Revisiting the thermal relaxations of poly(vinyl alcohol)

被引：12

作者：

Betzabe Gonzalez-Campos, J. ^{[2
]}

Garcia-Carvajal, Zaira Y. ^{[1
]}

Prokhorov, E. ^{[1
]}

Gabriel Luna-Barcenas, J. ^{[1
]}

Mendoza-Duarte, M. E. ^{[3
]}

Lara-Romero, Javier ^{[2
]}

del Rio, Rosa E. ^{[2
]}

Sanchez, Isaac C. ^{[4
]}

机构：

[1] CINVESTAV, Queretaro 76230, Qro, Mexico

[2] Univ Michoacana, Morelia 58060, Michoacan, Mexico

[3] Ctr Invest Mat Avanzados, Chihuahua 31109, Mexico

[4] Univ Texas Austin, Dept Chem Engn, Austin, TX 78712 USA

来源：

JOURNAL OF APPLIED POLYMER SCIENCE | 2012年 / 125卷 / 05期

关键词：

dielectric properties; glass transition; molecular dynamics; GLASS-TRANSITION TEMPERATURE; DIELECTRIC RELAXATIONS; BLENDS; PVA; CONDUCTIVITY; CELLULOSE; CHITIN; WATER;

D O I：

10.1002/app.33615

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

The molecular dynamics of poly(vinyl alcohol) (PVA) were studied by dielectric spectroscopy and dynamic mechanical analysis in the 20-300 degrees C range. The well-established plasticizing effect of water on the glass-transition temperature (Tg) of PVA was revisited. Improper water elimination analysis has led to a misinterpretation of thermal relaxations in PVA such that a depressed Tg for wet PVA films (ca. 40 degrees C) has been assigned as a secondary beta relaxation in a number of previous studies in the literature. In wet PVA samples, two different VogelFulcherTammann behaviors separated by the moisture evaporation region (from 80 to 120 degrees C) are observed in the low- (from 20 to 80 degrees C) and high- (>120 degrees C) temperature ranges. Previously, these two regions were erroneously assigned to two Arrhenius-type relaxations. However, once the moisture was properly eliminated, a single non-Arrhenius a relaxation was clearly observed. X-ray diffraction analysis revealed that the crystalline volume fraction was almost constant up to 80 degrees C. However, the crystallinity increased approximately 11% when temperature increased to 180 degrees C. A secondary beta c relaxation was observed at 140 degrees C and was related to a change in the crystalline volume fraction, as previously reported. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

引用

页码：4082 / 4090

页数：9

共 38 条

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