The Effect of Step Isothermal Crystallization on the Polymer Crystalline Morphology: The Case of Isotactic Polystyrene

Abstract

Simulations have shown that temperature changes during the growth of lamelae/ribbons of a polymer crystal induce alterations in the thickness of the lamelar crystal. Therefore, the lamelae/ribbons would melt at different temperatures. This is demonstrated experimentally here for spherulites of Isotactic Polystyrene (iPS). The results were obtained following the melting process of selected spherulite structures through temperature scanning. The samples, in which chosen spherulites were observed, were crystallized from the melting state at successive crystallization temperatures. Observations of these spherulite melting processes were made with an optical polarized microscope, using a hot stage to apply the temperature scan

Biorelevant Media Slows the Solution-Mediated Phase Transformation of Amorphous Spironolactone

“…47,48 The details in the appearance of spherulites are affected by the rate of crystal growth. D'Alkaine and Otaguro 49 captured the image of a single spherulite of polystyrene grown in 2 stages at 2 different growth rates by adjusting the temperature between stages (Fig. 7).…”

“…The main difference between the 2 materials was particle size (<2 mm for SD vs. <200 mm for MQ). However, a high force is used to directly compact the material so that the surface is flushed with the bottom 49 of the flow channel in the flow-through dissolution apparatus, eliminating the effect of the particle size.…”

“…Figure 7. PLM images of the same polystyrene spherulite grown in 2 stages at different temperatures: (a) after 16 hours at 140 C, (b) followed by 3 hours at 180 C. Reprinted from D'Alkaine and Otaguro 49. …”