In-situ-Pultrusion of ε-caprolactam with glass- and carbon-fibers, producing profiles based on PA6 (thermoplastic)

Pultruded profiles with a thermoplastic matrix are becoming increasingly interesting for the industry due to their special advantages such as easy recyclability and the ability to be functionalized (e.g. overmolding, thermoforming, etc.). The production of these thermoplastic profiles can be done several ways. The reactive processing of the monomer ε-caprolactam which polymerizes to polyamide 6 (the so-called "in-situ pultrusion") makes it possible to achieve high fiber content, excellent mechanical properties and competitive raw material costs. Up to now, the Fraunhofer ICT proved the production of profiles with 73% FVC of glass and 74% FVC of carbon fibers at production speeds up to 2 m/min.To prove the competitiveness of reactive thermoplastic pultrusion compared to thermoset based profiles, we conducted a mechanical benchmark study with the most common matrices (Thermoplastics: Nylon 6, PMMA; Thermosets: VE, EP, UP – all reinforced by glass fibers and some also with carbon fiber). The samples were tested on bending, tensile, compression and shear properties. To counter the first critical arguments regarding moisture absorption of thermoplastics, we also did the testing under different conditions and even at 120°C. Besides the mechanical benchmark, the mechanical recycling via shredding and subsequent compounding and injection molding was investigated for different amounts of recyclate and different fractions of the shredded profiles (course, dust, mixed).The presentation will highlight the high potential and key advantages of the in-situ pultrusion process focused on a mechanical benchmark study and supported by the prove of recycling ability within the results of a mechanical recycling study.