The structure and physical properties of copolymers of lactams

Abstract

SynopsisCopolymers of caprolactam with caprylolactam and laurolactam were prepared by activated anionic copolymerization under adiabatic conditions, at an initial polymerization temperature of 2'0 = 130°C. The drop of the crystalline phase content and changes of the copolymer morphological structure depending on the content of comonomers result in increasing toughness and deformability due to enhanced yielding ability. The dependences of the copolymer structure and properties on the concentration of comonomers are different for the two series of copolymers. This results from different courses of the polymerization and crystallization history as a consequence of a large difference between polymerization rates of caprylolactam and laurolactam.

Activated anionic ring-opening polymerization of ε-caprolactam with magnesium di(ε-caprolactamate) as initiator: effect of magnesium halides

“…Sodium salt of e-caprolactam (CLNa) or its precursors (sodium hydride, sodium methoxide) are a most used initiator in the (co)polymerization of lactams [7,9,[11][12][13][14][15][16][17]. The main disadvantages of this initiator are rather high content of cyclic oligomers [18][19][20] in obtained polymers and relatively low thermal stability [5] of resulting polyamides.…”

Anionic copolymerization of nylon 6/12: A comprehensive review

“…Some preliminary work in this field has been done by Kubota and Nowell , Šimůnková et al . , Frunze et al . , and Godovskii et al .…”

“…In comparison to the polyamide homo-polymerization, the copolymerization happened with a decrease in reaction efficiency and molecular weight [8,30,31,34,42,48]. The obtained result might be attributed to the distinct chemical structure of LL and its higher molecular weight compared to CL, which leads to a lower reactivity of LL than CL [26,30,43,46,49]. In addition, incorporation of LL reduces the exothermic heat of reaction, which directly correlates with the very low heat of LL polymerization [50].…”

“…The anionic copolymerization of different lactam pairs and the properties of their copolyamide have been examined by many researchers since 1960s [17][18][19][20][21][22][23][24] and anionic copolymerization of CL with ω-laurolactam (LL) which are industrially available lactams, has been a frequently explored field of study during the recent decades. Some preliminary work in this field has been done by Kubota and Nowell [25], Šimůnková et al [26], Frunze et al [27,28], and Godovskii et al [29], who particularly focused on copolyamide 6/12 (nylon 6/12).…”

“…However, the advantages of CL anionic copolymerization along with LL predominate over its disadvantages. The most important benefits of these copolymers include excellent mechanical properties (especially tensile strength), low moisture absorption, low melting point, and acceptable chemical resistance among others [1,6,25,26,28,29].…”