Preparation of novel high performance poly (vinyl alcohol) materials

The preparation of ultra high modulus polyethylene ( PE) fibers and films from the ultra drawing of dried gels, produced by gelation from semi dilute solution, has been extensively studied in recent years. ( Smith, 1980; Smith, 1981; Smith, 1981; Sawatari, 1985; Matsuo, 1986) Matsuo and Sawatari produced ultra high drawn PE with a Young's modulus at 20degreesC of 216 GPa. ( Matsuo, 1986) Poly (vinyl alcohol) ( PVA) with a planar zigzag structure, such as PE, has the potential to induce high modulus and high strength. The crystal modulus of PVA and the strength of perfectly oriented PVA fiber are high; they are estimated to be 250 similar to 300 GPa and similar to 30 GPa, respectively. ( Sakurada, 1966; Tashiro, 1977) To this day, despite various attempts the limited values have not been obtained experimentally for PVA ( Yamaura, 1996). Recently, numerous studies have been reported. ( Bin, 2001; Agawa, 2001; Matsuo, 2001; Lyoo, 2001; Nagara, 2001; Abd, 2002; Suzuki, 2002) A Young's modulus of 115 GPa is the highest value reached so far. (Kunugi, 1990) But it does not reach the theoretical values yet. This have been considered to cause by intermolecular hydrogen bonding, which interferes with drawing. Authors have found that atactic PVA (a-PVA) hydrogels with NaCl have got higher melting points (90 similar to 100degreesC) (Dai, 2002; Shaheen, 2002) and the films (Yamaura, 2002) and fibers (Yamaura, 2003) obtained from a-PVA/NaCl/H2O systems had high degree of crystallization and high drawability. In this conference, we present the results for gels, films, and fibers obtained from the solutions of a-PVA/NaCl/H2O systems.