Cohesional Entanglement of Amorphous Polymer in Glass State as Probed by Equilibrium Swelling in a “Non-Solvent”†
✍ Scribed by Yan-Sheng Yu; Ren-Yuan Qian
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 651 KB
- Volume
- 20
- Category
- Article
- ISSN
- 0256-7660
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✦ Synopsis
Instituiz of Chemistry, Chinese A c h y of Sciences , Beijing 1 OOO80, China
The equilibrilrm swelling of the system Polystyrene (PS) ( M = 1.7 x 16, mowdisperse)/diethyl ether at 30 '32 and 35 '32 has been studied in detail in quiescent state for a time span over 150 d. Arguments are given to show that the swelling process in a "non-dvent" is a network swelling rather than a phase separation process. It is different from the cloud point curve (CPC) experiment studied in literature. where the experiment starts from a one-phase solution, so that the cohesional entanglement present in the solid polymer is disrupted by dissolution. The M hesional entanglement sbucturr of the d i d polymer, on the contrary, is retained in the concentrated phase on swelling, at least in the initial stage. The cwrse of swelling as presented by thecurve V , ( t ) WBS found to pruceed in three stages, where V, is the volume of the concentrated phase. In the 6rst and thirdstagesof V , ( t ) , thecurvegoesupswothly, whileinthe second stage the curve V , ( t ) shows large up and down jumps, indicating probably a readjustment in the network structum.
Someresults on a mowdisperse PS sample of M = 5 . 8 x 16 and a pdydisperse sample of M = 2.0 x 1 6 are a h given. m e values of V, observed at swelling equiliirium are not in accord with the expeded cloud point temperature. The cloud point curve represents a phrw separation process occurring in local regiow (space limited to pm) and in time Scale of the order of minute, while the p-V , ( t > occumd in the whde space of the concentrated phase, in time scale of days. For quantitative characterization of the network present in the concentrated phase, a precise * of the polymer-solvent interaction parameterxisneeded.