The changes of physical properties(morphology. stress-strain behavior, swelling, antral shrinkage) of undrawn fibers spun from 15wt% DMF/H2O/PAN solution have been studied in relation to the variation ill the coagulation bath concentration(CBC) at the temperature of 1$0^{circ}C$. It has been found that the void content, swellability, and shrinkage of talc fiber decrease according to the DMF content in the coagulation bath(i.e., increasing CBC) while the elongation at break of undrawn acrylic fibers increases. These results may be explained in view of structural densification caused by slow coagulation near the critical value of CBC(around 80% for the present system).