Morphology and texture development of uniaxially stretched poly(ethylene naphthalene‐2,6‐dicarboxylate)

Abstract

The texture development of PEN films with different semicrystalline morphologies have been studied by X-ray diffraction. These different structures have been obtained by uniaxially stretching PEN amorphous films at 100 and 1608C (below and above T g ) at different drawing ratios. Samples have also been characterized by DSC to determine the crystallinity ratios, the crystallization, and melting temperatures. To define the orientation of crystallites in the oriented samples, pole figures have been constructed, as a function of temperature and drawing ratio (DR) in the range 1.5-4. In the range from DR ¼ 2 to 4 the orientation is clearly uniplanar-axial. At T draw ¼ 1008C the crystallinity shown by DSC analysis is higher than the sample stretched at 1608C. The orientation is also higher when samples are stretched at 1008C. The naphthalene rings mainly stay in the plane of the film with a lower fraction perpendicular to the plane of the film.

Orientation of uniaxially stretched poly(ethylene naphthalene 2,6‐dicarboxylate) films by polarized infrared spectroscopy

“…Pole figure constructions detailed in previous work26 show a higher crystalline phase orientation for the films stretched at 100 °C. As a result, the higher crystallinities of films drawn in the glassy state are the consequence of their higher molecular orientation.…”

“…The evolution of the crystalline phase orientation increases with the draw ratio. At the same time, it was shown for the same samples using X‐ray scattering26 that drawing also induces an increase in the crystallinity ratio.…”

“…The effect of molecular orientation can also be discussed in relation with a slight evolution of β angles, as can be shown for bands located at 1138, 1180, 1405, and 1501 cm −1 that are assigned to aromatic ring vibration, thus reflecting the effect of drawing on microstructure evolution. Moreover, some authors26, 34 report that aromatic groups align parallel to the surface during drawing. This can bring additional interpretations elements to the difference in the evaluation of the structural angle for band at 1501 cm −1 and those calculated by Scott et al17…”

Crystal morphology and isothermal crystallization kinetics of short carbon fiber/poly(ethylene 2,6‐naphthalate) composites

“…It has attracted considerable attention because of its superior thermal, mechanical, barrier, and chemical resistance properties compared with poly(ethylene terephthalate) (PET) 5, 6. These properties make PEN useful in a wide range of applications, especially in films, magnetic tapes, and packaging materials 7–9…”

Controlling Crystal Microstructure To Minimize Loss in Polymer Dielectrics

“…Also similarly to PET, PEN can be readily quenched into the glassy state, and cold crystallizes when heated above the T g (for amorphous PEN: ∼120 °C) . Crystalline PEN primarily adopts a triclinic unit cell with one chain per cell (α-form), , although a second isomorph can be obtained under certain high temperature conditions (β-form), which is also triclinic but has a larger cell to accommodate four chains. , Previous studies have explored the effect of thermal treatment − and orientation ,,,,,,,− on the semicrystalline morphology of PEN films. The presence of RAF ,− ,, or development of an oriented mesophase on drawing ,, has been inferred in a few cases for PEN as well.…”