Cellulose Acetate Polymer Research Articles

Macroplastic accumulation in roadside ditches of New York State's Finger Lakes region (USA) across land uses and the COVID-19 pandemic

Macroplastics are a ubiquitous and growing environmental contaminant with impacts in both marine and terrestrial systems. Marine sampling has dominated research in this field, despite the terrestrial origins of most plastic debris. Due to the high surface water connectivity facilitated by roadside ditches, these landscape features provide a unique sampling location linking terrestrial and surface water systems. We collected and analyzed macroplastic accumulation by number of pieces, mass, and polymer type in roadside ditches across four land uses, before and during the COVID-19 pandemic in the Finger Lakes Region of New York State. Commercial land use plastic accumulation rate was highest, while forested land use accumulation rates were lowest on a piece basis. Pre-COVID-19 piece accumulation rates were significantly higher than COVID-19 piece accumulation rates across all land uses. Mass accumulation rates followed similar patterns observed in piece accumulation, but the patterns were not always statistically significant. Plastic type 4 (i.e. thin plastic films), especially plastic bags and wrappers, was the most frequently collected type of macroplastic by piece across all land uses within the 1–7 Resin Identification Codes. By mass, the data were distributed less consistently across land uses. Cigarette filters, containing the polymer cellulose acetate, were the most frequently found roadside plastic, but are not within the 1–7 classification system. Our results suggest that policies in place limiting plastic bag usage could substantially reduce roadside plastics but other plastics, such as food wrappers and other single use plastic films, which comprised a large proportion of the plastic debris collected, should also be regulated to further decrease macroplastic pollution.

Covalent immobilization of bromocresol purple on cellulose nanocrystals for use in pH-responsive indicator films

This study developed pH-indicator films by combining esterified cellulose nanocrystals (e-CNCs) with activated bromocresol purple (a-BCP) via covalent bonding for pH-sensitive color-changing applications. The e-CNC/a-BCP particles were incorporated into cellulose acetate polymer to prepare pH-sensitive color changing films. Binding of a-BCP to e-CNCs was proven by attenuated total reflection infrared (ATR-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Colorimetric analysis showed that films containing 10% or 15% e-CNC/a-BCP particles had critical color changes either at pH 4–5, or pH 7–8. The films with 10% e-CNC/a-BCP particles also revealed excellent leaching resistance under acidic conditions. Color changes were reversible between pH 2 and 10. These pH-indicator films had visible color changes in response to pH variations, color reversibility, leaching resistance, and sufficient rigidity even though mechanical properties decreased as the e-CNC/a-BCP content increased from 0% to 15%.

ASYMMETRIC CELLULOSE ACETATE MEMBRANES USED IN SEPARATION APPLICATIONS

This work focused on the use of cellulose acetate polymer for the preparation of porous asymmetric membranes using a phase inversion process. These membranes were characterised by scanning electron microscopy, a bubble-point method and sorption measurements. The preparation method used induced membrane anisotropy. The capacity of the membranes in the removal of electrolyte (NaCl) from aqueous solution was investigated. A good retention of 58.6% and a high flux rate of 8.9 × 10–4 m/s using NaCl solution of 200 mg/L concentration were obtained by cellulose acetate membranes prepared with water as non-solvent. The results showed that the membrane performance was affected by the membrane structure, which was determined by the conditions of membrane preparation.

DNA as a Natural Flame Retardant for Cellulose Acetate Polymer Mixtures

AbstractThe combustion properties of natural DNA mixed with the nature‐derived thermoplastic cellulose acetate (CA) were determined. The flame retarding properties of DNA in mixtures with CA were significant and concentration dependent, the higher the DNA content the better the flame retardation. Ammonia was detected during the heating of CA‐DNA mixtures. In contrast, carbon monoxide (CO) formation was distinctly reduced during combustion of the CA mixtures with DNA when compared with pure CA. Thus, DNA can be considered as a natural and re‐growing polymeric flame‐retardant for versatile applications of CA‐based thermoplastic polymers in order to form eco‐friendly polymer mixtures.

CELLULOSE ACETATE FLOATING MICROSPHERES OF METFORMIN HYDROCHLORIDE: FORMULATION AND CHARACTERIZATION

In this study, floating microspheres of metformin hydrochloride were prepared by using cellulose acetate polymer by solvent evaporation method. Four formulations were prepared by varying the ratio of drug and polymer. The prepared microspheres were then subjected to various evaluation parameters such as drug content, micromeritic evaluations, FTIR, SEM, floatability and in vitro dissolution study. Formulation F1 (1:1 ratio of polymer and drug) showed the highest drug release and drug content with good flow properties. The cumulative percentage of drug release significantly decreased with decreasing drug concentration with a constant polymer ratio. Scanning Electron Microscopy images of all formulations showed that the prepared floating microspheres were irregular in shape, and the surface was found to be non- uniform and rough. In vitro release studies indicated the mechanism of the drug release to follow the Korsemeyer-Peppas model, and “n” value was found to be between 0.54-1.89, indicating anomalous transport mechanism.

Development and Characterization of Cellulose/Iron Acetate Nanofibers for Bone Tissue Engineering Applications.

In tissue engineering, design of biomaterial with a micro/nano structure is an essential step to mimic extracellular matrix (ECM) and to enhance biomineralization as well as cell biocompatibility. Composite polymeric nanofiber with iron particles/ions has an important role in biomineralization and collagen synthesis for bone tissue engineering. Herein, we report development of polymeric cellulose acetate (CA) nanofibers (17 wt.%) and traces of iron acetates salt (0.5 wt.%) within a polymeric solution to form electrospinning nanofibers mats with iron nanoparticles for bone tissue engineering applications. The resulting mats were characterized using field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The resulted morphology indicated that the average diameter of CA decreased after addition of iron from (395 ± 30) to (266 ± 19) nm and had dense fiber distributions that match those of native ECM. Moreover, addition of iron acetate to CA solution resulted in mats that are thermally stable. The initial decomposition temperature was 300 °C of CA/Fe mat > 270 °C of pure CA. Furthermore, a superior apatite formation resulted in a biomineralization test after 3 days of immersion in stimulated environmental condition. In vitro cell culture experiments demonstrated that the CA/Fe mat was biocompatible to human fetal-osteoblast cells (hFOB) with the ability to support the cell attachment and proliferation. These findings suggest that doping traces of iron acetate has a promising role in composite mats designed for bone tissue engineering as simple and economically nanoscale materials. Furthermore, these biomaterials can be used in a potential future application such as drug delivery, cancer treatment, and antibacterial materials.

Design of helical groove/hollow nanofibers via tri-fluid electrospinning

Electrospinning of multilevel structured micro/nanofibers have obtained considerable attention recently. In this study, inspired by the unique properties and functions of helical, groove and hollow structures in nature, we prepared a new type of multilevel structured nanofibers with helical and groove/hollow structures. Based on the fiber formation mechanism, a combination of cellulose acetate and other appropriate polymers were applied to generate helical groove/hollow nanofibers using a designed tri-fluid electrospinning system. By varying the capillary dispositions of the spinneret, the fibers with helical groove and helical hollow structures were obtained. To explore the forming process of the composite fibers, high speed photography was employed to record the Taylor cone and jet path under the spinnerets. By characterizing the morphologies and specific functions of the as-prepared nanofibers, the unique helical groove/hollow structure were generated and present good properties in wettability and mechanical behavior.

First-Principles Model to Evaluate Quantitatively the Long-Life Behavior of Cellulose Acetate Polymers.

A deep understanding of the degradation of cellulose diacetate (CDA) polymer is crucial in finding the appropriate long-term stability solution. This work presents an investigation of the reaction mechanism of hydrolysis using electronic density functional theory calculations with the B3LYP/6-31++G** level of theory to determine the energetics of the degradation reactions. This information was coupled with the transition-state theory to establish the kinetics of degradation for both the acid-catalyzed and noncatalyzed degradation pathways. In this model, the dependence on water concentration of the polymer as a function of pH and the evaporation of acetic acid from the polymer is explicitly accounted for. For the latter, the dependence of the concentration of acetic acid inside the films with the partial pressure on the surrounding environment was measured by sorption isotherms, where Henry’s law constant was measured as a function of temperature. The accuracy of this approach was validated through comparison with experimental results of CDA-accelerated aging experiments. This model provides a step forward for the estimation of CDA degradation dependence on environmental conditions. From a broader perspective, this method can be translated to establish degradation models to predict the aging of other types of polymeric materials from first-principles calculations.

Tuning permeation characteristics of cellulose acetate membrane embedded with raw and amine-functionalized silicon carbide nanoparticle for oil-water separation

The current research aimed to develop a polymeric nanocpmposite membrane with a low cost nanoparticle for efficient oil-water separation. Cellulose acetate (CA) polymer was used to synthesis membrane by phase inversion method and membrane property was influenced by the addition of functioalized silicon carbide (SiC) nanoparticles. The obtained results indicated that high water flux was achieved using the modified nanocomposite membranes, which manifested improved attributes in terms of pore size, hydrophilicity, porosity, and water content. To know more about the membrane morphology and physicochemical properties field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), X-ray powder diffraction (XRD), tensile test were utilized as characterization techniques. The functionalised SiC nanopacticle was also analysed by XRD, FTIR and FESEM techniques. The water contact angle of the pure CA membrane was 77.13 ± 2.9, whereas it was as low as 58.6° ± 4.2 after modification. The modified membranes, as such, mirrored reasonably enhanced hydrophilicity. Besides, reasonable improvement in the antifouling attributes of the membranes was also observed. The pure water flux offered by the modified membranes in a microfiltration test unit was increased by 89 %. Though there was no significant improvement in BSA rejection, the competence of the modified membranes apropos of separation of toluene from its emulsion in water was adequately substantiated.

Mechanical Reinforcement of Lime Pastes by Electrospun Cellulose Acetate Polymer Fibers

Lime-based composites have been extensively used throughout the years as plasters/renders and jointing mortars in building construction. However, the low flexural strength and tensile ductility of these composite building materials, that are currently still used in the structural and thermal upgrading of existing structures of high cultural and architectural significance, have been a significant drawback. Therefore, researchers have been focusing on the development of novel composites involving the use of additives to enhance the tensile and flexural capacity of lime-based materials. For the first time in this study, naturally-derived polymer fibers produced by electrospinning have been successfully introduced as additives in lime pastes aiming to investigate their effect on the mechanical performance of the end composites. More precisely, the introduction of electrospun cellulose acetate (CA) microfibers within lime pastes resulted to a tremendous improvement of the mechanical properties of the latter. Consequently, the present study paves the pathway towards the use of electrospun fibrous additives in the development of advanced composite lime-based building materials, which is currently an unexplored area.

CO2/CH4 and He/N2 Separation Properties and Water Permeability Valuation of Mixed Matrix MWCNTs-Based Cellulose Acetate Flat Sheet Membranes: A Study of the Optimization of the Filler Material Dispersion Method.

The main scope of this work is to develop nano-carbon-based mixed matrix cellulose acetate membranes (MMMs) for the potential use in both gas and liquid separation processes. For this purpose, a variety of mixed matrix membranes, consisting of cellulose acetate (CA) polymer and carbon nanotubes as additive material were prepared, characterized, and tested. Multi-walled carbon nanotubes (MWCNTs) were used as filler material and diacetone alcohol (DAA) as solvent. The first main objective towards highly efficient composite membranes was the proper preparation of agglomerate-free MWCNTs dispersions. Rotor-stator system (RS) and ultrasonic sonotrode (USS) were used to achieve the nanofillers’ dispersion. In addition, the first results of the application of the three-roll mill (TRM) technology in the filler dispersion achieved were promising. The filler material, MWCNTs, was characterized by scanning electron microscopy (SEM) and liquid nitrogen (LN2) adsorption-desorption isotherms at 77 K. The derivatives CA-based mixed matrix membranes were characterized by tensile strength and water contact angle measurements, impedance spectroscopy, gas permeability/selectivity measurements, and water permeability tests. The studied membranes provide remarkable water permeation properties, 12–109 L/m2/h/bar, and also good separation factors of carbon dioxide and helium separations. Specifically, a separation factor of 87 for 10% He/N2 feed concentration and a selectivity value of 55.4 for 10% CO2/CH4 feed concentration were achieved.

Engineering and Characterization of Antibacterial Coaxial Nanofiber Membranes for Oil/Water Separation.

In the present study, a coaxial nanofiber membrane was developed using the electrospinning technique. The developed membranes were fabricated from hydrophilic cellulose acetate (CA) polymer and hydrophobic polysulfone (PSf) polymer as a core and shell in an alternative way with addition of 0.1 wt.% of ZnO nanoparticles (NPs). The membranes were treated with a 2M NaOH solution to enhance hydrophilicity and thus increase water separation flux. Chemical and physical characterizations were performed, such as Fourier transform infrared (FTIR) spectroscopy, and surface wettability was measured by means of water contact angle (WCA), mechanical properties, surface morphology via field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and microscopy energy dispersive (EDS) mapping and point analysis. The results show higher mechanical properties for the coaxial nanofiber membranes which reached a tensile strength of 7.58 MPa, a Young’s modulus of 0.2 MPa, and 23.4 M J.m−3 of toughness. However, treated mebranes show lower mechanical properties (tensile strength of 0.25 MPa, Young’s modulus of 0.01 MPa, and 0.4 M J.m−3 of toughness). In addition, the core and shell nanofiber membranes showed a uniform distribution of coaxial nanofibers. Membranes with ZnO NPs showed a porous structure and elimination of nanofibers after treatment due to the formation of nanosheets. Interestingly, membranes changed from hydrophobic to hydrophilic (the WCA changed from 90 ± 8° to 14 ± 2°). Besides that, composite nanofiber membranes with ZnO NPs showed antibacterial activity against Escherichia coli. Furthermore, the water flux for the modified membranes was improved by 1.6 times compared to the untreated membranes.

A Clean Process for Obtaining High-Quality Cellulose Acetate from Cigarette Butts.

The main purpose of this study is to introduce a modified method for recovering and recycling huge number of cigarette butts (CBs) and convert them into a fashion product. CBs are non-biodegradable waste, generally, discarded improperly into the environment. CBs consist of cellulose acetate, which can be recovered through extraction and purification processes. CBs are the most numerically frequent form of waste in the world. A relevant portion of CBS are discarded improperly into the environment. The principal filter components are plasticized cellulose acetate fibers that have the slowest degradation rate (up to years). In fact, a limiting step is the hydrolysis of cellulose acetate polymer into cellulose and acetic acid, which is extremely slow under ambient conditions and represents a relevant environmental risk. A number of studies have been realized on recycling cigarette butts with encouraging results, and several methods have been studied, including recycling of cigarette butts in asphalt concrete and fired clay bricks, as a carbon source, sound-absorbing material, corrosion inhibitor, biofilm carrier, and many more. In this study, we propose a novel, green, low cost, simple, and efficient extraction method of cellulose acetate fibers (CA) from discarded cigarette butts (DCBs). CBs extraction procedure involves a two-step process consisting of washings in water and some subsequent washings in ethanol. The obtained samples of CA are dried at 60 °C for 60 min in the oven. The quality and properties of cellulose acetate extracted and purified are comparable to the pure cellulose acetate fiber used for cigarette butts. The preliminary results obtained on the recovered CA look promising to the use of this recovery material from cigarette butts to obtain a wide consumption fashion product, such as eyeglass frames.

Christiansen Effect‐Based Physical Coloration of a Cellulosic Monolith Conveniently Fabricated Using Thermally Induced Phase Separation

AbstractA cellulose acetate (CA) polymer monolith is conveniently fabricated using the thermally induced phase separation method. When a CA monolith in sheet form is immersed in a non‐solvent mixture with a suitable refractive index, transparent coloration due to the Christiansen effect is observed. This colorization is arbitrarily controlled by temperature and the non‐solvent composition. The wavelength of maximum transmission of the immersed monolith spectrum increases—with high sensitivity—at high temperatures and in non‐solvent with a low refractive index, while being independent of the monolith morphology. Following the alkali hydrolysis of the CA monolith, the transmission spectrum of regenerated cellulose monolith immersed in mixed non‐solvent clearly shifts by the Christiansen effect, whereas natural cellulose fibrils (wood cellulose and bacterial cellulose) with high crystallinity in the same non‐solvent are opaque or shows no Christiansen effect, respectively. The results indicate the potential of the amorphous cellulose monolith for use as a chemosensor.

In vitro release studies of ferulic acid in semi-solid formulations with optimized synthetic membrane

Cutaneous release assays are a fast, low-cost procedure, which allows to obtain essential preliminary results for the development of topical formulations containing new active substances. In this sense, this study aimed to obtain and characterize a low-cost and easy-to-reproduce membrane model, based on a biodegradable polymeric cellulose acetate membrane, which had similarity with the lipid composition of skin and then mimicked its barrier function. For this purpose, membranes prepared by impregnation of a lipid solution in a synthetic membrane were tested for ferulic acid (FA) release from semi-solid and stable formulations using Franz diffusion cells. Thermal features of impregnation were investigated by Differential Scanning Calorimetry, while membranes were structurally characterized by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Gel and cream-gel formulations containing 0.5% (w/w) FA were submitted to in vitro skin release tests in phosphate-buffered saline + Tween 80, pH 7.4, using either the synthetic membrane or that optimized by Franz diffusion cell testing. AFM demonstrated membrane impregnation through a change in surface roughness, while SEM showed significant reduction of pore size as well as lipid deposition in the polymer network of the synthetic membrane. With the optimized membrane the gel formulation released almost the same FA percentage (52.36%) as the cream-gel one (52.40%), while with the synthetic one the release was slower and less effective, even if the former formulation performed better than the latter (49.55 vs. 46.04%). Whereas with the synthetic membrane the two formulations showed the same release profile, the optimized membrane was more selective for FA diffusion, thus leading to different release profiles. The results of this study suggest that the optimized membrane may be applied in a simple and accessible way to both initial screening of topical formulations and in vitro release tests.

Investigations on thermo-mechanical properties of organically modified polymer clay nanocomposites for packaging application

Eco-friendly packing polymer materials are in the spotlight but, lack of new biodegradable polymers either natural or synthetic is yet to establish the market more competitively. So, in the present work, clay as a nano-filler is embedded and organically modified in some synthetic and natural polymers which are well established commercially to enhance their biodegradability. The impact of clay on the properties of synthetic polymers namely, poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and natural polymer cellulose acetate butyrate (CAB) was studied. Results from differential scanning calorimetric (DSC) showed a decrease in the glass transition temperature of organically modified polymer clay nanocomposites (PCC) than pure polymers. Scanning electron microscopy (SEM) displayed a uniform surface with small-sized crystallites distributed on the polymer surface. X-ray diffraction (XRD) spectra revealed the formation of enhanced intercalated structures in PCC. Furthermore, FTIR studies showed that the interlayer bonding (Si–O bands) of pure clay is deformed in PCCs. The tensile strength of PCC increased with an increase in organo-clay loading. This unique mechanical behavior is due to the agglomeration of organo-clay particles. Finally, the biodegradation studies revealed enhanced hydrolytic degradation in PCC than pure polymers. Hence, these PCCs are environmentally friendlier than their pure synthetic polymers without significant compromise in their properties, which makes it suitable for packaging industries.

Cellulose acetate nanofibers loaded with crude annatto extract: Preparation, characterization, and in vivo evaluation for potential wound healing applications.

In this study we prepared annatto-loaded cellulose acetate nanofiber scaffolds and evaluated both in vitro cytotoxicity and potential for wound healing in a rat model. Annatto extract, which has been used to accelerate wound healing, was added to cellulose acetate polymer and the resulting material was used to produce nanofiber scaffolds via electrospinning. Physicochemical, and thermal evaluation of the resulting nanofiber mats showed that incorporating annatto did not significantly affect the thermal or chemical stability of the polymer. Annatto extract did not demonstrate cytotoxicity in the HET-CAM assay or MTT assay for fibroblast culture. Scanning electron microscopy of the fibroblasts confirmed that cells spread and penetrated into the nanofiber. In vivo experiments confirmed that cellulose acetate retained its biocompatibility when associated with crude annatto extract, and suggested that dose/response modulation occurs between the annatto-functionalized nanofibers and mast cells, indicating the potential of this material for wound healing applications.

Highly porous and thermally stable cellulose acetate to utilize hydrated glycerin

In this study, nano-pores in cellulose acetate matrix were generated by utilizing glycerin with water pressure without metal salts as additive. When cellulose acetate polymer membrane fabricated with glycerin as an additive was exposed to water pressure as external physical force, nano-pore generation depends on the pressure-strength exerted on the membrane. On the principle of the nano-pore generation, the chains became weakened in the portion of the cellulose acetate, in which glycerin was surrounded by abundant water molecules, resulting in plasticization capable of easily generating nano-pores with water pressure. We found that pore size and numbers of nano-pore could be easily controlled by adjusting the water pressure. Thus, we succeeded in preparing the porous cellulose acetate with high porosity of 78.3%.Generated pores in cellulose acetate polymers were confirmed by scanning electron microscopy (SEM) images and porosimeter. The coordinate interactions between cellulose acetate (CA) polymers and glycerin were investigated by FT-IR and TGA analysis.

A template of cellulose acetate polymer-ZnAl/C layered double hydroxide composite fabricated with Ni NPs: Applications in the hydrogenation of nitrophenols and dyes degradation.

In this work, cellulose acetate polymer (CA) sheet and 2% ZnAl grafted on activated carbon grown in the form of layered double hydroxide (ZnAl/C-LDH) incorporated into CA polymer (CA-ZA2) 5wt% (CA-ZA5) and 10wt% of ZnAl/C-LDH (CA-ZA10) sheets were synthesized by simple casting method. All the stated sheets were fabricated with zero-valent Ni nanoparticles by adsorption of Ni+2 ions followed by subsequent reduction with NaBH4 and named as CA@Ni, CA-ZA2@Ni, CA-ZA5@Ni, and CA-ZA10@Ni NPs. The synthesized Ni NPs were investigated through FESEM, FTIR, XRD and EDS techniques. These supported and stabilized Ni NPs were largely used for the reduction of 4-nitrophenol (PNP), and 2-nitrophenol (ONP) in the presence of NaBH4 which act as a reducing agent. Similarly, the catalytic efficiency was also assessed against the removal of dyes. The linear relationship and Kapp were obtained from pseudo-first-order kinetics. The rate constant Kapp of CA@Ni NPs for the reduction of PNP is 1.5 × 10-1 and CA-ZA2@Ni (Kapp=2.6 × 10-1), CA-ZA5@Ni (Kapp=3.2 × 10-1), and CA-ZA10@Ni is 5.7 × 10-1min-1. The highest rate constant for PNP reduction was observed with CA-ZA10@Ni NPs. The rate of CR removal with ZA10@Ni NPs is 2.05 × 10-1 while the adjacent R2 is 0.9013. Similarly, the rate constant and adjacent R2 values were calculated for the degradation of other dyes and nitrophenols.

Investigation of melamine and DOPO-derived flame retardants for the bioplastic cellulose acetate

In order to identify suitable flame retardant additives for the eco-friendly polymer cellulose acetate (CA), high-melting derivatives of the known flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) were combined with the thermoplastic CA and the combustion properties were tested. CA mixtures with bis-phosphonamidates (EDA-DOPO and PIP-DOPO) showed distinct flame retardation effects and a reduction of peak heat release rates (PHRR) by up to 18%. CA mixtures with MDOP, a melamine salt of DOPA (an oxidation product of DOPO), also showed considerable effects and a reduction of PHRR by up to 27%. While producing more smoke than pure CA and CA plus melamine, owing to its aromatic component, MDOP was superior to the CA mixtures with DOPO, EDA-DOPO and PIP-DOPO in this regard. The mixture of CA with melamine gave rise to a distinctly reduced formation of toxic CO and smoke when compared with pure CA. Thus, these additives can be considered for future applications of CA-based polymers with enhanced flame protection.