Alexander Lüking

One Step Production of Bicomponent Yarns with Glass Fibre Core and Thermoplastic Sheath for Composite Applications

The film stacking method is the industrial standard for the manufacturing of fibre reinforced thermoplastic composites (FRTCs). An alternative to this is commingling thermoplastic fibres with reinforcement fibres, e. g. glass fibres, into hybrid yarns. However, the composites produced by the use of film-stacking or hybrid yarns cannot achieve an optimal impregnation of reinforcement fibres with the matrix polymer. This stens from the high melt viscosity of thermoplastics, which prevents a uniform wetting of the reinforcement fibres. Leaving some fibers is unconnected to the matrix. This leads to composite lower strength than theoretically possible. The aim of the research is the coating of a single glass filament in the glass fibre nozzle drawing process to achive a homogenous distribution of glass fibres and matrix in the final composite. The approach uses particles with a diameter from 5 to 25 μm of polyamide 12 (PA 12) which are electrostatically charged and blown at an Eglass filament in the nozzle drawing process as seen in. The particles adhering to the filament are melted by infrared heating and winded afterwards. This development will allow the homogenous distribution of fibres and the matrix in a thermoplastic composite allowing a higher fibre volume content leading to improved mechanical properties. Even though the glass filaments could be coated with PA 12, a homogenous sheath could not be achieved in this investigation. Therefore, further research will focus on an improved homogeneity by reducing the agglomeration of PA 12, using dried PA12 and enhancing the coating setup.

SILICA-AERO. Production of Lightweight Silica AerogelFibers for Excellent Heat Insulating Application

Aerogels are today the lightest solids and the best thermal insulating materials in the world. Silica aerogels are the most common aerogels. On one hand, silica is inorganic, fire proof and thermal stable up to 900 °C; one the other hand, the material is brittle and rigid. Due to their brittleness combined with the ultrahigh porosity of aerogels (over 80 %), silica aerogels are very difficult to process into a product. Commonly lightness is a required characteristic in transport sectors like aircraft, spacecraft or automobile. Due to the vibrations, it is difficult to use aerogels in these sectors. It is already possible to make brittle materials flexible. Glass, ceramic and carbon fibers are nowadays used for several applications in the form of flexible textiles and fabrics. Aim of this paper is to introduce a new developed process for the production of silica aerogel fibers. The fibers have been successfully produced and showed the same porosity and pore structure like in their corresponding bulk material.