| 초록 |
The double-stage uniaxial drawing process was used, in order to improve the low drawing ratio of PET sheet at the single-stage uniaxial drawing. At the double-stage uniaxial drawing, the first stage drawing created the intial morphology and the second stage is extremely important with regard to properties achieved after the first stage drawing. At the second stage drawing PET, the tensile strengths of each sample were measured at each strain rate at constant draw temperature. The tensile strength of PET sheet was increased as the draw ratio was higher. It had a tendency to be improved by high strain rate in the high draw ratio range. It suggest that at double-stage drawing process, the tensile strength of PET sheet was strongly developed by strain rate, the double-stage drawing process could be evolved more highly tensile strength of PET sheet than the single-stage drawing process. |
