X-ray Microdiffraction Study of Chain Orientation in Poly(p-phenylene terephthalamide)

Abstract

Single fibers of poly(p-phenylene terephthalamide) (PPTA; trade names: Kevlar 29 , Kevlar 49 , and Kevlar 149 ) have been scanned through a 3 µm diameter X-ray beam and the degree of orientation (fc) determined at every point. All samples show a gradient in fc values from the skin to the core. The highest degree of orientation was found at the edges of the fibers. This effect is particularly strong for Kevlar 29 . In addition, ripples in orientation were observed along the fiber axis for Kevlar 29 , but on a smaller scale than the transversal gradient. Upon tensile deformation up to about 3 GPa applied stress, the transversal fc anisotropy is gradually reduced and disappears at the highest stress values. Kevlar 29 attains at about 1.5 GPa applied stress the same degree of orientation as Kevlar 49 .

In Situ Visual Observation of Fracture Processes in Several High-Performance Fibers

“…Rather than fine fibrillation, the Dyneema Ò SK76 fiber fracture surface looks to typically possess plate-like failure surfaces along with fine fibrillation [6,14]. Though not conclusive, in all micrographs found in this set of experiments, the plate-like features originated from the skin portion of the fiber, which is a reasonable failure process, as it is well known that high-performance polymeric fibers typically possess a skin-core architecture [23][24][25][26]. It is important to note that mass fine fibrillation was also uncovered in a few of the post-mortem rupture morphologies, which can be seen in the first high-rate micrograph shown in the Dyneema Ò SK76 section of Fig.…”

From diffraction to imaging: New avenues in studying hierarchical biological tissues with x-ray microbeams (Review)

“…11-13 for reviews͒, and has applied them particularly to polymers and biopolymers. [13][14][15][16][17] User applications at the ID13 beamline include many fields of modern materials science covering among others metals, 18 carbon fibers, 19 synthetic polymers, [20][21][22] as well as biopolymers and biological tissues. [23][24][25][26][27][28][29] In the meanwhile, x-ray microbeams with high photon flux are available also at other sites, and dedicated instruments for scanning SAXS/WAXS have been built 30 or are in the construction phase.…”

Evaluation of molecular orientation in injection molded parts with microscale features by Raman spectroscopy

“…[6][7][8][9] In addition, X-ray scattering are usually applied to analyze the crystallinity and chain axis of crystallites, but amorphous polymers are normally used for optical devices. [10][11][12][13] Hence, these techniques are not suitable for the evaluation of the microstructure of amorphous polymers in the localized region of the microscale features such as several 10 lm.…”