Thermomechanical and optical characteristics of stretched polyvinylidene fluoride

The thermomechanical and optical characteristics of polyvinylidene fluoride (PVDF) are investigated using a thermomechanical, a nanoindentation, anda 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. Consequently, shrinking occurs because of higher cohesion at the tie chains of the amorphous regions. Additionally, there are almost uniform hardness and Young's modulus of about 0.25 ± 0.01 and 3.44 ± 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 α to β phase transformations. The results provide information to optimize PVDF films for applications in flexible designs. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 949–958, 2008