Crystallization morphology change upon

Solids from the batch precipitation tests were also examined by scanning electron microscopy. In tests where no adipic acid was added, the calcium sulfite solids formed a single platelet crystal. However, upon addition of 3,000 ppm adipic acid prior to solids precipitation, the calcium sulfite crystals formed as platelet clusters or rosettes. As the concentration of adipic acid was increased the crystals became smaller and less plate-like until at 10,000 ppm adipic acid in the slurry solution the crystals were submicron in size and resembled popcorn shaped spheres (5). These results suggest that adipic acid effects the nuclea-tion rate of calcium sulfite and certainly can drastically change the particle size distribution and crystal morphology of precipitated solids. 

Fig. 3 Reversible surface morphology change of crystals of 5 upon irradiation with light. Reprinted with permission from Ref. [II]. Copyright 2000 by American Association for the Advancement of Science. (View this art in color, at www.

It is well-known that POM has a very low thermal stability, probably as it is readily oxidized upon heating. Thus, the atmosphere during annealing affects the micro (fine) structure of the polymer crystal. For example, the subcrystals disappear when FTOX is heated to 170 °C for 2 h in air. Therefore, the annealing ccmdition must be specified in order to investigate fire precise morphological change of the sample. 

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