The degree of crystalline orientation as a function of draw ratio in semicrystalline polymers: a new model based on the geometry of the crystalline chain slip mechanism

Abstract

The orientation behaviour of a range of high density polyethylenes (PEs) drawn to different draw ratios has been investigated by measurements of optical birefringence and wide angle Xray diffraction (WAXS). Consistent with previous research, it can be concluded that birefringence relates to the overall degree of orientation of the amorphous and crystalline phases, and is described to a good approximation by the pseudo-affine deformation scheme.The WAXS results show that crystalline orientation is also related uniquely to the applied strain and moreover is independent of the characteristics of the polymer concerned. It is shown that the crystalline orientation follows a new model based on the geometry of the crystalline slip mechanism where the crystalline phase deforms affinely in the longitudinal drawing direction.

Crystallization behavior of polypropylene/graphene nanoplatelets composites

“…This characterization was also carried out on polished disks at ambient temperature, using a PANalytical X'pert Pro MPD in the same operating conditions as for pole figures. The peak areas were fitted with Pearson VII functions adapted to the crystalline phases, using Origin software.…”

Self‐assembled fibrillar polyethylene crystals with tunable properties

“…Scherer equation (Equation (2)) was used for the calculation of crystal size. [17] In this equation, crystal size is expressed as "L." The X-ray wavelength (λ) is constant as 1.54056 Å for CuKμ used in θ−2θ Bragg-Brentano geometry, [18] and k value is 0.94 [19] for spherical crystals with cubic-metric lattice symmetry. B is shortened as FWHM, and it is defined as the full width half maximum and calculated in radian angle in the formula:…”

“…The crystal orientation factor was calculated according to Herman's orientation factor (Equation (3)), [17] which is obtained according to by azimuthal angle (¢) between oriented crystallographic axis and fiber axis. The azimuthal intensity distribution for the (110) and (200) planes were scanned to determine the crystal orientation factor of f c .…”

Structural Formation of UHMWPE Film Tracked by Real-Time Retardation Measurements during Uniaxial/Biaxial Stretching

“…Free-width stretching occurs as the width of the film shrinks and has been studied as a fundamental stretching mode. Relationship between draw-ratio and strengthening in mechanical properties was investigated by Gao et al [15], the orientation behavior drawn to different draw-ratios was studied using deformation models by Bandeira et al [16]. In contrast to free-width stretching, constrained-width stretching maintains constant width by clamping the sides of the film.…”