The variety of wide‐angle x‐ray scattering (WAXS) patterns exhibited by nylon‐6 fibers with different fabrication histories is rationalized using a model comprising three limiting structures, viz., an α, a γ, and a pleated α structure. The γ and pleated α structures both have a single broad reflection in the range 2θ = 19° −25°, but differ in their annealing behavior. At 205° (in vacuo), the pleated α structure converts to the normal α structure by removal of the pleats, without breaking any hydrogen bonds. The γ structure, however, remains unchanged under this annealing condition since it is necessary to break all the hydrogen bonding in the structure to convert it to the α form. Different fabrication routes produce fibers which resemble the three ideal structures to varying extents. Fibers extruded at low speeds (and hence low spinline tension) resemble a mixed conventional α/pleated α structure with only a small γ component. Increasing the take‐up speed (and hence the spinline tension) of the as‐spun fiber, or in‐line drawing of the low orientation fiber (without prior storage), increases the γ content. If drawing of the low orientation fiber takes place after several hours storage (off‐line drawing), a largely α structure is produced. The intensity of the 020 reflection in the γ structure is shown to be very dependent on the degree of crystalline orientation in the sample.

SynopsisA method is described for calculating crystallinity indices and crystalline orientation functions for the CY and y components of the crystalline phase of nylon 6 filaments using wide-angle x-ray diffraction (WAXS) analysis. The method is shown to be applicable to a wide range of filament samples ("conventional" as-spun, fast spun, drawn, and annealed) even when only a single broad diffraction maximum is observable from the WAXS photograph. The component indices can be used to illustrate differences present in the filament microstructure which would be unobservable if a total crystallinity index, such as that determined by density, were determined alone. For example, the initially mixed a-y structure is retained in low-temperature drawing (75-15OOC) of nylon 6 fiber, but the predominantly (Y form is produced a t higher draw temperatures.

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pans-[CHJWH~CN(CH~)~) Pt @' (CH3)2C&)2] PF6 in the monoolefin compound (-)-(fumaric a~id)Fe(CO)~ where two of the three crystallographically independent molecules have a carbon-carbon double bond inclined to the equatorial plane at an angle of 17' .'The hydrogen atoms of the double-bond carbon atoms are of considerable interest since they appear to be directed away from the rhodium atom. If the double bond remains olefinic, these hydrogen atoms are expected to be coplanar with the C=C bond. In order to investigate the olefin hydrogens further, the plane C,+, , Cn+2, and Cn+3 (see Figure 5) was calculated and the angles between the respective C-H bonds and the plane were computed. Table X gives the planes, lines, and angles. The angles can be summarized as follows for the structure HA, ,%+I F=C \ HB HC HA-C ranges from 1.2 to 5.8', HB-C from 14.2 to 27.2', and H,-C from 17.1 to 27.5' out of the plane. Although hydrogen atoms are determined poorly at best in a structure containing heavy atoms, there would seem to be significant nonplanarity of the olefin and this would be consistedt with a change from sp2 toward a more complex hybrid due to metal-carbon bonding.Selected intermolecular contacts29 and the appropriate symmetry operations are listed in Table XI.