Function Of Peroxide Concentration Research Articles

Nanocomposite films as electrochemical sensors for detection of catalase activity.

Cross-linked hydrogel substrates have garnered attention as they simultaneously enable oxidoreductase reactions in a control volume extended to adsorption of redox capacitors for amplification of electrochemical signals. In this study, the effect of catalase immobilization in mold-casted alginate-based thin films (1 mm × 6 mm × 10 mm) containing multi walled carbon nanotubes (MWCNT) coated with chitosan has been studied via amperometry. The amperometric response was measured as a function of peroxide concentration, at a fixed potential of −0.4 V vs. SPCE in phosphate-buffered saline (pH = 7.4). Results indicate substrate detection is not diffusion-limited by the 100 μm thick chitosan layer, if the cationic polyelectrolyte is in contact with the sensing carbon electrode, and the linear detection of the enzyme absent in solution is enabled by immobilization (R 2 = 0.9615). The ferricyanide-mediated biosensor exhibited a sensitivity of 4.55 μA/mM for the optimal formulation at room temperature comparable to other nanomaterial hybrid sensing solution namely amine-functionalized graphene with an average response time of 5 s for the optimal formulation. The suitability of the optimized chitosan-coated alginate slabs nano-environment for co-encapsulation of catalase and carbon nanotubes was confirmed by cyclic voltammetry.

Correlation Between Reactive Modification Conditions and Degree of Long‐Chain Branching in Chemically Modified Linear Low Density Polyethylene Using Response Surface Experimental Design

Changes induced in the molecular architecture of linear low‐density polyethylene during early stages of peroxide modification in a microcompounder are monitored by means of size exclusion chromatography and dynamic shear oscillatory measurements as a function of peroxide concentration, mixing temperature and resident time. By the use of a response surface method and according to a box Behnken statistical design, various contour plots are constructed to establish correlations between the processing parameters and degree of long‐chain branching. All investigated process parameters are shown to have a significant effect on the degree of long‐chain branching, the order of significance being concentration > temperature > mixing time. The interactive effects of these factors are determined.

The Effect of Hydrogen Peroxide in a Citric Acid Based Copper Slurry on Cu Polishing

The removal and etching behaviors of Cu were evaluated in citric acid based slurries as functions of slurry pH and concentration during Cu chemical mechanical planarization (CMP). In an acidic slurry (pH 4), the dissolution reaction of Cu was more dominant than the passivation reaction. The static and dynamic etching rates reached their highest values at . The polishing rate, however, was linearly increased as a function of peroxide concentration. As the slurry pH increased to 6, the static and dynamic etching rates drastically decreased with increasing concentrations due to the formation of thick Cu oxide as a passivation layer. The removal rate reached a maxima in slurry at of then started to decrease. The removal rate of Cu was determined by both the chemical dissolution and mechanical abrasion of the passivation layer which were strongly related to slurry pH and concentration. In the slurry of low concentration of and low pH, the passivation layer was too thin to prevent the chemical dissolution from occurring. However, the increase of pH and concentrations grew a thicker oxide on Cu which made the removal rates dependent on the mechanical reaction.

A structural study of EPDM networks––the influence of the crosslinking mode on their microscopic structure

This work was performed to examine the network characteristics obtained for a given elastomer when various curing modes are used. We focused on the crosslinking procedures by peroxide, electron beam irradiation and mixed treatment (peroxide + electron beam irradiation), applied to an ethylene–propylene type polymer. The changes on the network have been followed as a function of peroxide concentration and irradiation dose. The effect on the curing efficiency of both the presence of the antioxidant and the termonomer have been especially considered. The network heterogeneity has been addressed.

Properties of Low Density Polyethylene/Polypropylene Blends

ABSTRACT The role of di-cumyl peroxide (DCP) as compatibilizer in low density Polyethylene/Polypropylene (LDPE/PP) blends has been explored. Mixtures with varying LDPE/PP ratio were prepared in a Brabender plasticorder and tested for their mechanical properties and calorimetric response. Then peroxide was added at concentrations up to 0.5%, and the mechanical properties of the these new blends were measured. Also, the mixing torque, melt flow index and gel content of the above products were recorded as a function of peroxide concentration. It was found that the incorporation of DCP restricts the thermoplastic characteristics of the melt, which was primarily attributed to branching which occurs in LDPE. This results in an enhancement in the adhesive bonding between the two polymers mainly due to chain entanglements. This was further supported by the fact that mechanical properties of the treated blend were significantly improved.

Reactive processing of LLDPES in corotating intermeshing twin‐screw extruder. II. Effect of peroxide treatment on processability

AbstractCommercial ethylene–octene linear low‐density polyethylenes (LLDPEs) were reactively extruded with low levels of a peroxide [2,5‐dimethyl‐2,5‐di(t‐butylperoxy)hexane] to modify polymer molecular structure and processing properties. Peroxide levels were kept low to avoid crosslinking. This article reports the effects of this reactive extrusion on viscoelastic properties. Rheological properties are more sensitive than are molecular structure characteristics to the changes produced by reactions of very low peroxide concentrations. Complex viscosity increases are seen, especially at low frequencies. Shear‐thining behavior is also accentuated. The crossover between G′ and G″ moves to lower frequencies. A modified Cole–Cole presentation of these data shows that the elastic component is more predominant for extrusion‐reacted materials. Peroxide‐modified materials all have higher Bagley end correction values than those of barefoot resins. The former exhibit lower power indices (more shear thinning). All these properties indicate more long‐chain branching and higher melt elasticity. However, die swell decreased as a function of peroxide concentration. Peroxide treatment results in an enhancement of elongational viscosity, both under isothermal and cooling conditions, along with a decrease in drawdown ability. The rheological changes parallel those reported earlier in molecular characteristics but are more sensitive and suitable to evaluate the effects of reactive processing. The effectiveness of the reactive extrusion process for improving processability of LLDPEs depends critically on the extrusion conditions. © 1995 John Wiley & Sons, Inc.

Influence of High Peroxide Concentration on the Mechanical Properties of Cross-Linked Low Density Polyethylene

Abstract In this paper are presented the static and dynamic mechanical investigation of chemically cross-linked low density polyethylene (XLPE) prepared in our laboratory. This polymer has been tested mechanically at different frequencies, amplitudes, and temperatures as a function of cross-link density which is indicated to some extent by the amount of peroxide used in the cross-linking. The main findings can be described as follows: mechanical damping in XLPE at the α-relaxation point as a function of peroxide concentration is different for shear and compression modes of deformation. Moreover, the dynamic investigation at very small amplitudes indicated two relatively rigid structures. One structure at low concentration of peroxide is attributed to excessive crystallinity; the other one at the high peroxide concentration is probably due to the very regular and perfect polyethylene network. These two interesting structures are not detected by dynamical testing with large amplitudes. As far as Young's mod...

Effect of degumming conditions on removal and quality of soybean lecithin

AbstractA commercially extracted crude soybean oil (570 ppm phosphorus, 1.74% acetone insolubles) was degummed in the laboratory under a wide range of reaction conditions (water concentration, temperature, time and agitation). The reaction conditions were correlated with phosphorus removal from the oil as well as with color and acetone‐insoluble content of the gum fraction. Efficiency of removal of phosphorus‐containing compounds was independent of time, temperature and agitation. Water concentration had the most significant effect on removal of phosphorus from crude soybean oil. Some darkening of the lecithin was observed at temperatures above 60 C and with increased agitation. Individual conditions of time and temperature had relatively little effect on the acetone‐insoluble content of the gums. Low agitation rates and water in concentrations of other than 2% (either more or less) entrained excessive amounts of oil in the gums. Under our experimental conditions, the optimal conditions with respect to phosphorus removal, lecithin color and acetone‐insoluble content are estimated to be: time‐short (15 min); agitation‐moderate to rapid (400 rpm); temperature‐60 C; water concentration‐2% or an amount close to the phosphatide content of the crude oil. Bleaching with hydrogen peroxide to produce single‐bleached lecithin was investigated. From limited data, it appears that when degumming and bleaching are performed simultaneously, effectiveness of bleaching is a function of peroxide concentration and time. Thus, longer degumming times are required to prepare bleached lecithin compared to unbleached products.