Thermal expansion of epoxide–amine networks in the glassy state
✍ Scribed by A. Tcharkhtchi; E. Gouin; J. Verdu
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 142 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
The dilatometric curves of 21 epoxide-amine network samples made from five distinct epoxide-amine pairs, with variable amine/epoxide functional ratio values for three of these pairs, were recorded in the 200 K to T g (glass-transition temperature) Ϫ 50 K temperature range. The curves display a quasiparabolic shape consistent with an expansion law derived from a thermodynamic study [Bongkee, C. Polym Eng Sci 1985, 25(18), 135]:
where V and V 0 are the volumes at T and 0 K, respectively, and A is a coefficient that varied for the studied samples between 2.5 ϫ 10 Ϫ7 and 5.0 ϫ 10 Ϫ7 K Ϫ2 . A tentative study of the structure-property relationships in this field revealed that A does not depend significantly on the crosslink density, the cohesive energy density, the T g , or the local mobility. In contrast, A seems to be sharply related to the chain flexibility, which essentially depends on the aromatic content in the studied structural series.