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Synthesis and characterization of surface sulfonated polypropylene films

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2004
Ecevit, Safiye Tuba
The basic reseach on the surface sulfonation of the polypropylene is very important due to the surface design for higher functionalization. For this purpose, liquid-phase sulfonation of the polypropylene surfaces at various temperatures for different time periods were performed by concentrated sulphuric acid. The physical and chemical changes formed by the effect of the sulfonation on the polypropylene surfaces were determined by contact angle measurement, mechanical analysis, UV-Vis spectrometer, differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). The surface polarity and wetting properties of the samples were evaluated by contact angle measurement. It is seen that, sulfonation at low temperatures and short time periods improve these two properties of the polypropylene surfaces. Sulfonation at high temperatures and long time periods however, cause the partial breakdown of the polymer by degradation. Noticeable color change due to the degradation and carbonization of the polypropylene films sulfonated at high temperature and long time were supported by the UV-Vis spectra of the samples. Mechanical properties of sulfonated PP films were investigated. Consequently, after the sulfonation process the mechanical properties of the PP films showed a general trend of decrease with sulfonation time for a given temperature and a very fast decrease at high temperature of sulfonation. Thermal characteristics were found by differential scanning calorimeter (DSC). Thermal analysis revealed that sulfonated PP film samples displayed an additional endothermic peak. The physical effects of the sulfonation