Spectroscopic characterization of the matrix–silane coupling agent interface in fiber-reinforced composites

The copolymerizations of anhydride-cured epoxy resin on fiberglass surfaces treated with a N-methylaminopropyltrimethoxysilane coupling agent has been investigated using Fourier-transform infrared spectroscopy. The structure of the interface of the silane and the resin in fiber-reinforced composites is composed of copolymers of the epoxy resin with the organofunctionality of the deposited silanes. The number of interfacial bonds formed depends on the amount of silane coupling agent deposited on the fiberglass and the reaction conditions. The silane induces additional esterification and increases the curing density of the epoxy matrix near the fiber surface by about 5–10% relative to the bulk resin.     

Effect of uniaxial stress on electrical conductivity of sulphur nitride polymer

The effect of uniaxial stress on the room temperature electrical conductivity of polymeric sulfur-nitride is reported. The results provide additional evidence of the importance of interchain coupling on the electrical properties of (SN)_x and demonstrate that the perpendicular transport is limited by interfiber contacts.     

Assay of Aspirin,Ethenzamide and Caffeine Mixture by 13C NMR Spectrometry

¹³C FT NMR method of gated decoupling without NOE was applied in the quantitative analysis of aspirin, ethenzamide and caffeine mixture (antipyretic). Spectra were obtained in pyridine-d⁵, containing anisole as an internal standard and chromium(III) acetylacetonate as a paramagnetic relaxation reagent, The results were generally satisfactory.     

Design of a new thin-film electro-optic switch

A new thin-film electro-optic switch employing two stable states of polarization is proposed and investigated. The design can be further employed to realize a TE-TM polarization converter by constructing a Mach-Zehnder type interferometer integrated optical switch. The limitations and design procedures for electro-optic devices are also discussed.     

Improved synthesis of 2,2'-dibromo-9,9'-spirobifluorene and its 2,2'-bisdonor-7,7'-bisacceptor-substituted fluorescent derivatives

Pure 2,2'-Dibromo-9,9'-spirobifluorene was synthesized by a method that did not involve troublesome dibromination of 9,9'-spirobifluorene or Sandmeyer reaction of 2,2'-diamino-9,9'-spirobifluorene. A series of donor-acceptor orthogonally substituted 9,9'-spirobifluorene was subsequently prepared showing rich variation of fluorescence in solution and in solid state. [reaction: see text]