Morphology of polyacrylonitrile

The present investigation revealed that the features like: single crystals, twin crystals, hedrites and spherulites could be grown by changing the concentration or temperature of crystallization of polyacrylonitrile (PAN) from its solution in propylene carbonate and following the technique of film‐formation method of crystallization. Different stages of growth have been also reported. The well defined single crystals of PAN could be grown in the temperature range of 105 to 150°C, even from the dilute solution. Single crystals of PAN could be also grown from concentrated solution (> 2.5%) at higher temperature. Formation of spherulites from sheaf and hedrites has been achieved by increasing the concentration of the polymer solution. Lamellar thickness is found to increase with crystallization temperature. The potentiality of the film‐formation technique is that it provides an extended range of concentration and temperature not only for the kinetic study but also for the growth of single crystals from polymer solutions.