Abstract
The crystal of p-aminohippuric acid was polymerized in the solid state by annealing at a temperature below its melting point. The reaction was carried out on the p-aminohippuric acid crystal at 170°C for 260 h under reduced pressure. The specimens formed through the thermal solid state polycondensation procedure from original monomer single crystals were examined mainly by means of differential thermal analysis (DTA), X-ray diffractometry and scanning electron microscopic (SEM) observation. In DTA measurements, whereas the endothermic spike peak of a monomer single crystal was observed approximately at 200°C. the endothermic peak of a polymerized specimen appeared approximately at 380°C. The polymerized crystal showed slightly oriented polymer rings in the X-ray diffraction pattern. As the result of SEM observation, the many fibrillar structures were found on the surface of polymerized specimens. In conclusion, it is considered that the single crystal of p-aminohippuric acid was converted into aromatic polyamide crystal by the thermal solid state polycondensation.
