Highly Oriented Thermoplastic Poly (vinyl alcohol) Films by Uniaxial Drawing: Effect of Stretching Temperature and Draw Ratio

Abstract

With the advantages of excellent processability and biodegradability, polyvinyl alcohol (PVA) becomes an environmentally friendly and biocompatible material in many fields currently. To further improve the mechanical properties of thermoplastic PVA films, the orientation was adopted and studied. In this work, the uniaxial stretched PVA films with ethylene glycol as plasticizer were prepared to explore the influence of stretching temperature and draw ratio on the structure and properties of oriented PVA films. The introduction of ethylene glycol improves the thermoplastic processing capacity of PVA. When the stretching temperature was lower than 100 °C, the strength of the film increased with the increase of temperature. However, as the temperature continued to increase, the strength decreased since the process of disorientation accelerated. In addition, with the increase of draw ratio, an increase in the tensile strength and Young’s modulus of the films and a decrease in the elongation at break were observed. When the draw ratio at 5, the tensile strength and Young’s modulus of the PVA films reached the maximum of 219.7 MPa and 219.6 MPa respectively. Thus through controlling the orientation conditions and plasticizers, the PVA films with enhanced performance could be obtained.