Physical Structure
X-ray diffractogram of A. atlas fibers has been com- pared to B. mori silk fibers in Figure 3. A. atlas fibers had two strong distinct diffracting peaks at 17 and 20° corresponding to the reflections from the 002 and 201 planes whereas B. mori silk had a single diffracting peak at about 20.6° corresponding to the 201 plane reflection [12, 13]. However, other non-mulberry silks also showed the presence of two diffracting peaks at 17 and 20°. It has been suggested that the nature of crystals in silk is dependent on the alanine/glycine ratio. The higher ala- nine content provides a better crystallographic form for the A. atlas silk compared to B. mori silk. The % crystal- linity of A. atlas fibers was 32.8 % close to the high end reported for B. mori (20–41 %) silk fibers [12, 13].