Structural Organization of Syndiotactic Polypropylene Films Quenched at Different Temperatures
作者:
L. GUADAGNO,
L. D'ARIENZO,
V. VITTORIA,
P. LONGO,
G. ROMANO,
期刊:
Journal of Macromolecular Science, Part B
(Taylor Available online 2000)
卷期:
Volume 39,
issue 4
页码: 425-439
ISSN:0022-2348
年代: 2000
DOI:10.1081/MB-100100397
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Films of highly syndiotactic polypropylene (sPP) were quenched at different temperatures between 0°C and 100°C and analyzed as soon as prepared and after 1 month of aging at room temperature. Wide-angle X-ray diffractograms (WAXDs) showed that all the samples crystallized in the disordered helical form I, with the crystallinity increasing both on increasing the quenching temperature and on aging, although to a lower extent. The analysis of sorption and diffusion of dichloromethane vapor at low activity shows that, in some samples, the fraction of impermeable phase is consistently higher than the crystalline fraction. This induced us to hypothesize the presence of an intermediate phase, or mesophase, not crystalline, yet impermeable to the vapors. The fraction of mesophase decreases on increasing the quenching temperature, and it is a very small quantity at 100°C. The dynamic-mechanical analysis showed two transitions in the aged samples, which could correspond to the lower and upper glass transitions, already suggested for aged films of isotactic polypropylene (IPP).
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