Adhesives epoxy-polysulphide

Adhesives. Epoxy-polysulphide adhesives are elastomeric in nature. Therefore, they can withstand movement and vibration. They reduce stress between dissimilar bonded materials. They are used as... 

Epoxy-polysulphide coatings exhibit excellent adhesion to steel, aluminium and concrete without the use of primers (Morton International,... 

As the base volume cylinder and hardener cylinder reciprocate, they displace the two material components in the required ratio to the outlet ports. This proportioner may be used to meter and mix silicones, polyurethanes, epoxies, adhesives or polysulphide sealants. 

Tertiary amines also catalyse interaction between the hydroxyl groups formed and remaining epoxy groups and a cross-linked structure is built up. Epoxy-polysulphide compositions have good impact strength and find use in adhesives and castings. 

Epoxy-polysulphide Polyvinyl acetate > Wood adhesives — 0 101 0 35 Krueger (1962)... 

In this book I have confined discussion to those polymeric materials which are cured by chemical reaction and which have found widespread application in the construction industry. As such, the book covers materials based on epoxies, polyurethanes, silicones, polysulphides, alkyds and polyesters. In addition, there is a chapter on hybrid polymer systems and one on acrylics. It is true that acrylic emulsions are not strictly thermosetting polymer systems, but their widespread use and importance made their exclusion difficult. These materials find use as coatings, sealants, adhesives, grouts, flooring compounds, repair compounds and waterproofing agents. 

The practice of modifying epoxy resins with liquid polysulphides may not be new but the method of doing so has advanced significantly in recent years to the extent that these systems are being given serious consideration in the design of specialist coatings, primers, adhesives and encap-sulants (Morton International, undated a Rees and Wilford, 1994 Rees et al., 1994). 

Chemical resistance. Unmodified epoxy resins have excellent resistance to dilute acids, alkalis and certain solvents. The incorporation of an LP component into the epoxy resin extends this resistance to a wide variety of oils, aromatic and aliphatic hydrocarbons, esters and ketones. Coatings and adhesives based on polysulphide-epoxy resins exhibit reduced swell and maintenance of flexibility and adhesion when immersed in these fluids. In view of this, LP-modified epoxies are used on oilrigs, fuel-storage installations and chemical plants (Figure 10.4). 

Table 2.5 summarises typical values of these bulk mechanical properties at around 20 °C for a range of epoxy adhesives. Of particular note is the low strength and stiffness of the epoxy polyamides and polysulphides as compared to those with aliphatic polyamine hardeners. For the design of bonded assemblies, joint tests are often used to determine the relevant mechanical properties. It must be remembered, however, that the results will be highly dependent on the specimen geometry and testing conditions and... 

Epoxy formulations with amine hardeners, cured at room or elevated temperature, have a tendency to become hard and brittle. The addition of polysulphide modifiers increases elasticity, although at the expense of generally lower bond strength. These adhesives permit a fairly thick cement line . 

---