New technology for thermal processing of poly(vinyl alcohol)

Thermal processing of poly(vinyl alcohol) (PVA) has been a big challenge worldwide because its melting point is very close to its decomposition temperature. Based on intermolecular complexation and plasticisation, an amido containing compound (Ac), which has a complementary structure to PVA, together with water, were adopted to improve thermal processing of PVA. The results show that water and Ac can control the supramolecular structure of PVA, confine its crystallisation, decrease its melting point, thus obtain the thermal processing window for PVA. In this way, melt spinning of PVA fibres, extrusion blowing of PVA films and extrusion blowing moulding of PVA containers are realised. Then PVA high performance fibres with tensile strength over 1·9 GPa, PVA blown films with good mechanical properties and transparency, and PVA containers with good gasoline barrier properties and thermal resistance are obtained. Compared with the traditional wet processing of PVA solution, the thermal processing technology adopted for modified PVA is much more simple, effective and cost saving. More encouragingly, the PVA container with excellent chemical resistance and physical properties will open a new application field for PVA.