Blends of polypropylene and ethylene octene comonomer with conducting fillers: Influence of state of dispersion of conducting fillers on electrical conductivity

Blends of polypropylene/ethylene octene comonomer (PP/EOC) with conducting fillers viz., carbon black (CB) and multiwall carbon nanotubes (MWNT) were prepared using melt mixing technique with varying filler concentration and blend compositions. Thermo gravimetric analysis studies indicated that presence of filler enhanced the thermal stability of PP/EOC blends. Morphological analysis revealed the formation of matrix‐dispersed droplet and co‐continuous type of morphology depending on the blend compositions. Significant reduction in droplet size and finer ligament thickness in co‐continuous structure were observed in the blends with filler due to compatibilization action. Fillers were found to be aggregated in the EOC phase irrespective of blends compositions and could be related to the affinity of the fillers toward EOC phase. The electrical conductivity of PP/EOC blends with CB and MWNT was found to be highest for 80/20 composition and decreased as EOC content increased. The percolation threshold of CB was between 10 and 15 wt% for the 80/20 and 70/30 blends whereas it was 15–20 wt% for blends with EOC content higher than 30 wt%. The percolation threshold was 2–3 wt% MWNT for PP/EOC blends. This was attributed to the aggregated filler network preferentially in the EOC phase. The melt‐rheological behavior of PP/EOC blends was significantly influenced in presence of both the fillers. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Pilot-Scale Evaluation of Ozone vs. Peroxone for Trihalomethane Formation

Both the direct ozone reaction and the indirect hydroxyl radical reaction are important in the ozonation of drinking water. This paper investigates the effectiveness of ozone versus ozone coupled with hydrogen peroxide (peroxone) with respect to trihalomethanes formation. The investigation was conducted on a pilot-scale at various H₂O₂:O₃ dose ratios of 0.1, 0.2, and 0.35 and change in peroxide addition point (pre- and post-ozonation). It was observed that the addition of peroxide, either before or after ozonation, increased trihalomethane concentrations and that increasing H₂O₂:O₃ increased trihalomethane concentrations. In comparing the addition point of peroxide, addition prior to ozonation better controlled trihalomethane formation than after ozonation.     

An analysis of strain in chip breaking using slip-line field theory with adhesion friction at chip/tool interface

A slip-line field model for orthogonal cutting with step-type chip breaker assuming adhesion friction at chip/tool interface is developed using Kudo's basic slip-line field. An alternative method is suggested for estimation of breaking strain in the chip. The model proposed predicts that with decrease in distance of chip breaker from the cutting edge of the tool, the breaking strain and shear strain in the secondary deformation zone increase while the total plastic strain decreases. The breaking of the chip is found to be solely dependent on the breaking strain, and not on ‘material damage’ or the specific cutting energy. The chip radius of curvature, cutting ratio, range of position of chip breaker for effective chip breaking are computed. The calculated results are found to be in general agreement with experimental measurements.     

Topography of the flank wear surface

In many applications, topography represents the main external features of a surface. This paper describes the topography of the flank wear surface and also presents the relationship between the maximum flank wear and the topography parameters (roughness parameters) of the flank wear surface during the turning operation. A modern CNC lathe machine (Okuma LH35-N) was used for the machine turning operation. Three-dimensional surface roughness parameters of the flank wear surface were measured by a surface texture instrument (from Talysurf series) using surface topography software (Talymap). Based on the resulting experimental data, it is found that as the flank wear increases, the roughness parameters (sR_a, sR_q, and sR_t) on the flank surface increase significantly. The greater the roughness value of the flank wear surface, the higher the friction of the tool on the workpiece and the greater the heat generation that will occur, thus ultimately causing tool failure. On the other hand, positive skewness (sR_sk) indicates the presence of a small number of spikes on the flank surface of the cutting tool, which could quickly wear off during the machining process.     

An analytical and experimental approach for pressure distribution analysis of a particular lobe and plain bearing performance keeping in view of all impeding varying parameters associating with fixed lubrication SAE20W40

This paper presents both analytical and experimental pressure analysis approach of a typical Lobe and plain bearing for determining effective performance of the bearing. This is found to be dependent on several variables viz. angular velocity (1200-1900 rpm), load (300-750 N) and pressure angle (0°-180°). This study in particular has been carried out for better rectifications and comparative prediction of lobe and plain bearing in terms of pressure distribution behavior under lubrication oil grade of SAE20W40. Influencing parameters were varied in this set up only to get optimum parametric combination considering all relevant practical issues. The experimentation was done based on significant directives of relevant literatures in these sectors. Attempt was made to compare the analytical findings with experimental results and found matched appreciably. After that attention was diverted to find the nature of pressure and load carrying capacity at various fluctuating speed and load with a fixed lubrication of SAE20W40 for appropriate decision making towards its characteristic performance. The analytical data generated by MATLAB are compared with experimental data which is generated by JBTR.

     

Investigation of Pt and Pd Modified WO<Subscript>3</Subscript> and ZnO Based Thin Film Sensors for Ethanol Sensing

Ethanol sensors based on different WO₃ and ZnO structures are studied in the present work. The XRD and SEM processes are used to characterize the sensing layer’s surface morphology which reveals the presence of nanoparticle in sensing layer. Further reducing the nanoparticle diameter by the addition of palladium (Pd) and platinum (Pt) for both the sensors (ZnO and WO₃) gives good results on sensitivity, operating temperature, response time and recovery time. Nanoparticle diameter for undoped WO₃, Pd-modified WO₃ and Pt-modified WO₃ based sensors is 11.8, 6 and 5.4 nm, whereas nanoparticle diameter for undoped, Pd-modified and Pt-modified ZnO based sensors is 20, 14 and 11 nm, respectively. Analysis of dynamic response of the sensors when exposed to different concentrations of ethanol vapour (from 500 to 10,000 ppm) and various temperatures indicate the improvement in sensitivity up to 77.2% for WO₃ and 74.6% for ZnO based sensors.     

Design of an Ultra-Compact and Highly-Sensitive Temperature Sensor Using Photonic Crystal Based Single Micro-Ring Resonator and Cascaded Micro-Ring Resonator

Silicon - In the present report, a photonic crystal based micro-ring resonator (MRR) structure is proposed which is very compact in size and has very fast response and is employed for temperature...     

Determination of forces in high speed blanking using FEM and experiments

The increasing demand for micro-formed and stamped parts such as connectors in the electronic industry is forcing manufacturers to push the speed limit of conventional press technologies to improve throughput. Designing dies/tooling for higher speeds and obtaining extended tool life requires a thorough understanding of the process. This paper discusses an experimental study of the interaction between punch, stripper plate and sheet material at various blanking velocities up to 1600 mm/s. The effect of velocity on punching force is also studied. A methodology to obtain high strain and strain rate dependent material flow stress data using blanking test and finite element modelling is presented.     

Nutrient budgeting for phosphorus and potassium in a long-term fertilizer trial

Influence of N, P and K application through inorganic and organic fertilizers on P and K removal in crop plants, changes in soil fertility status and their balance in the soil-plant (maize-wheat-cowpea fodder) studied for the first 22 years of a long-term experiment at Punjab Agricultural University farm, Ludhiana, India. The results showed that P uptake by wheat was about 1.5 times that of maize, whereas K uptake by wheat was only 1.1 times that of maize. The apparent P recovery by both maize and wheat depended on the rates of N, P and K application. Fertilizer rates greater than the recommended (150% NPK) resulted in lower P recoveries. At optimum level of N, P and K application (100% NPK) the mean P recovery (for 22 years) was 30.3% (±5.47) in wheat as compared to 20% (±11.35) in maize. The apparent P recovery in maize declined as the number of cropping years progressed. In 100% NPK plots, it declined from 45.6% in 1973 to 12.5% in 1992. The decline in P recovery was due to the accumulation of plant available P in the soil which increased from the initially low status to high-very high due to continuous application of P fertilizer. The application of FYM in conjunction with 100% NPK led to significantly greater accumulation of available P as compared to 100% NPK treatment alone despite the higher amount of total P removal in the former treatment than that from the latter. A trifle build-up in available K was observed in K amended plots notwithstanding the negative balance of K based on the approach of input-output relationship. The release of K from non-exchangeable form contributed towards K uptake by the crops. The results suggested the need for modifying the existing K fertilizer recommendations to compensate for gradual loss of native soil K fertility.     

High vacuum tribology of polycrystalline diamond coatings

Polycrystalline diamond coatings have been grown on unpolished side of Si(100) wafers by hot filament chemical vapour deposition process. The morphology of the grown coatings has been varied from cauliflower morphology to faceted morphology by manipulation of the growth temperature from 700°C to 900°C and methane gas concentration from 3% to 1·5%. It is found that the coefficient of friction of the coatings under high vacuum of 133·32×10^?7 Pa (10^?7 torr) with nanocrystalline grains can be manipulated to 0·35 to enhance tribological behaviour of bare Si substrates.