No abstract

In this paper, we are reporting the influence of cationic CTAB surfactant on the interaction of chromium(III) complex of glycylphenylalanine [Cr(III)-Gly-Phe]2+ with ninhydrin under varying experimental conditions. The reaction follows irreversible first-order reaction kinetics with respect to [complex] and fractional-order with respect to [ninhydrin]. With progressive increase in [CTAB], the rate constant (k Ψ) for condensation of ninhydrin into [Cr(III)-Gly-Phe]2+ complex increased, reached a maximum value, and then decreased. The results are best accounted for by the distribution of substrate into micellar and aqueous pseudo-phases as well as combination of substrate molecules with surfactant molecule. On the basis of above results, template mechanism has been discussed.

Additions of 3 and 5 wt.% Al have been investigated as a low-cost method for transformation acceleration in nano-bainitic steels. For both Al contents, two groups of steels with C-content in the range ~0.7 to ~0.95 wt.% were studied. Thermodynamic and physical simulations were used in alloy and heat treatment design. Characterization was performed via dilatometry, scanning and transmission electron microscopy, Synchrotron X-ray diffraction, and tensile and impact testing. Fast bainitic-transformation time-intervals ranging from 750–4600 s were recorded and tensile strengths up to 2000 MPa at a ductility of ~10 elongation percent were attainable for the 3 wt.% Al group at an austempering temperature of 265 °C. Higher Al additions were found to perform better than their lower Al counterparts as the austempering temperature is dropped. However, Al lowered the austenite stability, increased the martensite start temperature, austenitization temperatures and, consequently, the prior austenite grain size, as well as limiting the austempering temperatures to higher ones. Additionally, the lowered austenite stability coupled with higher additions of hardenability elements (here carbon) to maintain the martensite start at around 300 °C, causing the 5 wt.% Al group to have a large amount of low stability retained austenite (and consequently brittle martensite) in their microstructure, leading to a low elongation of around 5%.

No abstract

An adequate dispersion of fine particles is essential for improved properties in particle-reinforced composites. State-of-the-art methods mainly rely on mechanical (shearing) dispersion methods that do not yield the requested homogeneity within the final composite. This leads to a deterioration and inhomogeneity of mechanical properties. Other non-conventional methods such as in-situ polymerisation or solution compounding are not yet applicable on an industrial scale. This study tackles these problems and provides a novel method for the fabrication of well-dispersed particle-reinforced polymer composites while making use of conventional machinery on the one hand and allowing industrial applicability on the other hand. The presented technique makes use of the pyrolysis of a low thermally stable polymer within a conventional melt compounding process to produce well dispersed carbon particles throughout a thermoplastic matrix in an in-situ process. For this purpose, Carboxymethylcellulose particles are used. The selection of decomposition parameters around the processing temperature of polypropylene yields well-dispersed carbon particles, as evidenced by scanning electron microscopy. This further interprets the resulting promising mechanical properties.