Acetate Yarns Research Articles

Ultrasound-assisted dyeing of cellulose acetate

The possibility of reducing the use of auxiliaries in conventional cellulose acetate dyeing with Disperse Red 50 using ultrasound technique was studied as an alternative to the standard procedure. Dyeing of cellulose acetate yarn was carried out by using either mechanical agitation alone, with and without auxiliaries, or coupling mechanical and ultrasound agitation in the bath where the temperature range was maintained between 60 and 80°C.The best results of dyeing kinetics were obtained with ultrasound coupled with mechanical agitation without auxiliaries (90% of bath exhaustion value at 80°C). Hence the corresponding half dyeing times, absorption rate constants according to Cegarra–Puente modified equation and ultrasound efficiency were calculated confirming the synergic effect of sonication on the dyeing kinetics. Moreover the apparent activation energies were also evaluated and the positive effect of ultrasound added to mechanical agitation was evidenced by the lower value (48kJ/mol) in comparison with 112 and 169kJ/mol for mechanical stirring alone with auxiliaries and without, respectively.Finally, the fastness tests gave good values for samples dyed with ultrasound technique even without auxiliaries. Moreover color measurements on dyed yarns showed that the color yield obtained by ultrasound-assisted dyeing at 80°C of cellulose acetate without using additional chemicals into the dye bath reached the same value yielded by mechanical agitation, but with remarkably shorter time.

Orientational processes in the yarns of high-molecular-mass cellulose acetate in vapors of nitromethane and its mixture with water

The phenomenon of spontaneous changes in the linear dimensions (elongation-contraction) is described for commercial and laboratory samples of acetate yarns processed by wet spinning from high- molecular -mass cellulose diacetate in vapors of a mesophas ogenic solvent (which is able to form a lyotropic LC phase with the polymer), nitromethane, and its mixtures with water. The thermodeformational, elastic- plastic, physicomechanical, and surface characteristics of the yarns at different stages of their spontaneous deformation are analyzed. When samples are treated with probe vapors, orientational processes in the polymer matrix are activated, and this observation makes it possible to prepare yarns with improved physicomechanical characteristics and with low linear density. A new phenomenon (to our knowledge) of cyclic three- stage deformation of acetate monofilaments in nitromethane vapors is discovered. This evidence is interpreted from the standpoint of phase (amorphous glassy-liquid crystalline state) and conformational transitions as well as by the mechanism of interaction between polymers and solvent vapors and related development of the LC phase.

OPT scheduling performances: A case study

A deep insight into Optimized Production Technology (OPT) is sought for by analysing a case study regarding a leading producer of high quality acetate yarns for the textile market. The case study highlights the importance of setting proper values for OPT management parameters in order to achieve desired performances in terms of both system efficiency as well as system effectiveness. A suitable experimental design and a statistical analysis framework allowed the recognition of the impact of single OPT management parameters. Furthermore, the optimal set-points of these parameters were determined in order to cope with resource constraints in a critical manufacturing department. Scheduling performances achievable as output of 'computeraided' scheduling with OPT were confronted with traditional 'man-made' scheduling on the basis of due date performances and setup-related parameters. The results achieved allowed to avoid problems due to a scheduling procedure that underutilized OPT scheduling characteristics.

Stress relaxation during the orientation stretch of synthetics fibres

Results of investigating structural changes during the process of orientation stretching above the glass point (“hot” stretching) for a number of thermoplastic fibres have been examined: polyethylene, polypropylene, polyvinyl chloride, chlorine, kapron, nitron, lavsan, vinol, and acetate yarns, plus results of heat-treatments under tension and in the free state. The possibility of describing the relaxation of internal stresses in these fibres in terms of the concept of “operating” volume has been shown.

Properties of acetate yarns having an increased content of elementary filaments

A process has been developed for preparing 11/32 and 16.6/38 tex complex acetate yarns. Thereupon the yarn strength is increased by a factor of 1.2, and the resistance to repeated bending by a factor of 1.2–1.4.

Introduction of new instrumental methods for the analysis of raw material in the manufacture of acetate and triacetate yarns

The development and performance of measures on assimilating and introducing new technology-instrumental methods of rapid analysis of SCA and CTA quality in plants for producing them or processing them into fibre will make it possible to reconstruct requirements on raw material quality and to develop appropriate technological corrections in processes for the preparation and processing of SCA and CTA.

Normalization of specific electrical resistance characteristic of complex acetate yarns

It has been shown that, regardless of the type of lubricant or its content on acetate textile yarn, an essentially identical decrease in specific electrical resistance is observed.

Water sorption by size films

The present work deals with the investigation of diffusion and structural properties of sizing agents used for sizing secondary acetate yarns in the presence of plasticizers including water. The plasticizers (glycerin, Turkey red oil, water) are found to act as structure forming agents by changing the packing density of structural units of the diffusion medium.

Orientation processes in acetate yarns under the influence of certain solvent vapors

Treatment of acetate yarns with vapors from solvents which form a liquid-crystal phase with the polymer leads to initiation of orientation processes which are accompanied by spontaneous yarn elongation. This makes it possible to prepare yarns of low linear density and with improved physicomechanical properties.

Radiation resistance of acetate and triacetate yarns

The radiation resistance of acetate and triacetate yarns has been studied. It has been shown that, in retention of physico-mechanical properties at a radiation dose of 10 Mrad, the yarns may be placed in the series: acetate, dull > acetate, bright > acetate dyed > triacetate, bright.

Graft polymerization of acrylonitrile on acetate yarn under the action of gamma radiation

The graft polymerization of acrylonitrile from the vapor phase on acetate yarn under the action of γ-radiation has been studied. Conditions have been discovered for the preparation of modified acetate yarns with a degree of acrylonitrile grafting from 1.5 to 68.0 by wt. The possibility of increasing the resistance of acetate yarns to abrasion no less than 15-fold, with a simultaneous increase in breaking strength and retention of resistance to double bends, has been demonstrated.

Technological features of the manufacture and textile processing of acetate yarns having enhanced compactness

The technological features of the manufacture of pneumatically connected twisted (80 twists/m) yarns and possibilities of their textile processing have been examined.

Effect of spinneret hole diameter on the spinning and properties of acetate fibre

The effect of the number and diameter of spinneret holes on hole clogging and the properties of acetate yarns has been investigated under manufacturing conditions.

Test of the K�-250-ShS machine for twisting acetate yarn

An attempt has been made to use the KE-250-ShS machine for twisting acetate yarns. It has been found that in developing a new twisting machine it is advisable to use a checkerboard disposition of the spindles in its lower part with the objective of reducing the noise level, and also to use pedal braking to stop the spindles. This helps increase the productivity of twister labor, and mechanization and automation of operations associated with transfer in removing packages of weight not less than 3 kg.

A device for the take-up of pneumatically tangled acetate yarns onto a spinning package

Three variants of take-up and winding devices have been developed; these permit one to take up yarn from the spinning machine onto a commercial package by a frictionless method and ensure a constant linear velocity of yarn winding.

Spinning cellulose acetate fibres in a nitrogen stream

Results of studies on the spinning of acetate yarn in a current of nitrogen, at elevated concentrations of acetone vapor in the vapor-gas mixture in the spinning tower, have been presented.

Effect of the physicochemical properties of cellulose acetate solutions on the quality of acetate yarns

Effect of the physicochemical properties of cellulose acetate solutions on the quality of acetate yarns

Effect of the physicochemical properties of cellulose acetate solutions on the quality of acetate yarns

Effect of the physicochemical properties of cellulose acetate solutions on the quality of acetate yarns

Texturing cellulose acetate yarns with the aid of laser techniques

Texturing cellulose acetate yarns with the aid of laser techniques

Abrasion resistance of acetate yarn

Abrasion resistance of acetate yarn