Preparation and Characterization of Ethylene Vinyl Acetate (EVA)/Natural Rubber (SMR L)/Organoclay Nanocomposites: Effect of Blending Sequences and Organoclay Loading

Ethylene vinyl acetate (EVA)/natural rubber (SMR L)/organoclay thermoplastic elastomer nanocomposites were melt compounded in an internal mixer, Haake Rheometer, at 120°C and 50 rpm rotor speed. In this paper, we demonstrate the effect of different blending sequences and organoclay loading from 2 to 10 phr (parts per hundred resins) on the tensile properties, morphology, thermal degradation, flammability, and water absorption behavior of EVA/SMR L/organoclay nanocomposites. EVA/SMR L/organoclay TPE nanocomposites were prepared by three different blending sequences, and each exhibited different tensile properties. Results indicated that the presence of organoclay increases the tensile properties, resistance toward thermal degradation, resistance to water permeation, and flame retardancy for all the nanocomposites prepared via different blending sequences. However, the optimum results for all the properties studied were achieved when EVA was blended with organoclay first and SMR L was incorporated later into the blend. The optimum organoclay loading was achieved at 2 phr. Results from scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies showed that at 2 phr organoclay loading, nanostructures of individual silicate layers were achieved, whereas at 8 phr organoclay loading, agglomeration was observed. Flammability of the nanocomposites decreased when the organoclay loading increased.     

An Efficient Cross Layer Design of Stability Based Clustering Scheme Using Ant Colony Optimization in VANETs

Wireless Personal Communications - Road Accident is a significant concern in every county. According to WHO (World Health Organization) reports, 1.3 million people died in road traffic crashes, and...     

Current Development of Electron Beam Irradiation of Natural Rubber–Polymer Blends

The application of electron beam irradiation in polymers blend with natural rubber such as thermoplastic polymers, specialty polymers, and thermoset polymers are discussed in this paper for the aspects of physical, mechanical, and thermal properties. The interaction of additives and irradiation for natural rubber blends were also been analyzed. The addition of cross-linking agent such as trimetylolpropane trimethacrylate with appropriate amount could enhance the mechanical properties of the polymer–natural rubber blend and lower the optimum dose of electron beam irradiation. In short, electron beam is another potential aspect worth for study in natural rubber research area.     

Modelling of low-latitude ionosphere using modified planar fit method for GAGAN

Several countries have been developing satellite-based augmentation systems (SBAS) for improving positional accuracy of global positioning system (GPS). India is also developing one such system popularly known as GPS aided geo augmented navigation (GAGAN) system. Modelling of ionospheric effects is one of the major challenges in developing precise and reliable GAGAN. The high values of total electron content (TEC), the large diurnal and seasonal variability and intense irregularities present in the low-latitude ionosphere, lead to unacceptable positional errors in GAGAN service region. Todd Walter et al. of Stanford University, USA have made significant contribution in the area of SBAS ionospheric grid modelling by developing the popularly known planar fit model. It is reported by Walter et al. (2000) that a constant decorrelation value of 35 cm was proposed over the wide area augmentation system (WAAS) service region. To provide accurate estimation of ionospheric delays at user ionospheric pierce points (IPP) during a storm or intense irregularities, an irregularity detector and a decorrelation adaptor are incorporated in the modelling. As planar fit model is not adequate to model intense irregularities of Indian ionosphere, a modified planar fit model is applied for GAGAN data on similar lines as was done for WAAS and the results are encouraging.     

SELECTIVE FLAT PLATE COLLECTORS FOR SOLAR DRYERS

ABSTRACT

Five different selective surfaces coated with oxides of nickel, manganese, chromiUm, lead, am iron on galvanized iron substrate by electro-deposition or chemical method were studied for properties such as absorptivity, emissivity, temperature rise of the surface and stagnation air temperature. The properties of the surfaces which may change due to weather conditions were predicted by: subjecting the collector surfaces to accelerated tests. The best among them was found to be black nickel, followed by manganese, chromium, lead, and iron oxides. Black nickel and manganese surfaces were included in the solar drying system and their drying air temperatures recorded. With selective surfaces, a temperature rise between 250to 4sOC was observed depending on the surface (either manganese oxide or nickel oxide)., Hence high mo~sture content food crops can be dried in less than half the time using selective surface     

Effects of different preparation methods on the properties of poly[ethylene‐co‐(vinyl acetate)]/(Standard Malaysian natural rubber)/organoclay nanocomposites

Poly[ethylene‐co‐(vinyl acetate)] (EVA)/(Standard Malaysian natural rubber) (SMR L)/organoclay nanocomposites were prepared by using melt intercalation and solution blending methods. In both preparation methods, the EVA: (SMR L) ratio was prefixed at 50:50, while the organoclay loading was varied from 0 to 10 phr. The effects of two different processing routes and organoclay loading on the morphology, tensile, properties thermal properties, and flammability of the nanocomposites were studied. X‐ray diffraction results and transmission electron microscopy images proved that solution blending promotes better dispersion of organoclay than melt intercalation. Thus, the nanocomposites prepared by the solution‐blending method exhibited higher values of tensile strength, stress at 100% elongation (M100), and thermal stability. The M100 value and thermal stability improved proportionally with the increase of organoclay content, owing to the demobilizing effect and the barrier properties of the organoclay. The optimum tensile strength value was achieved at a 2‐phr organoclay loading. Further increases in loading decreased the strength of the nanocomposites. Tensile fracture surfaces of the nanocomposites prepared by both methods showed different fracture behavior, as evidenced by scanning electron microscopy images. Flammability decreased when the organoclay loading increased for the nanocomposites prepared by both methods. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Differentiated survivability with improved fairness in IP/MPLS-over-WDM optical networks

This paper addresses the priority-fairness problem inherent in provisioning differentiated survivability services for sub-lambda connections associated with different protection-classes in IP/MPLS-over-WDM networks. The priority-fairness problem arises because, high-priority connections requiring high quality of protection such as lambda level pre-configured lightpath protection are more likely to be rejected when compared to low-priority connections which may not need such a high quality of protection. A challenging task in addressing this problem is that, while improving the acceptance rate of high-priority connections, low-priority connections should not be over-penalized. We propose two solution-approaches to address this problem. In the first approach, a new inter-class backup resource sharing (ICBS) technique and a differentiated routing scheme (DiffRoute) are adopted. The ICBS is investigated in two methods: partial- and full-ICBS (p-ICBS and f-ICBS) methods. The DiffRoute scheme uses different routing criteria for the traffic classes. In the second approach, two rerouting schemes are developed. The rerouting schemes are applied with the DiffRoute and ICBS. The rerouting schemes employ inter-layer backup resource sharing and inter-layer primary-backup multiplexing for the benefit of high-priority connections, thus improving fairness. Our findings are as follows. (1) The application of p-ICBS and DiffRoute yields improved performance for high-priority connections. However, it shows penalized performance for low-priority connections. On the other hand, the collective application of f-ICBS and DiffRoute yields significantly improved performance for high-priority connections with no penalized performance as the performance of low-priority connections is also improved. (2) The rerouting schemes, when applied with the DiffRoute and ICBS methods, further improve the performance of high-priority traffic without significantly affecting the performance of other traffic.     

Modification of PVC/ENR blends by electron beam irradiation

The effects of electron irradiation, with doses ranging from 20 to 100 kGy on the physical properties of poly(vinyl chloride)/epoxidised natural rubber blends (PVC/ENR50 blends) were investigated. The enhancement in tensile strength, elongation at break, hardness, and aging properties of the blends have confirmed the positive effect of irradiation on the blends. Crosslinking of the ENR50 phase proved to play a major role in the improvement of mechanical properties of blends. The results also revealed that at any blend composition the enhancement in properties depends on the irradiation dose which controls the degree of radiation-induced crosslinking. The single glass transition temperature obtained confirms that the blends remain miscible upon irradiation.     

Hydrogel coating of RVNRL film by electron‐beam irradiation

The tackiness properties of radiation‐vulcanized natural rubber latex (RVNRL) film surfaces coated by various monomers were investigated in order to define the suitable hydrogels which reduce the tackiness of the film. In this context, different types of monomers, namely, N‐vinyl‐2‐pyrrolidone (NVP), N,N‐dimethylaminoethylamide (DMAEA), acrylic acid (AAc), n‐butyl acrylate (n‐BA), and 2‐hydroxyethyl methacrylate (HEMA) as well as the monomer mixtures were tried with varying degrees of success. Coating the RVNRL film with 80% HEMA/20% n‐BA by irradiation at 80 kGy using a low‐energy electron beam gave a remarkable reduction in the surface tackiness of the RVNRL film. Several other attempts were made such as priming the RVNRL film with acid and aluminum sulfate prior to coating, mixing the aluminum sulfate into the monomer mixtures, and dipping the partially wet RVNRL film into the monomer to enhance the wettability of the monomers with the film. The photomicrographs taken illustrate that the decrease in tackiness with the coating is due to the increase of the surface roughness at an 80‐kGy irradiation dose. The studies also revealed that the reduction in the contact angle and the increase in water absorption of the RVNRL film after irradiation are due to the formation of the hydrogel layer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1421–1428, 1999