Release stress

In the present phenomenological model, only regions that have not yet equilibrated (i.e., of size s > s t)) can release stress energy in the form of a net amount of heat to the surroundings. This means that only transitions with AF < 0 contribute to the overall relaxation toward equihbrium. Therefore, the rate of energy dissipated by the system can be written as... 

ASTM D2838, lest Melhodfor S brink Pension and Orientation Release Stress of Plastic Him and Vhin Sheeting, Vol. 8.02, ASTM, Philadelphia, Pa., 1989. 

After firing, the supports are machined to the required dimensions and polished until a shiny surface is obtained. Before use the supports are cleaned in ethanol by ultrasonic treatment to remove any loose particles in the pores caused by machining of the samples. After cleaning the supports are fired at 800°C to remove any ethanol left in the pores and to release stresses induced by machining and polishing. Typical dimensions are a diameter of 39.0 mm and a thickness of 2.0 mm. 

ASTM D283X, Shrink tension and orientation release stress of pla.stic film and. sheeting. 1995. 

It descends the stress gradient of coal around drill by using hydraulic flushing caused coal gas permeability increased by a large margin while release stress, the gas released and gas pressure gradient fell sharply, not eliminate the stress and gas condition aroused by... 

Orientation-release stress n. The internal stress remaining in a plastic sheet after orientation, which can be relieved by reheating the sheet to a temperature above that which it was oriented. This stress is measured by heating the sheet and determining the force per unit cross-sectional area exerted by the sheet as it attempts to revert to its pre-orientation dimensions. 

To date, research efforts regarding protective thin films have primarily focused on compact textures. In fact, smdies have confirmed that mesoporous thin films could confer corrosion protection for magnesium alloys. Furthermore, a mesoporous structure is beneficial to the integrity of the outer surface. This mesoporous structure could effectively release stress in the thin film and ameliorate the mismatch between the substrate and coating thus, crack-free thin films can be successfully prepared. In addition, smdies have reported that mesoporous thin films can easily induce apatite formation and have high bone-forming ability owing to the enhancement of cell activity and protein adsorption. ... 

Figure 10.14. Release stress of polyurethane parts molded at 70°C with 2% zinc stearate as the internal mold release vs. number of shots. [Data from Willkomm, W. R. Jennings, R. M. Macosko, C. W., Plast. Rubber Composites Proces. Appl, 19, 2,69-76, 1993.]...

In the reaction injection molding process, the release force also depends on cure time. As cure progresses, less free isocyanate groups are available for reaction with the mold surface and the release stress decreases. Longer cure times also give zinc stearate more time to migrate to the mold surface. 

A parallel plate rheometer was utilized for the development of a suitable test to measure mold release forces in reactive injection molding." The results from this oscillatory test were compared with a pull test performed in a specially designed mold. The results of both tests were in agreement. The experimental setup allowed comparison of release stresses under variable process conditions, such as different molds, the number of repeat releases from a surface, mold temperature, amount and t5q)e of release agent, and duration and temperature of cure. 

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