The photoelastic behaviour of dry and swollen networks of poly (N,N-diethylacrylamide) and of its copolymer with N-tert.butylacrylamide

✍ Scribed by J. Hrouz; M. Ilavský; K. Ulbrich; J. Kopeček

• Publisher: Elsevier Science
• Year: 1981
• Tongue: English
• Weight: 412 KB
• Volume: 17
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(81)90137-3

✦ Synopsis

The viscoelastic and equilibrium behaviour of dry and water-swollen networks of poly(N,Ndiethylacrylamide) and of its copolymer with N-tert.butylacrylamide with a small amount of methylenebis-acrylamide as the cross-linking agent was investigated. Superimposed curves of the mechanical and optical functions of dry networks have a form typical of amorphous polymers with side-chains: the mechanical and optical shift factors obtained by using the time-temperature superposition exhibit the same temperature dependence. Increasing temperature pronouncedly reduces the degree of swelling of gels in water but in the range 275-325 K the gels are in the rubberlike state, because the rise in temperature compensates for deswelling. The equilibrium mechanical behaviour corresponds to that predicted for Gaussian networks, while the optical behaviour is more complicated. The observed fast increase in the negative stress-optical coefficients (C~) with swelling and the network density may be qualitatively explained by assuming correlations between the side chains. Cross-links and swelling interfere with these correlations, while the introduction of the tert. butyl group into the side-chain stabilizes them, owing to the steric hindrances to the motion of ethyl groups of diethylacrylamide units.