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Optimization of Morphology in Order to Produce Polypropylene Antistatic Fiber Containing Polyaniline

Khosronezhad, Fatemeh | 2022

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55069 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Bagheri, Reza
  7. Abstract:
  8. In this study, the synthesis conditions of polyaniline were optimized in order to produce a blend based on polypropylene (PP) containing polyaniline (PANI) with the electrical conductivity in the antistatic range. A form of PANI that has adequate electrical conductivity and thermal stability, which is suitable for melt-mixing and melt-spinning conditions, was synthesized. Thermal stability and electrical conductivity of polyaniline were investigated by thermal gravimetric analysis (TGA), differential calorimetric analysis (DSC) and high-temperature electrical conductivity. It was found that the synthesized PANI has required thermal stability and electrical conductivity (106 ohm.cm) at the process temperature (220 ° C). Then, binary blends of PP/PANI and ternary blend of PP/PA6/PANI were melt mixed and the effect of using dioctyl phthalate (DOP) as a plactisizer, and polyamide 6 on electricical properties was investigated. The obtained blend was studied by Fourier transform infrared (FTIR) and DSC to examined the thermal properties and the interaction between phases. In addition, the morphology, dispersion of PANI in the blend and the preferential phase for PANI localization were examined by field emission scanning electron microscopy (FE-SEM) and X-ray dot mapping. It was found that, polyaniline particles are selectively localized inside and on the surface of PA6 droplets, which are dispersed in the PP matrix. Increasing the PANI weight percent, raises the PA6 droplet size by increasing the amount of PANI placed inside the PA6 droplets. Trapped polyaniline in discontinuous PA6 droplets, prevents the formation of conductive pathways and reduces the conductivity of ternary blend (PP/ PA6/ PANI) compared to binary blend (PP/ PANI). During melt-spinning process, for the blends with appropriate size of PA6 droplets, droplets are joined together and the double percolation threshold phenomenon occurs, which leads to the formation of conductive pathways and remarkably improves the electrical conductivity of the fibers. According to electrical conductivity measurement, results show that, when blends with 10 wt.% PANI were melt-spinned, electrical resisitivity decreases from 109 Ωcm to 106 Ωcm. Mechanical properties of fibers were examined by tensile test. It was found that, mechanical properties are also improved by the intrinsic strength of PANI and the formation of an interconnected network of PANI-containing PA6 droplets; PP/ PA6/ PANI fibers containing 10 wt.% PANI have a strength equal to pure PP and a two times higher maximum elongation compared to pure PP
  9. Keywords:
  10. Polypropylene ; Polyamide 6 ; Polyaniline ; Melt Spinning ; Double Percolation ; Anti-static Coating ; Thermal Gravimetric Analysis

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