Follow‐up of the course of the anionic ring‐opening polymerization of lactams onto an isocyanate‐bearing polymer backbone in the melt

Abstract

ABSTRACT:In this study, a batch mixer was used as a rheoreactor to carry out and follow up in real time the rate of the anionic polymerization of -caprolactam onto a 3-isopropenyl-␣,␣-dimethylbenzene isocyanate bearing polypropylene (PP-g-TMI) in the presence of sodium -caprolactam as a catalyst. The isocyanate group in the PP-g-TMI was capable of activating the anionic polymerization, leading to the formation of a graft copolymer with polypropylene as the backbone and polyamide 6 as the grafts. The polymerization rate was related to the viscosity increase of the polymerization system. The latter then resulted in a concomitant torque increase. It was shown that torque was a rapid, convenient, and approximate measure of the polymerization rate. The use of the torque allowed for rapid and approximate evaluation of the effects of chemical and operating conditions on the polymerization rate without the need to determine the monomer conversions. Torque profiles were also a very useful piece of information for the design of a reactive extrusion process for the same type of polymerization system.

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“…Therefore, they are unlikely suitable for a reactive extrusion process whose mean residence time is typically short, much less than a few minutes anyway. Hu et al3, 4, 9–11 used an isocyanate‐bearing polypropylene as an activator. It showed much higher activation performance.…”

Kinetics of the anionic polymerization of ε‐caprolactam from an isocyanate bearing polystyrene

“…Second, considering the fact that the melting temperature of PA6 was about 210°C, the polymerization temperature had to be above that value. Otherwise, the growing PA6 chains would crystallize [14]. The second argument was very likely.…”

“…Limited amounts of copolymer formed by interfacial reactions are due to limited amounts of interfacial volume that are available for reaction between two immisicible polymers, even under intense mixing conditions [8, 9]. Hu [10–14] had reported on a novel method to synthesize the pure PP‐ g ‐PA6 graft copolymer by activated anionic polymerization of ε‐caprolactam (CL) using sodium ε‐caprolactam (NaCL) as catalyst and a 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) bearing polypropylene (PP) as activator (PP‐ g ‐TMI).…”

Polymers and Related Composites via Anionic Ring-Opening Polymerization of Lactams: Recent Developments and Future Trends

“…The other aspect to be considered is whether this polymeric macroactivator is soluble only in a common solvent with lactams or in the melt of the latter (which is strongly preferred). Hu et al [ 76 , 77 ] developed a method to graft PA-6 into PP (PP- g -PA-6). This was done by functionalizing the PP chain with isocyanate (–NCO) groups.…”