In situ formation and compounding of polyamide 12 by reactive extrusion

Abstract

ABSTRACT:The anionic polymerization of lauryllactam was initiated at 270°C using sodium hydride as an initiator and N,NЈ-ethylene-bisstearamide (EBS) as an activator (NaH:EBS molar ratio of 2). Polymerization occurred in less than 2 min and was successfully performed in an internal mixer and a twin-screw extruder with corotating intermeshing screws (Werner & Pfleiderer ZSK 25). The content of residual monomer, as determined by thermogravimetric analysis, was lower than 0.5 wt %. Molecular weight, as measured by size exclusion chromatography, was governed by the lauryllactam:NaH molar ratio calculated on a M n of 25 kg/mol at a constant NaH:EBS molar ratio of 2. Blends were prepared in situ by polymerization of lauryllactam solutions of various polymers. When poly(ethylene-co-butylacrylate) (Lotryl ; Atofina) was dissolved in lauryllactam, rubber-toughened polyamide 12 blends were obtained. Mechanical properties of the injection-molded polymers were examined by stress-strain as well as notched Charpy impact tests at different temperatures. Blend morphologies were imaged by scanning electron microscopy (SEM).

Impact Fracture and Failure Behavior of in-situ Polymerized, Ethylene/Butyl Acrylate Rubber Toughened Polyamide-12

“…A detailed description of the reactive extrusion process can be found elsewhere. [8] The results of the size exclusion chromatography of the homopolyamides as measured in a high temperature gel permeation chromatograph (GPC) using benzylic alcohol as eluent are summarized in Table 1.…”

“…The recent developments with the lauryllactam polymerization resulting in high molecular weight polyamide-12 (PA-12) are very promising as some of the aforementioned drawbacks were addressed and likely solved. [8,9] The engineering application of in-situ polymerized PAs requires a substantial higher toughness than given inherently by the related system. This was possibly the driving force to develop block copolymers (Nyrimm technology; e. g. ref.…”

Numerical simulation of reactive extrusion processes for activated anionic polymerization

“…However, the reactive extrusion process is more complex than traditional polymer synthesis processes because there are complex interactions among such variables as the fluid flow, heat transfer and chemical reaction (Janssen, 1998;Berghaus and Michaeli, 1991;Hoecker et al, 1996;Wollny et al, 2003;Si et al, 2002;Michaeli et al, 1993aMichaeli et al, , 1993bSiadat et al, 1979), which cause the researches on reactive extrusion processes to be very difficult.…”

A Reactive Blending Method for Preparation of Polyvinyl Chloride/Thermosetting Polyurethane Blends

“…New developments in polymer blends and alloys have been increased sharply because reactive blending can provide viable cost-effective mechanisms for elaboration of the desired blend [4][5][6][7] .…”