Cellulose Diacetate Films Research Articles

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.

Measurement of particle/membrane interactions by a hydrodynamic method

A fundamental study of particle detachment of micron-sized glass particles from a model membrane surface is made. The model membrane surface consisted of a cellulose diacetate film which is the polymeric constituent of the hollow fibre membranes used in industrial water treatment. This experimental study aims to analyse the factors leading to the retention of particles on these membranes. We used a hydrodynamic method in which the release of deposited particles was measured under the action of fluid flow. The hydrodynamic force is calculated under well defined hydrodynamic conditions and related to the total adhesive force acting on the particle. We studied the influence of several factors such as, pH, solution salinity, and the effects of adsorbed polymer or non-ionic surfactant on the particles. In the absence of organic solutes adsorbed on the particles, the magnitude of the particle-membrane interaction depended on the pH and the salinity of the aqueous medium, as predicted by the DLVO theory. When adsorbed polymer layers are coated on the surface of the particles, the adhesive force between the particles and the surface was found to be significantly greater than that for bare particles. This contrasted to the decrease in adhesion force observed for particle coated with non-ionic surfactant.

Sorption of vapors and gases by cellulose acetate films

Cellulose diacetate and triacetate films 6–55 µm thick with a total porosity of 0.8–2% were prepared by pouring a solution on an immobile surface and by calendering. Sorption of H2S and CO2 gases and acetone vapors on these films was investigated in static and dynamic conditions. It was shown that films 6–10 µm thick prepared by calendering should be used for purification of air from H2S and CO2 and films 15–20 µm thick prepared by pouring should be used for removal of acetone vapors.

Effects of Enhanced Ultraviolet-B Radiation with a Modulated Lamp Control System on Growth of 17 Rice Cultivars in the Field.

To investigate the effects of enhanced UV-B radiation on the growth of rice, 17 lowland cultivars from a variety of geographical regions were pot-grown for two months in the field under eight 40W fluorescent sunlamps filtered with 0.13mm thick cellulose diacetate film (Transmission down to 290nm) in Tsukuba, Japan (360°01′N, 140°07′E, 25m elevation). As a control, 0.13mm thick Mylar D film, which effectively absorbs radiation below 320nm, was used in place of the cellulose diacetate film. Output of the UV lamps in the field was supplied by a feedback control system throughout the day to provide a supplemental levels proportional to ambient solar UV-B. UV-B irradiance weighted with generalized plant response action spectrum normalized at 300nm (UV-BBE) was controlled to 2.67 tims control plots at the plant height from August 25 to October 22, 1992. No significant effects of the two-month supplemental UV-B irradiation treatment were detected on any growth parameters for all the cultivars. For example, plant height, tiller number, heading date and dry weight of whole plants were unaffected by extremely high UV-B irradiation. On the other hand, the concentration of UV-absorbing compounds and chlorophyll in rice leaves exposed to supplemental UV-B tended to increase in many cultivars, although these differences were not statistically significant except a few cultivars.

A comparative study of the thermal discharge behaviour of cellulose diacetate and cellulose triacetate films

AbstractThe thermal discharge behaviour of cellulose diacetate (CA2) (39% acetyl content) and cellulose triacetate (CA3) (44% acetyl content) films was studied at different polarizing temperatures and fields. Cellulose diacetate exhibited two peaks, one at low temperatures and the other at high temperatures, whereas cellulose triacetate exhibited only one peak. The origin of these peaks in CA2 is attributed to dipolar orientation and space charge polarization respectively, while the only peak in CA3 is due to space charge polarization. The difference in thermal discharge behaviour of CA2 and CA3 is attributed to the difference in acetyl contents of the two acetates.

Aerobic biodegradation of cellulose acetate

AbstractTwo separate assay systems were used to evaluate the biodegradation potential of cellulose acetate: anin vitroenrichment cultivation technique (closed batch system), and a system in which cellulose diacetate (CDA) films were suspended in a wastewater treatment system (open continuous feed system). Thein vitroassay employed a stable enrichment culture, which was initiated by inoculating a basal salts medium containing cellulose acetate with 5% (v/v) activated sludge. Microscopic examination revealed extensive degradation of CDA (DS = 2.5) fibers after 2–3 weeks of incubation. Characterization of the CA fibers recovered from inoculated flasks demonstrated a lower average degree of substitution and a change in the mol wt profiles.In vitroenrichments with CDA (DS = 1.7) films were able to degrade > 80% of the films in 4–5 days. Cellulose acetate (DS = 2.5) films required 10–12 days for extensive degradation. Films prepared from cellulose triacetate remained essentially unchanged after 28 days in thein vitroassay. The wastewater treatment assay was less active than thein vitroenrichment system. For example, approximately 27 days were required for 70% degradation of CDA (DS = 1.7) films to occur while CDA (DS = 2.5) films required approximately 10 weeks before significant degradation was obtained. Supporting evidence for the biodegradation potential of cellulose acetate was obtained through the conversion of cellulose [1‐14C]‐acetate to14CO2in thein vitroassay. The results of this work demonstrate that cellulose acetate fibers and films are potentially biodegradable and that the rate of biodegradation is highly dependent on the degree of substitution. © 1993 John Wiley & Sons, Inc.

SPECTRAL QUALITY OF TWO FLUORESCENT UV SOURCES DURING LONG‐TERM USE

Abstract—The characteristics of a fluorescent ultraviolet (UV) lamp (UVB‐313), UV‐B transmitting cellulose diacetate (CA) and UV‐B absorbing polyester (PE) films were determined during actual use. Although lamp emission was stable between 70 and 386 h of burn time (longer times were not investigated), the absorbance of UV‐B and UV‐A radiation by CA and PE films, respectively, increased with time when wrapped around lamps. As a result, the irradiance of lamp/filter combinations decreased steadily (even when CA films were presolarized for 10 h), making it necessary to compensate by adjusting the height of the lamp bank or by changing filters frequently. Note that corrective action is required for UV‐A controls (PE films) as well as UV‐B experimental treatments (CA films). Changing filters is preferable, since aging of CA filters caused shifts in the ratio of UV‐B to UV‐A. However, in spite of these shifts, the normalized spectrum of weighted biologically effective UV‐B radiation did not change to a large extent.

Peculiarities of the deformational behaviour of cellulose diacetate films in “active” fluids

AbstractThe rheological behaviour of cellulose diacetate films preliminarily oriented in ethanol has been studied under conditions of constant stress and constant load in the range of temperatures from 40 to 60°C. The analysis of the flow curves shows that the observed effects can be explained in terms of “a negative longitudinal viscosity”. This is probably caused by the occurence of a mesophase in the material. A method for measuring of “the negative longitudinal viscosity” is proposed.

Features of the extensional flow of cellulose diacetate films in active media

The behaviour of cellulose diacetate films that had been previously oriented in ethanol has been studied during uniaxial extension in a water-phenol mixture under conditions of constant stress and constant force in the temperature range 40–60°C. Analysis of the flow curves obtained has enabled it to be concluded that the observed relationships may be explained in terms of a “negative extensional viscosity”, the internal source of which is apparently a mesophase formed in the material. A direct rheological method of measuring the “negative extensional viscosity” is proposed.

Cotton Effect Induced in Optically Inactive Molecules and Molecular Complexes by Optically Active Environment. II. Acridine and Phenazine in Cellulose Diacetate Film

Abstract Ultraviolet absorption spectra and induced circular dichroism (ICD) of acridine and phenazine were measured in cellulose diacetate film. The induced Cotton effect corresponding to each absorption maxima of these systems appeared. From the correspondence between the maxima of ICD and the peaks of the resolved absorption spectra, it was found that the sign of ICD is negative in the region where the molecular long-axis polarized transition plays a part in the CD induction and it is positive in the region where short-axis polarized transition does. A mechanism of CD induction tentatively proposed is that a dye molecule is imprisoned in a cage formed by an assembly of the folded chains of cellulose diacetate and the Cotton effect is induced by an electrostatic interaction between electronic transition dipole moments of the dye and of the chromophores involved in the cellulose diacetate cage.

Photo-conversion of cellulose triacetate and the effect of stabilizing additives

A study was made of photo-conversion of cellulose triacetate and diacetate films in air and in vacuum exposed to a DRSh-100 lamp or 254 nm monochromatic light (BUV-30 P lamp). Quantum yields of decomposition of acetyl groups (1·5 × 10 −2), ether groups (1 × 10 −2) and the formation of acetic acid (7 × 10 −3−8 × 10 −3) were determined. Quantum yields of the formation of carbonyl (2 × 10 −3−6 × 10 −3) and hydroxyl groups (5 × 10 −3) were evaluated. It was shown that the light resistance of polymers is increased by anti-oxidants in concentrations of the order of 0·01% and UV absorbents in concentrations of the order of 0·01% and UV absorbents in concentrations of the order of 1%, evidently acting by different mechanisms. The protective effect of UV absorbents considerably exceeds their screening action.

Kinetic Consideration of Photofading of Fluorescent Brightening Agent

Fluorescent brightening agents, 1, 2-bis 5-methylbenzoxazolypethylene and its derivatives, are dimerized by uv light both in solution and in polymer film. With increase in concentration, the rate of the fading of the dye increases to a certain limit and then decreases. This tendency is more pronounced in polymer film, such as cellulose diacetate and polypropylene, than in ethanol and benzene solutions.In this paper, behaviors of fading of the dye in solution and polymer film are discussed from the chemical kinetic point of view.If diffusion of the dye is assumed to be restricted strongly in polymer film, rate of fading of the dye molecule will decrease with increasing distance from the irradiating surface. A rate law of fading under restricted diffusion is constructed and solved by assuming several initial conditions.The calculations, however, show that restricted diffusion has no effect on the overall decay of the dye (Table 2).Another rate law (equation (10)), constructed by assuming the retardation effect, can not afford a reasonable explanation of the observed decay curves.On the other hand, the experimental results in solution and polymer film appear to be accommodated by considering the simultanious trans-cis photoisomerization and photodimerization, if steady state approximation for concentration of cis-isomer is assumed (Table 4). The decay in cellulose diacetate film is explained by assuming that the photoreaction proceeds in two phases: the one is discrete dispersion and the other assembly phase, and that considerable amount of the dye molecule is restrained in the former phase.The kinetic parameters in solution and in polymer film are compared and discussed (Table 3).

The swelling of cellulose diacetate films obtained from gels

The swelling of cellulose diacetate films obtained from gels