Rheo-Optics and X-Ray Scattering Study of Elastomeric Polypropylene
Elastomeric polypropylenes (ePP) have been known since the early history of polypropylene. Elastomeric polypropylenes were first synthesized by Natta using heterogeneous Ziegler-type catalysts; he attributed the elastomeric behavior to their low crystallinity and stereoisomer blocks consisting of alternating isotactic crystalline and atactic amorphous segments. Subsequent to Natta's work, there have been a number of reports of the production of related materials produced with different catalysts, with notable advances by Collette, Chien, and Collins. Recently, we reported that metallocene catalysts derived from 2-arylindene ligands produce elastomeric polypropylenes which can be separated into fractions differing in tacticity and crystallinity. Studies of the elastomeric polypropylenes using rheological and optical-polarimetry methods reveal evidence of a physical network in contrast to the blend of atactic and isotactic fractions. Dynamic infrared (IR) polarimetry studies provide evidence of cocrystallization of solvent fractions of the materials subjected to step-shear flows. In the current study, we examine the tensile flow properties of elastomeric polypropylene and its solvent fractions derived from 2-arylindene metallocenes catalysts. The origin of tensile set is studied by simultaneously measuring the tensile stress and optical birefringence. The birefringence follows the flow-induced anisotropy arising from amorphous chain orientation and oriented crystallites. Wide Angle and Small Angle X-ray Scattering (WAXS and SAXS, respectively) were performed to investigate the crystallite orientation as well as strain-induced crystallinity.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC03-76SF00515
- OSTI ID:
- 798896
- Report Number(s):
- SLAC-PUB-9028; TRN: US200222%%7
- Resource Relation:
- Other Information: PBD: 16 Oct 2001
- Country of Publication:
- United States
- Language:
- English
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