure effects

It has been shown that in some polymers the effect of e+ exposure on I3 is completely reversible if the samples are annealed at temperatures near or above their Tg s. This implies that in thermal studies, methods should be developed... 

Picker, J., von Seggem, H., Rost, H., Fix, W., Clemens, W. and McCulloch, I., Influence of intensive light exposure on polymer field-effect transistors, Appl. Phys. Lett, 85, 1377-1379, 2004. 

When each of the acrylate or methacrylate polymers was preincubated with whole plasma, the platelet reactivity of the surfaces upon subsequent exposure to whole blood decreased significantly (Fig. 3). On the other hand, with many other polymers this effect of plasma was not seen. Of 20 varieties of segmented polyurethanes examined, none showed this behavior (22), and platelet adhesion to polystyrene was also unaffected by plasma pretreatment ( ). The phenomenon of plasma-induced passivation of methacrylate and acrylate polymers presumably involves selective adsorption of specific plasma proteins by the surfaces and/or a particular alteration of the adsorbed protein once bound. 

Exposure to gaseous and humid environments affects mechanical properties, friction, and wear of polymers. Synergistic effects between abrasion, wear, and corrosion result in amplified damage (59, 60). The dominant and synergistic influence of some factors may be noted as follows. 

As with all organic polymers, exposure of aromatic polyesters to heat and oxygen can, especially over long time periods, result in degradation of the polymer. This thermo-oxidation manifests as discoloration of materials, loss of physical properties, and complete failure of the substrate. To prevent (or more likely control) such processes it is necessary to incorporate additives which can protect the host polyester against the effects of heat and oxygen antioxidants. 

Figure 12.2 Differential photocalorimetry of photopolymers (a) No. 1 rapid polymer, No. 2 slow cure polymer (b) Effect of exposure on glass transition of photopolymers. Source Author s own files)...

Exposure to PTFE can arise from ingestion, skin contact, or inhalation. The polymer has no irritating effect to the skin, and test animals fed with the sintered polymer have not shown adverse reactions. Dust generated by grinding the resin also has no effect on test animals. Formation of toxic products is unlikely. Only the heated polymer is a source of a possible health hazard (120). 

Prolonged exposure to thermal decomposition products causes so-called polymer fume fever, a temporary influenza-like condition. It may be contracted by smoking tobacco that has been contaminated with the polymer. It occurs several hours after exposure and passes within 36—48 hours the temporary effects are not cumulative. 

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