Effect of composition and component structure on thermal behavior and miscibility of polypropylene catalloys

✍ Scribed by Yonggang Shangguan; Liyang Tao; Qiang Zheng

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 187 KB
• Volume: 106
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.26501

✦ Synopsis

Abstract

The thermal behavior and the miscibility of an in‐situ polypropylene blend named polypropylene catalloys (PP‐cats) were investigated by using modulated differential scanning calorimeter (MDSC). It is found that all PP‐cats samples present two glass transitions, one of which is ascribed to the ethylene‐propylene random copolymer (EPR), and the other, to isotactic polypropylene (PP). However, no glass transition of ethylene‐propylene block copolymer (E‐b‐P) responsible for a third component in PP‐cats could be found. With the increase of EPR, the glass transition temperatures responding to PP and EPR components, T~g~, ~PP~ and T~g~, ~EPR~, shift to low temperature, because of the enhancement of the interaction between PP and EPR component and the increase of ethylene content in EPR, respectively. Furthermore, the difference between T~g~, ~PP~ and T~g~, ~EPR~ remarkably decreases with the increase of the total ethylene content in PP‐cats, which indicates that the miscibility of PP‐cats is strongly dependent on the composition. Comparing the T~g~, ~PP~ and T~g~, ~EPR~ with T~g~ of fractionated PP and EPR, we ascribe the T~g~ change of PP fraction to the increase of EPR content; while that of EPR, to the increase of ethylene content in EPR. These experimental results suggest that the existence of E‐b‐P plays an important role in improving the miscibility between propylene homopolymer and EPR in PP‐cats. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007