Thermomechanical and optical characteristics of stretched polyvinylidene fluoride

Abstract

The thermomechanical and optical characteristics of polyvinylidene fluoride (PVDF) are investigated using a thermomechanical, a nanoindentation, and a photometric analyzer for flexible electronic applications. Experimental results show that thermomechanical characteristics, thermal elongation, and expansion, are greatly influenced at stretching ratios of over four in the stretching direction. Conse- quently, shrinking occurs because of higher cohesion at the tie chains of the amor- phous regions. Additionally, there are almost uniform hardness and Young's modulus of about 0.25 6 0.01 and 3.44 6 0.14 GPa when the penetration depth is about 1000 nm. Unstretched PVDF films have a higher absorbance in the ultraviolet light range than stretched films do. PVDF films stretched over three times their original length have transmittance of above 90% at near infrared light. In addition, PVDF films stretched at lower temperatures show a lower transmittance because the films easily whitened during a to b phase transformations. The results provide information to optimize PVDF films for applications in flexible designs. V C 2008 Wiley Periodicals, Inc. J Polym Sci