Effect of chemical modification of oil fly ash and compatibilization on the rheological and morphological properties of low‐density polyethylene composites

In this study, the effect of oil fly ash (OFA), a by‐product of oil fuel power plants, on the rheological and morphological behavior of low‐density polyethylene (LDPE) is investigated. As received and acid‐functionalized OFA (COOH‐OFA) are used to examine the effect of surface modification of OFA on polymer–filler composites. LDPE/OFA composites were prepared by melt mixing with filler loading in the range 1–10 wt %. The results are compared with pure LDPE. The effect of polyethylene‐grafted‐maleic anhydride (PE‐g‐MA) as a compatibilizer was also studied. Both viscous and elastic properties of composites increased with OFA loading especially at low frequency. The surface modification of OFA has influenced the properties of OFA. As‐received OFA showed some agglomeration at high loading that resulted in two‐phase system as described by scanning electron microscopy (SEM) and Cole–Cole plot. Field emission‐SEM (FE‐SEM) images showed improvement in the dispersion of COOH‐LDPE/OFA composites. In addition, the surface modification reduced the size of agglomeration. In general, the COOH modification of OFA improved both the dispersion and rheological properties of OFA. With chemical modification, the concentration of the filler can be increased to 10% without compromising the properties of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Stochastic model for living radical polymerisation of styrene initiated by epoxide radical ring opening

A stochastic model was developed to simulate the polymerisation kinetics and the detailed microstructure of the resulting polymers made by the living radical polymerisation of styrene initiated by epoxide radical ring opening. The model was used to predict monomer conversion, average molecular weight, polydispersity index, and molecular weight distribution as a function of polymerisation time. Simulations were used to explore the effects of rate constant values on chain microstructures and polymer properties and validated with experimental data published in the literature. It was found that some parameters, such as the exchange rate constant, have no significant effect on the polymerisation kinetics, whereas major effects were observed when other rate constants, such as the reduction rate constant, were changed.     

Antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense

The in vitro antifungal activity of chitosan against Fusarium oxysporum f. sp. cubense Race 4 (FocR4) the causal agent of banana wilt was investigated. Chitosan at all concentrations tested reduced the hyphal growth of FocR4 on potato dextrose agar media and recording maximum inhibition of 76.36% at 8 mg/mL. The inhibitory effect was found to increase as chitosan concentration increases. The 50% effective concentration value was estimated by probit analysis, and it was 1.4 mg/mL. Chitosan was more effective in potato dextrose broth where it completely inhibited the mycelial growth of FocR4 at all concentrations tested. Chitosan inhibited the sporulation of FocR4 by a maximum of 96.53% at 8 mg/mL chitosan, and 100% inhibition for spore germination was recorded at all concentrations tested. Chitosan at concentrations of more than 1.6 mg/mL was also found to induce morphological changes in FocR4 characterized by agglomeration of hyphae, abnormal shapes, vesicles, or empty cells devoid of cytoplasm in the mycelia. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication of core–shell nanocomposites with enhanced photocatalytic efficacy

The current study establishes the unprecedented involvement in the evolution and production of novel core–shell nanocomposites composed of nanosized titanium dioxide and aniline‐o‐phenylenediamine copolymer. TiO₂@copoly(aniline and o‐phenylenediamine) (TiO₂@PANI‐o‐PDA) core–shell nanocomposites were chemically synthesized in a molar ratio of 5:1 of the particular monomers and several weights of nano‐TiO₂ via oxidative copolymerization. The construction of the TiO₂@PANI‐o‐PDA core–shell nanocomposites was ascertained from Fourier transform IR spectroscopy, UV–visible spectroscopy and XRD. A reasonable thermal behavior for the original copolymer and the TiO₂@PANI‐o‐PDA core–shell nanocomposites was investigated. The bare PANI‐o‐PDA copolymer was thermally less stable than the TiO₂@PANI‐o‐PDA nanocomposites. The core–shell feature of the nanocomposites was found to have core and shell sizes of 17 nm and 19–26 nm, respectively. In addition, it was found that the addition of a high ratio of TiO₂ nanoparticles increases the electrical conductivity and consequently lowers the electrical resistivity of the TiO₂@PANI‐o‐PDA core–shell nanocomposites. The hybrid photocatalysts exhibit a dramatic photocatalytic efficacy of methylene blue degradation under solar light irradiation. A plausible interpretation of the photocatalytic degradation results of methylene blue is also demonstrated. Our setup introduces a facile, inexpensive, unique and efficient technique for developing new core–shell nanomaterials with various required functionalities and colloidal stabilities. © 2018 Society of Chemical Industry     

Compressive mechanical properties of sawdust/high density polyethylene composites under various strain rate loadings

This article is concerned with the static and dynamic mechanical properties of high‐density polyethylene (HDPE) reinforced with sawdust (SD) at a strain rate of up to 10³ s^?1. In this study, the static and dynamic properties of HDPE/SD composites with different filler loadings of 5, 10, 15, 20, and 30 wt% SD were deliberated at different levels of strain rates (0.001, 0.01, 0.1, 650, 900, and 1100 s^?1) using a conventional universal testing machine and the split Hopkinson pressure bar apparatus. The results showed that the stress–strain curves, yield behavior, stiffness, and strength properties of the HDPE/SD composites were strongly affected by both the strain rate and the filler loadings. Furthermore, the rate sensitivityof the HDPE/SD composites showed a great dependency on the applied strain rate, increasing as the strain rate increased. However, the thermal activation values showed a contrary trend. Meanwhile, for the postdamage analysis, the results showed that the applied strain rates influenced the deformation behavior of the tested HDPE/SD composites. Moreover, for the fractographic analysis at dynamic loading, the composites showed that all the specimens underwent a severe catastrophic deformation. J. VINYL ADDIT. TECHNOL., 24:162–173, 2018. © 2016 Society of Plastics Engineers     

Dispersion in steady and time-oscillatory flows through an eccentric annulus

A multiple-scale perturbation is conducted to derive an averaged equation for predicting the longtime solute transport in an eccentric annulus in which the uniaxial flow may oscillate periodically in time. A proof for the positiveness of the dispersivity is presented, implying that over a cycle of oscillation a solute cloud always broadens. For a steady flow driven by a fixed pressure gradient, increasing the eccentricity and annulus size gives rise to stronger dispersion. This relationship holds when the flow becomes unsteady. In the limit of slow oscillation, dispersion due to an oscillatory flow asymptotes to one-half of that by a steady flow. Increasing the oscillation frequency leads to a two-step decay of the dispersivity. The maximum dispersion in an oscillatory flow can be achieved in the limit of slow oscillation and large eccentricity, where dispersion can be O(10³) times larger than that in an otherwise concentric annulus.     

Birthweight and Lipids in Adult Life: Population-Based Cross Sectional Study

The purpose of this study was to examine the association of birthweight with lipid profile in the general adult population. Participants in the second-wave of a nationally representative cross sectional AusDiab-study were asked to complete a birthweight questionnaire. Fasting total cholesterol (TC), LDL-C, HDL-C, and triacylglycerol levels were modeled against birthweight. Four thousand five hundred and two people reported their birthweights, mean (SD) of 3.4(0.7) kg. Females with low birthweight-LBW had higher levels of TC, LDL-C, and triacylglycerols, but no difference in HDL-C, than those with normal-birthweight-NBW;≥2.5 kg. People with LBW showed a trend toward increased risk for high TC (≥5.5 mmol/L) compared to NBW. Among females with LBW, the risk for high LDL-C (≥3.5 mmol/L) was increased compared to those of NBW. The risk for low HDL-C (<0.9 mmol/L) was increased among males with LBW compared to those with NBW. Examination of the relationship on the continuum showed no differences except for high triacylglycerol levels among females with the lowest birthweight quintile compared to the higher birthweight quintile. However, the risk for various abnormalities by birthweight quintiles was similar to that when we used the traditional definition of LBW vs. NBW. Females and males with low birthweight differ in their risk for lipids abnormalities. Females had higher risk for high LDL-C, whereas males had high risk for low HDL-C (<0.9 mmol/L). In addition, females with low birthweight had the highest triacylglycerol levels. High LDL-C, low HDL-C, and high triacylglycerols are well-recognized risk factors for cardiovascular disease.     

Hot compaction of polyoxymethylene. II. Structural characterization

The structural characterization of sintered polyoxymethylene was carried out to determine the mechanism of sintering. Thermal behavior and small‐angle X‐ray scattering (SAXS) of sintered samples reveal that an improvement in either crystal size or perfection, or both, takes place during the sintering process, in comparison with compression‐molding from the melt. The loss modulus data also give evidence of crystal reorganization during sintering that improves the continuity of the crystalline phase and enhances its mechanical contribution. These findings eliminate the occurrence of major melting during sintering. However, the high mobility of the chains in the crystalline phase in the temperature range of the melting onset suggests that short range rearrangements of the chains in the crystalline lamellae are likely to occur during the time of the process. The proposed mechanism of sintering is that of crystallographic welding of crystals from neighboring particles, as a result of the combined effect of plastic flow and temperature during the hot compaction operation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Terpolymers as precursors for CuO nanoparticles synthesis

This work describes the synthesis of terpolymers of aniline, diphenylamine, and o‐anthranilic acid (PANIDPAA) by 1 : 1 : 1 molar ratio of the respective monomers doped by different concentration of copper ions via in situ chemical terpolymerization. The results are justified by measuring spectral characteristics namely, UV‐vis absorption spectra, FTIR, and TGA. Calcining these PANIDPAA terpolymers doped by copper at temperatures in the range of 700°C led to the formation of CuO nanoparticles in the nanoscale by thermal decomposition in air directly. The stages of decompositions and the calcination temperature of the precursors have been determined from thermal analysis data sheet. The obtained CuO nanoparticles have been characterized by X‐ray diffraction and transmission electron microscope (TEM). TEM showed a particle size less than 40 nm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41150.     

Moving ion fronts in mixed ionic‐electronic conducting polymer films

The aim of this paper is to analyze moving front dynamics of ions and holes in a planar, mixed ionic‐electronic conducting polymer film. As cations invade the film, holes evacuate; thus, an ionic current is converted to an electronic signal. Recent experiments show that the location of the advancing ion front increases as the square‐root of time, a scaling typically associated with diffusive transport, which is surprising given the large driving voltages utilized. Ionic and electronic transport is modeled via the drift‐diffusion equations. A similarity transformation reduces the governing partial differential equations to ordinary differential equations that are solved numerically. The similarity transformation elucidates the origin of the square‐root‐of‐time front scaling. The similarity solution is then compared to the numerical solution of the full drift‐diffusion equations, finding excellent agreement. When compared with experimental data, our model captures the front location; however, qualitative differences between the ion profiles are observed. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1447–1454, 2015