Effect of filler surface treatment on the properties of recycled high‐density polyethylene/(natural rubber)/(Kenaf powder) biocomposites

Biocomposites were prepared from a kenaf core powder and recycled high‐density polyethylene/(natural rubber) blend by using an internal mixer at 165^oC and 50 rpm. The effect of the filler content and the filler surface treatment was studied. Chemical modification of kenaf filler was performed with alkali pretreatment followed by treatment with silane. Scanning electron microscopy and infrared spectroscopy studies confirmed changes in the chemical compositions and structural characteristics induced through the modification. It was found that treated biocomposites offered higher tensile strength and tensile modulus, but lower elongation at break compared with untreated biocomposites. Lower water absorption and higher thermal stability of the resultant biocomposites were also obtained when treated fillers were used. J. VINYL ADDIT. TECHNOL., 20:218–224, 2014. © 2014 Society of Plastics Engineers     

Thermal properties and aging characteristics of chemically modified oil palm ash-filled natural rubber composites

The chemically modified oil palm ash (OPA) with the cetyltrimethylammonium bromide (CTAB) solution was prepared prior to compounding with the natural rubber and other curing ingredients. The aging resistance and thermal stability of CTAB-modified OPA-filled natural rubber composites were evaluated in the same manner as non-modified OPA samples. The retention tensile properties after thermal aging was measured and based on the result shown, the CTAB-modified OPA-filled natural rubber composites imparted insignificant effect to aging resistance as compared to the non-modified OPA-filled natural rubber composites at very low OPA loading; however, the effect became apparent beyond 3 phr OPA loading where the CTAB-modified OPA-filled natural rubber composites provided better aging resistance than the corresponding non-modified OPA-filled natural rubber composites. The thermogravimetric analysis indicated that the CTAB-modified OPA-filled natural rubber composites exhibited lower thermal stability which showed lower temperature at their respective weight loss and lesser char residue than that of non-modified OPA-filled natural rubber composites. This was attributed to the CTAB which started to decompose at the temperature of 210 °C. However, for the range from ambient temperature to 210 °C, the CTAB-modified OPA-filled natural rubber composites produce better thermal stability than those of non-modified OPA-filled natural rubber composites.     

Characterization of pyrogenic black carbon by desorption atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry

We present a new method for molecular characterization of intact biochar directly, without sample preparation or pretreatment, on the basis of desorption atmospheric pressure photoionization (DAPPI) coupled to Fourier transform ion cyclotron resonance (FTICR) mass spectrometry. Conventional ionization methods (e.g., electrospray or atmospheric pressure photoionization) for characterization of natural organic matter have limited utility for the characterization of chars due to incomplete solubility in common solvents. Therefore, direct ionization techniques that do not require sample dissolution prior to analysis are ideal. Here, we apply DAPPI FTICR mass spectrometry to enable the first molecular characterization of uncharred parent oak biomass and after combustion (250 °C) or pyrolysis (400 °C). Parent oak is primarily composed of cellulose-, lignin-, and resin-like compounds. Oak combusted at 250 °C contains condensed aromatic compounds with low H/C and O/C ratios while retaining compounds with high H/C and O/C ratios. The bimodal distribution of aromatic and aliphatic compounds observed in the combusted oak sample is attributed to incomplete thermal degradation of lignin and hemicellulose. Pyrolyzed oak constituents exhibit lower H/C and O/C ratios: approximately three-quarters of the identified species are aromatic. DAPPI FTICR MS results agree with bulk elemental composition as well as functional group distributions determined by elemental analysis and solid state (13)C NMR spectroscopy. Complete molecular characterization of biomass upon thermal transformation may provide insight into the biogeochemical cycles of biochar and future renewable energy sources, particularly for samples currently limited by solubility, separation, and sample preparation.     

Effect of Synthesis Technique and Carbonate Content on the Crystallinity and Morphology of Carbonated Hydroxyapatite

The syntheses of nanosized carbonated hydroxyapatite（CHA） were performed by comparing dropwise and direct pouring of acetone solution of Ca（N0₃）₂-4H₂0 into mixture of（NH₄）₂HP0₄ and NH₄HCO₃ at room temperature controlled at pH 11.Direct pouring method was later applied to study the increment of carbonate content in syntheses.The as-synthesized powders were characterized by various characterization techniques.The crystallographic results of the produced powders were obtained from X-ray diffraction analysis,whilst the carbonate content in the produced powders was determined by the CHNS/O elemental analyzer.Fourier transform infrared analysis confirmed that the CHA powders formed were B-type.Field emission scanning electron microscopy revealed that the powders were highly agglomerated in nanosized range and hence energy filtered transmission electron microscopy was employed to show elongated particles which decreased with increasing carbonate content.     

Study the Performance of the AC/DC Resistors During Their DC and AC Measurements

Some of traceability chains for the AC resistance measurements are based on AC/DC resistors. In this paper, performance of two types of them with different values has been investigated for their optimum utilization. Tinsley and Cambridge AC/DC resistors have been measured as DC resistors using different measurement methods and as AC resistors at various frequencies. DC direct method using digital reference multimeter is more accurate for the resistance values 1, 10, 100 Ω, and 1 kΩ. For the values 10 and 100 kΩ; measurement results are very near by using the DC direct and ratio methods. At 100 kΩ; representation of the resistance as an equivalent series resistance is not suitable at frequencies above 10 kHz, while for 100 mΩ and 1 Ω; the equivalent parallel representation is not suitable above the same frequency. The uncertainty analysis is also studied for all the obtained results.     

Construction and remote calibration of an automated resistance measuring system

The calibration of resistances was being performed manually at National Institute of Standards (NIS), Egypt till now. In this paper, a fully automated system for the remote calibrations of resistances is described. This sytem is mainly used for routine calibrations for low precision calibrations. The calibration of many resistors can be performed in this system automatically through the Resistors Automatic Changer which is controlled by a LabVIEW program developed and described in the present research work. Not only these calibrations of resistances are performed automatically but are also controlled remotely via an internet connection. Some simple remote and automated resistance measurements are carried out just to confirm our new measuring system.     

Analysis of experimental design with multivariate response: A contribution using multiblock techniques

In many application areas, experimental approaches both involve an experimental design that determines changes in the studying factors and an untargeted analytical method (IR, LC-MS, NMR,…) used to characterize the samples by a large number of variables. This leads to a resulting data set which can be structured in blocks with respect to the different levels of the experimental factors. Among the methods that have been developed to address this situation, the ANOVA-Simultaneous Component Analysis (ASCA) is the only one which proposes the use of a multiblock technique to date. Nevertheless, other possibilities are achievable. Therefore in this article, we propose 1) to adopt another way of defining and organizing the blocks from the initial matrix and 2) to apply Multiple Co-inertia Analysis (MCoA) a multiblock method different from Simultaneous Component Analysis to manage this new scenario. The complementarities of our proposal with ASCA are demonstrated on a case study related to cheese processing.     

In vivo measurement of lower back deformations with Fourier-transform profilometry

Through the variation of their cross sections, the in vivo response of lower back muscles to low loading in an upright seated posture is explored by the Fourier-transform profilometry technique. The maximization of its sensitivity allows us to reach an adequate resolution for the evaluation of low-back displacements. Refinements of the fringe pattern analysis permit the minimization of errors. The experiments show an asymmetric distribution of the displacement during head rotation movements. Significant contribution of the lower back to grasping exertions is also observed. These results are thought to be useful for early defect detection in the lower back.     

Effect of lime on the dissolution of two phosphate rocks in acid soils

The effect of pH and calcium (Ca) on the dissolution of Gafsa (GPR) and Christmas Island A (CIPR) phosphate rocks (PR) was examined in closedincubation and open-leaching systems in six acid, Malaysian soils. The pH of the soils was increased to between 4.5 and 6.1 by incubating with calcium carbonate (CaCO₃); soil was also incubated with calcium chloride (CaCl₂) to provide equivalent amounts of Ca without causing any marked change in pH. In the closed-incubation system, dissolution of reactive GPR was overall higher (11–70%) than for the less reactive CIPR (12–43%) after 60 days of incubation. Dissolution of PR decreased with increasing levels of CaCO₃ or CaCl₂, but the decrease was more pronounced in CaCO₃-treated than in CaCl₂-treated soils. Increasing additions of CaCl₂ decreased the size of the available sink for Ca from 84.0 to 0 mmol (+) kg^–1 soil. Although the addition of CaCO₃ increased the cation-exchange capacity (CEC) of these variable-charge soils (from 23.0 to 199.0 mmol (+) kg^–1 soil), most of the newly-created exchange sites were occupied by Ca added through CaCO₃. This was responsible for the decrease in size of the sink for Ca. Addition of CaCO₃ also decreased the proton supply from 260.7 to 0 mmol (+) kg^–1 soil, which in conjunction with the decrease in size of the Ca sink decreased the dissolution of PR. The effect of CaCO₃ and CaCl₂ on PR dissolution varied between soils and was related to pH-buffering and the Ca-sink size. In an open-leaching system, large amounts of Ca (8–40%) added as CaCO₃ were removed in the leachate and hence the decrease in GPR dissolution with CaCO₃ addition was less in the open-leaching than in the closed-incubation system.     

Properties and characterization of ([Mengkuang leaf fiber]‐filled ethylene vinyl acetate)/(natural rubber) blend: Effects of blending sequences and mengkuang leaf fiber loading

(Ethylene vinyl acetate [EVA])/(natural rubber [NR])/(Mengkuang leaf fiber) (MLF) thermoplastic elastomer composites were prepared by using three different blending sequences in an internal mixer. The blending sequences studied were (i) B1: NR was added followed by MLF into the molten EVA; (ii) B2: MLF was added followed by NR into the molten EVA; (iii) B3: MLF was added followed by EVA into the molten NR. The effect of different blending sequences and fiber loadings from 10 to 40 parts by weight per hundred parts of resin on the torque development, tensile properties, thermal degradation, and morphology of EVA/NR/MLF composites was studied. Of the blending sequences investigated, the B1 system is considered the best method for the preparation of EVA/NR/MLF composites. The B1 system produces composites with lower stabilization torque, higher tensile strength, and better thermal stability compared with other systems. At 40 parts by weight per hundred parts of resin of MLF loading, the tensile strength of the composite prepared by using the B1 system was 15% higher than that of B2 system composites, and 8% higher than that of the B3 system. Scanning electron micrographs of the tensile fracture surfaces indicated this system also had good fiber dispersion in the EVA/NR matrix. An increase in MLF loading resulted in an increase of the values of the stabilization torque and the Young's modulus, but a decrease in values of the tensile strength, the elongation at break, and the thermal stability of the composites. Scanning electron microscopy revealed increased fiber pullout in the composites as the loading increased. J. VINYL ADDIT. TECHNOL., 24:109–115, 2018. © 2016 Society of Plastics Engineers