The Role of Interlamellar Chain Entanglement in Deformation-Induced Structure Changes During Uniaxial Stretching of Isotactic Polypropylene

Journal Article · Mon Jan 01 04:00:00 EST 2007 · Polymer

DOI:https://doi.org/10.1016/j.polymer.2007.08.065· OSTI ID:959876

Zuo, F; Keum, J; Chen, X; Hsiao, B; Chen, H; Lai, S; Wevers, R; Li, J

In-situ small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD) were carried out to investigate the deformation-induced structure changes of isotactic polypropylene (iPP) films during uniaxial stretching at varying temperatures (room temperature, 60 C and 160 C). From the WAXD data, mass fractions of amorphous, mesomorphic and crystal phases were estimated. Results indicate that at room temperature, the dominant structure change is the transformation of folded-chain crystal lamellae (monoclinic {alpha}-form) to oriented mesomorphic phase; while at high temperatures (>60 C); the dominant change is the transformation of amorphous phase to oriented folded-chain crystal lamellae. This behavior may be explained by the relative strength between the interlamellar entangled network of amorphous chains, which probably directly influence the tie chain distribution, and the surrounding crystal lamellae. It appears that during stretching at low temperatures, the interlamellar entanglement network is strong and can cause lamellar fragmentation, resulting in the formation of oriented mesomorphic phase. In contrast, during stretching at high temperatures, the chain disentanglement process dominates, resulting in the relaxation of restrained tie chains and the formation of more folded-chain lamellae.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: Doe - Office Of Science
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 959876
• Report Number(s): BNL--82862-2009-JA
• Journal Information: Polymer, Journal Name: Polymer Journal Issue: 23 Vol. 48; ISSN 0032-3861; ISSN POLMAG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHAINS
DEFORMATION
DISTRIBUTION
FRAGMENTATION
LAMELLAE
POLYPROPYLENE
RELAXATION
SCATTERING
TRANSFORMATIONS
X-RAY DIFFRACTION
national synchrotron light source