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Thermoplastic matrix composites by aqueous electrocopolymerization onto graphite fibers
Author(s) -
Iroh Jude,
Bell J. P.,
Scola D. A.
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070410321
Subject(s) - comonomer , copolymer , materials science , glass transition , polymer chemistry , differential scanning calorimetry , graphite , composite material , styrene , aqueous solution , chemical engineering , polymer , chemistry , organic chemistry , physics , engineering , thermodynamics
Electrocopolymerization of 3‐carboxyphenyl maleimide and styrene onto Hercules AS‐4 graphite fiber surfaces has been successfully carried out from an aqueous solution containing monomers and dilute sulfuric acid. Initiation of copolymerization of the monomers dissolved in a small amount of dimethylacetamide is achieved by constant‐current electrolysis in the cathodic chamber of a three‐compartment electrolysis cell. Polymerization is initiated at the fiber surfaces; little polymer is formed in the cell solution. Electrocopolymerization is very consistent and rapid. The amount of polymer increases predictably with increasing comonomer concentration and current density. Using a 0.4 M (1 : 1) comonomer concentration, 0.0125 M sulfuric acid solution, and a current density of 20 mA/g, more than 60 wt % of copolymer coating per unit weight of graphite fibers is obtained within thirty minutes. Thermal gravimetric analysis showed the copolymer to be very stable at elevated temperatures and has initial and final decomposition temperatures of 430 and 520°C, respectively. The glass transition temperature measurement of the copolymer coatings was carried out by differential scanning calorimetry. A single glass transition temperature was obtained of about 210°C for most samples. The glass transition temperature of the copolymers did not change significantly with changing comonomer feed composition. Functional group and compositional analysis of the copolymer was done by FTIR spectroscopy. The copolymer composition remained relatively the same for copolymers made from different styrene/3‐carboxyphenyl maleimide feed composition, confirming a strong tendency toward alternation for the system.