Characterization and Selection of Microcrystalline Cellulose from Oil Palm Empty Fruit Bunches for Strengthening Hydrogel Films

Microcrystalline cellulose(MCC)is one of the cellulose derivatives produced as a result of the depolymerization of a part of cellulose to achieve high crystallinity.When implemented in other polymers,high crystallinity correlates with greater strength and stiffnes,but it can reduce the water-holding capacity.The acid concentration and hydrolysis time will affect the acquisition of crystallinity and water absorption capacity,both of which have significance as properties of hydrogel filler.The study aimed to evaluate the properties and select the MCC generated from varying the proportion of hydrochloric acid(HCl)and the appropriate hydrolysis time as a filler for film hydrogel.MCC was produced by hydrolyzing cellulose of oil palm empty fruit bunches(OPEFB)with the HCl solution at varied concentrations and periods.The results show that the longer hydrolysis times and higher HCl concentrations increase crystallinity and density while lowering yield and water absorption.The extensive acid hydrolysis reduces the amorphous area significantly,allowing the depolymerization to occur and extend the crystalline area.The morphological properties of the MCC,which are smaller but compact,indicate the presence of disintegrating and diminishing structures.A 2.5 N HCl concentration and a 45-min hydrolysis time succeed in sufficient crystallinity as well as maintaining good water absorption capacity.The treatment produced MCC with absorption capacity of 4.03±0.26 g/g,swelling capacity of 5.03±0.26 g/g,loss on drying of 1.44%±0.36,bulk and tapped density of 0.27±0.031 g/cm^(3) and 0.3±0.006 g/cm^(3),respectively,with a crystallinity index of 88.89%±4.76 and a crystallite size of 4.23±0.70 nm.The MCC generated could potentially be utilized as a hydrogel film filler,since a given proportion will be able to maintain the strength of the hydrogel,not readily dissolve but absorb water significantly.

Synthesis of Microcrystalline Cellulose—Polyvinyl Alcohol Stabilized Polyvinyl Acetate Emulsion

Polyvinyl alcohol (PVA) colloid stabilized Polyvinyl acetate (PVAc) based wood adhesive has poor performance in highly humid conditions. Currently, the addition of natural fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive in highly moist conditions. Microcrystalline cellulose (MCC) are strong renewable, bio-based material and has great potential in a reinforcement of the polymeric matrix. Hence, the present work investigates the applicability of microcrystalline cellulose incorporated 3% and 5% in situ emulsion polymerization PVAc wood adhesives. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with different proportions of MCC were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was increased by increasing the concentration of MCC. The mechanical properties like tensile strength of adhesives with MCC were measured by universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that MCC can improve bonding strength as compared to PVAc Homo based adhesive in the wet condition which was validated through a contact angle study. The hardness of PVAc films were also changed positively by the addition of MCC. Here, we studied the effect of the addition of different concentrations of MCC materials in situ polymerization of PVAc on their performance properties.

Doped-Chamber Deposition of Intrinsic Microcrystalline Silicon Thin Films and Its Application in Solar Cells

A series of microcrystalline silicon thin films were fabricated by very high frequency plasma enhanced chemical vapor deposition （VHF-PECVD） at different silane concentrations in a P chamber. Through analysis of the structural and electrical properties of these materials,we conclude that the photosensitivity slightly decreased then increased as the silane concentration increased,while the crystalline volume fraction indicates the opposite change. Results of XRD indicate that thin films have a （220） preferable orientation under certain conditions. Microcrystalline silicon solar cells with conversion efficiency 4. 7% and micromorph tandem solar cells 8.5% were fabricated by VHF-PECVD （p layer and i layer of microcrystalline silicon solar cells were deposited in P chamber）, respectively.

Influence of Atomic Hydrogen on Transparent Conducting Oxide During Hydrogenated Microcrystalline Si Preparation by PECVD

The hydrogen plasma degradation of transparent conduction oxides （TCO） is studied for hydrogenated microcrystalline Si（μc-Si：H）prepared by plasma enhanced chemical vapor deposition （PECVD）. TCO films such as SnO2 and SnO2/ZnO bi-layer films were exposed to atomic H at various substrate temperatures and for various treatment times. A decrease in the transmittance due to reduction by atomic H was scarcely observed for SnO2 / ZnO bi-layer,while a decrease for SnO2 was found to depend strongly on the substrate temperature. The resistivity of SnO2 films decreases significantly when substrate temperature exceeds 150℃in H-plasma. However, H-plasma treatment has little impact on the resistivity of SnO2/ZnO bi-layer film. The reason for the decrease in the transmittance is the appearance of metallic Sn on the surface, and under this condition no μc-Si： H film is deposited. SnO2/ZnO bi-layer is very effective for the suppression of the reduction of TCO during μc-Si：H deposition. The performance of microcrystalline silicon solar cells fabricated on ZnO/SnO2/glass is also investigated.

Large Scale Homogeneous Growth Mechanics of Microcrystalline Silicon Films on Rough Surface

Large scale homogenous growth of microcrystalline silicon （μ.c-Si：H） on cheap substrates by inductively coupled plasma （ICP） of Ar diluted Sill4 has been studied. From XRD and Raman spectrum, we find that substrates can greatly affect the crystalline orientation, and the μc-Si：H films are comprised of small particles. Thickness detection by surface profilometry shows that the thin μc-Si：H films are homogenous in large scale. Distributions of both ion density and electron temperature are found to be uniform in the vicinity of substrate by means of diagnosis of Langmuir probe. Based on these experimental results, it can be proposed that rough surfaces play important roles in the crystalline network formation and Ar can affect the reaction process and improve the characteristics of μc-Si：H films. Also, ICP reactor can deposit the thin film in large scale.

Formation mechanism of incubation layers in the initial stage of microcrystalline silicon growth by PECVD

The incubation layers in microcrystalline silicon films （μc-Si：H） are studied in detail. The incubation layers in μc- Si：H films are investigated by biracial Raman spectra, and the results indicate that either decreasing silane concentration （SC） or increasing plasma power can reduce the thickness of incubation layer. The analysis of the in-situ diagnosis by plasma optical emission spectrum （OES） shows that the emission intensities of the SiH＊（412 nm） and Hα （656 nm） lines are time-dependent, thus SiH＊/Hα ratio is of temporal evolution. The variation of SiH＊/Hα ratio can indicate the variation in relative concentration of precursor and atomic hydrogen in the plasma. And the atomic hydrogen plays a crucial role in the formation of μc-Si：H; thus, with the plasma excited, the temporal-evolution SiH＊/Hα ratio has a great influence on the formation of an incubation layer in the initial growth stage. The fact that decreasing the SC or increasing the plasma power can decrease the SIH＊/Hα ratio is used to explain why the thickness of incubation layer can reduce with decreasing the SC or increasing the plasma power.

Preconcentration by Using Microcrystalline Phenolphthalein for Determining Trace Molybdenum(Ⅵ) in Water by GFAAS

Molybdenum（ Ⅵ ） is a biologically essential trace element and its role in an extremely wide variety of systems has been reported. Most common methods often fail to determine trace Mo （ Ⅵ ） in the analysis of molybdenum-containing samples, due to limitations such as inadequate detection limits and matrix interference, which make the direct determinations impossible. To solve this problem, various approaches are employed to concentrate and separate Mo（ Ⅵ ） to detectable levels. Concentration and separation methods play a main role in the analysis of trace Mo（Ⅵ）. Therefore, many separation and preconcentration procedures have been developed for the determination of Mo （ Ⅵ ）.

In-Situ Microscopic FTIR Spectroelectrochemistry of Ascorbic Acid in Poly(ethylene glycol)/LiClO_4 Electrolyte Paste and in the Presence of Dispersed Cobalt Hexacyanoferrate Microcrystalline Powder

In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.

Effect of substrate temperature and pressure on properties of microcrystalline silicon films

In this paper intrinsic microcrystalline silicon films have been prepared by very high frequency plasma enhanced chemical vapour deposition （VHF-PECVD） with different substrate temperature and pressure. The film properties were investigated by using Raman spectra, x-ray diffraction, scanning electron microscope （SEM）, and optical transmittance measurements, as well as dark conductivity. Raman results indicate that increase of substrate temperature improves the microcrystallinity of the film. The crystallinity is improved when the pressure increases from 50Pa to 80Pa and the structure transits from microcrystalline to amorphous silicon for pressure higher than 80Pa. SEM reveals the effect of substrate temperature and pressure on surface morphology.

Fabrication and application of nano/microcrystalline composite diamond coated drawing dies using alternative carbon sources

Nano/microcrystalline composite diamond films were deposited on the holes of WC-6%Co drawing dies by a two-step procedure using alternative carbon sources, i.e., methane for the microcrystalline diamond（MCD） layer and acetone for the nanocrystalline diamond（NCD） layer. Moreover, the monolayer methane-MCD and acetone-NCD coated drawing dies were fabricated as comparisons. The adhesion and wear rates of the diamond coated drawing dies were also tested by an inner hole polishing apparatus. Compared with mono-layer diamond coated drawing die, the composite diamond coated one exhibits better comprehensive performance, including higher adhesive strength and better wear resistance than the NCD one, and smoother surface（Ra=65.3 nm） than the MCD one（Ra=95.6 nm） after polishing at the same time. Compared with the NCD coated drawing die, the working lifetime of the composite diamond coated one is increased by nearly 20 times.

The effect of initial discharge conditions on the properties of microcrystalline silicon thin films and solar cells

This paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon （μc-Si：H） films by Raman spectroscopy and spectroscopic ellipsometry, through delaying the injection of SiH4 gas to the reactor before plasma ignition. Compared with standard discharge condition, delayed SiH4 gas condition could prevent the back diffusion of Sill4 from the reactor to the deposition region effectively, which induced the formation of a thick amorphous incubation layer in the interface between bulk film and glass substrate. Applying this method, it obtains the improvement of spectral response in the middle and long wavelength region by combining this method with solar cell fabrication. Finally, results are explained by modifying zero-order analytical model, and a good agreement is found between the model and experiments concerning the optimum delayed injection time.

Biocomposite Films of Polylactic Acid Reinforced with Microcrystalline Cellulose from Pineapple Leaf Fibers

Poly(lactic acid)(PLA)composite films reinforced with microcrystalline cellulose(MCC)extracted from pineapple leaf fibers(PALF)were prepared by a solution casting procedure.In an attempt to improve the interaction between PLA and cellulose,two approaches were adopted;first,poly(ethylene glycol)(PEG)was used as a surfactant,and second,the cellulosic fibers were pre-treated using tert-butanol(TBA).Lignocellulosic and cellulosic substrates were characterized using Fourier transform infrared(FTIR),wide-angle X-ray scattering(WAXS),and thermogravimetrical analysis(TGA).MCC from PALF showed good thermal stability,left few residues after decomposing,and exhibited high crystallinity index.Mechanical,thermal and thermomechanical properties of the PLA composites were also evaluated.Multiple PLA endotherms were observed in composites with TBA-treated MCC due to crystal nucleation effects.The ultimate tensile strain values for all composites were lower than that of the pristine PLA.However,4 wt.%MCC content provided balanced engineering properties in terms of static and dynamic tensile properties.

Phase Transformation and Enhancing Electron Field Emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing

Cu ion implantation and subsequent rapid annealing at 500℃ in N2 result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm2 V-1S-1 for microcrystalline diamond （MCD） films. Its electrical field emission behavior can be turned on at Eo = 2.6 V/μm, attaining a current density of 19.5μA/cm2 at an applied field of 3.5 V/#m. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron mi- croscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation.

Influences of grain size and microstructure on optical properties of microcrystalline diamond films

Microcrystalline diamond(MCD)films with different grain sizes ranging from 160 nm to 2200 nm are prepared by using a hot filament chemical vapor deposition(HFCVD)system,and the influences of grain size and structural features on optical properties are investigated.The results show that the film with grain size in a range of 160 nm–310 nm exhibits a higher refractive index in a range of(2.77–2.92).With grain size increasing to 620±300 nm,the refractive index shows a value between 2.39 and 2.47,approaching to that of natural diamond(2.37–2.55),and a lower extinction coefficient value between 0.08 and 0.77.When the grain size increases to 2200 nm,the value of refractive index increases to a value between 2.66 and 2.81,and the extinction coefficient increases to a value in a range of 0.22–1.28.Visible Raman spectroscopy measurements show that all samples have distinct diamond peaks located in a range of 1331 cm-1–1333 cm-1,the content of diamond phase increases gradually as grain size increases,and the amount of trans-polyacetylene(TPA)content decreases.Meanwhile,the sp2 carbon clusters content and its full-width-at-half-maximum(FWHM)value are significantly reduced in MCD film with a grain size of 620 nm,which is beneficial to the improvement of the optical properties of the films.

Rapid and Efficient Adsorption Removal of Reactive Blue 4 from Aqueous Solution by Cross-Linked Microcrystalline Cellulose–Epichlorohydrin Polymers: Isothermal, Kinetic, and Thermodynamic Study

In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the cross-linking of the microcrystalline cellulose were obtained by Fourier transform infrared spectroscopy, X-ray diff raction, Brunauer–Emmett–Teller analysis, thermogravimetric analysis, and scanning electron microscopy. We investigated the eff ects of adsorbent dosage, p H, initial dye concentration, temperature, and contact time on the dye adsorption capacity. The results showed that the adsorption equilibrium time was just 20 min and the maximum adsorption capacity was 69.79 mg/g. The adsorption isotherm data fitted the Langmuir isotherm model well, and the adsorption kinetics data followed the pseudo-second-order kinetic model. The results of the thermodynamic analysis suggest that the adsorption process was spontaneous and exothermic. Recyclability experiments demonstrated the good reusability of this adsorbent. Electrostatic interaction was found to dominate the adsorption process.

The study of amorphous incubation layers during the growth of microcrystalline silicon films under different deposition conditions

The structural un-uniformity of microcrystalline silicon, thin film, amorphous incubation layerc-Si：H films prepared using very high frequency plasma-enhanced chemical vapour deposition method has been investigated by Raman spectroscopy, spectroscopic ellipsometer and atomic force mi- croscopy. It was found that the formation of amorphous incubation layer was caused by the back diffusion of SiH4 and the amorphous induction of glass surface during the initial ignition process, and growth of the incubation layer can be suppressed and uniform μc-Si：H phase is generated by the application of delayed initial SiH4 density and silane profiling methods.

Preparation of Light-burned MgO by Microcrystalline Magnesite and Its Application Prospect Analysis

In order to widen the application of microcrystalline magnesite, the microcrystalline magnesite in Sichuan and Tibet area was used as the raw material to prepare light-burned MgO at 700,800,900, 1 000, 1 100 and I 200 ~C for 3 h, respectively. Then the physical and chemical properties of the light-burned MgO were detec- ted, and its application prospect was analyzed. The re- sults show that： （1） microcrystalline magnesite com- pletely decomposes forming light-burned MgO calcined at the temperature range of 700 - 1 200 ~C ; the MgO con- tent of the light-burned MgO is higher than 96. 51% ; the chemical activity is 88 - 130 s and the grain size is 40 - 200 nm ; it has the advantages of high purity, high activity and fine grain; （2） the light-burned MgO pre- pared with microcrystalline magnesite can be widely used in many industries; it can be used in refractories indus- try to prepare high-purity sintered magnesia and large crystal fused magnesia, or as an additive for refractory products, etc. ; it can also be used in magnesium chemi- cal industry to prepare electrical grade magnesia, sili- con-steel magnesia, environmental friendly flame retard- ant magnesium hydroxide, magnesium sulfate fertilizer, pharmaceutical grade magnesia, food grade magnesia, etc.

Preconcentration/separation and determination of mercury using microcrystalline phenolphthalein modified by ethyl violet

A novel method was developed for enrichment and separation of trace mercury using phenolphthalein modified by ethyl violet （EV）. The effects of different parameters, such as stirring time, various metal ions and salts, and the amounts of phenolphthalein, NH4SCN, and EV on the extraction rate of mercury were studied, to select the experimental conditions. Under optimum conditions, mercury can be adsorbed on the surface of microcrystalline phenolphthalein by the intermolecular acdon strength. The possible reaction mechanism for the enrichment of mercury was discussed in detail. Hg（Ⅱ） could be completely separated from Fe（Ⅱ）, Co（Ⅱ）, Ni（Ⅱ）, Mn（Ⅱ）, Cd（Ⅱ）, Cr（Ⅲ）, and Al（Ⅲ） in the solution. The proposed method has been successfully applied to the determination of trace mercury in industrial wastewater with the recoveries above 99%. The relative standard deviation for five replicate determinations of 0.04 μg·mL^-1 of Hg（Ⅱ） was found to be 1.4%, 1.1%, and 1.2%, respectively. The analytical results were very satisfactory.

Properties of Microcrystalline Chitosan-Calcium Phosphate Complex Composite

Nature itself uses materials like, cellulose to provide the structure of plants, chitin as the exoskeleton of several insects and molluscs, collagen for mechanical support in connective tissues and so on. At present, the socioeconomic situation of the modern world has raised the interest in renewable materials being used in regenerative medicine. The composition of MCCh/?-TCP complex in sponge shape is derived from the junction of two or more different materials, containing organic and inorganic materials, including bioactivity and biodegradability as a characteristic. The chemical characteristics of MCCh/?-TCP complex composites showed that both of the components organic and inorganic exist in the material. All sponge preparations, with MCCh/?-TCP have a well-shaped 3-dimentional structure, a highly porous and interconnected and homogenous pore structure to ensure a biological environment conducive to cell attachment and proliferation as well as tissue growth, providing the passage of nutrient flow. These materials can be used in future for medical applications as a base for scaffolds production and as implants in regenerative medicine.

Investigation on Microcrystalline Wax Doped Asphalts by Temperature Control Mode of Atomic Force Microscopy

Because of its economical and environmentally friendly characteristics, the warm mix asphalt(WMA) is widely used in pavement engineering. However, the lack of microscopic study of WMA brings difficulties in understanding of its mechanical behavior and mechanisms at macroscopic scale which finally hinders the enhancement of WMA's performance. Therefore, this article aims to use atomic force microscopy(AFM), a promising microscopic technique, to investigate the effects of wax-based warm mix agents on asphalt microstructures and micromechanical properties at different temperatures. For simplicity's sake, microcrystalline waxes are selected as an alternative of these wax-based additives. It is shown that the sample preparation method has a vital impact on the morphology of asphalt samples. The effects of microcrystalline wax on asphalt's mechanical properties can be well captured by AFM tests. Results show that the blending of #70, #80 and #90 microcrystalline waxes lowers the modulus(20—60 MPa) of Pen70 asphalt at 25 ℃ while increasing its adhesion force(5—20 n N). The results of this study may shed some light on the comprehension of the effects of wax-based additives on asphalt materials at macroscopic level which can help estimate and predict its actual performance.