ABSTRACT
These are quite contrasting requirements and can be satised only by using sealants composed of mixtures of different resins of different characteristics. Many systems have been devised to achieve the conditions for compromise between toughness and exibility. In general, toughness and strength are achieved by using epoxy resins, and extensive reviews of their use as bridge sealants exist [1]. Epoxide resins are distinguished by many good properties. However, cured products have exibility and toughness that are inadequate for certain applications. A large number of additives that have a exibilizing action have, therefore, been described in the literature, including compounds that contain thiol groups [2]. Among these, the liquid polysul-de polymers, which are known under the trade name thiokols and are in most cases used in combination with amine-curing agents, have received the most attention [3]. Several patents describe in detail a variety of these systems [4]. The U.S. Pat. No. 3,090,793 [5] describes polyesters-containing mercaptan groups, obtained by reacting mercaptoalcohols, for example, 2-mercaptoethanol, with polycarboxylic acids having at least 18 carbon atoms, especially polymeric fatty acids, and the use of these
15.1 Introduction ................................................................................................. 435 15.2 Chemistry .................................................................................................... 437 15.3 Mechanical and Dynamical Characterization of the Resins .......................440 15.4 Thermal Measurements ............................................................................... 443 15.5 Crosslinking Kinetics ..................................................................................445 15.6 Conclusion ..................................................................................................446 References ..............................................................................................................447
