Caprolactam termination reaction

Aud.nopropyl triethoxysilane, 140 Amorphous systems, polyurethane elastomers, 33 Anionic polymerization, caprolactams, 136-38 initiation, 138 thermal initiation, 137f termination reaction, 136 Annular cone and plate, 100-102 Annular vs. truncated cones, 101f Aromatic diisocyanate(s), RIM elastomers, 81... 

Hergenrother and Ambrose have prepared butadiene-imide and butadiene-caprolactam(73,74)block copolymers using polybutadiene capped on each terminus by isocyanate groups. Poly(ethylene-propylene adipate-b-methyl methacrylate) was prepared by heating hydroxy terminated poly(methyl methacrylate) with the isocyanate terminated reaction products of hydroxy terminated poly(ethylene-propylene... 

On an industrial scale, PA-6 is synthesized from e-caprolactam with water as the initiator. The process is very simple if the reaction is earned out at atmospheric pressure. The polymerization is earned out in a VK-reactor (Fig. 3.23), which is a continuous reactor without a stirrer, with a residence time of 12-24 h at temperatures of 260-280°C.5,28 Molten lactam, initiator (water), and chain terminator (acetic acid) are added at the top and the polymer is discharged at the bottom to an extruder. In this extruder, other ingredients such as stabilizers, whiteners, pigments, and reinforcing fillers are added. The extruded thread is cooled in a water bath and granulated. The resultant PA-6 still contains 9-12%... 

Synthesis of PDMS-b-(e-caprolactam) ABA block copolymers was reported 343 In these reactions, anhydride-terminated PDMS oligomers were used to initiate the polymerization of -caprolactam in the presence of a catalytic amount of sodium hydride in melt at 130 °C. Under these conditions, the reaction was reported to be completed in... 

Copolymers. Copolymers from mixtures of different bisphenols or from mixtures of dichlorosulfone and dichlorobenzophenone have been reported in the patent literature. Bifunctional hydroxyl-terminated polyethersulfone oligomers are prepared readily by the polyetherification reaction simply by providing a suitable excess of the bisphenol. Block copolymers are obtained by reaction of the oligomers with other polymers having end groups capable of reacting with the phenol. Multiblock copolymers of BPA-polysulfone with polysiloxane have been made in this way by reaction with dimethyl amino-terminated polydimethylsiloxane the products are effective impact modifiers for the polyethersulfone (79). Block copolymers with nylon-6 are obtained when chlorine-terminated oligomers, which are prepared by polyetherification with excess dihalosulfone, are used as initiators for polymerization of caprolactam (80). 

The thermal polymerization of /3-carboxymethyl caprolactam results in a novel polyimide which has been identified as a poly(2,6-dioxo-l, 4-piperidinediyl)trimethylene. The formation of this structure is explained by a mechanism that consists in an initial isomerization of the caprolactam derivative to 3-(3-aminopropyl)glutaranhydride or its linear dimer and subsequent polymerization by condensation involving the terminal amino group and the anhydride moiety. Suggested reaction schemes and corresponding kinetic equations are based upon the premise that the extent of polymerization is represented by the concentration of imide linkages. Results of rate studies carried out at 210°-290°C. support the proposed mechanism. 

The production of cast mineral-reinforced nylon 6 products was terminated in 1971. Research was then directed at expanding the range of properties obtainable from the anionic polymerization of caprolactam through nylon block copolymers and their fabrication by reaction injection molding. 

POLYESTERAMIDE PREPOLYMER In the prepolymer reaction, the multifunctional acyllactam which normally acts as initiator for caprolactam polymerization, also functions to combine the polymeric polyol moeities. An excess of acyllactam is used so that the resulting prepolymer is terminated by acyllactam. The reaction occurs slowly with heat (13), but in the presence of an alkaline catalyst is completed within seconds. The prepolymer may be prepared in mass or in the presence of inert organic solvents, or in caprolactam as part of the total copolymerization reaction. See Reaction B. 

Nylon-6 will undergo re-equilibration with the cyclic monomer as well as with larger cyclics at elevated temperature. This is the reverse of the polymerization process, which occurs at 200 °C and takes place through an intermediate carboxy-terminated hydrolysis fragment that undergoes intramolecular (or intermolecular) reaction to generate the cyclic monomer s-caprolactam as shown below in Scheme 1.63. 

A British patent describes preparations of block copolymers in two steps. In the first, two different salts of hexamethylenediamine are formed one with carboxylic acid terminated polyoxyethylene and the other with adipic acid (nylon-6,6 salt). In the second step the two salts are reacted in the melt. Caprolactam can be used in place of the second salt." Also, a Japanese paper describes formations of block copolymers by reacting polyoxyethylene in melt condensation reactions with caprolactam in the presence of dicarboxylic acids." ... 

The characteristics of the thermal degradation have been studied most fully for aliphatic polyamides [1-3], from which cyclic monomers are split rather readily. Thus, of the volatile products of the thermal degradation of polycaproamide at temperatures above 300 °C, mainly e-caprolactam is observed in a dry inert atmosphere. Simultaneously the molecular mass of the polycaproamide decreases. The monomer is supposed to be released via a depolymerisation reaction proceeding from terminal COOH groups ... 

In addition to caprolactam and water, considerable quantities of carbon dioxide, ammonia, carbon monoxide, methane, and so on, are released via secondary reactions during the thermal degradation of aliphatic polyamides. Thus decarboxylation of the terminal COOH groups of polyamides results in release of carbon dioxide. Ammonia forms because of the self-interaction of terminal amino groups [2, 6] ... 

The hydroesterification of butadiene is not well developed, although much effort in many industrial laboratories has been spent to develop this process as a method to prepare adipic add and caprolactam. Because little information on this process has been disclosed in 1he academic literature, this topic is not presented in detail here. Challenges encountered in developing this reaction include the regioselectivity for formation of terminal esters, the potential to form stable allyhnetal intermediates, and the potential to form polymeric or oligomeric products containing multiple diene units. 

As mentioned in Section 3, typical aramid-6-polyether elastomers are synthesized by the polycondensation reaction of polyether diol with the aramid compound I in the presence of transesterification catalysts. Under these conditions, the synthesis of aramid-6-polyester elastomers gave only low molecular weight elastomers with a broad segment length distribution due to transesterification reactions of the polyester segments. This result inidicated that in the obtaining of aramid-6-polyester elastomers, transesterification catalysts should be avoided. Later, a method for the obtaing of this type of elastomers was developed, which consisted in the copolymerization of an activated acyl lactam-terminated aramid compound II with polyester diols in the molten state, in the absence of transesterification catalysts [40,42]. Compound II was obtained by the reaction of N-(p-aminobenzoyl) caprolactam with terephthaloyl chloride, as shown in Scheme 8 [61]. 

The diamine-terminated nylon 6/66 copolyamide oligomers (CPA, Scheme 6), having the values shown in Table 7 were synthesized by the melt polycondensation reaction of e-caprolactam (CA), adipic acid (AA), and hexamethylene diamine (HA) [37,39]. An excess of HA over AA was used to obtain CPA with terminal amine groups and the molecular weight was controlled by a stoichiometric imbalance of reactants, ie., by varying the AA/HA feed molar ratio at a fixed CA/AA feed molar ratio (Table 7). The diamine-terminated nylon 6... 

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