Polyurethanes (PUs) were prepared by using diols containing polar groups such as carbonic groups -O-COO-, carbonic and ester --COO- groups, carbonic and ether -O- groups. Synthesis and film preparation conditions are given. The physical properties of the PUs such as density, glass transition temperature, Tg, melting point, Tin, are all presented. A correlation between T~ and the rotational energy barriers of the polydiol single units is discussed. The PUs were characterized by mechanical tests on dry samples. The crosslink density of the PU network was evaluated by mechanical equilibrium relaxation tests on samples swollen in toluene. The results are discussed according to the more recent Flory's theory of rubber elasticity. PUs containing a CO3 group present an affine-like behaviour while PUs containing both CO3 and ether or ester groups show a behaviour in between affine and phantom models.
Посилання на статтю:
Crosslinked polycarbonate polyurethanes: preparation and physical properties / N. Cao, M. Pegoraro, F. Severini, L. Di Landro, G. Zoia // Polymer. – 1992. – Vol 33. – P. 1384-1390.