Effect Of Solvent Treatment Research Articles

Effect of Solvent Treatment on the Composition and Structure of Santanghu Long Flame Coal and Its Rapid Pyrolysis Products.

Easily soluble organic components in Santanghu long flame coal (SLFC) from Hami (Xinjiang, China) were separated by CS2 and acetone mixed solvent (v/v = 1:1) under ultrasonic condition, and the extract residue was stratified by carbon tetrachloride to obtain the light raffinate component (SLFC-L). The effect of solvent treatment on the composition and structure of the coal and its rapid pyrolysis products was analyzed. Solvent treatment can reduce the moisture content in coal from 9.48% to 6.45% and increase the volatile matter from 26.59% to 28.78%, while the macromolecular structure of the coal changed slightly, demonstrating the stability of coal's complex organic structure. Compared with raw coal, the relative contents of oxygen-containing functional groups and aromatic groups in SLFC-L are higher, and the weight loss rates of both SLFC and SLFC-L reached the maximum at about 450 °C. In contrast, the loss rate of SLFC-L is more obvious, being 33.62% higher than that of SLFC. Pyrolysis products from SLFC at 450 °C by Py-GC/MS are mainly aliphatic hydrocarbons and oxygenated compounds, and the relative contents of aliphatic hydrocarbons decreased from 48.48% to 36.13%, while the contents of oxygenates increased from 39.07% to 44.95%. Overall, the composition and functional group in the coal sample were changed after solvent treatment, resulting in a difference in the composition and distribution of its pyrolysis products.

Effects of Solvent Treatment on the Formation of Oxygen Vacancy in TiO2 via Vacuum Annealing

In this work, vacuum annealing of hydrothermally prepared titanium dioxide (TiO2) washed with water (W-TiO2) or ethanol (E-TiO2) at different temperatures was performed. Total organic carbon and Fourier transform infrared characterizations confirm the adsorption of washing solvents by TiO2. As the vacuum annealing temperature increases, W-TiO2 appears as white powders, whereas E-TiO2 shows a gradually deepening color with certain absorption of visible light due to the pyrolysis of ethanol. Electron paramagnetic resonance analyses demonstrate that the crystallization of W-TiO2 creates oxygen vacancy (Vo), and the pyrolysis of ethanol favors its formation in E-TiO2. Diffuse reflectance spectra and photocatalytic performances of all TiO2 photocatalysts suggest that Vo is not responsible for visible light absorption. Our work proves that the formation of Vo in TiO2 via vacuum annealing is influenced by the solvent treatment and gives new insights into the origin of Vo as well as its role.

Effect of Solvent Treatment on Siro and Ring Spun TFO Polyester Yarn

Yarns and fabrics can be improved through structural modifications. Using an organic solvent is a novel and popular approach for a structural modification in the field of textiles. In the present work, Siro-spun® and TFO (Two for one Twisters) polyester yarns were modified with a solvent-acid mixture of aceton and trichloroacetic acid : methylene chloride (TCAMC). Both types of yarn samples were treated in a relaxed state with various concentrations of the solvent’s mixture at room temperature. The influence of the treatment with respect to linear density and TCAMC concentration on mechanical properties was investigated. Modified yarns exhibited higher breaking elongation, improved abrasion resistance and lower tenacity. It was also found that the methods of yarn manufacturing contribute significantly to the tensile behaviour of modified yarns. The improvement in elongation was higher in the treated TFO yarn. The abrasion resistance index was found to be lower in the case of siro polyester yarns. Furthermore, significant mass loss in yarn was observed after the treatment of TCAMC.

The effect of solvent treatment on the buried PEDOT:PSS layer

Solvent treatment has been widely used to improve the device performance of both Organic Light Emitting Diodes (OLEDs) and Polymer Solar Cells (PSCs). One of the proposed mechanisms is the modification of the buried PEDOT:PSS layer underneath the organic active layer by the permeating solvent. By measuring the lateral electric conductivity of the PEDOT:PSS layer, the 3 orders of magnitude's enhancement on the conductivity after solvent treatment confirms that the solvent permeates through the top organic active layer and modifies the PEDOT:PSS layer. Using a “peel-off” method, the buried PEDOT:PSS layer is fully exposed and studied by UV–vis spectra, XPS spectra, and c-AFM images. The data suggest that the permeating solvent dissolves PSS, changes PEDOT:PSS′ core-shell structure into a linear/coiled structure, and moves PSS from the bulk to the surface. As a result, PEDOT becomes more continuous in the bulk. The continuous conducting PEDOT-rich domains create percolating pathways for the current which significantly improve electric conductivity.

Effect of solvent treatment on morphology, crystallinity and tensile properties of cellulose acetate nanofiber mats

Aligned nanofiber mats were prepared from cellulose acetate using an electrospinning technique. The nanofiber mats were then immersed in an ethanol/acetone mixture. The solvent treatment led to denser, more compact fibrous structure and slight decrease in fiber alignment. It increased fiber diameter and polymer crystallinity within fibers. These effects resulted in increase in the tensile strength of fibrous mats. Solvent treatment may offer a simple, efficient approach to improve the mechanical strength of nanofibrous mats.

Effects of Solvent Treatment on the Characteristics of InGaZnO Thin-Film Transistors

The solvent effects on the back channel of InGaZnO (IGZO) thin-film transistors (TFTs) were investigated. IGZO-TFTs with methanol treatment on the back channels exhibited higher mobility, smaller subthreshold swing, and smaller hysteresis in the transfer curves compared to those without treatment. Systematic studies showed that methanol treatment can reduce the loosely bound oxygen impurities, and reduce the surface energy of the IGZO films. As a result, the air adsorption/desorption effect on the TFT back channel was reduced greatly, leading to higher mobility and stability.

The effect of solvent treatment on the performance of various carriers in dry powder inhalations containing salbutamol sulphate.

Objective(s) : It has been suggested that the efficiency of dry poder inhaler (DPI) is generally low. Therefore, the aim of the present research work was to use the solvent treatment of the carrier in DPIformulations to see the possibility of inducing desirable characteristics. Lactose sieve fractions of 63-90 µm were submerged in ethanol or 80% v/v ethanol, methanol or propanol. Lactose crystals were then blended with either 1% w/w or 4% w/w salbutamol sulphate using a Turbula mixer. Drug detachment was studied using a multistage liquid. Laser particle size analyzer, DSC, and pycnometer were used to characterize the treated lactose and mannitol samples. SEM was used to study surface morphologies. In case of mannitol as a carrier only ethanol was used as a solvent. SEM images displayed less rugosities and increased surface smoothness after submersion. Although the tomahawk like shape remained fairly constant in most lactose samples, the solvent treatment changed the shape of mannitol particles which was proved by SEM results. Deposition results showed that the type of solvent had an influence on fine particle fraction. In addition, the payload had also a big impact on fine particle fraction values. Generally, treated samples showed better performance compared to untreated samples. Solid state analysis by DSC showed that no major changes occurred in the treated samples compared to untreated samples. The solvent treated method can be used as an approach to improve the performance of carriers such as lactose and mannitol in dry powder inhaler.

Effects of solvent treatment and high-pressure homogenization process on dispersion properties of palygorskite

Dispersion of natural palygorskite in distilled water, methanol, ethanol, isopropanol, dimethyl formamide, and dimethyl sulfoxide was carried out using high-pressure homogenization. The effects of solvent parameters on the microstructure, morphology and colloidal properties of palygorskite were investigated in detail. Elemental analysis, infrared spectroscopy (IR) and thermogravimetric analysis (TGA) confirmed that some solvent molecules were encapsulated within the tunnels of palygorskite. The efficiency of the homogenization process to disperse palygorskite aggregates was closely correlated to the solvent parameters, particularly solvent vapor pressure and viscosity. A well disaggregated palygorskite was obtained after dispersing in dimethyl sulfoxide. It was also confirmed that colloidal stability and suspension viscosity were affected by the solvent nature. A more stable suspension with higher viscosity of 2364 mPa s was obtained by dispersing palygorskite in isopropanol.

Effects of solvent treatments on characteristics of superporous hydrogels

The synthesis of an acrylamide-based superporous hydrogels (SPHs) was carried out by solution polymerization. SPHs were submerged in one of the organic solvents: diethyl ether, acetone, absolute ethanol, or hexane for 48 h. The characterization studies were performed by measurement of apparent density, porosity, swelling, mechanical strength, and scanning electron microscopy (SEM). The swelling ratio was calculated based on the mass of SPHs in the swollen state and in the dried state. The penetration pressure of the SPHs was measured from the force required for complete fracture of SPH. SPHs showed porosities of more than 60%. In double distilled water SPHs showed tremendous increase in equilibrium swelling capacity. But, when the same SPHs were placed in artificial gastric fluid for swelling, they showed very low equilibrium swelling capacity. The solvent treated SPHs showed good swelling characteristics in both the swelling media compared to that of SPH without solvent treatment. When an artificial gastric fluid was used as a swelling medium, ethanol- and hexane-treated SPHs showed higher penetration pressure compared to SPH without solvent treatment, while diethyl ether- and acetone-treated SPHs showed less penetration pressure. SEM images clearly indicate the formation of interconnected pore and capillary channels. The characterization studies revealed that the SPHs treated with solvents showed remarkable effects on their characteristics compared to SPH without solvent treatment. The results of the present study provide background for the selection of solvent for SPH treatment to improve characteristics that will lead to modification of the available SPH-based gastric retention devices. Keywords: superporous hydrogel, solvent, scanning electron microscopy, swelling, penetration pressure

Evaluation of solvent and thermal induced modifications in polyamide 6 fibres: an optical approach

Optical investigation has been conducted on chemically treated polyamide (nylon) 6 fibres using a strongly interacting solvent, dimethylformamide (DMF). A comparison has been carried out between the effect of solvent treatments and the effect of thermal treatment on the structure and properties of the fibres. The two-beam interference Pluta microscope is used to calculate the refractive indices parallel and perpendicular to the fibre axis and the birefringence. Optical and structural parameters related to the refractive indices and birefringence are evaluated. Crystallinity, specific refractivity of the isotropic dielectric, polarizability per unit volume and orientation functions are among the parameters obtained and plotted versus the time of treatment. Increases in the birefringence, crystallinity and orientation functions with time of treatment are obtained. The results indicate that DMF modifies the fibre structure and enhances its optical anisotropy. Moreover, immersion of the fibre samples in DMF prior to thermal treatment gives rise to different results for the optical and structural parameters than those immersed in DMF and thermally treated at the same time. The study revealed a considerable change in the molecular orientation of the nylon 6 fibres due to solvent and thermal treatments. This could enhance and expand their utilization in industrial applications.

Effect of solvent exposure on the properties of hydroxy‐terminated polybutadiene‐based polyurethanes

AbstractHydroxy‐terminated polybutadiene‐based prepolyurethanes and diamine chain extended polyurethane‐ureas were prepared and treated with various organic solvents in the moisture‐cured state in order to modify their ultimate strength. FTIR studies with solvent‐treated polyurethanes and polyurethane‐ureas confirmed that organic solvents penetrated inside the polyurethane hard segments and affected hydrogen bonding. The polar and non‐polar solvents showed different abilities to penetrate into polyurethane hard segments. Solvent treatment after moisture curing increased the tensile strength of these polyurethanes and polyurethane‐ureas with respect to control samples. The stress–strain behaviour of solvent‐treated polyurethane follows the constrained junction model. The change in hard segment crystallinity on solvent treatment has been explained by wide‐angle X‐ray diffraction study. The better orientation in polybutadiene soft segments evidenced from SEM (scanning electron microscopy) pictures is believed to be the main reason behind the improved tensile properties of solvent‐treated polyurethane samples. The effect of solvent treatment, as well as stretching, on the diffusion coefficient of hexane in polyurethanes was investigated. Copyright © 2003 Society of Chemical Industry

Effects of solvent treatment on glass transition characteristics of treated poly(p-phenylene sulphide)

The relationship between solvent-crystallized morphology and glass transition characteristics of poly(p-phenylene sulphide) that had been previously processed with 1-chloronaphthalene is reported. Dielectric relaxation studies revealed a strong positive offset in glass transition temperature (Tg) of the solvent-crystallized samples compared to the corresponding amorphous sample, as well as thermally crystallized samples of similar bulk crystallinity. Additionally, the apparent activation energy for the α-relaxation was higher for the solvent-crystallized case. The dielectric relaxation strength (Δε=ε0−ε∞) determined for the solvent-crystallized PPS is small and showing weak temperature dependence, leading to an increase in Δε as the temperature increased above Tg. This was explained by the existence of a large amount of tightly bound, or rigid-amorphous materials in the solvent-treated sample. We suggested that the large amount of immobile amorphous material, and its ability to relax at temperatures above Tg, is related to strong secondary crystallization process in solvent-treated PPS.

Effect of solvent exchange on length change and creep of D-dried hydrated C3S paste

The results of a study on creep of D-dried hydrated C3S paste after exchange of water in saturated samples with organic solvent are presented. Length and mass changes were also measured when saturated C3S paste prepared at a water-solid ratio of 0·4 was immersed in both methanol and isopropanol. A differential thermogravimetric technique was used in order to determine the effect of solvent treatment on dehydration of C3S paste, and its correlation with pore structure, modulus of elasticity and microhardness. Methanol and isopropanol exchanges prior to drying reduce the magnitude of creep in the dry state, suggesting an irreversible interaction of solvent with C-S-H.

Microcrystalline cellulose from soybean husk: effects of solvent treatments on its properties as acetylsalicylic acid carrier

Microcrystalline cellulose (MCC) is a very important product in pharmaceutic, food, cosmetic and other industries. In this work, MCC was prepared from soybean husk, produced in large quantities in soybean oil processing industries. It was characterized through various techniques (scanning electron microscopy (SEM), infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC)) and compared with a commercial MCC. The results obtained show that the prepared sample has similar crystallinity and lower particle size than the commercial MCC. Both MCC samples were treated with organic solvents (chloroform, acetone, ethanol and ethyl ether), for structural modifications to be introduced, and used as acetylsalicylic acid (ASA) carrier. Pretreated MCC and MCC/ASA 1:1 mixtures were analyzed through FTIR and thermal analysis. The drug release was evaluated in buffer solution of pH 4.5 and in pure water, at 37°C. The MCC pretreated with different solvents show different thermal properties and ASA release rates, each MCC showing a particular behavior.

Characterization of Plasma-Polymerized Allylamine Using Waveguide Mode Spectroscopy

Amine-functionalized thin films were prepared by plasma-induced deposition of allylamine. Radio frequency (rf) plasma polymerization was carried out under both continuous wave (CW) and pulsed conditions to control the film chemistry. The chemical and physical nature of plasma-polymerized allylamine films was investigated, as well as the effect of solvent treatment on the structure of the polymeric material. The film properties were studied using Waveguide Mode Spectroscopy (WaMS), which enabled an independent determination of film thickness and refractive index. Fourier transform infrared (FTIR) spectroscopy showed that changes in duty cycle led to different film chemistries. WaMS carried out on thin films (d < 60 nm) showed changes in the refractive index with increasing thickness believed to suggest intermolecular reactions occurring in the bulk while the film is depositing. All films studied showed a significant loss of soluble material from the surface upon solvent extraction. After extraction however, the films were stable and could be reversibly swollen in ethanol.

Structural stability and in vitro biological activity of ribonuclease a during microencapsulation into biodegradable polymers

The effects of solvent treatment and physical stresses encountered by the model protein ribonuclease A (RNase A) during microencapsulation into biodegradable polymeric microspheres were examined. Stability of the protein at each step of the microencapsulation procedure was monitored by using fluorescence, circular dichroism, and sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS-PAGE) methods to characterize the tertiary structure, secondary structure, and aggregation characteristics, respectively. Enzymatic activity was determined by a spectrophotometric assay. The microspheres were characterized for size distribution, surface morphology, encapsulation efficiency, protein release profiles, and protein activity. Heptane treatment caused a change in the fluorescence spectrum of RNase A but the secondary structure remained intact. No gross aggregation or change in the activity of the solvent-treated samples was detected. Uniformly spherical microspheres in the 20–60 µm size range with smooth surfaces and high encapsulation efficiencies were prepared by the solvent extraction method. The microspheres showed an initial burst release followed by complete release of RNase A in 8 days. However, the released RNase A showed loss of enzymatic activity. Interaction of the protein with the polymer matrix may have resulted in its inactivation.

Effects of solvent treatment on cold crystallization behavior and morphology of poly(ether ether ketone)

AbstractIsothermal crystallization kinetics at temperatures between 160–194°C and the morphology of virgin and solvent‐treated poly(ether ether ketone) (PEEK) were investigated by using differential scanning calorimetry, scanning electron microscopy (SEM), and wide‐angle X‐ray scattering analysis. Kinetic analysis showed that the cold crystallization of virgin (untreated) PEEK proceeds with an Avrami exponent of n = 2,5–2,6, and the SEM results revealed a grainy‐texture morphology with no regular spherulites, suggesting a planar growth. The X‐ray characterization revealed low to medium crystallinity, which is consistent with the SEM results. This is quite different from the typical impinged spherulitic morphology of high crystallinity in melt‐crystallized PEEK. Post cold‐crystallization annealing at temperatures near the melting point (300–320°C), however, induced a spherulitic morphology resembling that produced from melt crystallization. Furthermore, methylene dichloride treatment on PEEK was found to significantly affect the cold‐crystallization kinetics and the resulting morphology. The cold crystallization of solvent‐desorbed PEEK samples proceeds with n = 1,0–1,2, reflecting probably an irregular line growth with heterogeneous nucleation. Additionally, SEM examination revealed a highly porous texture in the desorbed/cold‐crystallized PEEK that hindered direct observation of the actual crystalline morphology; nevertheless, neither spherulites nor planar lamellar crystals were observed.

Effects of solvent treatment on crystallization kinetics of poly(p‐phenylene sulfide)

AbstractIsothermal melt crystallization kinetics were investigated by differential scanning calorimetry (DSC) for virgin and α‐chloronaphthalene solvent‐treated poly(phenylene sulfide) (PPS) systems. The overall crystallization rates were found to be much faster for the solvent‐treated PPS than for the virgin neat PPS. Additionally, the Avrami crystallization plot for the solvent‐treated PPS samples appeared as two straight portions with an apparent discontinuity, but as a continuous straight line for the virgin PPS system. After the treatment of solvent dissolution and subsequent drying, the residual trace α‐chloronaphthalene, upon being quenched to the crystallization temperatures, initiated some localized solvent‐induced nuclei‐like crystals in PPS. It was the nuclei that enhanced secondary crystallization in treated PPS during the second stage, and the higher extents of secondary crystallization in the solvent‐treated PPS caused the apparent discontinuous break in the Avrami plots. The causes for the difference were explained and the mechanism of the sequential primary/secondary crystallization kinetics for the solvent‐treated PPS was satisfactorily described with a proposed series‐parallel crystallization model. ©1995 John Wiley &amp; Sons, Inc.

The effect of solvent treatment on the chemical composition and organoleptic acceptability of traditional condiments from Nigeria.

Three Nigerian condiments from locust bean, melon, and soya bean were prepared by the traditional technique of uncontrolled fermentation and then partly defatted by hexane and di-ethyl ether extraction respectively. Proximate analysis and consumer preference tests were conducted. Results showed that while crude protein, ash and fibre contents remained virtually unchanged, the carbohydrate contents of the treated condiments (derived by difference) increased remarkably. The increase was associated with the significant reduction of about 50% (p = 0.05) in lipid contents of the three condiments. The observed solvent effect correlated positively with panelists' preference rating for the treated locust bean and melon condiments. Except with the soya bean condiment, higher mean scores were observed after the solvent treatment for the four sensory attributes assessed. However, condiment-type and treatment notwithstanding, colour and odour appear to critically determine the level of acceptability of condiments.

Effect of Solvent Treatments on the Handle of Wool Fabrics

The KES-F system has been used to investigate solvent treatments of wool, in par ticular dry cleaning and solvent scouring. Solvent scouring is compared to similar aqueous treatments by both objective and subjective measurements.