Anionic polymerization of lactams: A comparative study on various methods of measuring the conversion of ε‐caprolactam to polyamide 6

Abstract

Anionic ring-opening polymerization of lactams leads to the formation of poly(lactams) or polyamides. This work aimed at comparing the performance of four methods for measuring the conversion of -caprolactam (CL) to polyamide 6. The latter was either a homopolymer (PA6) or grafts onto polystyrene (PS-g-PA6 graft copolymer). Those four methods were mass balance based on solvent extraction (methanol, water, THF, or acetone), mass balance based on vacuum drying at 140°C, thermogravimetric analysis (TGA), and elemental analysis based on nitrogen. The mass balances based on methanol extraction and vacuum drying at 140°C and TGA were all suitable for measuring the conversion of CL, whether the resulting polymer was the PA6 or PS-g-PA6. The mass balance based on water extraction was good for the PA6 and not good for the PS-g-PA6. The elemental analysis based on nitrogen was not suitable for the PA6 nor for the PS-g-PA6.

Blend composition dependence of the compatibilizing efficiency of graft copolymers for immiscible polymer blends

“…The PS‐ g ‐PA6 graft copolymers were obtained by the anionic polymerization of CL onto a random copolymer of styrene (St) and TMI in the presence of NaCL. Details on the polymerization principle, procedure, and the structural analysis methods of PS‐ g ‐PA6 can be found elsewhere [27–29]. Table 2 shows the selected characteristics of four PS‐ g ‐PA6 graft copolymers used in this work.…”

“…They found that substantial improvement in the elongation at break and ductility using the graft copolymer with PS segments with molecular weight as high as 66,000 g/mol and with a PS proportion equal to or higher than EVA. Our previous work reported on a novel method to synthesize a graft copolymer with a controlled structure by the activated anionic polymerization of ε‐caprolactam (CL) using sodium ε‐caprolactam (NaCL) as catalyst and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) bearing polypropylene (PP) or PS as activator (PP‐ g ‐TMI or PS‐ co ‐TMI) [25–29]. The graft copolymer (PS‐ g ‐PA6) with PS as backbone and polyamide 6 (PA6) as grafts with different structures and compositions were used as compatibilizer for PS and PA6 blends [30, 31].…”

Polyamide from lactams by reactive rotational molding via anionic ring-opening polymerization: Optimization of processing parameters

“…This makes PA6 one of the main engineering materials in use today. According to different reports [10][11][12][13][14][15][16][17], there are three main parameters that govern the polymerization of APCL: the catalyst (type and concentration), activator (type and concentration), and also the initial polymerization temperature. In almost all published studies, this process has been carried out in an inert atmosphere.…”

Instability of graft copolymers under polymer blending conditions

“…Details on the synthesis and characterization procedures can be found in the literature (Zhang et al, 2006(Zhang et al, , 2007a(Zhang et al, , 2008a. Table 1 gathers selected characteristics of the PS-g-PA6.…”