Fiber X-ray Diagrams

The value of the angle of tilting of the texture can be determined from the analysis of x-ray fiber diagrams. As Urbanczyk noted [18], the position of layer reflexes oil and ill or the position of equatorial reflexes 010 and 100 can be analyzed. In the first case, the tilting angle of the texture (v ) can be determined from the equation ... 

Figure 6. X-ray fiber diagram of poly(5-methyl-1,4-hexadiene) prepared with a Etj,AlCl/S-TiCl, catalyst at 0°C in pentane solvent. Compression molded sample cold drawn to four times its original length.

The variations resulting from the above methods are not complete without mentioning one added complication—the differences in x-ray intensity data sets obtained by different investigators. As shown in Fig. 1, a typical x-ray fiber diagram contains many overlapping diffraction maxima whose intensities should be resolved into as many individual components as is possible, for increased precision of analysis. Because of varying methods... 

According to the expts of Andress (Ref 5) the composition of the Knecht compound after being kept under reduced press for some time should be denoted by the formula 2C6H 0Os.HNO3. He demonstrated that the compound produces a characteristic X-ray fiber diagram... 

Figure 4. X-ray fiber diagrams of ethoxy-substituted, hexamethylene-spacer poly(ester). a, Before magnetic alignment b, after magnetic alignment and c, fiber. Sample-to-film distance, 4.7 cm.

Single crystals for electron micrography and diffraction were obtained by dissolution of the polymer in nitrobenzene at 170°C followed by filtration. The solution was slowly cooled to 134°C and kept at this temperature for 12 h. The polymer that had crystallized was filtered and redissolved in nitrobenzene at 170°C, cooled to 139°C then very slowly to 136°C, kept at this temperature for 24 h and cooled to room temperature leaving the polymer single crystals in suspension in nitrobenzene. A total of 25 reflections could be observed on the electron dif-fractogram (hkO section) of this material. This was an improvement over the X-ray fiber diagram since only five reflections had been recorded on the equator (see Table I). 

The d-values of the electron diffractogram allowed us to fully index the X-ray fiber diagram using a triclinic unit cell. Without the electron diffraction reciprocal cell parameters (a, b, Y ) the task of indexing the fiber diagram would have been more difficult because of the paucity of hkO reflections on the equator. 

Indexing of the hkO level of the X-ray fiber diagram using electron diffraction data for 6GT... 

Figure 1. X-ray fiber diagram of Sample B in vacuum. The fiber axis is vertical...

Figure 6. The variation of x-ray fiber diagrams of the wet, fibrous curdlan specimen (DPn 400) dried in the air (20). Starting from the original gel specimen (A), photographs from (B) to (E) were taken at regular intervals (1 hr).

Takeda et at. (19) heat-treated the wet fibrous specimen in a sealed bomb in the presence of water. At temperatures above 120°C the annealed specimen showed a remarkably different X-ray fiber diagram (Fig. 9) the first layer disappered, the fiber... 

Figure 9. X-ray fiber diagrams of heat-treated (>120°C) curdlan specimen (DFn 400) (20) (A) dried in air and (B) dried in vacuum...

Figure 2. X-ray fiber diagram of intact ovipositor of Megarhyssa lunator. (Reproduced, with permission, from Ref. 26. Copyright 1980, Academic Press.)...

---