Spectral and thermal studies on polyaniline-epoxy novolac resin composite materials

Synthesis and characterization of crystalline poly(N-(2-hydroxyethyl)aniline) microspheres

Poly( N-(2-hydroxyethyl)aniline) microsphere was prepared in aqueous hydrochloric acid (HCl) in one step, using ammonium persulphate as an oxidant. The effect of monomer, oxidant, HCl concentrations and temperature on polymerization rates was investigated. The data show that polymerization rate increases with increasing reactant concentrations. In addition, the initial rate increases with raising the temperature. The apparent activation energy found was 57.4319 kJ/mole. Also, Δ H* and Δ S* found were 55.0691 kJ/mole and 78.3662 J/mole K respectively. Infrared and proton nuclear magnetic resonance spectroscopies, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and elemental analysis characterize the obtained polymer sample to confirm the suggested structure. The mechanism of the polymerization reaction are discussed.

ELECTRICALLY CONDUCTIVE NANOCOMPOSITES OF EPOXY/POLYANILINE NANOWIRES DOPED WITH FORMIC ACID: EFFECT OF LOADING ON THE CONDUCTION AND MECHANICAL PROPERTIES

This paper reports the preparation and characterization of nanocomposites consisting of epoxy resin (EP) and conducting polyaniline nanowires doped with formic acid (PANI-FA). The percolation threshold of this nanocomposites was obtained at 8 wt.% of PANI-FA loading. On the other hand, 8 wt.% of PANI-FA resulted in reduction of tensile and flexural modulus up to 30% and 16%, respectively. The fracture morphological analysis revealed a distinct PANI-FA domain on the EP matrix after the percolation threshold has been reached. Using the scaling law of the percolation theory, it was found that the conductivity of the nanocomposites exhibited an exponential factor, (t) of 0.417.

Analysis of polyaniline oligomers by laser desorption ionization and solventless MALDI

While direct laser desorption ionization of soluble polyaniline dried onto metal sample plates results in mass spectra that are similar to previously shown electrospray ionization data of similar samples, laser desorption of unsolubilized solid polyaniline results in major fragmentation of the phenyl rings. Solventless MALDI, a recently developed technique for insoluble or slightly soluble species, involves the use of only solid analyte and matrix during sample preparation. Solventless MALDI of solid polyaniline results in mass spectra that are similar to the direct laser desorption ionization spectra of the soluble oligomers with some larger molecular weight oligomers also being detected. Based on the matrix used, different series of polyaniline with dissimilar end groups are detected. The matrix also affects the percentages of benzenoid and quinoid units in the oligomers. Thus, solventless MALDI appears to be a promising new technique for the mass spectrometric analysis of low solubility, but industrially important, polyanilines.

Estudo das Propriedades de Compósitos de Polianilina e Resina Epoxídica

Compósitos condutores de eletricidade envolvendo polianilina e resina epoxídica foram preparados utilizando-se o método da polimerização in situ. O método consiste da polimerização em emulsão da anilina na presença da resina epoxídica. Ácido dodecilbenzenossulfônico foi utilizado como agente dopante, que age também como surfactante da polimerização em emulsão. A condutividade elétrica do sistema Pani/resina epoxídica alcançou valores tão altos quanto 2 x 10-3 S/cm, com uma concentração de Pani correspondente a 7% em peso. O conteúdo de Pani na mistura foi determinado por análise elementar. O efeito do método de cura da resina epoxídica na condutividade elétrica, temperatura de transição vítrea e propriedades mecânicas do sistema foi também investigado.