Secondary Cellulose Acetate Research Articles

Miscibility and dynamical properties of cellulose acetate/plasticizer systems.

Due to its biodegradability and renewability, a great interest has been devoted to investigating cellulose acetate in order to expand its potential applications. In addition, secondary cellulose acetate (CDA) could also be considered as a model system for strongly polar polymer system. The dynamical behavior of CDA is supposed to be governed by H-bonding and dipolar interaction network. Due to their high glass transition temperature, cellulose acetate-based systems are processed when blended with plasticizers. It is thus of utmost importance to study the miscibility and plasticizing effects of various molecules. We prepared CDA films via solvent casting method with diethyl phthalate as the plasticizer. Miscibility diagrams were established by calorimetry and thermo-mechanical (DMTA) experiments. Dynamical properties were analyzed by DMTA and broadband dielectric spectroscopy. We could identify the α-relaxation of these CDA-plasticizer systems in the frequency range from 0.06 Hz to 10(6)Hz, which allowed for describing the dynamics in the so-called Williams-Landel-Ferry/Vogel-Fulcher-Tammann regime.

Modification of acetate fibers by adding fluoropolymers to the spinning solution

The ability to prepare modified acetate fiber by adding fluoropolymer to the spinning solution was examined. Poly-2-perfluoropentoxytetrafluoropropylacrylate was used as the modifier. The rheological properties of the spinning solution of secondary cellulose acetate with added fluoropolymer were investigated. Fibers were spun from composite solutions of secondary cellulose acetate and various amounts of poly-2-perfluoropentoxytetrapropylacrylate using a coagulation (wet) method. Their lipophobic properties were studied. The thermal properties of the modified acetate fiber were studied using thermogravimetric analysis.

Vapour-phase Dyeing of Synthetic-polymer Fibres

Absorption isotherms at high temperatures for some disperse dye vapours and secondary cellulose acetate film have been determined and found to be linear. In order to calculate dye vapour concentrations, two methods have been used for the determination of vapour pressures, and from the results it is shown that disperse dye molecules can associate in the vapour phase. The absorption of dye vapour by polyester fibre in the form of small packages over the range 180–220°C, as well as a laboratory machine that can be used for this purpose, are described. Package dyeing on a larger scale with dye vapour is considered to be possible.

Ultrafiltration membranes made of secondary cellulose acetate modified with active carbon

It was hypothesized that active carbon will play the role of an inert filler and cause the formation of a more developed pore structure in membranes since pores are formed as a result of the counteraction of the forces of contraction and adhesion during phase separation in evaporation of the solvent. The carbon particles perturb the structure of the polymer network The porosity of the membranes also increases because the filler has a porous structure. Active carbon can be used to improve the performance properties of membranes.

Preparation and properties of silicon oxycarbide fibers

Silicon oxycarbide fibers have been prepared from vinyl trimethoxysilane (VTMS) by a modified sol–gel method and with secondary cellulose acetate (SCA) as the fiber-forming aid. Its main advantage over a normal sol–gel fiber processing is that the spinning dope remains spinnable for a long period of time. The effect of the pre-hydrolysis of VTMS on the dope spinnability is studied. At H2O/VTMS = 4, the resultant sol transforms into gel very quickly, unsuitable to obtain a spinnable dope; at H2O/VTMS = 2, too much un-reacted VTMS exists in the sol, making the extruded fiber difficult to solidify; at H2O/VTMS = 3, a dope with good spinnability and stability, and thus high ceramic yield is obtainable. Pyrolysis at 1,000 °C in argon/5% hydrogen results in silicon oxycarbide fibers with the maximum tensile strength (940.0 MPa), moderate Young’s modulus (63.2 GPa) and high carbon content (33.2%).

Rheological properties of spinning solutions for cellulose acetate ultrafiltration membranes

Addition of ethyl alcohol in the amount of 5 to 25 wt. % significantly reduces the viscosity of secondary cellulose acetate (SCA)—acetone—water spinning solutions. The effective viscosity of the spinning solutions decreases significantly when the shear stress changes. SCA membranes made from solutions with lower viscosity have higher permeability both for water and for cheese whey. The data obtained can be used to vary the performance properties of ultrafiltration membranes within wide limits.

Optical properties of process solutions of secondary cellulose acetate in acetone

Addition of alcohol to SCA—acetone spinning solutions for manufacture of ultrafiltration membranes causes disaggregation of microgel particles and results in more homogeneous solutions. Decreasing the concentration of the spinning solution also causes disaggregation of microgel particles. Membranes made of 5% SCA—acetone solutions swell more rapidly than membranes from 7 and 10% solutions and have higher throughput of water and cheese whey for the same alcohol content.

Effect of the Kinetics of Evaporation of Solvent on the Performance Characteristics of Ultrafiltration Membranes Made of Secondary Cellulose Acetate

Two methods are proposed for dry-wet formation of membranes from SCA for ultrafiltration of cheese whey: dry formation followed by modification in aqueous medium and spontaneous gelation on a calender followed by modification in aqueous medium, which significantly differ in the solvent evaporation rate (12 h and 3–5 min). It was shown that the solvent evaporation rate affects formation of the pore structure of the membranes. In formation with the spontaneous gelation method on a calender, membranes with a less developed pore structure and better permeability for water and cheese whey are obtained in comparison to membranes formed by the dry method. The pore structure of the membranes can be regulated with NaHCO3 filler. Membranes from 5–7% solutions of SA at a 3–4 wt. % NaHCO3 content are the most efficient.

Vat Dyeing Properties of a Novel Regenerated Cellulosic Fiber

The dyeing behavior of a novel regenerated cellulosic fiber (enVix®), prepared from secondary cellulose acetate fibers by the hydrolysis of acetyl groups, is investigated with three vat dyes. The effect of liquor ratio, temperature, and dye concentration on the dyeing properties of the enVix and viscose rayon are evaluated. The enVix exhibits better dyeability and fastness than viscose rayon, presumably due to its lower crystallinity.

Monomeric dioxouranium(VI), chromium(III), cobalt(II), nickel(II) and copper(II) complexes with primary cellulose acetate (PCA)

Monomeric UO 2 2+ , CrIII, COII, NiII and CuII complexes with primary cellulose acetate (PCA) have been prepared and characterized. Infrared,1H NMR, UV/visible spectroscopy, elemental analysis, therniogravimetry, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that PCA exhibits octahedral coordination with CrIII, CoII, NiII and a square planar form with CuII whereas the UO2 moiety is virtually linear. PCA acts as a neutral bidentate chelating agent via the two oxygen atoms of the vicinal ester groups in the secondary positions forming a five-membered chelate ring. A comparative study between chelates of PCA and those previously prepared with secondary cellulose acetate (SCA) has been undertaken.

Photoinduced Graft Copolymerization of Styrene onto Secondary Cellulose Acetate Containing Vanadium(V) Chelate

Abstract Photoactive polymer has been prepared by the reaction of VOQ2OH (Q: 8-quinolyloxo ligand) with secondary cellulose acetate in dry benzene solution. The photoactive polymer produced, red-violet in color, was characterized by IR and UV-visible spectroscopy. Irradiation of this type of polymer in styrene monomer, both in bulk and in benzene solutions, produces a graft and cross-linked copolymer. This indicates that a radical is produced on the backbone of the secondary cellulose acetate molecule by the so-called intraphotoredox reaction. UV-visible spectral changes during irradiation in styrene solution suggest that the photoreaction is relatively uncomplicated with production of vanadium(IV) species. The grafted polymer was characterized by IR spectroscopy, and the percent grafting and grafting efficiency were determined and monitored as a function of the photoactive cellulose acetate concentration.

Preparation and characterization of cellulose acetate complexes

Metal chelates of secondary cellulose acetate (SCA) with chromium(III), copper(II), cobalt(II), nickel(II) and UO22+ were prepared and characterized by elemental analyses, magnetic moments and spectral studies. SCA acts as a uninegatively charged bidentate ligand and reacts with the metal ion via the oxygen atom of the secondary unacetylated hydroxyl group in the glucose subunit of the polymer, plus the oxygen atom of the vicinal ester group, to form a five-membered chelate ring.

Secondary cellulose acetate hollow nanofiltration fibre

The studies showed that addition of certain amounts of glycerin and PEG to solution causes corresponding changes in structure and allows obtaining hollow fibres with nanofiltration properties. The parameters for spinning a hollow nanofiltration fibre for purification of part of the wastes from production of viscose fibres were developed based on the data obtained.

Biodegradable Plastics Based on Cellulose Acetate

Abstract It is generally known that secondary cellulose acetate (with 53 to 56% acetyl groups) is suitable for thermoplastic processing. With appropriate plasticizers a plastic material is obtained which excels in transparency and pleasant texture, and it is therefore often used for tool handles, combs, spectacle frames, and the like. In principle, cellulose acetate with such a degree of substitution is biodegradable, although degradation proceeds extremely slowly. However, when common plasticizers are substituted by specific esters and other low molecular components (at least 30% by weight), the “plastic material” has the same thermoplastic properties but will decompose in soil or water within just a few years. For example, a cellulose acetate cup buried in sewage sludge lost more than 70% of its original weight within about 18 months. In an aqueous environment (Sturm's test), the decomposition amounted to more than 60%. Under appropriate composting conditions or conditions of anaerobic fermentation, the...

Studies on Cr III-cellulose acetate complexes

Cr III complexes with acetylated bagasse dissolving pulp (I) and acetylated bagasse kraft paper pulp(II) have been prepared and characterised by means of electronic and vibrational data. The electronic absorption spectra of Cr III with I and II exhibit absorption bands at 16 666 and 23 324 cm −1, which are assigned in octahedral symmetry to the transitions 4T 2g ← 4A 2g and 4T 1g ← 4T 2g, respectively. The third highest band, associated with the 4T 1g ← 4T 2g transition, is not observed, being obscured by charge transfer absorption. The ligand field parameters Dq and B have been calculated. The nephelauxetic parameter, β, has the value 0·67 suggesting strong covalency in the metal-ligand σ bond. Cr III-II complexes have higher optical absorbance than Cr III-I complexes. Since I has a greater acetyl content and lower D.P. than II, that is II has more unacetylated hydroxyl groups, then the hydroxyl groups must be more involved in chelation. The secondary cellulose acetate (SCA) acts as uninegatively charged bidentate ligand and coordinates via the O-atom of the hydroxyl group and the O-atom of the ester group to form stable five-membered rings.

Effect of molecular and compositional heterogeneity on the rheological properties of cellulose acetate solutions

The properties of acetate fibers are essentially a function of the physical and chemical heterogeneity and the rheological properties of solutions of secondary cellulose acetates (SCA). For this reason, the study of the effect of the molecular and compositional heterogeneity of cellulose acetates on the rheological properties of solutions is important.

Sorption isotherms of disperse dyes on various polymers from water.

Sorption isotherms of purified disperse dyes on various polymers from water were carefully measured. Azo dyes (C.I. Disperse Orange 5, Red 1, 17, 19, etc.) and an anthraquinone dye (Disperse Red 15), and cellulose film, secondary cellulose acetate fiber, Nylon 6 film and fiber and poly(ethylene terephthalate) microfiber and film were used. Most of the sorption isotherms measured were not linear but curved convex to upward and were expressed satisfactorily in terms of dual-sorption model of the linear combination of Nernst-type partitioning and Langmuir sorption. The amounts of the dyes sorbed by Langmuir sorption were usually smaller than that by the partitioning

Influence of Spinning Dope Additives and Spin Bath Temperature on the Structure and Physical Properties of Acrylic Fibers

We have studied the effect of spinning dope additives and spin bath temperatures on the structure and properties of wet spun acrylic fibers. The dope additives were secondary cellulose acetate, polyvinyl pyrrolidone, polyvinyl acetate, and glycerol. Amounts of 5% (w/w) of each of these were added to the spinning dope of acrylonitrile vinyl acetate sodium methallyl sulphonate (92.7:7.0:0.3 by wt) terpolymer, and wet spun using 45:50 (v/v) of dimethyl acetamide : water, varying the spin bath temper ature from 10 to 60°C. Fibers with 5% secondary cellulose acetate as an additive exhibited low density values, highest moisture regain (2.6% against 1.6% of the parent acrylic fiber), and a three- to four-fold increase in water retention values. The tenacity was greatest in fibers with 5% polyvinyl acetate, added and spun at a 45°C spin bath temperature. We also studied the microstructure of the protofibers and the final fibers using both optical and elecqon microscopy for a better understanding of the effect of spin bath temperature on physicomechanical properties.

Effects of pressure and solvent on the diffusion of aromatic compounds through polymers

The diffusion of six azo and five anthraquinone derivatives through nylon 6, poly(ethylene terephthalate) and secondary cellulose acetate films were studied under high hydrostatic pressures of up to 3000 bar and at temperatures 80–130 °C, by analyzing the diffusion profiles yielded in a stacked multiple film, placed in the solution of the diffusant. It was found that the diffusion coefficient,D, of the diffusant decreased with increasing pressure, giving a linear relationship between InD and the pressure, the slope of which gave the activation volume for the diffusion,ΔV≠. It was revealedΔV≠ increased linearly with increasing intrinsic molecular volume of the diffusant,Vw, the slopes being different between the azo and the anthraquinone derivatives. The ratio ofΔV≠ toVw (ΔV≠/Vw) ranged from 0.13 to 0.93, depending in a sensitive manner on the degree of swelling of the polymer matrix which in turn was varied by the solvent. The overall results could be explained in accordance with the formulation,Vf, local +ΔV≠=Vw, whereVf, local represents the free volume contribution. It was proposed thatVw is increased by solvation when the solvent is good for the diffusant.

EFFECT OF SOLVENT ON <i>Δ</i><i>V</i> FOR THE SORPTION OF <i>p</i>-AMINOAZOBENZENE IN SECONDARY CELLULOSE ACETATE

Pressure effect on the sorption equilibria of p-aminoazobenzene (pAAB) from the solutions to secondary cellulose acetate (CDA) has been investigated under pressures up to 2500 bar and at a temperature of 80°C. The solvents used were water, benzene, n-propanol, n-pentanol and n-heptanol. Under the pressures all the sorption isotherms were found to be linear and the pressure dependence of the partition coefficient, K, was analyzed in terms of ΔV, the difference in the partial molar volumes of pAAB between the polymer and the solution phases, as obtained by where R, T and P are the gas constant, absolute temperature and pressure, respectively.ΔV was found to be independent of pressure. It was -4.8cm3/mol for the aqueous solution system, while, for the organic solvent systems, pressure had much less effect on the sorption and ΔV's were found to be much smaller in the absolute values, 0_??_-1.3cm3/mol. The negative value of ΔV found for the aqueous solution system was ascribed to the volume contraction induced by the intermolecular attractions between pAAB and CDA, which should be stronger than those between pAAB and H2O as suggested from the large value of the partition coefficient. In contrast, for the organic solution systems, it is considered that pAAB molecule is strongly solvated by the solvents and such solvation is much likely preserved in the polymer phase swollen with the solvent, leading to a chemically similar situation around the pAAB molecule both in the solution and in the polymer phases. It was pointed out that the above explanations were in accord with our previous studies on the activation volume for the diffusion conducted with respect to the same systems.Finally, ΔV's obtained in our studies were compared with the heat of sorption data reported on similar systems. ΔV's and ΔH°'s took negative values and a positive correlation between ΔV and ΔH° was found, which is understandable because both negative ΔV and ΔH° are induced by approaching closer with each other between nonbonded atoms in the sorption system.