Correlation of chemical and mechanical property changes during oxidative degradation of neoprene

Abstract

The field of microfluidics is undergoing rapid growth in terms of new device and system development.Among the many methods of fabricating microfluidic devices and systems, surface micromachining is relatively underrepresented due tw difficulties in the introduction of fluids into the very small channels produced, packaging problems, and difficulties in device and system characterization. The potential advantages of using surface micromachining includti compatibility with the existing integrated circuit tool set, integration of electronic sensing and actuation with microfluidics, and fluid volume minimization. In order to explore these potential advantages we have developed first generation surface micromachined microfluidic devices (channels) using an adapted pressure sensor fabrication procms to produce silicon nitride channels, and the SUMMiT process to produce polysilicon channels. The channels were characterized by leak testing and flow rate vs. pressure measurements. The fabrication processes used and results of these tests are reported in this paper.

Oxidation of unvulcanized, unstabilized polychloroprene: A kinetic study

“…7, where chlorine content is plotted as a function of acid chloride concentration. It appears that chlorine content does not decrease much, even for high oxidation level; this result is in accordance with previous observations made by Celina [7]. It has to be noted that a Fig.…”

“…As frequently found, the apparent activation energy for global oxidation is higher at high temperature (typically above 80 C) than at low temperature [6,7]. This behaviour has been explained by the fact that termination processes, which are the most dependent on segmental mobility among all the other elementary steps of oxidation radical chains, are less and less efficient when the temperature decreases [8].…”

“…Highly sensitive methods for measuring oxygen absorption allowed interesting quantitative results to be obtained: values of the order of 1.3$10 À9 [6] or 3e4 10 À9 mol kg À1 s À1 [7] have been observed at 50 C. The measurements reveal that a steady state is established rapidly after the beginning of exposure. As frequently found, the apparent activation energy for global oxidation is higher at high temperature (typically above 80 C) than at low temperature [6,7].…”

Review of nuclear power plant safety cable aging studies with recommendations for improved approaches and for future work.

“…For materials influenced by DLO effects, the air-exposed outside surfaces will age at the same rate as they would have in the absence of DLO effects (the interior regions will age at a slower rate). Since cracks originating at the air-exposed surfaces often propagate rapidly through the material leading to tensile failure, elongation measurements are often unaffected by DLO effects [3][4]32,[52][53][54][55][56] Since this is the case for the Okonite neoprene material, both the homogeneous and the non-homogeneous data are analyzed using the DED method. Since we found above that the E a values appropriate to this material were 89 kJ/mol above 70C and 71 kJ/mol below this temperature, these values are used for the t-T-DR superposition procedure with the results at a temperature of 50C shown in Figure 40.…”

Long-Term Deterioration of High Damping Rubber Bridge Bearing

“…Besides, for thick rubbers, it is obvious that the surface is more easily affected by deterioration factors than the interior because of the diffusion-limited oxidation effect 14), 15) . In order to understand the variation of the material properties inside HDR bearings, accelerated tests were performed using rubber blocks focusing on the most significant degradation factor, thermal oxidation.…”