초록
Thermoreversible nylon 6 gels were prepared in benzyl alcohol (BA) solution and in the mixture solution of BA and formic acid(FA). The non-isothermal gelation behavior and the properties of fibers gel-spun from the solution were investigated. The isothermal and non-isothermal sol-gel transition temperatures measured using a test-tube tilting method and differential scanning calorimetry (DSC), respectively were compared. The sol-gel transition temperature of the solution on cooling varied largely with cooling rate, and it was much lower than that in the isothermal condition. However the sol-gel transition temperature determined by extrapolating to the cooling rate at 0 $^{\circ}C$/min was very close to the isothermal value. Investigation of dependence of gel forming enthalpy on the cooling rate revealed the gelation of nylon 6/BA solution resulted in polymer crystallization. The experimental gelation time decreased with increasing cooling rate, which agreed relatively well with that calculated using an Arrhenius equation. The gelation behavior for BA/FA mixture solution was dependent on the volume fraction of BA as well as polymer concentration. As the volume fraction of BA increased, the critical polymer concentration for gel-forming was lowered. The gelation time in mixed solution was associated with the volume fraction of FA. The mechanical properties of gel-spun fibers were affected by coagulating temperature. The tenacity decreased with increasing coagulating temperature, but the modulus increased due to the increase of crystallinity.
