Containing Cellulose Acetate Research Articles

Synchronously enhanced breakdown strength and energy storage ability of cellulose acetate flexible films via introducing ultra-low content of carbonized polymer dots

Developing green and environmentally friendly biomass materials for energy storage and application is of great significance to sustainable development. Novel composite films containing cellulose acetate (CA) and carbonized polymer dots (CPDs) are reported herein. The CPDs have strong hydrogen bonding interactions with CA matrix, in which CPDs act as the physical crosslinking points and enhance the entanglement density of the matrix. And the composite films demonstrate a significant enhancement in breakdown strength (Eb), reaching up to 520.58 MV/m with the addition of 0.1 wt% CPDs (1.62 times higher than 321.94 MV/m of pure CA). Furthermore, the discharging energy density (Ud) achieves 2.55 J/cm3 at 450 MV/m, which is 1.36 times higher than that of the pure CA film (1.87 J/cm3 at 400 MV/m) and simultaneously, the energy efficiency (η) is maintained at 73.3 %. The Coulomb-blockade effect induced by the ultra-low content of CPDs effectively inhibiting carrier migration, and the enhanced entanglement density of the matrix improving mechanical properties and reducing polarization loss, mainly contribute to the enhanced dielectric performances. Furthermore, CPDs also improve the mechanical properties of the composite films apparently. This work provides some references for the fabrication of the next generation of environmentally friendly dielectric composite films.

Hybrid nanocomposite membranes containing cellulose acetate @ CuO/ZnO for biological interest

The current work is aimed to fabricate a set of hybrid nanocomposite membranes containing cellulose acetate (CA) reinforced by pure zinc oxide or mixed metal oxides in the form of CuO(0.01, 0.05, 0.1)/ZnO for biological Interest. Pure ZnO and CuO(0.01, 0.05, 0.1)/ZnO mixed oxides have been also prepared using eco-friendly, non-toxic, and low coast methods. CA@ZnO nanocomposite and CA@CuO(0.01, 0.05, 0.1)/ZnO hybrid nanocomposite membranes have been synthesized by a simple, straightforward, non-toxic, and environmentally acceptable casting approach. The chemical structure for the fabricated materials has been confirmed by common characterisation tools including: XRD, SEM, HRTEM, TGA thermal analysis. The average size of the prepared nanoparticle was 25.40 and 10.3 nm for ZnO and CuO/ZnO, respectively. The order of higher thermal stability for the fabricated materials are: CA@CuO(0.01)/ZnO < CA@CuO(0.05)/ZnO = CA@CuO(0.1)/ZnO. R500 for all CA@ZnO and CA@CuO(0.01, 0.05, 0.1)/ZnO membranes shows almost similar residu value which is in agreement with the loading ratio (10%). Furthermore, the biological activity of the fabricated samples has been also investigated by the biological screening against some selected Gram-positive, Gram-negative and some fungi. A higher biological activity was observed for CA@CuO(0.05)/ZnO hybrid nanocomposite membrane compared to the other materials. All the hybrid membranes do not exhibit any antibacterial activity against B. subtilis.

DEVELOPMENT OF ACID MODIFIED CELLULOSE ACETATE MEMBRANES FOR SALT WATER TREATMENT

The main objective of this work has been to study the performance of membranes developed for water treatment. Polymeric membranes (CTP and CTP-Acid) were developed from solutions containing cellulose acetate (CA), cellulose triacetate (CTA) and polysulfone (PSF), using maleic acid (MA) and acetic acid (AA) as additives and chloroform/dioxane as solvent. The NIPS-type phase inversion method was chosen as the membrane film manufacturing technique. The incorporation of 2.5% and 5% by weight of acids in the membrane mixture allowed us to study the additive effect on the morphological structure, and to predict the performance of the membranes formed. The characterization of the membranes was performed by SEM and FTIR analyses. Examining the flux, permeability and selectivity of the membranes also permitted to study the efficiency and performance of each membrane. The addition of AA and MA additives within the mixture increased the hydrophilic character and improved the flux rate by increasing it from 75 Lm-2h-1 to 142.74 Lm-2h-1 for 5% maleic acid addition. The 5% CTP AA membrane gave very satisfactory results in terms of selectivity, with a maximum removal of 84% of NaCl salt. Therefore, this membrane has been considered to be the most efficient one, with a flux of 120 Lm-2h-1 to 15 bar and a NaCl salt retention that meets the standards required by the World Health Organization (WHO).

Novel antibacterial cellulose acetate fibers modified with 2-fluoropyridine complexes

The complexes represented with the general formula [ML2Cl2] (L: 2-fluoropyridine; M: Ni (II), Cu (II), Co (II)) were synthesized and their structures were characterized via FT-IR and 1H NMR techniques. Thermal properties of the complexes were also investigated via TG/DTA combined system under N2 atmosphere. The complexes containing cellulose acetate (CA) micro/nano-fibers, which is a biocompatible and biodegradable polymer, were obtained via electrospinning technique. The fibers were characterized via FT-IR spectroscopy. FE-SEM images of the fibers were used to investigate their morphologies and for to determine the diameters of the fibers. Thermal properties of the fibers were investigated via TG/DTA combined system. Antibacterial studies of the complexes and fibers were investigated against the bacteria strains E. coli and Methyciline Resistant Staphylocaucus aureus via disc diffusion, broth microdilution and JIS L 1902: 2008, Testing method for antibacterial activity of textiles. Different levels Antibacterial activity was observed for all complexes and fibers.

3D printed robust superhydrophilic and underwater superoleophobic composite membrane for high efficient oil/water separation

The preparation of superhydrophilic and underwater superoleophobic membrane for achieving highly efficient oil/water separation through a facile method is still a great challenge. In this work, a superhydrophilic and underwater superoleophobic membrane with an ordered porous structure is fabricated via a facile direct inkjet writing (DIW) 3D printing technology for the application of oil/water separation. To print the membrane, a solid-like solution containing cellulose acetate (CA), poly (viny1 alcohol) (PVA), and silica nano-particles (SiO2 NPs) is used as the printed ink. As a result, the optimal 3D printed membrane exhibits a quite low water contact angles in-air about 18.14 ± 2.61° and a high underwater oil contact angle about 159.14 ± 0.59°, demonstrating its superhydrophilic and underwater superoleophobic characteristics. In oil/water separation process, the optimal printed membrane maintains high oil/water separation efficiency about 99.0% driven by gravity. In contrast to the traditional composite mesh preparing by coating CA/PVA/Si layer on the surface of commercial steel meshes, the printed membrane exhibits superior mechanical stability even after 30 min sonication or 100 bending cycles. Most importantly, the printed membrane still maintains good anti-fouling characteristics and high separation efficiency for separating oil/water mixture after 50 cycles.

Improved Impact Properties in Poly(lactic acid) (PLA) Blends Containing Cellulose Acetate (CA) Prepared by Reactive Extrusion.

Poly(lactic acid)/triacetine plasticized cellulose acetate (PLA/pCA) blends were prepared by extrusion at two different temperatures and tetrabutylammonium tetraphenyl borate (TBATPB) was added as a transesterification catalyst to reactively promote the formation of PLA-CA copolymer during the reactive extrusion. The occurrence of chain scission in the PLA phase and branching/crosslinking in the CA phase in the presence of TBATPB, resulting also in a darkening of the material, were demonstrated by studying torque measurements and by performing proper thermogravimetric tests on CA with the different additives. Tensile and impact tests onto the blends prepared at the lower temperature showed better properties than the ones obtained at a higher temperature. Then, the mechanical properties of PLA/plasticized cellulose acetate (pCA) blends prepared at the lower temperature were investigated as a function of the content of plasticized CA in the blend. A range of compositions was observed where blends exhibited improved impact properties with respect to pure PLA without a significant decrease in their elastic modulus. The study of the phase morphology of the blends revealed that the occurrence of reactive compatibilization did not significantly affect the phase distribution. In general, fibrillar CA particles were formed in the PLA matrix during extrusion, thus allowing the preparation of CA fibre reinforced composites. The trend of morphology as a function of the composition and processing conditions was then discussed by considering the evolution of phase morphology in immiscible polymer blends.

Development of antioxidant food packaging materials containing eugenol for extending display life of fresh beef

In this study, clove essential oil (CL) or eugenol (EU) containing cellulose acetate (CA) or acrylic component/hydrophobically modified starch (AC/S) coatings on corona treated oriented polypropylene film (OPP) were designed and investigated for their possible applications as antioxidant packaging materials for fresh meat. The antioxidant properties of the coatings were investigated by Vapour Phase-DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The CA coatings containing CL or EU showed 43–92% and 43–94% inhibition against DPPH free radicals through the vapour phase, respectively, whereas AC/S/CL and AC/S/EU coatings resulted in DPPH inhibition of 21–65% and 25–84%, respectively. AC/S/EU and CA/EU coatings on OPP containing from 0.32 ± 0.03 to 6.40 ± 0.14 g/m2 of EU were used to prepare packaging for fresh beef (Longissimus thoracis). After 14 days, the lipid oxidation in beef steaks kept in control and antioxidant packages was 3.33 and 1.00–1.22 mg of malondialdehyde per kilogram of meat, respectively. Moreover, red colour of beef in antioxidant packages was retained.

Photocatalytic degradation of organic dyes using composite nanofibers under UV irradiation

In this work, photocatalytic degradation of organic dyes such as methylene blue (MB) and indigo carmine (IC) have been studied by composite nanofibers systems containing cellulose acetate (CA), multiwall carbon nanotubes (CNT) and TiO2 nanoparticles under UV light. The amino factionalized TiO2–NH2 NPs cross-linked to the CA/CNT composite nanofibers works as a semiconductor catalyst. The morphology and crystallinity were characterized by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction, and Fourier transform infrared spectroscopy. It was also seen that many factors affected the photodegradation rate, mainly the pH of the solution and the dye concentration, temperature, etc. The study demonstrated that IC degrades at a higher rate than MB. The maximum photodegradation rate of both organic dyes was achieved at a pH 2. In comparison to other studies, this work achieved high photodegradation rate in lower time and using less power intensity.

Inhibition of Inflammatory Cytokines and Induction of Myeloid-Derived Suppressor Cells by the Effects of Granulocyte and Monocyte Adsorption Apheresis.

Pro-inflammatory cytokines are involved in the pathogenesis of inflammatory skin diseases attributable to activated neutrophils and macrophages. Myeloid-derived suppressor cells (MDSCs) play an important role in the regulation of the immune response and possess strong immunosuppressive and anti-inflammatory properties. Granulocyte and monocyte adsorption apheresis (GMA), an extracorporeal apheresis instrument featuring columns containing cellulose acetate (CA) beads, is designed to remove pathogenic myeloid lineage cells. The purpose of this study was to investigate the effects of GMA on cytokine production and MDSC induction. The serum level of various inflammatory cytokines and the incidence of MDSCs in peripheral blood before and after GMA treatment were recorded. Cytokines were assayed with the suspension-array method in 38 patients. The incidence of MDSCs was analyzed by FACS in eight patients and the effect of GMA on in vitro MDSC induction was examined using a mini-column system that mimics GMA. The serum level of IL-2Rα (P = 0.030), IL-8 (P = 0.018), and MIF (P = 0.0002) was significantly decreased by GMA and the incidence of MDSCs was increased (P = 0.030). With the mini-column system, MDSCs were induced in the peripheral blood of five healthy volunteers; the in vitro induction was significantly inhibited by inactivation of the complement component iC3b. The clinical effectiveness of GMA may be attributable to the inhibition of pro-inflammatory cytokines and the induction of anti-inflammatory MDSCs by iC3b activation via the CA beads in the GMA column.

379 Granulocyte and monocyte adsorption apheresis is effective for refractory netrophilic disorders and induces myeloid-derived suppressor cells

Granulocyte and monocyte adsorption apheresis (GMA) is an extracorporeal apheresis unit designed to remove pathogenic myeloid lineage cells. GMA involves a column containing cellulose acetate (CA) beads that serve as adsorptive leukocyte apheresis carriers. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population comprised of cells at several stages of myeloid lineage differentiation, that differentiate into macrophages, neutrophils, and dendritic cells. MDSCs play an important role in the regulation of the immune response and have immunosuppressive and anti-inflammatory properties. We previously demonstrated that CA beads activate complement component iC3b. Recently, iC3b was shown to induce differentiation of myeloid cells to MDSCs. Based on these facts, we hypothesized that GMA induces MDSC differentiation. The purpose of this study was to investigate the clinical effectiveness of GMA for neutrophilic skin diseases and related arthropathy including pustular psoriasis and psoriatic arthritis and whether GMA induces MDSC. For the assessment of clinical effectiveness, 68 patients with skin lesions and 41 with arthropathy were enrolled. Skin and joint lesions were assessed by overall lesional assessment (OLA) and visual analog scale (VAS), respectively. The incidence of MDSCs was analyzed by FACS in 8 patients and the effect of GMA on MDSC induction was examined using an in vitro mini-column system that mimics GMA. GMA was effective in 56 of 68 patients (82.4%) with skin lesions and 36 of 41 (87.8%) with arthropathy. The incidence of MDSCs in the patients was significantly increased by GMA. In the in vitro mini-column system, MDSCs were induced in the blood of 5 healthy volunteers and the induction was inhibited by inactivation of iC3b. GMAis effective for neutrophilic disorders and the effect might be attributed, at least in part, to the induction of MDSCs via iC3b activation by the CA beads in the GMA column.

All-Cellulose Composite Fibers Obtained by Electrospinning Dispersions of Cellulose Acetate and Cellulose Nanocrystals

All-cellulose composite fibers were produced by electrospinning dispersions containing cellulose acetate (CA) and cellulose nanocrystals (CNCs). Precursor polymer matrices were obtained after dispersion of CA with different degrees of substitution in a binary mixture of organic solvents. The obtained fibers of CA loaded with CNCs had typical widths in the nano- and micro-scale and presented a glass transition temperature of 145 °C. The CA component was converted to cellulose by using alkaline hydrolysis to yield all-cellulose composite fibers that preserved the original morphology of the precursor system. Together with Fourier Transform Infrared Spectroscopy fingerprints the thermal behavior of the all-cellulose composite fibers indicated complete conversion of cellulose acetate to regenerated cellulose. Noticeable changes in the thermal, surface and chemical properties were observed upon deacetylation. Not only the thermal transitions of cellulose acetate disappeared but the initial water contact angle of the web was reduced drastically. Overall, we propose a simple method to produce all-cellulose composite fibers which are expected to display improved thermo-mechanical properties while keeping the unique features of the cellulose polymer.

Effect of membrane characteristics on the performance of membrane bioreactors for oily wastewater treatment

Influence of membrane material and pore size on the performance of a submerged membrane bioreactor (sMBR) for oily wastewater treatment was investigated. The sMBR had a working volume of about 19 L with flat sheet modules at the same hydrodynamic conditions. Five types of micro- and ultra-polymeric membranes containing cellulose acetate (CA), cellulose nitrate (CN), polyamide (PA), polyvinylidene difluoride (PVDF) and polyethersulfone (PES) were used and their filtration performance in terms of permeability, permeate quality and fouling intensity were evaluated. Characterization of the membranes was done by performing some analysis such as pore size distribution; contact angle and scanning electronic microscopy (SEM) microphotograph on all membranes. The quality of permeates from each membrane was identified by measuring chemical oxygen demand (COD). The results showed more irreversible fouling intensity for membranes with larger pore size which can be due to more permeation of bioparticles and colloids inside the pores. Membrane characteristics have a major role in the preliminary time of the filtration before cake layer formation so that the PA with the highest hydrophilicity had the lowest permeability decline by fouling in this period. Also, the PVDF and PES membranes had better performance according to better permeate quality in the preliminary time of the filtration related to smaller pore size and also their better fouling resistance and chemical stability properties. However, all membranes resulted in the same permeability and permeate quality after cake layer formation. An overall efficiency of about 95% in COD removal was obtained for oily wastewater treatment by the membranes used in this study.

Electrospun cellulose acetate fibers containing chlorhexidine as a bactericide

Submicron fibers with bactericidal properties were prepared from electrospinning of blends containing cellulose acetate (CA) as a polymer base, chlorhexidine (CHX) as a bactericidal agent, and organic titanate Tyzor® TE (TTE) as a cross-linker. A small amount of high molecular weight poly(ethylene oxide) (PEO) was incorporated into the blends to facilitate the electrospinning, and its effect on the extensional properties and spinnability of the N,N-dimethylformamide (DMF) solutions were evaluated. The CHX-containing fiber meshes were cured by TTE in the presence of water vapor, which created covalent links between the CA and CHX. The immobilization of CHX on or within the fibers was confirmed by FTIR, Raman and XPS measurements. The resulting fiber meshes exhibited bactericidal properties on contact, due to the CHX immobilized on the fibers, and within a zone of inhibition (ZoI), due to the release of unbound CHX. The relationship of ZoI for the gram-negative Escherichia coli and the gram-positive Staphylococcus epidermidis to the amount of unbound CHX in the fibers is described by a simple diffusion model. The contact bactericidal capacity against both E. coli and S. epidermidis was assayed after complete removal of unbound CHX from the fibers. A post-spin treatment to attach CHX onto CA–PEO fibers via TTE linkers was also shown to be effective.

Effect of hypochlorite concentration on properties of posttreated outer‐skin ultrafiltration membranes spun from cellulose acetate/poly(vinyl pyrrolidone) blends

AbstractAn outer‐skin hollow‐fiber ultrafiltration (UF) membrane was spun from a new dope solution containing cellulose acetate (CA)/poly(vinyl pyrrolidone) (PVP 360K)/N‐methyl‐2‐pyrrolidone (NMP)/water using a wet‐spinning technique. The as‐spun fibers were posttreated with a hypochlorite solution over a range of concentrations for a fixed period of 24 h. The experimental results showed that the pure water flux of the treated membrane increased with increasing hypochlorite concentration. The treated membrane experienced an increased fouling tendency with increasing hypochlorite concentration because the hydrophilicity of the treated membrane decreased as a result of the removal of PVP contents in the membrane matrix after hypochlorite treatment. SEM images revealed that the membrane had an outer dense skin, a porous inner surface, and a spongelike structure, which confirmed that addition of PVP favored the suppression of macrovoids in the membrane. The membrane pore size could be significantly increased when the hypochlorite concentration reached 200 mg/L. It was concluded that hypochlorite treatment provided an additional option to easily alter the pore size of UF membranes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 227–231, 2005

Development of a LCST membrane forming system for cellulose acetate ultrafiltration hollow fiber

A novel lower critical solution temperature (LCST) membrane forming system containing cellulose acetate (CA)/poly (vinyl pyrrolidone) (PVP 360K)/ N-methyl-2-pyrrolidone (NMP)/1,2-propanediol with a weight ratio of 24.0:5.0:62.6:8.4 had been developed. CA hollow fiber ultrafiltration (UF) membranes were fabricated using the dry–wet spinning technique. The fibers were post-treated with a 200 mg/L hypochlorite solution over a period of 6 h at pH 7. The experimental results showed that water flux of a membrane decreased while retention increased with increasing CA concentration in a dope. It was concluded that the membrane pore size decreased with increasing CA concentration. The membrane fouling tendency for BSA was 3 times higher than that for PVP 24K.

Adhesion dependent release of hepatocyte growth factor and interleukin-1 receptor antagonist from human blood granulocytes and monocytes: evidence for the involvement of plasma IgG, complement C3 and beta2 integrin.

Evolving evidence of anti-inflammatory effects is observed in patients with rheumatoid arthritis or ulcerative colitis following periodic adsorptive granulocyte and monocyte (GM) apheresis with a column containing cellulose acetate (CA) beads as apheresis carriers. This study was undertaken to obtain insights into mechanisms of anti-inflammatory actions of adsorptive GM apheresis with CA beads. In a series of in-vitro experiments, we investigated the effects of plasma proteins and the leucocytes beta2 integrin (CD18) on granulocyte adsorption to CA beads. Granulocyte adsorption to CA beads required plasma IgG, the complement C3 and was inhibited by an antibody to leucocytes CD18. Further, hepatocyte growth factor (HGF) and interleukin-1 receptor antagonist (IL-1ra) which have strong anti-inflammatory actions were released by granulocytes that adhered to CA beads. Plasma IgG, C3 derived complement activation fragments and leucocytes CD18 are involved in granulocyte adhesion to CA beads and hence the release of HGF and IL-1ra.

Cellulose acetate hollow fiber ultrafiltration membranes made from CA/PVP 360 K/NMP/water

Hydrophilic hollow fiber ultrafiltration (UF) membranes have been prepared from a new dope solution containing cellulose acetate (CA)/poly(vinyl pyrrolidone) (PVP 360 K)/ N-methyl-2-pyrrolidone (NMP)/water with a mass ratio of 19.0/5.0/74.8/1.2 by using a dry-jet wet spinning process. The effect of air-gap length was studied. The as-spun fibers were post-treated by means of a hypochlorite solution of 200 mg l −1 (200 ppm) over different duration. The morphology of the membranes was investigated by Scanning Electron Microscopy (SEM). Pure water fluxes and solute retentions of the membranes were measured and different fouling resistances were analyzed. The experimental results showed that water flux of a membrane decreased while retention increased with increasing air gap. Fluxes of hypochlorite treated membranes were three times higher than that of an untreated membrane and retentions of the treated membranes were much lower. A 6 h treatment with 200 mg l −1 hypochlorite solution could achieve a CA UF membrane with a high pure water flux of 220×10 −5 l m −2 h −1 Pa −1. SEM images revealed that, PVP additive would favor the suppression of macrovoids and the thickness of inner skin increased with increasing air gap. PVP contents in the blend membrane could be significantly removed with the hypochlorite treatment. As a result, the treated CA membrane experienced higher fouling tendency than the untreated membrane. It was concluded that hypochlorite treatment altered the pore size of hollow fiber UF membranes made from the blend of CA and PVP 360 K. This is an extended conclusion to the published results and an attempt at explaining some differences were provided.

Cellulose acetate beads induce release of interleukin-1 receptor antagonist, but not tumour necrosis factor-alpha or interleukin-1beta in human peripheral blood.

Dramatic improvements in clinical symptoms of rheumatoid arthritis and ulcerative colitis were observed after patients received granulocyte and monocyte adsorptive apheresis with a column containing cellulose acetate (CA) beads as adsorptive carriers. This study was to investigate the effect of CA beads on the generation of anti-inflammatory and pro-inflammatory cytokines in human blood. We incubated human whole blood with CA beads at 37 degrees C for up to 2 h and measured tumour necrosis factor-alpha (TNF-alpha) interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra) produced by leucocytes. IL-1ra was also measured at the inflow and outflow of a column containing CA beads as leucocyte adsorptive carriers for the treatment of patients with ulcerative colitis. CA beads induced significant release of IL-1ra from leucocytes, but not TNF-alpha or IL-1beta. In contrast, all three cytokines were released when leucocytes were stimulated with lipopolysaccharide. IL-1ra was also markedly elevated in the outflow of the leucocyte apheresis column. These results indicate that CA beads selectively induce IL-1ra release from leucocytes which should contribute to the anti-inflammatory effect of granulocyte and monocyte adsorptive apheresis with CA beads as apheresis carriers.