Nanotechnology in fibrous materials–a new perspective

This issue reviews various areas where nanotechnology has come up predominately in fibrous materials, namely in electrospun polymeric nanofibers and polymer layered silicate nanocomposites. It includes synthesis, characterization, various methods of collecting nanofibers, factors affecting electrospinning, methods of increasing the productivity of the electrospinning process, and different electrospinning designs. It also covers synthesis and characterization of polymer nanocomposites. Various properties of nanocomposites are discussed. The rheological behavior and morphology of nanocomposites are covered. Different modeling and simulation methods applicable to electrospun nanofibers and polymer layered silicate nanocomposites are discussed. Some of the potential application areas of electrospun nanofibers, polymer layered silicate nanocomposites, and various products available in the market based on nanotechnology are also discussed. Some of the lacking areas and future prospects in nanofibrous structures (nanofibers and nanocomposites) are emphasized in this issue.     

An analysis of the general benefits of a centralised VMI system based on the EOQ model

Within a vendor-managed inventory (VMI) agreement, the upstream supply chain member (the vendor) takes responsibility for managing the inventory of the downstream member (the customer) within specific levels previously agreed upon without the need of orders from the customer side to be placed. Therefore, the vendor can focus on optimising production efficiency and capacity planning, while the customer has to improve forecast accuracy. This paper analyses the benefits a VMI agreement could bring for a one-supplier, multiple-customer case through analysing two cases: a supply chain managed in a traditional manner and VMI when both the vendor and the customers belong to the same organisation. The analysis is based on the economic ordering quantity (EOQ) formula and its related total cost, and the novelty is captured by evaluating one vendor, multiple buyers, and multiple product situations. The modelling is done so as to capture the needs and factors which occur within the pharmaceutical industry and a numerical application will be executed with data from one of the main leaders within the pharmaceutical field.     

Effect of particulate fillers on thermal expansions and other critical performances of polycarbonate‐based compositions

Influence of different inorganic particulate mineral fillers on polycarbonate composites was explored. Among all the fillers assessed here only boron nitride and mica could appreciably reduce the thermal expansion of polycarbonate, particularly along the direction of flow. While measured in the normal to flow (cross‐flow) direction, the coefficient of thermal expansion (CTE) values decreased marginally in presence of boron nitride and mica as compared to the unfilled specimen. The anisotropicity in CTE is presumable due to preferential orientation of boron nitride and mica along the direction of flow in the injection molded samples. The effectiveness of fillers in reducing CTE of the polycarbonate composites was correlated to the dispersion of fillers in the polymer matrix. Better dispersion of boron nitride and mica, as observed through SEM, ensured their improved interaction with the matrix and thereby reducing the CTE. It was observed that in presence of particulate fillers the impact performance of the composites decreased appreciably with an increase in tensile modulus, in general. The flow behavior of the composites was by large dependent on the types of fillers used. In presence of some of the fillers such as BaSO₄, ZnO, ZnS, TiO₂, and alumina, flow of the composites increases significantly, primarily associated to appreciable reduction in molecular weights of the polycarbonate. On the other hand, with boron nitride flow remained almost unchanged upon its addition of 5 vol %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal performance of diesel engine exhaust heat recovery system using concentric tube heat exchanger inserts with different porous materials

This paper aims to analyse and improve the thermal performance of a concentric tube heat exchanger using porous material inserts. In this method, two different types of porous materials such as cast iron and mild steel were introduced on the outer surface of the inner tube wall of a concentric tube exchanger. The porous particle improves the convective heat transfer co-efficient between the tube wall and fluid flow surface. Experimentally, it was found that the inserted porous material enhances the heat exchanger effectiveness by 76% for cast iron and 77% for mild steel. The effect of inserting porous particles on the waste heat recovered from the engine exhaust was also investigated in the present study.     

Effect of Particle Size on Tribological Behavior of Rice Husk Ash–Reinforced Aluminum Alloy (AlSi10Mg) Matrix Composites

Rice husk ash of three different particle size ranges (50–75, 75–100 and 100–150 μm) a 3, 6, 9, and 12% by weight is reinforced with an aluminum alloy (AlSi10Mg) using the liquid metallurgy method. The dry sliding wear behavior of the composites in the cast conditions is examined using the pin-on-disc tribotesting machine for three different loads (20, 30, and 40 N) with three different sliding velocities (2, 3, and 4 m/s). The results reveal that the composite reinforced with the coarse rice husk ash particles exhibits superior wear resistance compared to the fine rice husk ash particles. The wear rate of the composite decreased with an increase in the weight percentage of rice husk ash particles for all size ranges. Finally, the wear mechanism was investigated with the worn surface using a scanning electron microscope.     

Enhancing methane production by anaerobic co-digestion of extruded organic wastes from slaughterhouse and vegetable market in batch and continuous processes

Clean Technologies and Environmental Policy - The organic wastes generated from centralized wholesale markets from urban centres are predominantly disposed in dumpsites/landfills. Although...     

Prediction of water retention capacity of hydrolysed electrospun polyacrylonitrile fibers using statistical model and artificial neural network

Box Behnken design of experiment was used to study the effect of process variables such as alkali concentration, temperature and time on water retention capacity of the alkaline hydrolysed electrospun fibres. The hydrolysis of electrospun polyacrylonitrile fibres was carried out using sodium hydroxide with different processing conditions like concentration of alkali, temperature and time. With the increase in the concentration of alkali, time and temperature, the water retention capacity of membrane was found to increase in the membranes. Water retention capacities of the membranes were modeled and predicted using empirical as well as artificial neural network (ANN model). The fiber diameter and mean flow pore diameter of electrospun polyacrylonitrile fibers and hydrolyzed fibers shown in SEM images were 310 ± 50, 275 ± 75 nm, 0.9258 and 1.12 microns, respectively. The present study indicated that the nanofibrous membranes have potential for the water absorbing applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Impact of the shape of electrode-tool on radical overcut of micro-hole in electrochemical micromachining

To make use of the full capability of electrochemical micro-machining (EMM), a meticulous research is needed to improve the material removal, surface quality and accuracy by optimizing various EMM process parameters. Keeping this in view, an indigenous development of an EMM machine set-up has been considered to carry out a systematic research for achieving a satisfactory control on the EMM process parameters to meet the micromachining requirements. In this study an EMM machine has been developed and experiments were conducted to study the influence of some of the major process parameters such as the machining voltage, electrolyte concentrations, the pulse-on-time and the machining current on the machining rate and accuracy. The effect of the shape of the tool electrode tips on EMM has been investigated experimentally with 304 stainless steel sheets. The machining rate and the overcut are significantly influenced by the shape of the tool electrode tip.     

Optimization of flux-cored arc welding process parameters by using genetic algorithm

The effect of flux-cored arc welding (FCAW) process parameters on the quality of the super duplex stainless steel (SDSS) claddings can be studied using Taguchi L9 design of experiments. In this experimental investigation, deposits were made with 30 % bead overlap. Establishing the optimum combination of process parameters is required to ensure better bead geometry and desired properties. The above objectives can be achieved by identifying the significant input process parameters as input to the mathematical models like welding voltage (X ₁), wire feed rate (X ₂), welding speed (X ₃), and nozzle-to-plate distance (X ₄). The identified responses governing the bead geometry are bead width (W) and height of the reinforcement (H). The mathematical models were constructed using the data collected from the experiments based on Taguchi L9 orthogonal array. Then, the responses were optimized using non-traditional nature-inspired technique like genetic algorithm (GA).