Diacetate Films Research Articles

Mechanically robust ultrathin nanofibrous films by using microfluidic-based continuous printing.

Ultrathin nanofibrous films with unique properties, such as controlled thickness, structures, and excellent mechanical robustness, play a vital role in flexible wearable devices, electronic skin, and rechargeable batteries. However, nanofibrous films are always facing limitations in their mechanical properties, even though they are strong when used as textiles, mainly owing to their structural shortcomings by using conventional fabrication methods. Herein, we present the fabrication of free-standing ultrathin nanofibrous films with good mechanical properties by using a microfluidic-based continuous printing strategy. Owing to the precisely controllable microfluidic flow in the micrometre-scale, the resulting aramid nanofibre (ANF) films can reach thicknesses as low as 140 ± 25 nm. Specifically, the tensile strength of such ultrathin ANF films is recorded at an impressive value of 667 ± 40 MPa, representing a 120% improvement compared to the films prepared by using casting method. Such excellent mechanical robustness comes from the double-sided protonation, which shows a symmetrically dense structure compared to the asymmetric structure of cast films. Furthermore, we demonstrate the continuous fabrication of thin regenerated cellulose nanofiber (RCNF) and cellulose diacetate (CDA) films using the microfluidic-based printing strategy. Both microfluidic-based films show significant enhancements in strength, with a 42% increase for RCNF and a 94% increase for CDA compared to their cast films. We envision that this microfluidic-based continuous printing strategy provides a promising pathway for the development of advanced ultrathin nanofibrous films towards practical applications.

Properties of Polymer Films Based on Cellulose Diacetate with Intercalated Zn{(NH2)2Co}2Br2

The work is devoted to the fabrication and study of electret material based on cellulose diacetate polymer film with an intercalated active component, polar macromolecules Zn{(NH2)2CO}2Br2. The introduction of macromolecules into the film was carried out during its formation from solutions of various concentrations of cellulose diacetate and Zn{(NH2)2CO}2Br2 in tetrahydrofuran with ethyl alcohol under the action of a constant electric field of 2–4 kV cm–1. The temperature curves of the dielectric constant ε, the dielectric loss tangent tan δ, as well as the thermally stimulated depolarization currents j of the resulting films were determined. It was established that modification leads to the appearance of additional maxima in the ε(T), tan δ(T), and j(T) curves caused by the active component embedded in the film. Modification of a cellulose diacetate film causes an increase in the value of j and the surface charge density found from the j(T) curve by more than two orders of magnitude. The results obtained indicate the possibility of application of the method under consideration to fabricate electret films.

Micro-porous cellulose diacetate films obtained from coffee parchment: Physicochemical properties, biodegradability, and their performance as dye adsorbent

Micro-porous cellulose diacetate films obtained from coffee parchment: Physicochemical properties, biodegradability, and their performance as dye adsorbent

Highly Transparent, Self-Reinforced, and Hydrophobic Cellulose Acetate Films Fabricated Based on Thermal Stretching and Surface Engineering

Imparting cellulose acetate with surface hydrophobicity and self-cleaning function without sacrificing its high transparency and mechanical robustness is a great challenge. In this work, we report a highly transparent, self-reinforced, and hydrophobic cellulose diacetate (CDA) film, prepared by the combination of non-solvent-induced phase separation, uniaxial thermal stretching, and slippery liquid injection (LI). Results indicate that the surface-modified CDA films have hydrophobicity, with the water contact angle (WCA) increasing from ∼58.2 to 105–109°. Meanwhile, by adjusting the draw ratio, the sliding of liquid on the film surface and the WCA hysteresis are effectively improved, especially the sliding angle of CDA-LI-1.7-200 film decreases from 30.5° (for the unmodified CDA film) to 9.4°. Notably, uniaxial stretching provides enhanced mechanical strength for this antifouling CDA film, with up to 60.2% increase in tensile strength (from 37.2 to 59.6 MPa). Meanwhile, it is noted that the modified CDA film also has excellent transparency (≥92%), even slightly higher than that of the unmodified CDA film (∼91.5%). In addition, the surface-modified CDA films show excellent anti-scratching performance and maintain good liquid repellency even after several cycles of severe scratching. The work would provide guidance for the facile preparation of high-performance and multifunctional CDA films.

Effects of plasticizers on the properties of breathable cellulose diacetate films

Effects of plasticizers on the properties of breathable cellulose diacetate films

Regulation of orientation birefringence for cellulose acetate film: The role of crystallization and orientation

Cellulose acetate (CA) based films are widely used in liquid crystal displays due to their outstanding transparency, and a certain orientation birefringence of CA films is required when they are used as retardation films. The regulation of orientation birefringence is usually from the perspective of stretch-induced orientation, while the effects of crystallization behaviors of CA films remain obscure. In this study, the roles of crystallization and orientation on the orientation birefringence of CA films were elucidated. For cellulose diacetate films, the orientation birefringence is dominated by the orientation degree. In comparison, apart from the orientation degree, crystallinity is another key variable to regulate the orientation birefringence of cellulose triacetate and plasticized cellulose triacetate films, originating from the birefringence heterogeneity of the crystalline and amorphous phases. These results provide valuable guidelines for the production of CA-based optical films with excellent optical performance.

Construction and properties of cellulose diacetate film derived from waste cigarette filters

The cellulose diacetate films derived from the commercial cellulose acetate or some biomass materials have a high cost and the synthesis is complex. It is meaningful to develop a green and low-cost method to prepare cellulose diacetate films and regulate their properties. In addition, it is necessary to recycle the wastes for reuse. Thus, waste cigarette filters were used as the source for preparing the cellulose diacetate films and glycerol as the plasticizer to improve the comprehensive properties in this paper. Hydrogen bonds were formed between glycerol and acetate fibers, and the glass transition temperature of samples decreased after adding glycerol. Moreover, the water contact angle decreased from 97.6° to 19.2° and the water vapor permeability increased from 1.585 × 10−12 to 7.797 × 10−12 with the increasing of glycerol content, demonstrating that the hydrophilic property of as-prepared films was improved. However, excessive content of glycerol decreased the mechanical properties of films. When the content of glycerol was 30%, as-prepared film with an elongation at break of 24% had the highest tensile strength of 24.3 MPa. When the content of glycerol exceeded 30%, the tensile strength declined sharply. Therefore, this paper proposed a simple and low-cost method to convert waste cigarette filters into cellulose diacetate films which can be applied in the packaging or engineering films.

Suppression of crystallization in thin films of cellulose diacetate and its effect on CO2/CH4 separation properties

This study elucidates the discrepancy in gas permeability between bulk films and asymmetric membranes of semi-crystalline cellulose acetates (CAs) from perspectives of thickness-confinement and crystallization suppression. CAs are the workhorse membrane materials for industrial CO2/CH4 separation. Bulk films of CAs often exhibit CO2 permeability values of 1.8–6.6 Barrers at 35 oC, which correspond to permeance values of 36–132 GPU for asymmetric membranes with assumed selective layers of 50 nm. However, commercial CA membranes can have CO2 permeance values as high as 200 GPU with a CO2/CH4 selectivity comparable to the bulk polymers. We hypothesize that as the CA films become thinner, the thickness confinement inhibits crystallization and thus increases gas permeability while retaining gas selectivity. To validate this hypothesis, freestanding cellulose diacetate (CDA) films with thicknesses ranging from 218 nm to 120 μm were prepared, and their crystallinity was determined using Differential Scanning Calorimetry and Wide-angle X-ray Diffraction analysis. Gas solubility and permeability can be satisfactorily correlated with the crystallinity using the empirical equations available in the literature. We demonstrate that the micro- or nano-confinement and dynamics in thin-film polymers are instrumental in understanding gas transport properties of industrial asymmetric membranes.

Solvent Effect on the Solid-Surface Fluorescence of Pyrene on Cellulose Diacetate Matrices

The effect of the solvent nature (acetonitrile, ethanol, dimethyl sulfoxide, and dioxane) and its concentration on the fluorescence intensity of pyrene sorbed on the cellulose diacetate (CDA) film from a water-organic solution was studied. Dimethyl sulfoxide and ethanol are shown to be the most effective solvent additives for pyrene solid-surface fluorescence (SSF). The maximum SSF signal of pyrene was found upon sorption of the substance from aqueous media containing 1.2-4.2 vol% DMSO. For the pyrene quantitation the concentration dependence of its SSF intensity at the maximum of the spectrum at λem = 394 nm and λexp = 320 nm was plotted. The dependence has a linear character in the pyrene concentration range 2·10−6 - 2·10-8 g/L, and the limit of pyrene detection is 2·10-11 g/L. The possibility of determining benzo(a)pyrene using SSF technique with the CDA matrix is proved. The proposed method is promising for use in environmental monitoring of polycyclic aromatic hydrocarbons.

Cellulose diacetate films as a solid-phase matrix for fluorescence analysis of pyrene traces in aqueous media

We report on the possibility of using cellulose diacetate (CDA) films as a solid-phase matrix for the fluorescence analysis of pyrene in aqueous micellar media. We examined the effect of the concentration of three surfactants—the anionic sodium dodecyl sulfate (SDS), the cationic cetyltrimethylammonium bromide (CTAB), and the nonionic polyoxyethylene (10) mono-4-isooctylphenyl ether (TX-100)—on the fluorescence of pyrene in aqueous micellar solutions before and after sorptional concentration and as adsorbed on CDA films. The increased fluorescence intensity of pyrene on the solid-phase matrix was due to pyrene solubilization in the surfactant hemimicelles formed on the sorbent surface. The highest degree of pyrene recovery on CDA was achieved in the presence of micelles of the cationic CTAB. The surface electric potential of the CDA films was negative (−31.5 ± 2.5 mV), affecting the hydrocarbon recovery degree. The recovery degree and the polarity index of the pyrene molecules’ microenvironment in solution decreased in the sequence CTAB > SDS > TX-100.

Formation of the liquid crystal state of cellulose diacetate in nitromethane vapor: A fourier IR study

The structure, intra- and intermolecular interactions, and conformations of macromolecules in cellulose diacetate films under the conditions of formation of the liquid crystal state in the course of nitromethane vapor sorption were studied by Fourier IR spectroscopy and polarization microscopy. The number of intramolecular hydrogen bonds stabilizing the rigid helical conformation of the macromolecules is preserved in the process. The anisotropic structure of cellulose diacetate films is also preserved after desorption of the sorbed solvent vapor.

Effect of tetraphenylporphine on the supramolecular structure of cellulose triacetate

The molecular-disperse distribution of tetraphenylporphine in solution-cast cellulose triacetate and diacetate films was established by X-ray structural analysis. It was shown that the low crystallizability during heat treatment is a characteristic feature of cellulose acetates membranes containing tetraphenylporphine. This could be due to fact that the porphyrin molecules are located in the intermolecular spaces of the amorphous phase of the polymer, thereby hindering crystallite growth. Evidence for the formation of a complex of tetraphenylporphine and cellulose acetates, where the additive resides in the crystal lattice of the polymer and alters its parameters, was obtained.

Synthesis of Electroconducting Narrowly Distributed Nanoparticles and Nanocomposite Films of Orthanilic Acid/Aniline Copolymers

A unique strategy for synthesis of narrowly distributed and inherently self-stabilized copolymer nanoparticles by a simple emulsifier-free polymerization from orthanilic acid and aniline was developed. The polymerization yield, electrical conductivity, size, and its distribution of the nanoparticles could be simultaneously optimized by facilely regulating the comonomer ratio, oxidant/comonomer ratio, polymerization temperature, and time. In particular, the nanoparticles evermore exhibit a size polydispersity index down to 1.066 and strong redispersibility in water or polymer solutions. This facile synthesis of functional nanoparticles using orthanilic acid as vital comonomer readily affords yields up to 80%. A low percolation threshold of the nanoparticles/cellulose diacetate and poly(vinyl alcohol) nanocomposite films was found to be 0.18 and 0.07 wt %, respectively. This study opens a simple and general route for fabrication of nanostructured polymer materials with controllable size, narrow size distribution, intrinsic self-stability, strong dispersibility, high purity, and regulable electroconductivity.

Facile Synthesis and Optimization of Conductive Copolymer Nanoparticles and Nanocomposite Films from Aniline with Sulfodiphenylamine

A new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine-4-sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV-visible spectroscopy, X-ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above-mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought-after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90x10(-4) to 1.15x10(-2) S cm(-1) with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98% of the transparency, 94% of the strength, and 5x10(7) times the conductivity of a pure cellulose diacetate film.

Analysis of Laminated Documents Using Solid-Phase Microextraction

To evaluate the condition of a laminated document, it is helpful to identify the plasticizers present in the cellulose diacetate lamination film. Plasticizers degrade more readily than the polymer, and some are less stable than others. Solid-phase microextraction in combination with gas chromatography—mass spectroscopy analysis is a simple, nondestructive, and sensitive technique for studying plasticizers and other additives in laminated documents. In this project, five types of solid-phase microextraction fibers were used to study films that contained various combinations of plasticizers. Laminated documents related to the Louisiana Purchase were also studied. Plasticizers were easily identified, as well as the possible degradation products phthalic anhydride and phenol. Various types of films were readily distinguished. With further study it may be possible to better understand the deterioration process by relating the original composition of the cellulose diacetate film to the present condition of a laminated document.

5.3 Solvent cast cellulose diacetate film

AbstractA review of the historical development, manufacture, properties and applications of solvent‐cast cellulose diacetate film.

Investigation of the Self-Organization of Lutein and Lutein Diacetate by Electronic Absorption, Circular Dichroism Spectroscopy, and Atomic Force Microscopy

Spontaneously forming H- and J-type chiral self-assemblies of lutein and lutein diacetate were studied by means of ultraviolet−visible and circular dichroism spectroscopy (CD). Spectroscopic properties of their thin films has been determined for the first time. Existence of chiral superstructures in both solution and solid phases with opposite and same handedness was demonstrated. The molecular exciton theory and the exciton chirality rule were applied to define both qualitatively and quantitatively the spectral shifts, band shape changes, and the highly intense but quite different excitonic CD activity in the two forms of aggregates. Atomic force microscopy images revealed definite threadlike morphology in lutein diacetate films referring to the formation of a nematic liquid crystal phase which probably exists in the aqueous solution either. On this basis, the vibronically coupled CD bands of lutein diacetate are attributed to an excitonic interaction arised from the twisted nematic layers.

Effects of supplemental UV-B radiation on the growth and yield of two cultivars of Japanese lowland rice ( Oryza sativa L.) under the field in a cool rice-growing region of Japan

An investigation was made of the variations in growth and grain yield in response to increased exposure to UV-B radiation of Japanese lowland rice ( Oryza sativa L.) in a cool rice-growing region. Two cultivars, UV-resistant cv. ‘Sasanishiki’ and UV-sensitive cv. ‘Norin 1’, were examined in a lowland field at Kashimadai (37°28′E, 141°06′E) in Miyagi Prefecture, Japan, for four cropping seasons from 1994 to 1997. The two cultivars were grown in a lowland field with or without supplemental UV-B radiation, which was provided by UV-B-emitting fluorescent lamps, with a 0.1-mm-thick cellulose diacetate film as a filter. In both cultivars, significant decreases in tiller number as the result of supplemental UV-B radiation were observed during the tillering stage in 1994, 1995 and 1997. Furthermore, decreases in grain size from supplemental UV-B radiation were recorded in all seasons. The trend towards small grain size was pronounced in 1996. In that year, the mean daily middle temperatures were lower throughout most of the cropping season and the mean daily hours of sunshine during the tillering stage and between the end of the panicle differentiation stage and the beginning of the ripening stage were shorter. In 1993 when the temperature and the amount of sunshine were both lower, the tiller number, the dry mass of aboveground parts and the panicle number were significantly reduced by supplemental unfiltered UV-B radiation. There was a cultivar difference in the inhibitory effects of supplemental UV-B radiation on growth between the sensitive cultivar Norin 1 and the resistant cultivar Sasanishiki. These results indicate that supplemental UV-B radiation has a positive effect on the growth and grain development of rice, which may be enhanced by unusual climatic conditions such as lower temperature and less sunshine, in cool rice-growing regions.

Growth, leaf anatomy, and physiology of Populus clones in response to solar ultraviolet-B radiation.

We compared the physiological and morphological responses of rooted cuttings of Populus trichocarpa Torr. & Gray and P. trichocarpa x P. deltoides Bartr. ex Marsh. grown in either near-ambient solar ultraviolet-B (UV-B; 280-320 nm) radiation (cellulose diacetate film) or subambient UV-B radiation (polyester film) for one growing season. Midday biologically effective UV-B radiation was 120.6 and 1.6 mJ m(-2) s(-1) under the cellulose diacetate and polyester films, respectively. Gas exchange, leaf chlorophyll, light harvesting efficiency of photosystem II, and foliar UV-B radiation-absorbing compounds (i.e., flavonoid derivatives) were measured in expanding (leaf plastochron index (LPI) 5), nearly expanded (LPI 10), and fully expanded mature (LPI 15) leaves of intact plants of plastochron index 30 to 35. Plants were then harvested and height, diameter, biomass allocation and leaf anatomical attributes determined. Net photosynthesis, transpiration, and stomatal conductance were significantly greater in mature leaves exposed to subambient UV-B radiation than in mature leaves exposed to near-ambient UV-B radiation. Concentrations of UV-B radiation-absorbing compounds (measured as absorbance of methanol-extracts at 300 nm) were significantly greater in mature leaves exposed to near-ambient UV-B radiation than in mature leaves exposed to subambient UV-B radiation. The UV-B radiation treatments had no effects on chlorophyll content or intrinsic light harvesting efficiency of photosystem II. Height, diameter, and biomass were not significantly affected by UV-B radiation regime in either clone. Leaf anatomical development was unaffected by UV-B radiation treatment in P. trichocarpa x P. deltoides. For P. trichocarpa, leaf anatomical development was complete by LPI 10 in the near-ambient UV-B radiation treatment, but continued through to LPI 15 in the subambient UV-B radiation treatment. Mature leaves of P. trichocarpa were thicker in the subambient UV-B radiation treatment than in the near-ambient UV-B radiation treament as a result of greater development of palisade parenchyma tissue. We conclude that exposure to near-ambient UV-B radiation for one growing season caused shifts in carbon allocation from leaf development to other pools, probably including but not limited to, UV-B absorbing compounds. This reallocation curtailed leaf development and reduced photosynthetic capacity of the plants compared with those in the subambient UV-B radiation treatment and may affect growth over longer periods of exposure.

FTIR evolved gas analysis of the decomposition products of cellulose diacetate

Evolved gas analysis of unplasticised cellulose diacetate flake and plasticised cellulose diacetate film (Clarifoil) was carried out as part of an assessment of the potential hazard that could occur as a result of overheating these materials during processing. In order to perform this work, a simple apparatus for heating a sample and introducing the evolved gases into an FTIR gas flow cell was constructed. These measurements were supplemented by thermogravimetry as part of another experiment. Studies of the infrared spectra and thermogravimetric data showed that both materials degrade above 250°C, generating CO, CO2 and acetic acid. In addition, Clarifoil releases plasticiser (diethyl phthalate) between 100° and 250°C. Since its flash point is 160°C, the potential fire hazard of this material needs to be taken into account during any processing operation which could reach this temperature.