Amine flexibilisers

Interesting amine flexibilisers have also been described. These materials are made by cyanoethylation of amine hardeners such as diethylenetriamine, to such an extent that only two reactive hydrogens remain and the material is only difunctional, e.g. Figure 26.21. 

Diluents, Flexibilisers and other Additives 771 The amine flexibilisers may be used in two ways ... 

Although in many respects they are similar to the liquid polysulphides, the amine flexibilisers differ in three important respects ... 

Progressive replacement of amine hardener by a low-viscosity flexibiliser will reduce mix viscosity, increase pot life and reduce the heat distortion temperature of the cured system. Higher impaet strengths are achieved using approximately equivalent amounts of hardener and flexibiliser. 

Polysulphides. Liquid polysulphide rubbers have been used as hardeners for epoxy resins for many years. However, they are generally used as blends with tertiary amines and will be considered further as flexibilisers. 

A flexibilised cold-curing epoxide adhesive containing an aromatic amine hardener is likely to be the most successful, particularly if... 

Figure 5.2. As the concentration of CTPEGA increases, the tensile strength decreases and percentage elongation at break increases slowly. This can be attributed to the increase in flexibility of the matrix as a result of the incorporation of flexible ether linkage (-0-) into the matrix. Moreover, due to the pre-reaction of epoxy with CTPEGA, the molecular weight (Mw) between crosslinks increases, which enhances the flexibility of the matrix. CTPEGA can be further reacted with diaminodiphenyl sulfone (DDS) to make an amine-terminated polysulfone (ATPS) [7] (Figure 5.3). ATPS can be used as hardener-cum-flexibiliser for epoxy resins [8].

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