Packing density of nonstoichiometric epoxide-amine networks

✍ Scribed by V. Bellenger; W. Dhaoui; J. Verdu

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 136 KB
• Volume: 33
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1987.070330729

✦ Synopsis

When epoxides, such as diglycidyl ether of bisphenol A (DGEBA), are cross-linked by diamines, such as metaphenylene diamine or diaminodiphenyl methane, practically no side reactions occur and the maximum value of the glass transition temperature Tg is reached when the reactants are in stoichiometric ratio. In certain cases, it has been ohserved that the density of the cured samples decreases when the amine concentration increases from 7 0 4 0 % to 100% of its stoichiometric value. This result was interpreted in terms of free volume creation or, more generally, decrease of packing density when the cross-link density increases.' Our aim is to demonstrate that changes of van der Waals volume linked to the epoxide-amine addition can be also involved in these density variations.