The influence of stereoregularity on the miscibility of poly(propylene)s

✍ Scribed by Ralph-Dieter Maier; Ralf Thomann; Jörg Kressler; Rolf Mülhaupt; Bernd Rudolf

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 409 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199705)35:7<1135::aid-polb12>3.0.co;2-a

✦ Synopsis

The melt miscibility of atactic poly(propylene) (a-PP) with isotactic (i-PP) and syndiotactic poly(propylene) (s-PP), respectively, is investigated by diffusion experiments of i-PP/a-PP/i-PP or s-PP/a-PP/s-PP sandwich specimens using polarized light microscopy. It is shown that the system a-PP/i-PP is miscible in the melt, whereas for the system a-PP/s-PP no evidence for melt mixing is found. Pressure-volume-temperature (PVT) measurements of the three poly(propylene)s are carried out in order to determine the characteristic parameters of the Flory-Orwoll-Vrij equation-of-state theory. Theoretical predictions using the solubility parameter concept are in agreement with the observed miscibility behavior of the blends. Differences in the cohesive energy densities of a-PP and i-PP on the one side, and s-PP on the other side, are found to be responsible for the phase behavior of the mixtures of poly(propylene)s with different stereoregularity.