Triacetate Fibers Research Articles

Reduction of Lactose of Milk by Entrapped β-Galactosidase. II. Conditions for an Industrial Continuous Process

The kinetics of hydrolysis of lactose in milk by β-galactosidase entrapped into cellulose triacetate fibers was studied. With active preparations of β-galactosidase, hydrolysis occurred at low temperatures. Seventy-five percent of milk lactose was hydrolyzed in 4h at 5C, and the quality of treated milk was good from a flavor and bacteriological view. Mesophilic and psychrophilic bacteria were always less than 15,000 per ml in treated milk.

INTERACTIONS BETWEEN CELLULOSE TRIACETATE FIBER AND ORGANIC SOLVENTS

Interactions between cellulose triacetate fiber and organic solvents are discussed with regard to the swelling behavior of cellulose triacetate fiber in many kinds of organic solvents involving chlorinated hydrocarbons such as trichioroethylene, tetrachloroethylene and 1, 1, 1-trichloroethane, important media for solvent dyeing and finishing. Results obtained were as follows:(1) The results on the equilibrium swelling of cellulose triacetate fiber in solvents showed that the interactions between cellulose triacetate fiber and solvent can be interpreted mainly by dipole force and two kinds of hydrogen bonds in which the solvent behaves as a proton accepter and a proton donor.(2) The diffusion behavior of solvents in cellulose triacetate fiber involves several kinds of unusual behavior. These are explained by the relaxation of the substrate structure interacting with solvent and the instantaneous internal stress caused by swelling.(3) From the relationship between the activation energy of diffusion and molecular volume of solvents, it is assumed that dispersion force and π-type hydrogen bond act between cellulose triacetate fiber and solvent.

Synthesis of L-Tryptophan from Indole and DL-Serine by Tryptophan Synthetase Entrapped in Fibres

The synthesis of L-tryptophan from indole and DL-serine catalyzed by tryptophan synthetase entrapped in cellulose triacetate fibres was investigated using batch and continuous feed recycle reactors. Tryptophan productivity, expressed as mg of tryptophan per hour per g of fibres, was 34 and 4 for the batch and the continuous reactor respectively; the final conversion of L-serine was 57% and 6.6%; practically all the indole was converted to tryptophan in the two reactors. Pyridoxal-5'-phosphate was necessary for the activity of the entrapped enzyme. D-Serine showed a slight inhibitory effect, was not utilized by the entrapped enzyme and after racemization at 160°C was reused. By increasing the molarity of the buffer used in the reaction mixture a decrease of tryptophan productivity was observed. The product, isolated from the reaction mixture was pure L-tryptophan.

Synthesis of L-Tryptophan from Indole and DL-Serine by Tryptophan Synthetase Entrapped in Fibres

Optimal culture conditions for microbial production of tryptophan synthetase were studied. It was found that on cultivation of Escherichia coli 476, a tryptophan auxotroph, in a medium containing 5g/liter glycerol as C source, supplemented with 1 g/liter of acid-treated peptone, cells with high tryptophan synthetase activity could be obtained.The enzyme was extracted from cells and 3-fold purified by heat treatment and ammonium sulfate precipitation. The overall yield of the isolation procedure was 60%.The partially purified tryptophan synthetase was entrapped in cellulose triacetate fibres. Under storage conditions, in refrigerator, the entrapped enzyme was stable at least for 6 months. The activity of the entrapped enzyme was about 75% with respect to the free enzyme.Similar behaviour for the free and entrapped enzyme was observed as to the effect of temperature and pH on the enzymic activity. The operational stability of the entrapped tryptophan synthetase was very good (activity unchanged after 50 day...

Effect of multiple extension on the thermal degradation of triacetate fiber

The effect of multiple extension on the vacuum thermal degradation of triacetate fiber, in the starting state and treated with hot air or saturated steam, has been experimentally investigated.

The effect of dioxane on cellulose acetylation and the properties of triacetate fibre

The effect of dioxane on cellulose acetylation and the properties of triacetate fibre

Reduction of Lactose Content of Milk by Entrapped β-Galactosidase. I. Characteristics of β-Galactosidase from Yeast and Escherichia coli

A comparative study of free or entrapped β-galactosidase from Escherichia coli and yeast is reported. The bacterial enzyme was stable up to 45C while yeast enzyme rapidly lost its activity above 30C. The rate of hydrolysis of lactose in milk was about 30% of the rate with pure lactose for β-galactosidase of Escherichia coli. The enzyme from yeast hydrolyzed milk and pure lactose at the same rate. β-galactosidases from Escherichia coli and yeast showed pH optima of 6.6 to 7.5 and 6.0 to 7.0. Behavior was the same for enzymes entrapped in cellulose triacetate fibers. The entrapped enzyme retained original activity for over 80 days during continuous operation. No leakage of activity from the matrix was detected after the first washing. Analysis of the properties of entrapped β-galactosidase indicated a potential industrial application in reducing lactose content of milk.

Influence of acetone-soluble fraction content on physicomechanical properties of cellulose triacetate

The influence of a change in the acetone-soluble fraction content on the physicomechanical properties of irradiated triacetate (CTA) fibers has been investigated. The results obtained showed that irradiation of CTA sharply alters the acetone-soluble content of CTA fibers, which correlates well with the changes in physicomechanical properties

Heat-treating wet-spun triacetate fibre in a plasticizing medium

Heat-treating wet-spun triacetate fibre in a plasticizing medium

The molecular weight of the polyethylene oxide as a factor in the physico-mechanical properties of wet-spun triacetate fibre

The molecular weight of the polyethylene oxide as a factor in the physico-mechanical properties of wet-spun triacetate fibre

Solvent loss and air pollution in the spinning rooms of the triacetate fibre sector

Solvent loss and air pollution in the spinning rooms of the triacetate fibre sector

Supramolecular structure and properties of modified triacetate fibres

Supramolecular structure and properties of modified triacetate fibres

Heat treatment of wet spun triacetate fibre

Heat treatment of wet spun triacetate fibre

Radiation‐induced graft copolymerization of mixtures of styrene and n‐butyl acrylate onto cellulose and cellulose triacetate

AbstractMixtures of styrene and n‐butyl acrylate of various compositions were grafted onto cellulose and cellulose triacetate fibers preirradiated with γ‐rays at 0°C in air. Monomer reactivity ratios of the grafted copolymers were found to be different from those of the nongrafted copolymers or those of AIBN‐initiated copolymers. The active species initiating the graft copolymerization were trapped radicals for cellulose and peroxides for cellulose triacetate. Kinetic investigations of the graft copolymerization of styrene onto preirradiated cellulose triacetate fibers were also carried out, and it was found that the kinetic scheme for radical polymerization is also applicable to graft copolymerization in a heterogeneous system.

Peak resolution and X-ray crystallinity determination in heat-treated cellulose triacetate

X-ray diffraction traces of cellulose triacetate fibres heat-treated in the range 220 – 290°C were resolved by a computational method which fits Gaussian or Cauchy functions to the peak profiles. A polynomial background is fitted at the same time so that the total area formed by the resolved peaks is a parameter for estimating crystallinity and the area under the background is a parameter for estimating the non-crystalline or disordered component. This measure of actual crystallinity is shown to be dependent upon the function chosen for the peak profile. After appropriate corrections, crystallite widths were obtained and compared with fibril widths measured on electron micrographs. Cauchy resolution data overestimate crystallite size whilst Gaussian resolution data underestimate it. In all cases the crystallites from fibres annealed at 290°C have greatly increased widths compared with crystallites from fibres annealed at 220°C or 250°C.

Physical and mechanical properties of triacetate fibre modified with ED-5 epoxy resin

Physical and mechanical properties of triacetate fibre modified with ED-5 epoxy resin

The dry-spinning conditions as a factor in the properties of triacetate fibre

The dry-spinning conditions as a factor in the properties of triacetate fibre

THE SAPONIFICATION OF CELLULOSE TRIACETATE FIBER

Cellulose acetate fibers of various acetyl contents were obtained from the saponification of cellulose triacetate (CTA) fibers with 0.01_??_0.2 N NaOH and 1.0_??_1.8 N HCl solutions. X-ray diffraction and dynamic viscoelastic property of these cellulose acetate fibers were measured and the deacetylation mechanism of cellulose triacetate fibers is discussed in connection with their dyeing behavior.When CTA fibers were saponified in NaOH solutions, the CTA crystals and αa absorption due to micro Brownian motion of CTA amorphous molecules disappeared at the same concentration of NaOH solution. This result indicates that deacetylation proceeds annularly from the outside of the fiber as obserbed from the dyeing behavior.On the other hand, saponification behavior with HCl solutions was fairly different from that of NaOH solutions. In the lower concentration of HCl solutions, saponification reaction didn't take place, but there was a change in the structure of CTA fiber, such as relaxation of the CTA chain molecules. In the middle concentration, the saponified fibers could be dyed with a direct dyestuff, but the CTA crystals still remained. In the higher concentration, the saponification proceeded to the crystalline regions, but the cellulose fibers formed with HCl saponification had a low thermal stability and low crystallinity. The saponification process of CTA fibers with HCl solution, therefore, does not agree with that speculated from their dyeing behavior.

Corrosion resistance of the metal materials in the triacetate fibre production sector

Corrosion resistance of the metal materials in the triacetate fibre production sector

Molecular weight distribution in cellulose triacetates and its effect on the mechanical properties of fibres

1. A precise method is defined for determination of the molecular-weight distribution of the original cellulose acetate by fractional precipitation of 1% methylene chloride solutions of the TAC in ethanol. 2. A method is developed for quantitative determination of low-molecular fractions which is based on extraction of the polymer from a mixture of methylene chloride and ethanol at 25°C with addition of ammonium thiocyanate. 3. The dependence of the physical and mechanical properties of triacetate fibres on the average molecular weight of the polymer is demonstrated.