Mechanisms of antioxidant action: The role of nitroxyl radicals in the stabilization of PVC

Hindered amines and their derived oxidation products, the hindered nitroxyls and hydroxylamines are processing stabilizers and photoantioxidants for poly(vinyl chloride). The evidence suggests that oxidation of the amines occurs very rapidly and completely during mechanooxidation and that the resulting redox couple operates by a catalytic mechanism as described previously for hydrocarbon polymers.     

Mechanisms of antioxidant action: The effect of spin traps during the processing and photooxidation of PVC

It is demonstrated by the use of spin traps that during the early stages of thermal processing of PVC considerable concentrations (> 3 × 10^?6 mol g^?1) of free radicals are produced which are primarily responsible for the initial products (hydroperoxides, unsaturation, and hydrogen chloride) previously shown to be formed in the polymer. From a semiquantitative analysis of these products, it is estimated that more than 50% of the radicals are formed from hydroperoxides and the rest by mechanoscission of the polymer chain. The spin traps are effective processing stabilizers in combination with a tin maleate HC1 scavenger. One of them (2-methyl-2-nitroso propane, MNP) has also been shown to be a photoantioxidant.     

EXTRUSION AND LUBRICATION FLOWS OF VISCOPLASTIC FLUIDS WITH WALL SLIP

The simplest model flow which approximates the extrusion (shallow screw channels) and lubrication flow is the steady, laminar flow occurring between two infinitely long parallel plates i.e., the generalized plane Couette flow. Here we develop an analytical model of the generalized plane Couette flow of viscoplastic fluids. The deformation and flow behavior of viscoplastic fluids can be realistically represented with the Herschel-Bulkley constitutive equation, which we have utilized as the basis for the development of our analytical model. Furthermore, as also demonstrated here, the deformation behavior of viscoplastic fluids is generally complicated by the presence of wall slip at solid walls, which occurs as a function of the wall shear stress. The wall slip versus the wall shear stress behavior of viscoplastic fluids can be experimentally characterized using viscomelric flows, including steady torsional and capillary flows. Thus determined Navier's wall slip coefficient can then be utilized in modeling of processing flows. In our analytical model of the generalized plane Couette flow of viscoplastic fluids the Navier's wall slip boundary condition was included. This model should be an important engineering tool, which provides design expressions for the extrusion and lubrication flows of viscoplastic fluids, with or without wall slip occurring at the walls. @KEYWORDS:Extrusion, lubrication, flow, viscoplastic, slip.     

The contextualization of divergent outlooks in a Greenfield master-planned community: a pathway towards reflexivity

Comprehensive design schemes and specifications have progressively shaped Master-Planned Communities (MPCs). The market largely predetermines these outcomes, with background input from communities. Therefore, this paper endeavours to define the fundamental structures that generate differences between market actors and residents within the North Lakes MPC. This study employs ‘habitus theory’, which is a sociological phenomenon describing the divergence of personal outlooks and expertise. The application of this theory is thus illustrative of the evolution of distinct observations within MPCs. Contemporary studies have under-researched these inherent gaps between communities, authorities, and critics, and these frictions could be exacerbated within restrictive developmental contexts. Epistemic and objectified content analyses collated over many years and sources will uncover the underlying differences between the relevant groups. These analyses will enable the progression of a framework for understanding power relation biases and how reflexivity can enhance current consultative methods.     

Electrochemical conversion of switchgrass and poplar in molten carbonate direct carbon fuel cell

One way of sustaining fuel cell technology is using renewable and sustainable energy means provided by biomass. This article explores switchgrass and poplar in a molten carbonate electrolyte direct carbon fuel cell. It investigates their electrochemical conversions and provides results of power density, current density, open circuit voltage (OCV) and other parameters. The biomasses were pyrolysed at 800°C to produce carbon fuels. Biomass carbon fuels were mixed with molten carbonate and subjected to different operating conditions (600–800°C) in the fuel cell. The electrochemical performances of the poplar fuel were better than those experienced with switchgrass fuel. At 800°C the OCV of poplar fuel (1.08?V) has higher output than switchgrass (0.87?V). The peak power density recorded for poplar fuel was 23.91?mW/cm² while switchgrass fuel was lower at 21.60?mW/cm². Poplar fuel (81.53?mA/cm²) gave a maximum current density with switchgrass fuel lower at 74.00?mA/cm².     

Catalytic hydrogenation of o-nitroanisole in a microreactor: Reactor performance and kinetic studies

Hydrogenation of o-nitroanisole to o-anisidine was conducted in a packed-bed microreactor as a model hydrogenation reaction of importance to the pharmaceutical and fine chemicals industries with the aim of investigating the reactor performance and kinetics of the reaction. The effects of different processing conditions viz. hydrogen pressure, o-nitroanisole concentration, temperature, and residence time on the conversion of o-nitroanisole, space-time yield (STY), and selectivity of o-anisidine were studied using 2% Pd/zeolite catalyst. The kinetic study was undertaken in a differential reactor mode keeping the conversion of o-nitroanisole at less than 10%. During the kinetic study, it was observed that the intermediate 2-methoxynitrosobenzene was present in the reactor at low catalyst loading and low conversions because of short residence time in the reactor. Therefore, for the kinetics study, the overall reaction was treated as comprising two separate reactions: first the reduction of o-nitroanisole to 2-methoxynitrosobenzene and then, the reduction of 2-methoxynitrosobenzene to o-anisidine. Internal and external mass and heat transfer limitations in the microreactor were examined. Different rate laws using different mechanisms from the literature were considered to fit the experimental data. Two rate equations for the two consecutive reactions assuming Langmuir-Hinshelwood mechanism provided the best fit to the experimental data. These two rate equations predicted the experimental rates within 10% error. Experiments were also carried out in an integral reactor, and the reactor performance data were found to be in agreement with the predictions of the theoretical models.     

Synthesis and characterization of polylactic acid-lecithin-starch bioplastic film

Plastic-induced environmental issues could be solved using biomaterials, such as polylactic acid (PLA) film. PLA film is a costly solution suggesting the need to add less expensive starch. However, PLA and starch do not mix due to their diverging water behavior. In this study, we evaluated the impact of lecithin as a compatibilizer in varying ratio of PLA and starch film. The results show that inclusion of lecithin in PLA/starch composite leads to enhanced mechanical properties compared with the composite without lecithin. All films' thermal properties were stable but the thermograph of PLA/starch display two peaks whose distance is impacted by lecithin. In addition, morphology and functional group fingerprints revealed that the addition of lecithin improved the interfacial adhesion between the two polymers. Lecithin influenced the positioning and dispersion pattern of starch granules and distinct transmittance characteristics. The improved compatibility of PLA/starch makes the resulting films less susceptible to water penetration and dissolution. This work demonstrated the possibility of using lecithin as emulsifier between PLA and starch which could expand the application of PLA/starch film especially in packaging industries and bale net wrapping.     

An apparatus for quantitative measurement of interparticulate friction in a non-compacted powder mass

This paper describes a new test apparatus developed for measuring interparticulate friction. The results obtained using this apparatus are compared with Hausner ratio as well as the angle of repose results made on identical powders and under identical environmental conditions. The resistance to flow of a mass of uncompacted power is determined by measuring the torque needed to prevent the rotation of a vane shaft embedded in the powder while the powder column is rotated at a constant speed. The vane shaft, located at the center of the apparatus, is coupled to a load cell and the force developed is recorded on a strip chart. The load cell is capable of measuring forces up to 500 gf with a limit of resolution of about 0.5 gf. Results obtained for a number of different particulate materials are presented.     

Implementing IoT/WSN based smart Saskatchewan Healthcare System

Wireless Networks - The Internet of Things (IoT) technology has recently experienced popularity and growth in every facet of life, and it has been applied to every industry in recent years. The...