高分子関連物質の高圧下におけるX線回折

抄録

Strain behavior of organic molecular crystal under hydrostatic high pressure up to 8 kb was investigated by x-ray diffraction method at 20°C. Crystalline polymers were mainly studied. It was found that strains of polymer crystals take place predominantly in the lateral direction to the fiber-axis. Even polypropylene and polyoxymethylene, which have low Young's moduli of crystal in the fiber-axis direction due to the helical structure of chain molecule, exhibited no detectable strain in this direction under hydrostatic pressure Adamantane displays reversible phase transition from cubic to tetragonal structure at pr =4800kg/cm², where it contracts 3.8% in one of the cubic axis but elongates 1.1% in both of the other two axis thus giving 1.4% volumetric compression. For the in terpretation of these results, an advanced theoretical (energetical) treatise in the molecular level seems to be required. The experimental results were discussed in terms of molecular conformation, equation f stote, anharmonicity, Grüneisen parameter, bulk compressibility, crystal density, packing density, etc.