Polybenzoxazine‐based composites as high‐performance materials

Polybenzoxazines are newly developed thermoset polymers exhibiting versatility in a wide range of applications including in the electronics and aerospace industries. When combined as composites, the attractive characteristics of both components are apparent. The chemistry of benzoxazine synthesis offers wide molecular design flexibility and thus facilitates preparation of various polybenzoxazine‐based composites. This article reviews recent developments in the preparation and thermal curing of benzoxazine composites with a focus on structure–property relations of cured materials. Copyright © 2010 Society of Chemical Industry     

Tensile fatigue,stress relaxation,and creep behaviors of worsted core spun yarns

The objective of this research was to investigate the time‐dependent behaviors of yarns, which have significant bearings upon the properties of stretch fabrics made from them. In this study, 100% wool, wool–lycra (W‐L) (97 : 3), and polyester–wool–lycra (P‐W‐L) (52 : 45 : 3) blended yarns were considered. These yarns were subjected to the tensile fatigue failure, stress relaxation, and creep experiments. The findings showed that of these three yarns, P‐W‐L blend exhibited maximum fatigue lifetime, stress retention, and creep recovery, the pure wool yarn followed suit albeit to a lesser extent, whereas the W‐L blend made it least. The investigation suggests that wool alone with lycra as a core component is not sufficient to impart the expected properties upon stretch fabrics, rather a blend of polyester and wool with lycra as in the former would definitely make a worthwhile product. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

How Suspended Particles Affect Surface Morphology in Powder Mixed Electrical Discharge Machining (PMEDM)

The effect of SiC powder mixing into the dielectric liquid on surface topology and structure of interstitial free (IF) steel has been studied. Four process parameters, namely pulse duration, pulse current, concentration of powder, and type of dielectric liquid material, have been selected as varying parameters. Surface modifications due to suspended SiC particles were identified by using optical, scanning electron microscopy, and X-ray diffraction analysis. It was observed that suspended particles around discharge column accelerated and gained sufficient velocity to penetrate to the molten pool before solidification by means of electrophoresis and negative pressure induced after cessation of a discharge, which leads a surface embedded with added fine particles under that prevent formation of penetrating cracks during machining. However, surface cracks that formed due to high transformational stresses developed during solidification were found to be unaffected by means of mechanical action of the particles.     

A study to determine the degree of partial blending of reclaimed asphalt pavement (RAP) binder for high RAP hot mix asphalt

The objective of this paper is to provide a methodology for determining the degree of partial blending in high RAP mixtures. When RAP is mixed with virgin aggregates and virgin binder, partial blending of RAP binder occurs in the hot mix asphalt. Agencies limit the amount of RAP because the degree of blending between the RAP and the virgin materials is not known. The methodology provides a systematic approach for determining the degree of partial blending in the RAP mixture. The ability to accurately determine the degree of partial blending will help in determining the virgin binder content to be added in the mixture. The degree of partial blending measured from this procedure for 25% RAP by weight of aggregates with PG 70-28 and 35% RAP by weight of aggregates with PG 58-28 are 70% and 96% respectively.     

Self-aligned and bundled electrospun fibers prepared from blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with a hairy-rod polyphenylene copolymer

Bundled and self-aligned fibers were obtained by electrospinning blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) with a hairy-rod polyphenylene-g-polystyrene/poly(a-caprolactone) (PP-g-PS/PCL) copolymer. The self-alignment and bundling characteristics of these electrospun fibers were ascribed to the unique molecular architecture of the conjugated polymer, PP-g-PS/PCL, and its interactions with the solvent and the polymer matrixes used for the electrospinning. The self-alignment and bundling was found to be much more pronounced for PP-g-PS/PCL-PS blend when compared to PP-g-PS/PCL-PMMA blend. Furthermore we found that the degree of self-alignment of the fiber bundles was enhanced by increasing the amount of PP-g-PS/PCL in the blends but the alignment completely disappeared when the solvent dimethylformamide was changed to chloroform.     

Modelling business processes in steel fabrication

This paper outlines the utilization of the Structured Analysis and Design Technique (SADT) in developing a business process model as part of an IMI-LINK research programme. The project investigates the integration of design and construction through a demonstrator project using steel roof trusses. The SADT modelling technique is a graphical language-based methodology that generates activity models depicting, in a successively detailed manner, process activities and their relationships to each other. The paper highlights the problems and limitations encountered during knowledge acquisition process for the model, the modelling process, and outlines the research programme for the re-engineering of the fabrication process.     

Synthesis of block copolymers by the combination of chain transfer polymerization and initer process

Radical polymerizations of styrene (St) and methyl methacrylate (MMA) were carried out in the presence of tri phenylmethyl mercaptan (TPMM) as a chain transfer agent to give trityl (triphenylmethyl) terminated polymers. Transfer constants were found to be 17.8 and 0.71 for St and MMA, respectively. Trityl terminated polymers served as thermal “INITERS” for polymerization of vinyl monomers which proceeded via a quasi-living radical mechanism. This procedure makes it possible to prepare block copolymers. © John Wiley & Sons, Inc.     

Rapid prototyping technology: applications and benefits for rapid product development

In recent years, rapid prototyping technology (RPT) has been implemented in many spheres of industry, particularly in the area of product development. Existing processes provide the capability to rapidly produce a tangible solid part, directly from three dimensional CAD data from a range of materials such as photocurable resin, powders and paper. This paper gives an overview of the growth and trend of the technology, areas of applications and its significant benefits to manufacturing industries.     

Phenol Degradation in a Bipolar Trickle Tower Reactor Using Boron-Doped Diamond Electrode

Electrochemical oxidation of phenol was studied in a bipolar trickle tower reactor using Raschig ring shaped boron-doped diamond (BDD) electrodes in recirculated batch mode. The model wastewater was prepared with phenol using distilled water. The effects of initial phenol concentration, concentration of Na2SO4 as a supporting electrolyte, current density, flow rate, and initial pH on the removal efficiency were investigated. The removal of phenol of 200?mg/L and chemical oxygen demand (COD) of 480?mg/L were achieved with efficiencies of 99.85 and 88.89%, respectively. In the same study, specific energy consumption of 0.676?kWh/g phenol removed was determined at the current density of 5?mA/cm2. On the other hand, for the initial phenol concentration of 500?mg/L and COD of 1,200?mg/L, 99.69 and 90.83% removal efficiencies were obtained at the current density of 5?mA/cm2, respectively. Microtox toxicity tests were performed to investigate the toxicity reduction potential of BDD anodes, and relatively good toxicity reductions were obtained with respect to the initial values. After determining optimum experimental conditions, petroleum refinery wastewater was also studied by monitoring the destruction of phenol and COD. In this study, phenol removal of 99.53% and COD removal of 96.04% were achieved at the current density of 5?mA/cm2. Chemical oxidation studies were also carried out and the results were compared with the electrochemical oxidation studies. According to the whole results, it can be said that Raschig ring shaped BDD anodes exhibited an excellent performance for the degradation of phenol and COD and for the reduction of toxicity.