Secondary aliphatic polyamines

Primary and secondary aliphatic polyamines These are low viscosity and low cost materials. In general, linear and branched primary and secondary aliphatic... 

Primary and secondary aliphatic polyamines, their derivatives, and modified aliphatic polyamines and aromatic amines react with and cure epoxy resins as indicated earlier. The aliphatic systems usually give adequate cures at room temperature (7 days above 60 F) however, under most conditions aromatic amines are less reactive and require curing temperatures of about 300 F to give optimum cured polymer properties. 

Multifunctional primary and secondary aliphatic polyamines are used as coreactants. They add readily to the epoxy group at low temperatures to produce highly cross-linked networks. The aromatic amines are somewhat slower than the aliphatic amines, but provide higher heat stability. Examples of amine curatives include diethylenetriamine, triethyl-enetetramine, N-aminoethylpiperazine, and m-phenylenediamine. 

When the metal salts dissolve in the aliphatic polyamines containing several primary or secondary amine groups, there takes place the formation of the chelate rings of the types (e.g.. Schemes 33 and 34 [534-537]). 

The most common aliphatic polyamines belong to the homologous series of diethylene triamine (BETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA), which contain both primary and secondary amine groups. 

Reactive Polyamide Resins. Another significant commercial appHcation of dimer acids is in reactive polyamide resins. These are formed by the reaction of dimer acids with polyamines such as diethylenetriamine to form polyamides containing reactive secondary amine groups (see DiAMlNES AND HIGHER AMINES, aliphatic). In contrast to nonreactive polyamides, these materials are generally Hquids at 25°C. 

This reaction is reported to proceed at a rapid rate, with over 25% conversion in less than 0.001 s [3]. It can also proceed at very low temperatures, as in the middle of winter. Most primary substituted urea linkages, referred to as urea bonds, are more thermally stable than urethane bonds, by 20-30°C, but not in all cases. Polyamines based on aromatic amines are normally somewhat slower, especially if there are additional electron withdrawing moieties on the aromatic ring, such as chlorine or ester linkages [4]. Use of aliphatic isocyanates, such as methylene bis-4,4 -(cyclohexylisocyanate) (HnMDI), in place of MDI, has been shown to slow the gelation rate to about 60 s, with an amine chain extender present. Sterically hindered secondary amine-terminated polyols, in conjunction with certain aliphatic isocyanates, are reported to have slower gelation times, in some cases as long as 24 h [4]. 

Several articles [7,8] have reported that a persulfate-amine system, particularly persulfate-triethanol amine and persulfate-tetramethylethylenediamine (TMEDA) can be used as redox initiators in aqueous solution polymerization of vinyl monomers. Recently, we studied the effect of various amines on the AAM aqueous solution polymerization and found that not only tertiary amine but also secondary and even primary aliphatic amine and their polyamines can promote the vinyl polymerization as shown in Table 6 [40-42]. 

Amines. Aliphatic mono-, di-, and polyamines derived from fatty and main acids make up this class of surfactants. Primary, secondary, and tertiary monoamines with Qg alkyl or alkenyl chains constitute the bulk of diis class. The products are sold as acetates, naphdienales, or oleates. Principal uses are as ore-flotation agents, corrosion inhibitors, dispersing agents, wetting agents for asphalt, and as intermediates for the production of more highly substituted derivatives... 

The synthesis of secondary amines from azides is efficient in terms of chemos-electivity [57] and has found valuable applications in the preparation of diamines [58,59], m-alkylaminoboronic esters [60], and in Diels-Alder-based amination reactions [61]. A convenient general route to open-chain polyamines, which play major roles in cellular differentiation and proliferation, has also been developed using the reductive alkylation of aliphatic aminoazides by (co-halogenoalk-yi)dichloroboranes as a key step [62] (Scheme 21). 

Primary and secondary di- and polyamines are used as chain extenders and cross-linkers. Aromatic amines are more reactive than aliphatic ones. 

Nonetheless, for the more than 50 years since the first publication in this field, NIPUs still do not have sufficiently broad application. This can be explained by certain features of these materials. Cyclic carbonate (CC) groups interact with aliphatic and cycloaliphatic polyamines at ambient temperatures more slowly than isocyanates with hydroxyl groups. The rate of this reaction is comparable to the rate of curing epoxy resins (ER) with amines. At the same time, the CCs react only with primary amino groups, in contrast to the ERs, which react with primary and with secondary amino groups. This results in a decrease in cross-linking density of the polymer network. 

A second important group of starters used in the synthesis of polyether polyols for rigid PU foams is the group of polyamines, aliphatic or aromatic, having 2-3 amino groups/mol (primary or secondary amino groups) such as ethylenediamine (EDA), diethylenetriamine (DETA), ortho-toluene diamine (o-TDA) and diphenylmethanediamine (MDA) [1,2] (see Chapter 4.2). The main properties of these polyamines which are of interest in polyurethane chemistry are presented in Table 13.2. 

P, primary amine S, secondary amine T, tertiary amine A, ammonia N, nitrosamine AA, aromatic amine PA, polyamine Al, aliphatic amine A, air H, water S, soil W, waste. 

In addition to primary polyamines, secondary and tertiary amines are also utilized. The tertiary amines, such as methylated aliphatic aromatic amines,are most commonly utilized. They can best be described as catalysts, rather than hardeners, since they speed up a reaction and contribute to cross-linking, rather than entering into the reaction itself. 

Aliphatic amines are classified in primary amines (RNH2), secondary amines (R2NH), and tertiary amines (R3N), with R representing in this very general scheme an alkyl chain of any length and further functionalization. Technically interesting classes of amines are shortalkyl amines (primary, secondary, and tertiary), fatty amines, di- and polyamines, as well as aromatic amines. Table 5.3.8 highlights... 

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