Abstract This study investigated the appropriate methodology required to measure single carbon fibers electrical resistivity. Two- and four-probe methods were evaluated for this measurement. Comparing results for single filaments of pitch-based and PAN-based fibers shows that the two-probe method gives acceptable results for PAN-based fibers, but much higher deviations from adjusted resistivity for pitch-based fibers (>15%). The four-probe method shows small deviations (<1%) for both precursors and is the most suitable for measurements of pitch-based carbon fibers. The four-probe method gives higher accuracy than the two-probe for all samples tested.
We report the development of copolymers based on 2-vinylpyridine with different porosity degrees. The copolymers were quaternized with methyl iodide and acrylonitrile to introduce quaternary ammonium groups on pyridine units. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized were impregnated with iodine. The antibacterial properties of all the polymers were evaluated ranging from of the Escherichia coli strain. The unmodified copolymers did not have antibacterial activity against E.Coli suspensions. The quaternization with methyl iodine and acrylonitrile increased the biocidal performance of these copolymers, but only the copolymer with the lowest porosity modified with methyl iodine showed significant bactericidal action for all E. Coli concentrations. The 2-vinylpiridine copolymers quaternized and impregnated with iodine had higher antibacterial activity than the impregnated ones. The charge transfer complexes derived from the copolymer with the lowest porosity and highest swelling capacity in water had the best bactericidal performance.
This manuscript describes the synthesis of three polymers based on styrene (STY), divinylbenzene (DVB) and two different vinyl monomers: methyl methacrylate (MMA) and acrylonitrile (AN). The STY-DVB, STY-DVB-MMA and STY-DVB-AN polymers were synthesized employing the aqueous suspension technique. Reaction yields were 73%, 81% and 75%, respectively. They were morphological and chemically characterized using different techniques. The extraction capacity of the polymers was evaluated using 2-chlorophenol. The polymer extraction capacities were evaluated varying contact time the (1 h, 3 h and 5 h), temperature (30 °C, 35 °C and 40 °C), and pH (3, 5.6 and 8). The STY-DVB-AN polymer was the most efficient; it removed around 95% of the analyte using a contact time 50 h.
We report the development of two copolymers based on 2-vinylpyridine, styrene and divinylbenzene (2Vpy-Sty-DVB) with different porosity degrees. The copolymers were subsequently quaternized with methyl iodide. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized with methyl iodine were impregnated with iodine. The antibacterial properties of the polymers were evaluated in dilutions ranging from 10² to 10(7) cells/mL of the auxotrophic OHd5-K12 Escherichia coli strain. It was possible to obtain materials with complete antibacterial activity even in the highest cell concentrations tested.