Studies On Synthesis And Properties Of Nylon Copolymers From Caprolactam And Laurolactam

With the development of selective laser sintering(SLS) technology, the application of nylon material ushered a new development space. Nowaday, among the nylon materialsapplied to SLS field, the polylaurolactam(Nylon 12) has 95 percent market share because of the lower sintered shrinkage, the lower water adsorption, lower warpage and the higher dimensional stability. However, the higher production cost of nylon 12 prohibited the widespread use. Considered the similar properties of caprolactam and laurolactam in structure and polymerization process, this article prepared the copolymer nylon with different mole ratio of caprolactam to laurolactam by anionic ring-opening polymerization and studied the properties of copolymer nylon in details. The blends of nylon 6 and nylon 12 were also prepared by soluting precipitation method. Then, the properties such as the thermal properties and the crystallization behavior of the two systems were discussed in details. And the mechanical properties, and material chains structure of copolymer nylon were studied as well.The TG test result of copolymer nylon prepared through dissolution and re-precipitation treatment indicated that the thermostability of the copolymer material increased with addition of laurolactam. The results of DSC and XRD showed that the addition of laurolactam was unfavorable to the orderly arrangement of molecular chain. With increasing the proportion of laurolactam, the crystallinity degree of copolymer nylon increased first and then slightly decreased, and both melting temperature and crystallization temperature decreased obviously. The result of FT-IR indicated that the adding of laurolactam was unfavorable to the formation of the intermolecular hydrogen bond, so that the –NH stretching vibration absorption center shifted obviously.The tensile testing result showed that tensile strength and breaking elongation of copolymer nylon increased obviously compared with that of pure nylon6. It was worth noting that the value of tensile strength and elongation were closed to that of the pure nylon12 when the mole ratio of caprolactam and laurolactam was 10:4, which implied that the copolymer nylon could replace nylon 12 applying in the 3D printing fields to reduce the cost and speed up the popularization of the technology.