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Push-Pull processing of fibre reinforced thermoplastics and liquid crystal polymers

Research was carried out in order to show that Push-Pull processing has the potential to provide a new way to produce multilayered composites by injection moulding. The following studies were made:
comparison between short and long discontinuous glass fibre reinforced thermoplastics for processing and mechanical properties;
development of a new Push-Pull mould to produce different plate geometries with different grades to nylon-6.6 and liquid crystal polymer (LCP) (fibre orientation measurements proved that Push-Pull processing can be used to produce highly oriented glass fibre reinforced samples and the influence of non-constant thickness, diverging and converging flow were investigated by fibre orientation measurements and tensile tests);
characterization of a range of fibre reinforced samples by 2-dimensional image analysis, 3-dimensional confocal laser scanning microscopy (CLSM) and ultrasonic, time of flight measurements (novel software extensions have been developed for pattern matching);
analysis of the molecular orientation in the samples for the different material grades using wide-angle X-ray diffraction (WAXS) and Fourier transform infrared (FTIR) spectroscopy;
use of Laue photographs, 2 theta diffractograms and azimuth scanning in the WAXS experiments (a much more refined analysis of the molecular orientation is achieved by a new technique, denoted as specular reflectance Fourier transform infrared, SR-FTIR, spectroscopy whereby, the molecular orientation in very thin layers of 1 to 2 um is obtained);
investigation of the crystallization of nylon-6.6 using differential scanning calorimetry (DSC) and hot-stage microscopy;
a study of thin microtomed sections of samples of different grades of nylon-6.6 (at faster crystallization rates, the morphology of the different grades becomes distinguishable, and spherulite sizes are reduced);
development of a new finite element based simulation software and use of the commercial injection moulding simulation program C-MOLD for modelling the Push-Pull process;
development of a rheological model for reinforced thermoplastics incorporating the new behaviour law.

Reported by

University of Stuttgart
Pfaffenwaldring 32
70569 Stuttgart
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