Amine end groups

Most elastomers that are used for nylon modification contain a small amount of maleic anhydride (0.3 to 2%). In the melt blending process, these elastomers react with the primary amine end groups in nylon, giving rise to nylon grafted elastomers. These grafts reduce the interfacial tension between the phases and provide steric stabili2ation for the dispersed mbber phase. Typically, thermally stable, saturated mbbers such as EPR, EPDM, and styrene—ethylene/butylene—styrene (SEBS) are used. 

Polyamide-imides may also be produced by reacting a diacid chloride with an excess of diamine to produce a low molecular mass polyamide with amine end groups. This may then be chain extended by reaction with pyromellitic dianhydride to produce imide linkages. Alternatively the dianhydride, diamine and diacid chloride may be reacted all together. 

Initially, the water slowly reacts with the isocyanate. However, the reaction can be catalyzed with an appropriate catalyst, such as dibutyltin dilaurate or a morpholine tertiary amine catalyst. The isocyanate will react with water to form a carbamic acid, which is unstable and splits off carbon dioxide, to produce a terminal amine end group (see p. 76 in [6]). This amine then reacts with more isocyanate-terminated prepolymer, as shown above, to form a polyurea. This process repeats itself, building up molecular weight and curing to become a polyurea-polyurethane adhesive. 

Blends based on polyolefins have been compatibilized by reactive extrusion where functionalized polyolefins are used to form copolymers that bridge the phases. Maleic anhydride modified polyolefins and acrylic acid modified polyolefins are the commonly used modified polymers used as the compatibilizer in polyolefin-polyamide systems. The chemical reaction involved in the formation of block copolymers by the reaction of the amine end group on nylon and anhydride groups or carboxylic groups on modified polyolefins is shown in Scheme 1. 

Scheme 1 The proposed acid/amine and anhydride/ amine reaction between carboxylic groups/anhydride groups on modified polyolefins and amine end groups on Nylon-6.

Polyamide 6 is produced by ring opening polycondensation of e- caprolactame. If no other reactants are used, the polymer chains contain one carboxylic acid and one amine end group. 

Although seven different functionality fractions are expected to be present in the sample, the contour plot in Fig. 17.21 reveals only two different elution areas. The fraction that elutes at about 3 mL in the first dimension (ordinate direction) can be assigned tentatively to a PA 6.6 having an acid and an amine end group by comparing the results with the plot in Fig. 17.19. Accordingly, the later eluting fractions are due to the other different linear functionality fractions, as shown in Table 17.1. 

Normal nylon 6.6 fibres contain only about 35-45 milliequiv./kg of amine end groups and... 

Figure 26.4 Plot of the glass transition temperatures of the polypropylene imine) dendrimers with nitrile ( ) and amine ( ) end-groups...

All dendrimers consist of inner tertiary amines, located at the branching points of the various dendritic shells (layers). The amine-terminated dendrimers, furthermore, have basic primary amine end-groups. Basicity is therefore one of the most dramatic properties of the polypropylene imine) dendrimers, and has been studied via titration experiments and calculations. Titration experiments of the dendrimers have been performed in water using 1 M hydrochloric acid. Only two equivalence points are observed for DAB-J nJr-(NH2)4 in a ratio of 2 1. From these titrations, pKa values of 10.0 (primary amine groups) and 6.7 (tertiary... 

We have previously reported the results of careful investigations of the solution carbonation (8) and oxidation (9) of polymeric organolithium compounds. These studies have been extended to the investigation of solid-state carbonation reactions and these results are reported herein. In addition, a new method has been developed for the synthesis of telechelic polymers with primary amine end-group... 

Amination. The synthesis of polymers with primary amine end-group functionality has been a challenge because the primary amine group can undergo rapid chain transfer and termination reactions with car-banionic chain ends (14). Schulz and Halasa (15) used a phenyllith-ium initiator with a bis(trimethylsilyl)-protected amine group to prepare amine-terminated polydienes. Nakahama and coworkers (16,17)... 

Amine, telechelic, synthesis, 139-145 Amine end-group functionality, primary, synthesis, 140-143... 

Star-burst polyamidoamine (PAMAM) dendrimers with primary amine end groups in d-methanol [306] and with hydroxyl or glucopeptide end groups in D2O [307] have been investigated by NSE in order to identify internal segment... 

Termination may also occur by chain transfer with the initiator (e.g., water or alcohol) or a deliberately added chain-transfer agent. Deliberate termination of growth is carried out to produce polymers with specific molecular weights or, more often, telechelic polymers with specific end groups. Hydroxyl and amine end groups are obtained by using water and ammonia as chain-transfer agents. Carboxyl-ended telechelics can be obtained by termination with ketene silyl acetal followed by hydrolysis with base [Kobayashi et al., 1989]. 

Propagation follows in a similar manner as a nucleophilic attack by the primary amine end group of a growing polymer chain (XXVII) on protonated monomer to yield XXVIII,... 

Propagation follows in the same manner as for propagation of species XXXVII except that the propagating chain has an acylated end group instead of the amine end group ... 

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