Structural studies on large spherulites of poly(p‐phenylene terephthalamide)

Morphology and Structure of Kevlar Fibers: A Review

“…The presence of a skin and core structure was also shown [46] by SEM photographs of the fracture surfaces of spherulites of PPTA grown from a sulfuric acid solution for half a year. The skin was separated from the core with a crevice and its thickness varied from 20 to 200 pm for spherulites 10 mm in diameter.…”

Structure and properties of aramid fibres

“…The precise state of the spindope, be it liquid or solidified, when entering the coagulation bath is not known, just as the precise nature of the steps taking place during the coagulation process are barely understood. Work by Gardner et al [Gar83] and others [Xu84,Iov82] has shown that for the polymer concentrations used in the spindope the nematic liquid crystalline solution forms ordered solvate crystals at lower temperatures. The solvate crystals are made up of hydrogen-bonded sheets consisting of polymer chains alternating with sulphuric acid molecules.…”

Morphorogical and Structural Studies on Large Spherulites of Poly(p-phenylene terephthalamide)

“…Micro beam X-ray diffraction patterns indicated that the orientation of PPT A molecules is random in the skin part. 7 Figure 4( c) shows the annular nucleus (about 50 pm in diameter) of a spherulite and that it consists of many fibrous structural units of several mi-crometers in diameter. Further, smaller fibrous units about 100 nm wide were observed on the surface of the fibrous units.…”