The Effect of Weight Content or Density on the Burning Behavior of Some Cellulosic Specimens

The effect of different densities of various cellulosic specimens on their burning behavior has been of interest in this investigation. By using a vertical flammability tester, burning times of different unfinished cellulosic samples, such as white paper, straw paper, and cardboard, have been chosen and their flammability characteristics have been determined. The obtained figures for the consumed identical samples show that, by increasing their densities, their burning time and temperature of burning have been increased. However a decrease in the burning rate could rationally be attributed. Furthermore a decrease in the burning temperature proved a reasonable synonymy toward the decrease in the burning rate. In addition to this, burning rate is antithetical toward the density of the consumed specimens. A thermogravimetric analysis of a selected cellulosic material fortified our hypothesis; i.e., the thermal decomposition temperature differs from the burning temperature, whereas the latter temperature is merely dependent on the weight content or density of the samples.     

Effects of three surfactant types of anionic, cationic and non-ionic on tensile properties and fracture surface morphology of epoxy/MWCNT nanocomposites

Three types of surfactants were used to enhance the dispersion of multi-wall carbon nanotubes (MWCNTs) in the epoxy matrix. MWCNTs were separately treated with non-ionic (polyoxyethylene octyl phenyl ether, Triton X-100), cationic (hexadecyl-trimethyl-ammonium bromide, CTAB) and anionic (sodium dodecyl sulfate, SDS) surfactants and their effects were evaluated on the dispersion state and surface chemistry, as well as on the tensile properties and tensile fracture surface morphology of MWCNTs/epoxy nanocomposites. The active surfaces of the carbon nanotubes were characterized by FTIR. The non-ionic surfactant, Triton X-100, had the best effect on dispersion of the MWCNT in the epoxy matrix, thus, positively affecting the tensile parameters of the corresponding nanocomposites which were attributed to the ??bridging?? effects between the MWCNT and epoxy, introduced by the hydrophobic and hydrophilic heads of the corresponding surfactant. Presence of MWCNTs as reinforcing agent increased the elastic modulus of nanocomposites, indicating the improved interfacial adhesion between CNTs and polymer matrix. The regions of nucleation and propagation of cracks were clearly seen in the SEM micrographs of the tensile fracture surface of the nanocomposites. The cracks deviated on reaching the carbon nanotubes. The dispersing aiding capabilities of the three surfactants used in the present study were as follows: cationic?<?anionic?<?non-ionic.     

Verification Concerning the Relative Superiority of a Cellulosic Fabric with Regard to Polyester in Terms of Flammability

In order to prove the superiority of cotton fabric to polyester with regard to flammability, we have studied the effect of Graham's salt as a moderate and nondurable finish on the flammability of pure polyester and cotton fabric. The laundered bone-dried, weighed fabrics were impregnated with suitable concentration of aqueous Graham's salt solutions by means of squeeze rolls and drying at 110°C for 30 min. They were then cooled in a desiccator, reweighed with analytic precision, and kept under ordinary conditions before the accomplishment of the vertical flame test. The optimum add-on value to impart flame retardancy was about 43.65% for polyester fabric and 36.78% for cotton fabric. The results obtained comply with the Coating Theory. Moreover, the superiority of cotton fabric to polyester fabric in terms of combustibility has been deduced.     

Synthesis,X-ray structure and study of a mixed ligand iron(III) complex with tridentate Schiff base as a homogeneous catalyst in the efficient oxidation of sulfides

A mononuclear mixed ligand complex of iron, [Fe^III(N-OPh-sal)(acac)EtOH], where Hacac and N-HOPh-Hsal denote acetylacetone and N-hydroxyphenyl-salicylideneamine, respectively, has been synthesized and characterized by elemental analysis, spectral studies and X-ray crystallography. The catalytic system containing this complex and urea hydrogen peroxide as oxidizing agent was used to selectively oxidize a range of sulfides to the corresponding sulfoxides in good yields under mild conditions. The electronic spectra of the catalytic system were applied to explore reactivity and stability of the catalyst during sulfide oxidation reactions and to examine the nature of active species, as well.