Flexibilisers, epoxy

Fig. 2.9. Influence of temperature and filler content on flow curves (Ref. 14). (a) Temperature effect on 1-part hot cure toughened epoxy. (i>) Filler content effect on 3-part flexibilised epoxy polyamine.

N. C. Paul, P. J. Pearce, D. H. Richards, and D. Thompson. Synthesis of Flexibilised Epoxy Resins in Adhesion-3 , ed. K. W. Allen, Applied Science Publishers, London, 1978. 

Adams RD, Singh MM (1995) The effect of immersion in sea water on the dynamic properties of fibre-reinforced flexibilised epoxy composites. Compos Struct 31 119-127... 

Epoxy resins produced by the reaction of bisphenol A and epichloro-hydrin are versatile polymers with several useful properties (subsection 2.2.2.1). However, one significant weakness is their brittle nature. Incorporation of plasticisers is not very useful. Dibutyl phthalate is an exception, showing good compatibility but offering only limited ability to flexibilise the resin. Moreover, plasticisers affect the mechanical properties and chemical resistance of the cured system. With polyurethanes it is possible to complement the flexibility of the epoxy system. Numerous attempts have been made to combine the two types to achieve beneficial modifications (Lee and Nivelle, 1967). These modifications proved successful under high-temperature cure but inferior results were obtained for ambient cures. 

Another development has been reported by P.A. Lucas, W.E. Stamer and S.G. Musselman of Air Products and Chemicals Inc. (Lucas et al., 1994). An acrylate functional urethane flexibiliser has been used to modify epoxy resin, which optimises reactivity and is more compatible with epoxy. Urethane-acrylate flexibiliser offers very tough hybrid epoxy systems meeting the more demanding requirements of civil engineering applications. 

As structural adhesives, epoxies are the most widely accepted and used. They typically contain several components, the most important being the resin. To the base resin is added a variety of materials, for example hardeners, flexibilisers, tougheners and fillers. These all contribute to the properties of the resulting adhesive. Formulations may be further varied to allow for curing at either ambient or elevated temperatures. The epoxies and polyesters, together with acrylics, polyurethanes and synthetic polymer lattices will be... 

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. 

The wide range of properties available from different combinations of epoxy resins and their hardeners can be further extended by the use of other additives. These include anti-oxidants, diluents, flexibilisers, stabilisers, tougheners, fillers, surfactants and adhesion promoters. 

Pot life definition (source) 2-part epoxy polyamide 2-part epoxy polyamine (aliphatic) 2-part epoxy polyamine (aromatic) 3-part flexibilised 2-part toughened epoxy polyamine epoxy ... 

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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