초록
The present study was performed to evaluate the relaxation patterns of rubber elastics, elastomeric modules and chains stored in the water bath. Initial loading profiles were established for extension of $100\%,\;200\%$ of their original length for elastomeric chains and of 21, 28, 35, 42, 49mm for rubber elastics and elastomeric modules. The tests were performed on materials stored in distilled water at $37^{\circ}C$ and extraoral elastics stored in dry state at room temperature, at 0 hour, 1 hour, 6 hours, 1 day, 1 week, 2 weeks, 3 weeks, and 4 weeks, respectively. The following results were drawn: 1. The relaxation of rubber elastics manifested no correlation with increments of the extension distances, but showed correlation with time lapse. Remaining forces of rubber elastics carne out $84.6-98.52\%$ after 1 day, $70.92-89.31\%$ after 3 weeks of period. 2. The relaxation of elastomers manifested no correlation with increments of the extension distances, however represented considerable relaxation with time lapse as rapid relaxation after 1 hour and then gradual relaxations with time lapse. Modules relaxed much more than chains. $60.58-67.05\%$ of remaining forces for chains and $37.77-65.17\%$ for modules after 1 hour were turned out, and $51.48-62.22\%$ for chains and $8.04-25.15\%$ for modules after 3 weeks as well. 3. Permanent deformation rates of rubber elastics could not be measured with present investigation, but elastomers underwent severe deformations. 4. $3-9\%$ of permanent deformations for chains, $3-10\%$ for modules at 0 hour were turned out, and $25-30\%$ for chains, $96-145\%$ for modules after 3 weeks as well.