Cellulose Acetate Butyrate Polymer Research Articles

The influence of cellulose acetate butyrate membrane structure on the improvement of CO2/N2 separation

Global warming has been identified as a serious environmental issue. The most promising way to stop the greenhouse gas effect is to develop a high-performance membrane for CO2 separation. In this study, research was conducted to determine the effects of different polymer concentrations (2 wt%, 4 wt%, and 6 wt%) and casting thicknesses (150 µm, 250 µm, and 300 µm) on the membrane performance. The obtained results showed cellulose acetate butyrate (CAB) membrane with polymer concentration of 4 wt% and casting thickness of 250 μm had a CO2/N2 selectivity of 1.398 ± 0.03. Thus, the mixed matrix membrane (MMM) was developed with 4 wt% of CAB polymer and 0.1 wt% functionalized multi-walled carbon nanotubes. Hence, this study confirmed that MMMs result in a better performance than polymeric membranes where the CO2 permeance, N2 permeance and CO2/N2 selectivity of the MMM were 365.741 ± 0.667 GPU, 73.410 ± 0.741 GPU, and 4.980 ± 0.050, respectively.

Incorporation of functionalized multi-walled carbon nanotubes (MWCNTs) into cellulose acetate butyrate (CAB) polymeric matrix to improve the CO2/N2 separation

Abstract Membrane-based technology has received much attention in the past decades due to attractive features offered. Through significant breakthroughs of this technology, the mixed matrix membrane (MMM) has demonstrated a promising carbon dioxide (CO2)/nitrogen (N2) separation performance. Among the polymer materials used, cellulose acetate butyrate (CAB) polymer was selected due to its outstanding characteristics, which subsequently could improve the CO2 sorption ability. In this study, MMM was prepared by incorporating the functionalised multi-walled carbon nanotubes (MWCNTs-F) as inorganic material into the CAB polymer matrix (MMM-4F). The CAB membrane (CAB-M) was also synthesised under similar fabrication parameters via the phase-inversion method to determine the CO2/N2 separation performance. The gas permeation results showed that the CO2/N2 separation performance increased dramatically from 6.12 ± 0.09 to 11.00 ± 1.92 when 4 wt% of MWCNTs-F was incorporated into the CAB polymer matrix. The increase in CO2 permeance within the MMM was due to the embedded MWCNTs-F within the CAB polymer matrix. In this study, the new synthesised MMM proved to possess excellent CO2/N2 separation performance. However, it could further be improved by manipulating the amount of MWCNTs-F incorporated into the CAB polymer matrix. This is suitable for the gas separation field.

Effects of organic medium on rheological properties of silver pastes for crystalline silicon solar cells

Purpose The purpose of this paper is to characterize and understand the effects of polymer binder, thixotropic agent, solvent and organic medium content on the rheological properties of silver pastes for screen printing front electrode films of solar cells. Design/methodology/approach Dispersions of silver particles (surface modified with oleic acid) in ethyl cellulose (EC) polymer solutions with and without thixotropic agent were prepared, and yield stress values were measured by setting shear stress to characterize the inter-particle interaction strength of pastes. Steady-state flow, three interval thixotropy shear test and oscillatory measurements were conducted to study the effect of EC polymer and thixotropic agent on viscosity, structure rebuilding and viscoelastic properties of electrode pastes. The effect of solvent was studied by investigating the steady viscosity of cellulose acetate butyrate (CAB) polymer solutions and Ag dispersions. Findings Weak flocculation network of silver particles was produced because of depletion flocculation. Besides the interaction between thixotropic agent micelles, EC polymer also has a significant interaction with thixotropic agent. Merely increasing EC polymer or thixotropic agent content is not the best way to prevent the layer printed from laying down. The effect of solvent on the viscosity of paste is mainly attributed to the difference of hydromechanics radius and configuration of CAB polymer in solvents. With the increase of organic medium content, the properties of electrode pastes were converted from rigidity to flexibility. Originality/value It is still a challenge to obtain high-quality front electrode films for crystalline silicon solar cells by screen printing, because of the difficulty in reducing shadowing losses while ensuring a low series resistance and high filling factor. The paste rheological properties are the key properties related to the paste’s passing ability through the meshes and resistance of paste spreading on the substrate. Organic medium as an important component of the paste is acknowledged to be used to tailor the paste’s rheological properties and have a great role in screen printing.

Comparison of Microencapsulation by Emulsion-Solvent Extraction/Evaporation Technique Using Derivatives Cellulose and Acrylate-Methacrylate Copolymer as Carriers

Microencapsulation is a useful method to prolong a drug release from dosage forms and to reduce its adverse effect (1) among various available methods. The microencapsulation of hydrophilic active ingredients requires the use of a polar dispersing phase such as a mineral oil. Acetone/paraffin systems are conventionally used. The current study aimed to investigate two different microencapsulation techniques comparatively, water in oil in oil (w/o/o) and oil in oil (o/o), for theophylline (TH) loaded ethylcellulose (EC), cellulose acetate butyrate (CAB), Eudragit RS and RL microspheres with regard to loading efficiency, release and degradation kinetics. Microspheres were prepared by the emulsification method by solvent diffusion/evaporation technique and different polymers which were incorporated into microspheres to control the release rate of drug. Theophylline (TH) was chosen as a model drug. The emulsion technique was investigated for to prepare theophylline microparticles. EC and CAB and acrylatemethacrylate copolymer corresponding to the above ratios were selected as microparticles wall materials. The effects of type polymers on the physical characteristics and dissolution of the microparticles were also studied. However, the TH loading efficiency (for w/o/o emulsion about 90.64% and o/o emulsion about 73.90/5 to 95.90%) and the TH release kinetics were influenced by the microencapsulation technique. The results demonstrated that the o/o microspheres (containing of CAB) was most appropriate, providing a high encapsulation efficiency (95.90%) and low initial burst release (6.45%). The microspheres prepared with CAB polymer showed faster dissolution rate than other polymers with 0.75: 1 drug to polymer ratio. The double emulsion technique with EC as wall material gave the high dissolution efficiency (80.48%) of microcapsules. Eudragit RS microspheres showed higher yield (90%). The release of TH from CAB and Eudragit RL walled microcapsules was slow whilst the release from those of EC and Eudragit RS were faster. The type of polymer and the drug to polymer ratio were found to be the key factors affecting the release profile which could lead to microspheres with desired release behavior.

Synthesis and characterization of photosensitive cinnamate-modified cellulose acetate butyrate spin-coated or network derivatives

The photochemical behavior of photosensitive materials obtained by spin-coating or network synthesis of a cellulosic polymer bearing photo-cross-linkable cinnamate groups was investigated. First, cinnamate groups were grafted on a cellulose acetate butyrate polymer, with different grafting densities. The photochemical properties of the polymers were studied in solution by UV–visible and 1H NMR spectroscopy. Then spin-coated films and networks were prepared and characterized as a function of the number of cinnamate groups per cellulosic unit. The water-wetting properties of both surfaces were studied by dynamic contact angle measurements, before and after photoirradiation, and subsequent heating. The surfaces obtained by the two methods have significantly different behaviors that can be assigned to the distinct photochemical pathways of the cinnamate groups upon irradiation depending on the sample preparation. Indeed, dimerization reaction is evidenced as the main process in the spin-coated films while the expected isomerization is predominant at the surface of the polymer networks.

Effects of three natural organic matter types on cellulose acetate butyrate microfiltration membrane fouling

This study aimed to clarify the effect of interactions between membranes and natural organic matter (NOM), which is considered to be the major membrane foulant in wastewater treatment processes. Sodium alginate (SA), humic acid (HA) and bovine serum albumin (BSA) were used as NOM models. Hollow fiber membranes were prepared using cellulose acetate butyrate polymer (CAB). Filtration experiments were carried out using SA, HA and BSA solutions and the membrane fouling behavior was examined. NOM adsorption on CAB membranes was measured by quartz crystal microbalance with dissipation (QCM-D), where NOM solutions were flowed across CAB spin-coated quartz crystal sensors and adsorbed. SA showed more severe permeate flux decline during the early stage of filtration and lower recovery of permeate flux after backwashing compared with HA. The severe flux decline for SA was due to pore-plugging and cake formation with high molecular weight components. The BSA solution, with no high molecular components, showed a gradual permeate flux decline and resulted in lower permeate flux after 240 min filtration compared with HA. The gradual permeate flux decline with the BSA solution was due to ready adsorption of BSA on the CAB membrane.

Effect of surface roughness of hollow fiber membranes with gear-shaped structure on membrane fouling by sodium alginate

In this work, the relationship between surface roughness of the membrane and membrane fouling was investigated with sodium alginate which is a kind of extracellular polymeric substances (EPS) and is regarded as a main foulant in membrane bioreactor (MBR). Cellulose acetate butyrate polymer which is superior in heat-resistance and mechanical strength was used as membrane material. The membranes having the gear-shaped structures of different heights on the outer surface were prepared by using the several spinnerets via thermally induced phase separation. The membrane having the higher projection on the outer surface showed higher antifouling property. The recovery of the permeability by backwashing also increased by the higher projection of the outer surface of the membrane. Although the membrane permeability decreased by adding calcium chloride into the alginate solution, the membrane with the higher projection also showed higher permeability and recovery by backwashing. The increase of the permeability and the recovery by backwashing was not owing to the increase of the outer surface area by the gear-shaped structure formation. From the observation of the membrane outer surface after filtration of sodium alginate and humic acid, it was revealed that foulants were accumulated in the valley between projections, while the top of the projection was clean. This is the reason for the higher antifouling property for the membrane with the higher projection structure.

Effect of membrane surface morphology on membrane fouling with sodium alginate

The object of this study is to clarify the effect of membrane surface morphology on membrane fouling with sodium alginate (SA) which is a kind of natural organic matter (NOM) and is considered to be the main foulant in membrane water treatment. Cellulose acetate butyrate polymer which is superior in heat-resistance and mechanical strength was used as membrane material. Four kinds of membranes having different surface and cross-sectional structures were prepared via thermally induced phase separation and non-solvent induced phase separation. In the case of the filtration of 50 mg L −1 SA solution from the outer surface to inner surface, the membrane having the dense outer surface showed higher permeability and higher recovery of permeability by backwashing. An addition of calcium chloride into the sodium alginate solution resulted in significant flux decline due to thick cake layer formed by cross-linking of sodium alginate. In this case, the membranes with the dense outer surface also showed higher permeability. Furthermore, it was found that membrane fouling with sodium alginate took place mainly on the outer surface rather than inside the membrane by measuring infrared absorption spectrum of the membrane after filtration of sodium alginate solution with and without calcium chloride.

PREPARATION AND EVALUATION OF SUSTAINED-RELEASE MICROCAPSULES OF FLUOXETINE HYDROCHLORIDE

The aim of present work was to prepare and evaluate enteric coated microcapsules of Fluoxetine hydrochloride using cellulose acetate butyrate polymer (CAB) by the modified emulsion solvent evaporation technique. The effect of sustained release of CAB microcapsules was evaluated by an invitro dissolution test, and the results were compared to a commercial product (Prozac® capsules). The results showed that CAB microcapsules loaded with Fluoxetine hydrochloride can be easily prepared and encapsulation efficiency and loading capacity were about from 77- 98 and 11%. The retardation of the release rate was dependant on the coat /core ratio, as well as pH of the dissolution media.

Preparation and in vitro evaluation of propylthiouracil microspheres made of Eudragit RL 100 and cellulose acetate butyrate polymers using the emulsion-solvent evaporation method

The objectives of this investigation are to evaluate the encapsulation efficiency of the anti-thyroid agent 6-n-propyl-2-thiouracil using two polymers of different characteristics (cellulose acetate butyrate polymer, (CAB-551-0.01) and ammonio methacrylate copolymer (Eudragit RL 100) and to study the effect of this encapsulation on the drug release properties. Polymers were used separately and in combination to prepare different microspheres. Also, the effect of polymer solution phase viscosity was studied for each of the polymers and for their combinations. An Ostwald viscometer was used to evaluate the relative viscosities of polymer solution phases and their combinations. Microspheres with 25% theoretical drug loading of 6-n-propyl-2-thiouracil core material were prepared by the emulsion solvent evaporation method. Microspheres prepared from CAB-551-0.01, which has higher relative polymer phase viscosity than Eudragit RL 100, showed significantly lower drug release rates and a noticeable lag time. Polymer combinations of CAB-551-0.01 and Eudragit RL 100 (1:1) showed an interesting synergistic increase in relative polymer solution viscosities at all concentrations. Unlike microspheres prepared from the two polymers separately which follow Higuchi spherical matrix release kinetics, microspheres prepared using a combination (1:1) of the two polymers showed near zero order with faster rates compared to those prepared using CAB-551-0.01 equivalent polymer concentrations. The results of this study suggest that 6-n-propyl-2-thiouracil was successfully and efficiently encapsulated and release rates of matrix microspheres are related to polymer solution phase viscosity, but when polymer combinations were used other factors such as structural effects must be considered.

Casting and characterization of cellulose acetate butyrate based UF membranes

This paper describes the development of ultrafiltration (UF) membranes from cellulose acetate butyrate polymer (CAB). The casting conditions are studied with reference to changes in composition of the casting solution, total thickness, solvent evaporation period and gelation bath temperature (GBT). The membranes are characterized in terms of product permeation rates and solute separation using poly (ethylene) glycols (PEG) of different average molecular weights, molecular weight cut-off (MWCO), pore size distribution profiles and scanning electron micrographs (SEM) of either surface of the membrane samples. The separation behaviour of CAB membranes prepared for turbidity, colouring matter, hardness and uranyl ion from aqueous streams indicate the feasibility of their use in water and effluent treatment applications.

Depolarization current characteristics of cellulose acetate–butyrate polymer films

AbstractCellulose acetate–butyrate films of thickness 5μm were grown by a solution growth technique. Thermally stimulated depolarization currents (TSDCs) were studied on these films as a function of polarizing field strength and polarizing temperature at a constant heating rate. In the present study, the TSDC spectra consist of a single current maximum, which was found to be independent of polarizing field strength. However, the current maximum shifted to higher temperatures with increasing polarizing temperature. The activation energies, relaxation parameters, charge associated with the current maximum and equivalent frequencies were evaluated. Based on these results, the origin of the TSDC was attributed to space charge polarization with some contribution arising from dipolar orientation.

Effect of iodine on electrical conduction in cellulose acetate-butyrate polymer films

Electrical properties can be tailored to a specific requirement by the addition of suitable dopant materials. A few studies on the effect of an impurity such as iodine on the conductivity of polymers are available, e.g. polyethylene [1, 2], poly(vinyl acetate) [3] , poly(vinyl chloride) [4] , poly(vinyl fluoride) [5] and poly(vinyl formal) [6]. The electrical conduction mechanism in cellulose acetate-butyrate films was investigated and the results were reported in [7]. In continuation of these studies, the conduction mechanism in iodine-doped cellulose acetate-butyrate films was investigated as a function of the dopant concentration, field and temperature, and is discussed in this letter. Pure and iodine-doped cellulose acetate-butyrate films of thickness 5/xm were grown by isothermal immersion [8] of glass substrates coated with metal electrodes. The films were dried in an hot-air oven for 24 h at a temperature of around 350 K. The top electrode was vacuum evaporated on the dried films. The thickness of the films was measured using the mechanical stylus method and was verified by the capacitance method. The electrical conduction of pure and doped cellulose acetate-butyrate films was studied in the sandwich configuration. The conductivity of the film was measured as a function of temperature, using a stabilised d.c. power supply, an electrometer (Keithley 617C) and a digital voltmeter. Before actual measurements were made, the films were annealed as described in [9]. The optical absorption measurements were made using a Hitachi U3400 u.v.visible spectrophotometer. Fig. 1 shows the conductivity of pure and iodinedoped cellulose acetate-butyrate films at a field strength of 5 x 106 Vm -1. Curve a corresponds to pure cellulose acetate-butyrate films and curves b-g correspond to iodine-doped cellulose acetate-butyrate films having iodine concentrations of 0.1, 0.25, 0.5, 0.75, 1.0 and 2.0 wt%, respectively. From the plots it is seen that the conductivity increases with temperature consist of two distinct regions of conduction. From the plots it is clear that the conductivity in the sample increases with increasing concentration of iodine up to 0.5 wt %. Above this concentration, however, the conductivity is found to decrease continuously with increasing iodine concentration. It is also observed that the conductivity in the doped sample is always more than that in the pure sample, even at higher concentration. The conductivity of the samples at 300 and 400 K are shown in Table I.