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Repeating Measurement of Dynamic Viscoelasticity for High-temperature Zone-drawn Nylon 6 Fibers
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Suzuki, Akihiro / Chida, Kimitaka / Kunugi, Toshio
The storage modulus (E') of nylon 6 fiber was found to increase during repeated measurements of dynamic viscoelasticity in the temperature range including the ż dispersion. The fibers used in the measurements were zone-drawn at high temperatures close to the melting point ; the first high-temperature zone-drawing (HT-ZD1) was carried out at a temperature of 180 under an applied tension of 16.6MPa, and the second (HT-ZD2) at 210 under 14.1MPa. The HT-ZD1 and HT-ZD2 fibers obtained have birefringence of 51xl0-3 and 59xl0-3 respectively. The repeated measurements were performed twice at a frequency of 110 Hz ; the first measurements were carried out in a temperature range from 0 to 180, and the second from 0 to 190. Upon repeating the measurements, E' at 0 of HT-ZD1 fiber increased from 7.9GPa to 12.3GPa, and that of HT-ZD2 fiber from 17.3GPa to 21.4GPa. These changes in E' were irreversible. The ża dispersion peak, which originates from the rupture of interchain hydrogen bonding due to the motion of chain segments in amorphous region, decreased in height and at the same time shifted to higher temperatures with repeated measurements. The birefringence of HT-ZD1 fiber increased up to 56xl0-3 and that of HT-ZD2 fiber up to 6lxl0-3 after the repeated measurements. Although the birefringence increased with repeated measurements, there was no change in crystallinity.
Key words: Nylon 6 fiber / Dynamic viscoelasticity / High-temperature zone-drawing / Repeating measurements / Storage modulus