Viscoelastic behavior of a New Semiaromatic Polyamide (PA9-T) fiber
Ahmed Jalal Uddin, Yutaka Ohkoshi, Yasuo Gotoh, Masanobu Nagura
Shinshu University, Ueda, Nagano, Japan
Japan

Keywords: Viscoelastic behavior, glass transition temperature, semiaromatic polyamide

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The several relaxation processes of semiaromatic semicrystalline polyamides, namely PA9-T, synthesized by Kuraray, Japan, from a long chain aliphatic diamine and aromatic terephthalic diacids were investigated as a function of moisture content by using dynamic viscoelastic analyzer (DVA) and differential scanning calorimeter (DSC). Moreover, the implication of moisture with the amorphous and crystalline domains was also examined by means of temperature-dependent wide-angle x-ray diffraction (WAXD) measurements. The characteristics of the relaxations such as a, b, g and the pronounced peak shoulder appeared at 50-70°C in DVA tand curves were found to be strongly susceptible to the presence of moisture. And the experimental data implies the existence of two types of water in the polymer matrix, as for example, loosely bound and tightly bound. The both types of moisture act as a plasticizer in the polymer matrix, which conjointly cause quite a large depression in its glass transition temperature (Tg) albeit a part was loosely bound. This lowering of the Tg can be explained in terms of a disruption of the strong hydrogen bonds and intermolecular bonds being replaced by polymer water bonds. Analyses of studies suggest that the mechanism of the g-process is associated with the molecular motion of both the amide and methylene units whereas that of the b-relaxation is involved with the motions of amide-water complex units. WAXD study corroborated the absorbance of water by solely amorphous regions, i.e, no rapport of water with crystalline parts.