SPCs by melt spinning and in situ copolymerization

The aim of the second case study was to investigate the feasibility of creating a SPC of PA-6 using melt spun PA-6 micro fibers in the form of continuous yarn and anionic polymerization of the PA-6 precursor, -caprolactam. 

To carry out the experiments, 150 g of caprolactam from BASF, commercially available in granular form, was placed in a 500 ml reaction vessel. Additionally, 3% of activator (type Bruggolen C 20 in powder form) and 4% catalyst (type Bruggolen C 10) were also added to the reaction mixture in solid state form at room temperature. PA-6 fibers kindly supplied by the Institut fUr Textiltechnik - RWTH Aachen in the form of continuous yarn (specifications 40 tex f44) were also used. The sizing (Dryfi L 11 C) present on the yarn is a mixture of heat-resistant lubricants, nonionic emulsifiers and antistatic agent, the details of which can be obtained from Schill + Seilacher GmbH [112]. 

In preparation for the experiment, a small dumbbell shaped Teflon-coated magnetic stirring bar was completely wrapped with PA-6 fibers and placed within the nonmolten mixture. For better detection of the PA-6 fibers, the outer layers were colored after winding. In total, 2.3 g of PA-6 fibers were used for the experiment. 

To initiate the anionic polymerization of the Caprolactam/activator/catalyst mixtme, the temperature was then increased to 155°C. After 1.5 minutes, a significant increase in viscosity could be detected. This was expressed, on one hand, by the significant slowdown of the rotation of the stirring bar and, on the other hand, through the development of the visible milky discoloration of the mixture. Three minutes after the increase of temperature, no rotational movement of the stirring bar could be maintained. The temp erature was then held further at 155°C for five minutes. Following this, it was cooled to room temperature while maintaining the inert atmosphere. 

It has been shown that the preparation of a SPC by in situ polymerization using PA-6 fibers and e-caprolactam is indeed possible. The considerably lower reaction temperature 

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