Mechanical and Thermal Properties of Polypropylene Reinforced with Almond Shells Particles： Impact of Chemical Treatments

Polypropylene （PP） matrix composites reinforced with chemically treated Almond Shell （AS） particles with and without compatibilizer （PP-g-MA） was prepared by a twin-screw extrusion at loading of 20 wt.% AS particles. Two types of chemical treatments （alkali treatment with sodium hydroxide and etherification with dodecane bromide） of the particles were carried out to improve the interface adhesion between particles and PP matrix. Results show that chemical modifications of AS particles affect the mechanical and viscoelastic properties of AS/PP composites. The composites reinforced with alkali treated particles and the compatibilized matrix lead to a notable increase in the Young＇s modulus （14%） compared to the composites with untreated AS particles. The ductility of composite was also evaluated by the yield strain, and results show a notable increase （31%） compared to that of composites with untreated particles. The thermal stability increased with the use of etherification （385 ℃）, with gains in the temperature up to 23 ℃ compared to neat PP （362 ℃）. The achieved results show that the AS/PP composites can be used in several applications. A thermoplastic matrix compsite mixed with treated AS particles appears to be a good alternative to obtain environmentally friendly products.

Atomic Force Microscopy Studies on the Chemical Treatment of Nanocrystalline Porous TiO_2 Films

AFM has been utilized to study the surface topography and the local conductivity of nanocrystalline TiO2 films. Improving the local conductivity by Ti(iso-C3H7O)4 treatment is characterized by quantitative analysis of the simultaneous current image. The mechanism of Ti(iso C3H7O)4 treatment is discussed.

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

Experiments were carried out to study the removal of heavy metals from municipal sewage sludge by proper method for land application. The sequential extractions for metal fractionation showed that the non digested sludge from Guangzhou contained Cu and Zn principally bound to carbonate and oxides and the metal sulfides were low. Among H 2SO 4, EDTA and NH 4HCO 3 extractant agents, H 2SO 4 was the most efficient and economic in removing the heavy metals, especially with the addition of the concentrated acid. Plant experiment in pots with Chinese cabbage ( Brassica Chinensis ) showed that the acidified sludges neutralized with alkaline amendments such as phosphate rock could increase significantly the plant yield and decreased the soil and plant contamination by heavy metals originated from sewage sludge.

Effect of a synthesized anionic fluorinated surfactant on wettability alteration for chemical treatment of near-wellbore zone in carbonate gas condensate reservoirs

The pressure drop during production in the near-wellbore zone of gas condensate reservoirs causes condensate formation in this area.Condensate blockage in this area causes an additional pressure drop that weakens the effective parameters of production,such as permeability.Reservoir rock wettability alteration to gas-wet through chemical treatment is one of the solutions to produce these condensates and eliminate condensate blockage in the area.In this study,an anionic fluorinated surfactant was synthesized and used for chemical treatment and carbonate rock wettability alteration.The synthesized surfactant was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.Then,using surface tension tests,its critical micelle concentration(CMC)was determined.Contact angle experiments on chemically treated sections with surfactant solutions and spontaneous imbibition were performed to investigate the wettability alteration.Surfactant adsorption on porous media was calculated using flooding.Finally,the surfactant foamability was investigated using a Ross-Miles foam generator.According to the results,the synthesized surfactant has suitable thermal stability for use in gas condensate reservoirs.A CMC of 3500 ppm was obtained for the surfactant based on the surface tension experiments.Contact angle experiments show the ability of the surfactant to chemical treatment and wettability alteration of carbonate rocks to gas-wet so that at the constant concentration of CMC and at 373 K,the contact angles at treatment times of 30,60,120 and 240 min were obtained 87.94°,93.50°,99.79°and 106.03°,respectively.However,this ability varies at different surfactant concentrations and temperatures.The foamability test also shows the suitable stability of the foam generated by the surfactant,and a foam half-life time of 13 min was obtained for the surfactant at CMC.

Particle size distribution and removal by a chemical-biological flocculation process

The particle characterization from the influent and effluent of a chemical-biological flocculation （CBF） process was studied with a laser diffraction device. Water samples from a chemically enhanced primary treatment （CEPT） process and a primary sediment tank process were also analyzed for comparison. The results showed that CBF process was not only effective for both the big size particles and small size particles removal, but also the best particle removal process in the three processes. The results also indicated that CBF process was superior to CEPT process in the heavy metals removal. The high and non-selective removal for heavy metals might be closely related to its strong ability to eliminate small particles. Samples from different locations in CBF reactors showed that small particles were easier to aggregate into big ones and those disrupted flocs could properly flocculate again along CBF reactor because of the biological flocculation.

Improvement of Bonding Strength of AZ31B Magnesium Alloy by Anodizing and Chromium-free Conversion Treatments

The influences of chromium-free chemical conversion treatment and anodizing treatment on bonding strength of AZ31 magnesium alloy were studied by lap-shear test, SEM and electrochemical methods. Both chemical conversion treatment and anodizing can increase the bonding strength. The anodizing treatment gives higher bonding strength and better corrosion resistance than chemical conversion treatment. The increase of bonding strength by the treatmetlts may be attributed to the uneven surface structures with micro-pores, resulting in increased bonding areas and the embedding effect.

Stress Relaxation of Chemically Treated Wood during Processes of Temperature Elevation and Decline

In order to clarify the effect of drying on structural changes of DMSO swell treated and DEA-SO2-DMSO decrystallization treated Chinese fir （Cunninghamia lanceolate） wood, the stress relaxation of treated oven-dry specimens during the processes of temperature elevation and reduction and that of treated wet specimens at constant temperature were determined. A stress decrease process and a stress increase process were observed in all stress ratio curves of wood during the processes of decreasing temperature. Untreated wood, during the process of temperature reduction under higher initial temperature conditions and during the process of temperature elevation, has a larger stress decrease than treated woods. In a wet state this trend is reversed. It indicated that the drying set made treated woods have a smaller increase in fluidity of wood constituents with increasing temperature. Some bonding between decrystallization reagents and wood molecules may occur.

Time-resolved Microwave Conductivity Studies on the Chemical Treatment of the Nanocrystalline Porous TiO2 Films

Effect of Ti(iso-C3H7O)4 treatment on the photoinduced charge carrier kinetics of nanocrystalline porous TiO2 films is studied by time-resolved microwave conductivity measurements. Analysis of the transient photoconductivity decays indicates that Ti(iso-C3H7O)4 treatment leads to an increased concentration of photogenerated charge carriers and a fast interfacial transfer rate of holes via the surface modification of the freshly growing TiO2 nanocrystallites.

Properties of Different Chemically Treated Woven Hemp Fabric Reinforced Bio-Composites

The objective of this work is to carry out the chemical treatment for the hemp fabrics in a closed vacuum system and to prepare bio-based composites using treated hemp fabrics.The change in surface tension of the treated fabrics was measured using contact angle measurement and the wetting behavior using a tensiometer.Bio-based composites were fabricated using bio-based epoxy resin and different chemically treated fabrics.The flexural strength and dynamic water absorption behavior of the composites were characterized.The acetylated fabrics showed very good wetting behavior,and the contact angle values were marginally low compared to other treatment techniques.The bio-based composites fabricated using maleic anhydride treated fabrics achieved the flexural strength of 148 MPa and the dynamic water absorption values were less than 6%.The acetylated and maleic anhydride treatment methods were effective chemical treatments for the hemp fabrics and they enhanced both the wettability and fiber-matrix interaction.The chemical treatment methods that are carried out in the sealed environment can be utilized for all other natural fabrics that help overcome the moisture absorption behavior.

Chemical Treatment of Carbon Nanotubes as Electrodes in Electrochemical Double-Layer Capacitors

Multi-walled carbon nanombes with homogeneous diameters （40 - 60 nm）, produced by chemical vapor deposition of hydrocarbon gas, are purified by nitric acids. Infrared and Raman studies indicate that oxygen containing surface groups, which are predominately carboxylic, phenolic and lactonic groups, are introduced into purified carbon nanotubes. Then three kinds of block-form porous tablets of carbon nanotubes are fabricated as electrodes in electrochemical double-layer capacitors. Using mounded mixture comprising carbon nanotubes and binder powders provides these tablets. Comparison of the effect of different processing on the structural performance of the capacitors is specifically investigated. Using chemically treated electrodes, electrochemical double-layer capacitors with a specific capacitance of about 33 F/g are obtained with 38 wt % H2SO4 as the electrolyte.

Effects of O_2 Plasma Treatment on the Chemical and Electric Properties of Low-k SiOF Films

With the progress of ULSI technology, materials with low dielectric constant are required to replace Si02 film as the interlayer to scale down the interconnection delay. Fluorinated Si oxide thin films (SiOF) are a promising material for the low dielectric constant and the process compatibility in existing technology. However, SiOF films are liable to absorb moisture when exposed to air. By treating the SiOF films with O2 plasma, it was found that the moisture resistibility of SiOF films was remarkably improved. The mechanism of the improvement in stability of dielectric constant was investigated. The results show that: 1) F atoms dissociated from the films and the bond angle of Si-O-Si decreased. 2) The plasma treatment enhanced the strength of Si-F bonds by removing unstable =SiF2 structures in the films. Resistibility of SiOF films in moisture was improved.

Influence of Chemical Precleaning on the Plasma Treatment Efficiency of Aluminum by RF Plasma Pencil

This paper is aimed to show the influence of initial chemical pretreatment prior to subsequent plasma activation of aluminum surfaces.The results of our study showed that the state of the topmost surface layer（i.e.the surface morphology and chemical groups）of plasma modified aluminum significantly depends on the chemical precleaning.Commonly used chemicals（isopropanol,trichlorethane,solution of Na OH in deionized water）were used as precleaning agents.The plasma treatments were done using a radio frequency driven atmospheric pressure plasma pencil developed at Masaryk University,which operates in Ar,Ar/O_2 gas mixtures.The effectiveness of the plasma treatment was estimated by the wettability measurements,showing high wettability improvement already after 0.3 s treatment.The effects of surface cleaning（hydrocarbon removal）,surface oxidation and activation（generation of OH groups）were estimated using infrared spectroscopy.The changes in the surface morphology were measured using scanning electron microscopy.Optical emission spectroscopy measurements in the near-to-surface region with temperature calculations showed that plasma itself depends on the sample precleaning procedure.

Determination on Microclimatic Conditions at Vines upon Development on Gray Mold (<i>Botrytis cinerea</i>)

One of the most important plant diseases in viticulture is gray mold caused by Botrytis cinerea Pers. Fr., the anamorph of an ascomycete fungus (Botryotinia fuckeliana Whetzel). Locality Smilica, Kavadarci, Republic of North Macedonia, was the place where experimental fields with white varieties Smedervka and Zilavka were continuously observed. Working hypothesis was to follow development of the disease after increasing glucose over 11% until the time of the grape harvest, and microclimate was monitored at the same time. In both white varieties Smederevka and Zilavka on the control variants weren’t used botricide treatments to distinguish between the variants that were conventionally treated against B. cinerea. The aim of the research was to determine how microclimatic conditions affect the development of B. cinerea and consequently to create forecasting model for gray mold. The forecasting model for B. cinerea is based on relationship between temperature and humidity in the vines’ canopies. The aim of the research is to prevent development of B. cinerea and consequently reduce the number of chemical treatments.

Effect of Post-spinning Modification on the PAN Precursors and Resulting Carbon Fibers

The impregnation of a special grade PAN precursor,fibers wus carried out in a 8 wt% KMnO4 aqueous solution to obtain modified PAN precursor fibers. The effects of modification on the chemical stncture and the mechanical properties of precursor fibers thermally stabilized and their resulting carbon fibers u＇ere characterized by the combiination use of densities, wide-angle X-ray diffraction （WAXD）, X-ray photoelectron speetroscopy （XPS）, elemental analysis （ EA ）, Fourier traasform infrared spectroscopy （FT-IR） and scanning electron microscope （SEM）, etc.KMnO4 as a strong oxidizer can swell, oxidize and corrode the skin of a precursor.fiber, and transform C≡N groups to C≡N ones, meamchile , it can decreuse the crystal .size increuse the orientation index and the costallinity index, furthermore it can increuse the densities of modified PAN precursors and resuhing thermally stabilized fibers. As a result, the carbon fibers developed from modified PAN fibers show an improvement in tensile strength of 31.25 % and an improvement in elongation of 77.78 % , but a decrease of 16. 52% in Young＇s modulus.

APPLICATION OF RARE EARTH IN SURFACE HEAT TREATMENT OF HOT-WORKING DIE STEELS

This paper studies a compound treatment. i. e. liquid S , N,C co-diffusing with rare earth (RE) and then oxidization , for hot-working die steels , and the effect of RE on thermal fatigue behavior of the diffused layer. XRD and SEM energy spectrum prove that trace RE element actually penetrates into the surface layer of steels. The result shows that RE can reduce the gradient of change of hardness in diffused layer, improve the morphology and distribution of compounds , and reduce the degree of surface alligator crack for thermal fatigue. The behavior of thermal fatigue of hot-working die steels is raised by 70% or so after the application of RE. The effect of RE is analysed according to the theory.

CNT toughened aluminium and CFRP interface for strong adhesive bonding

This study presents a simple technique for strengthening the adhesive-bond strength between aluminium(Al)substrate and carbon fibre reinforced polymer(CFRP) utilising resin pre-coating(RPC) with carbon nanotubes(CNTs). The CNT-containing RPC solution with 90 wt% acetone and 10 wt% resin(without hardener) was applied onto Al substrates, where micro-/nano-vertical channels had been created by chemical or mechanical surface treatments to accommodate CNTs. RPC was able to fill all micro-/nano-cavities over the Al substrate surface, then CNTs were pulled into those vertical micro-channels by the capillary action generated from acetone evaporation.Normal epoxy adhesive(resin + hardener) was applied after the CNT-containing RPC treatment. CNTs bridging across the interface between the adhesive joint and Al substrate and sealing of micro-/nano-cavities by RPC effectively enhanced the interfacial shear bond strength between the Al substrate and CFRP by 30–100%depending on the Al substrate surface profiles. Al substrates with two different chemical treatments were compared in this study for the effectiveness of CNT interfacial reinforcement. Results from a steel substrate after sandblasting were also included for comparison.

Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

Ultrafine barium hexaferrite（BaFe12O19） powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe（～99.7%） under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of BaS produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe^3＋/Ba^2＋ molar ratio and the addition of hydrogen peroxide（H2O2） on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. Single-phase BaFe（12）O（19） powder was obtained at an Fe^3＋/Ba^2＋ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization（48.3 A×m^2×kg^–1） was achieved in the material prepared at an Fe^3＋/Ba^2＋ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.

Preparation and Crystallization of Carbon Nanotube/maleic Anhydride-grafted Polypropylene Composites

Carbon nanotube （CNT）/maleic acid anhydride （MAH）-grafted polypropylene （PP） composites were prepared by in situ grafting method. Infrared spectroscopy showed that the CNTs were linked to PP by MAH grafting. The microstructures and calorimetry analysis indicated that the crystallization behaviors of the filled and unfilled PP were quite different. The addition of CNTs dramatically reduced the spherulite size, increased crystallization rate and improved the thermal stability of PP. These results confirmed the expected nucleant effect of CNT on the crystallization of PP. Scanning and transmission electron microscopy showed that the CNTs were dispersed homogeneously, indicating that the original CNT bundles were separated into individual tubes by the grafting.