Mechanical anisotropy in biaxially oriented polyvinyl chloride

Abstract

The mechanical anisotropy of polyvinyl chloride oriented in two perpendicular directions with different draw ratios has been studied. The results are compared with the anisotropy of uniaxial samples oriented at a common draw ratio. The propagation velocities of ultrasonic pulses have been measured by an immersion technique. Longitudinal wave velocities have been measured in three principal planes over a wide range of propagation directions. The limitations of measuring velocities in the planes containing the draw axes were mitigated by use of a special slicing technique. Measurements were performed at 2 MHz and 25°C. Velocities of the transverse waves were measured for incident wave angles greater than the critical angle. From these measurements, five elastic moduli were calculated for the uniaxially oriented samples, and nine elastic moduli were obtained for the biaxially oriented samples. In biaxially oriented samples, the moduli along the draw axes are directly proportional to the draw ratio in the same direction.

Polyvinylidene fluoride/magnetite nanocomposites: Dielectric and thermal response

“…Filled samples have higher activation energy values for α c -mechanism, compared to the pure PVDF matrix. These values are in very good agreement with those found by other researches [56,57] in similar composites. We also observe that the activation energy plots for the crystalline α c -relaxation almost coincide, which indicates that time scale of this relaxation process is independent of the filler loading.…”

The effect of uniaxial orientation on the dielectric relaxation behavior of α‐PVDF

“…4,10 The molecular chains, which are entangled, are rearranged along the draw axes and hence, the polymer shows anisotropic physical behavior. [16][17][18] In some polymers the orientation occurs during the polymerization process. However, in general the polymers are oriented by using various deformation methods.…”

“…The most common of these are, uniaxial or biaxial drawing and rolling. [17][18][19][20] The alignment of molecular dipoles in the field direction cannot take place instantaneously when an electric field is applied. This situation is similar to the strain, which takes time to develop after the application of a stress.…”

“…However, in general the polymers are oriented by using various deformation methods. The most common of these are, uniaxial or biaxial drawing and rolling 17–20…”

Elastic properties and mechanical relaxation behaviors of PVDF (poly (vinylidene fluoride)) at temperatures between −20 and 100 °C and at 2 MHz ultrasonic frequency

“…Ultrasonic measurements were performed with a UAC9 Ultrasonic spectrometer (Ultrasonic Engineering Co. Ltd.) working with an immersion technique. The details of the technique were described in the previous works 35, 40, 41. Commercial alcohol between –20 and 30 °C and silicon oil between 30 and 100 °C have been used as immersion liquid.…”