Hardeners amines

The two-part epoxy adhesive, readily available in hardware stores or other consumer outlets, comes in two tubes. One tube contains the epoxy resin, the other contains an amine hardener. Common diamine room temperature epoxy curing agents are materials such as the polyamides, available under the trade name Versamid. These polyamides are the reaction products of dimer acids and aUphatic diamines such as diethylenetriamine [111-40-0] ... 

Comparisons of the properties of solvent-free Hquid coatings based on unmodified bisphenol A epoxies cured with varying amine hardeners are shown in Table 6. Examples include diethylenetriamine [111-40-0] H2NC2H4NHC2H4NH2 (7), triethylenetetramine [112-24-3] ... 

An important appHcation is for filament-wound glass-reinforced pipe used in oil fields, chemical plants, water distribution, and as electrical conduits. Low viscosity Hquid systems having good mechanical properties (elongation at break) when cured are preferred. These are usually cured with Hquid anhydride or aromatic-amine hardeners. Similar systems are used for filament-win ding pressure botdes and rocket motor casings. 

For the high temperature systems, dicyandiamide and aromatic-amine hardeners are frequendy used. For room temperature systems, polyamide aminoamide, and aliphatic-amine hardeners are preferred. 

The commercial interest in epoxide (epoxy) resins was first made apparent by the publication of German Patent 676117 by I G Farben in 1939 which described liquid polyepoxides. In 1943 P. Castan filed US Patent 2 324483, covering the curing of the resins with dibasic acids. This important process was subsequently exploited by the Ciba Company. A later patent of Castan covered the hardening of epoxide resins with alkaline catalysts used in the range 0.1-5% This patent, however, became of somewhat restricted value as the important amine hardeners are usually used in quantities higher than 5%. 

As indicated in the preceding section, amine hardeners will cross-link epoxide resins either by a catalytic mechanism or by bridging across epoxy molecules. In general the primary and secondary amines act as reactive hardeners whilst the tertiary amines are catalytic. 

Typical amine hardeners are shown in Table 26.3 and their characteristics and behaviour are summarised in Table 26.4. 

Table 26.3 Typical amine hardeners for epoxy resins...

Table 26.4 Some characteristics of amine hardeners for use in low molecular weight glycidyl ether resins...

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. 

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. 

Acid anhydride and amine hardening agents, Adhesives, plastics, moulding resins and... 

P.Y.139 is sometimes used in conjunction with inorganic pigments for paints, especially to replace Chrome Yellow pigments. The systems are fast to overpainting (up to 160°C for 30 minutes), but they are not entirely fast to acids. The pigment performs very poorly in contact with alkali, therefore it is not suitable for use in amine hardening systems or in emulsion paints which are to be applied on alkaline substrates. 

Kay and Fust postulated the use of epoxy resin for inhibition of composite propellants [335] and as a consequence, epoxy resins were tried for the first time for the inhibition of HTPB-based composite propellants at Thiokol Corporation, USA. Subsequently, use of the amido-amine hardened modified bisphenol-A-based epoxy resin was reported as inhibitor for fluorocarbon-based composite propellants [336]. Epoxy resins are the most versatile resins for bonding applications for a variety of substrates. This is because of the following characteristics. 

Amines were one of the first hardeners of epoxy resins 1 12), and at present they retain their leading position among all known hardeners of this type. The amine hardeners will most likely also be used in the future because they are fairly accessible, highly reactive, and their properties can be readily modified. The mechanical properties of the cured resins obtained are far better than those of the known polymer binders 2 -4), they have high dielectric characteristics, chemical resistance, etc. 

Table 1. Volume expansion change at Tg density and glass transition temperature of amine hardened TGDDM-based resins...

The multicomponent FID observed in the amine-hardened diglycidyl ether of di-phenylpropane is believed to be a consequence of nonuniformity in the kinetic behaviour of the various network fragments in the case of three components, protons are ascribed to the following groups ends (molecules attached with with one end to a nodal fragment), spacers (chains between crosslinks) and nodal fragments, respectively 104). 

Amine hardeners -for epoxy resins [EPOXY RESINS] (Vol 9)... 

Aliphatic amine hardeners make it possible to formulate tough epoxide systems, but with limited resistance to high energy radiation. 

Aromatic amine hardeners confer the greatest radiation stability, on a mechanical basis, and also release the lowest levels of gaseous degradation products. 

The radiation effects on dielectric properties of an epoxy resin (Epilox EG 34 with aromatic amine hardener Nr 105) were studied by Jahn et al. with electron,... 

Among these hardeners, amines are the most versatile ones at room temperature as well as elevated curing temperature. The curing mechanisms with amines and the structures of the amine cured epoxy resins have been most sufficiently studied, and the systems of epoxy resins with amine hardeners are most extensively used in the practical industrial fields. 

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