Defect structure and molecular motion in the four modifications of n -tritriacontane. I. Study of defect structure in the lamellar interfaces using small angle x-ray scattering

Publisher Website
Google Scholar
Abstract
The paraffin C33H68 undergoes three solid‐solid phase transitions between room temperature and the melting point. The orthorhombic modification (A) stable at low temperatures is followed by two different monoclinic forms (B: 54.5°C < T < 65.5°C; C: 65.5°C < T < 68°C) and by the ``rotator phase'' (D: 68°C < T < Tf=71.8°C). Defect structures as they occur in the three high temperature modifications were determined with the aid of small angle x‐ray scattering experiments. A method is applied which permits us to decide about the presence of different types of defects after a measurement of the absolute intensities of the 00l reflections. It was found that each one of the modifications B, C, D is characterized by a specific type of disorder. One observes orientational disorder of the skeletal planes in modification B, a superposition of longitudinal shifts of the chains in modification C, and an additional introduction of intrachain defects in modification D.