Continuous flow of polyimide coating on silica optical fibre and its characterization

Abstract

Bare optical glass fibres possess poor mechanical properties, and thus are susceptible to breakage and cause optical loss. The polyimide coating on bare optical fibres using the precursor poly(amic acid) can be useful to impart good inherent strain for microbending resistance and harsh for high temperature environments. The coating process parameters were optimized to obtain uniform polyimide coating on an optical fibre having thickness about 12–15 μm. The rheological properties of coating precursor were characterized. The thermal, mechanical, spectroscopic and morphological properties of polyimide coatings imidized at different temperatures were investigated using differential scanning calorimetric, thermo-gravimetric analysis, mechanical testing, Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscope to gain insight into the structural and optical parameters of coatings at different temperatures.