Deformation-induced highly oriented and stable mesomorphic phase in quenched isotactic polypropylene
Qiu, Jie; Wang, Zhigang; Yang, Ling; Zhao, Junchai; Niu, Yanhua; Hsiao, Benjamin S.
Source PublicationPOLYMER
AbstractChanges of structure and morphology of quenched isotactic polypropylene (i-PP) film during tensile deformation at room temperature have been investigated by applying in situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WARD) techniques. SAXS patterns show that the isotropic diffuse scattering peak in the initial quenched i-PP film disappears after the film experiences necking and a strong streak, which accompanies obvious film stress-whitening, appears when strain reaches 600% and above. Explanation to the former is the dropping of density contrast between amorphous and mesomorphic phases due to deformation and that to the latter is the formation of microfibrils and/or microvoids in the film. WARD patterns indicate that i-PP chains in the mesomorphic phase become highly oriented along the drawing direction with the strain value more than 5% and the three-fold helical chain conformation keeps in the deformed mesomorphic phase. The mesomorphic structure in the initial quenched i-PP film does not transform into crystal phase although high orientation appears during tensile deformation and the highly oriented mesomorphic phase is considered to be quite stable. Thermal behaviors of the initial quenched i-PP and deformed i-PP with the strain value of 650% are examined by modulated differential scanning calorimetry (MDSC). MDSC results show that the highly oriented i-PP chains in deformed mesomorphic phase are stable, which brings about restriction to chain mobility and prohibits from phase transformation of mesophase to crystal phase in the temperature range normally measurable for the initial quenched i-PP. A model about tensile deformation of the quenched i-PP is outlined to distinctly illuminate the changes of structure and morphology in both the amorphous and mesomorphic phases. (c) 2007 Elsevier Ltd. All rights reserved.
KeywordDeformation Mesomorphic Isotactic Polypropylene
Indexed BySCI
WOS IDWOS:000251041200020
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Cited Times:41[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Corresponding AuthorWang, Zhigang
Affiliation1.Chinese Acad Sci, Inst Chem, Beijing Natl Lab Mol Sci, Joint Lab Polymer Sci & Mat,Key Lab Engn Plast, Beijing 100080, Peoples R China
2.Chinese Acad Sci, Grad Sch, Beijing 100049, Peoples R China
3.Univ Massachusetts, Dept Polymer Sci & Engn, Amherst, MA 01003 USA
4.SUNY Stony Brook, Dept Chem, Stony Brook, NY 11794 USA
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GB/T 7714
Qiu, Jie,Wang, Zhigang,Yang, Ling,et al. Deformation-induced highly oriented and stable mesomorphic phase in quenched isotactic polypropylene[J]. POLYMER,2007,48(23):6934-6947.
APA Qiu, Jie,Wang, Zhigang,Yang, Ling,Zhao, Junchai,Niu, Yanhua,&Hsiao, Benjamin S..(2007).Deformation-induced highly oriented and stable mesomorphic phase in quenched isotactic polypropylene.POLYMER,48(23),6934-6947.
MLA Qiu, Jie,et al."Deformation-induced highly oriented and stable mesomorphic phase in quenched isotactic polypropylene".POLYMER 48.23(2007):6934-6947.
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