Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5204653 | Polymer Degradation and Stability | 2008 | 12 Pages |
Abstract
The chain scission in the amorphous phase produces a higher mobility, allowing crystallization. The crystallinity also increases in the thermally treated samples, but the increase is limited to the first 48Â h and reaches about 89% of the initial value. Both in the thermally treated and UV irradiated samples the crystallite coherence length perpendicular to the 200 planes increases with time. The amorphous chains do crystallize at the beginning near the already formed crystals, thus increasing their dimensions. The carbonyl index shows an induction period of 48Â h, before a rapid increase which apparently is inversely proportional to the percentage of mesomorphic and crystalline phases of the irradiated samples, indicating that the photooxidative reactions took place mainly in the amorphous region. A comparison with data already published on the photooxidative behavior of samples crystallized in form I shows that the presence of compact domains in trans-planar mesophase led to an increase in the induction period and to a greater stability of the material in the first 150Â h of UV treatment.
Related Topics
Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Liberata Guadagno, Carlo Naddeo, Marialuigia Raimondo, Vittoria Vittoria,