A Novel Synthetic Strategy for Preparing Polyamide 6 (PA6)-Based Polymer with Transesterification

Abstract

In the polymerization of caprolactam, the stoichiometry of carboxyl groups and amine groups in the process of melt polycondensation needs to be balanced, which greatly limits the copolymerization modification of polyamide 6. In this paper, by combining the characteristics of the polyester polymerization process, a simple and flexible synthetic route is proposed. A polyamide 6-based polymer can be prepared by combining caprolactam hydrolysis polymerization with transesterification. First, a carboxyl-terminated polyamide 6-based prepolymer is obtained by a caprolactam hydrolysis polymerization process using a dibasic acid as a blocking agent. Subsequently, ethylene glycol is added for esterification to form a glycol-terminated polyamide 6-based prepolymer. Finally, a transesterification reaction is carried out to prepare a polyamide 6-based polymer. In this paper, a series of polyamide 6-based polymers with different molecular weight blocks were prepared by adjusting the amount and type of dibasic acid added, and the effects of different control methods on the structural properties of the final product are analyzed. The results showed that compared with the traditional polymerization method of polyamide 6, the novel synthetic strategy developed in this paper can flexibly design prepolymers with different molecular weights and end groups to meet different application requirements. In addition, the polyamide 6-based polymer maintains excellent mechanical and hygroscopic properties. Furthermore, the molecular weight increase in the polyamide 6 polymer is no longer dependent on the metering balance of the end groups, providing a new synthetic route for the copolymerization of polyamide 6 copolymer.

Premixed cellulose nanocrystal reinforcement of polyamide 6 for melt processing

“…The degradation could be due to the presence of water as a nucleophile from the CNCs absorbed by the PA 6 causing hydrolysis of the PA 6 peptide linkages, and thereby significantly reducing the average molecular mass and increasing the carboxylic and amine end group concentration. [ 7,30,31 ] Furthermore, the LPA6 content being higher in the MB 1090 also results in the increased concentration of these end groups. Therefore, it is possible that the increased moisture content instigates hydrolysis and a reduction in the molecular weight of the polymer.…”

Preparing cationic dyeable polyamide 6 filaments by combining the masterbatch technique with melt copolymerization

“…In this paper, all reactions were carried out in a 5 L stainless-steel reactor with a vacuum system and nitrogen bottle. Based on previous research work on aggregation methods, 26 the CD-PA6 masterbatch was prepared by replacing 5-SSIPA as a blocking agent.…”

“…In this paper, based on the previous study of the PA6 polymerization method, 26,27 5-SSIPA was introduced into the PA6 molecular chain by copolymerization. The CD-PA6 masterbatch with an addition amount of 10 wt% 5-SSIPA was prepared.…”

Composite yarns with antibacterial nanofibrous sheaths produced by collectorless alternating‐current electrospinning for suture applications

“…The additional peak that appeared at 1728 cm À1 could be attributed to the absorption of C═O from the by-products of the acid-catalyzed amide hydrolytic degradation which was initiated by formic, acetic, and sulfuric acid. [41][42][43] During the degradation process of PA6, oligomers in different lengths and monomers in the form of ions can be formed. 44,45 Hence, the C═O band at 1728 cm À1 could be originated from ketone, ester, carboxylic acid, or imide groups, which can be formed after the scission of the amide group.…”