Rayon Fabrics Research Articles

THE TECHNIQUE OF VISCERAL PACKING

Since 1986, we have cared for 17 patients whose abdomen could not be closed because of bowel edema and loss of abdominal wall compliance. These patients were managed by a technique of visceral packing with the intestines kept in place by a combination of rayon cloth, gauze packs, and retention sutures. This packing was changed in the operating room under general anesthesia until the edema was sufficiently resolved to allow for closure. Two patients died within 24 hours of operation from irreversible shock. The remaining 15 patients had their fascia successfully closed with an average of two additional anesthetics. There was one case of fasciitis associated with the development of an intra-abdominal abscess and one patient died of late sepsis. There was no early postoperative ventilatory compromise or acute oliguric renal failure. Other direct complications have been minor with no enterocutaneous fistulae, dehiscence, or incisional hernia. Visceral packing of posttraumatic abdominal wounds circumvents expected complications of intraperitoneal hypertension and enhances the chance for survival. Its ease and low morbidity also lends itself to a wide variety of other uses.

Management of the Difficult Abdominal Closure

Hemorrhagic shock and multiple trunk injuries, especially severe pelvic fracture, may cause massive swelling of intra-abdominal viscera and the abdominal wall, thereby precluding safe, primary abdominal wall closure. Primary closure, under tension in such patients, causes a multitude of problems including respiratory compromise, reduced cardiac output, oliguria, enterocutaneous fistulae, impaired abdominal wall nutrient blood supply, necrotizing fasciitis, evisceration, and death of the patient. Multiple methods have been described to aid the surgeon in circumventing these problems. The authors advocate the abdominal wall pack technique, which has the advantages of ease of implementation and a low rate of wound complications.

リン酸アミド類を用いるセルロース繊維の防縮加工に関する研究 第２報 セルロース系繊維の防縮加工剤としてのリン酸アミド類の適性

In the design of effective shrinking-proof modification of Cellulosics, the factors to be considered including cost, efficiency, durability of shrinking-proof, and effect of the treatment on the fabric properties. A number of finishing of rayon fabrics were performed by the use of crude phosphoryl amides prepared from the reaction of phosphoryl chloride with a saturated solution of ammonia in methanol (method A), from the reaction of ammonia with a solution of phosphoryl chloride (or chloro-phosphazene) in a solvent such as chlorinated alkanes or arenes, and ethers (method B).The most eminent characteristics in the use of the phosphoryl amides prepared by the method A were the more efficiently durable shrinking-proof and fastness against chlorine damage than the case of the method B. The increase in the amount of methoxy-substituted products at high temperatures in the method A caused the decrease in efficiency of shrinking-proof and whiteness of the treated rayon fabrics.Presence of water in methanol afforded hydroxy-substituted products and ammonium phosphate derivatives. However, the crude phosphoryl amides prepared in the presence of a small amount of water gave more desirable shrinking-proof, probably due to the catalytic effect of ammonium phosphate formed for the shrinking-proof. The optimum amount of water in the methanol was about 10%. Sodium borohydride treatment before the shrinking-proof increased the whiteness of the fabrics.

Swelling of silk fabric by organic solvents.

Swelling of silk and rayon fabrics by organic solvents depended on the kind and the temperature of the solvents and the period of immersion. The degree of swelling after the shrink proofing using phosphoryl amide was comparable to that before the proofing. Dimethyl sulfoxide was one of the best solvents for the shrink proofing by phosphoric amides. Some of the fundamentals govering the shrinkage of silk goods were explained on the basis of the release of the strains imposed during manufacturing processes, and the swelling produced on wetting. The mechanism of the swelling by organic solvents was explained in terms of the solubility parameter of the solvents and hydrogen bonding and dipolar interactions between silk and the solvents. The most important factor for the shrink-proofing would be cross-linking between the fibers in the very vicinity under the swelling, up to 100%, of the fabric by covalent bonding and/or adhesives.

Modelling carbon fibers oxidation in air at constant heating rates

Modelling of carbon fiber (CF) oxidation in air, at 25°–1000°C and heating rates ( HR) of 1°, 2°, 5°, 10°, and 20°C/min, has been performed. A simple thermogravimetric analysis technique has been used to examine the oxidation kinetics of three carbon fibers: a carbonized polyacrylonitrile fiber, a graphitized pitch fiber, and a graphitized rayon fabric. The modelling involved development of four main empirical eqns correlating HR to T 0.5, BO to T/ T 0.5, HR to R max , and R/ R max to BO. T 0.5 is the temperature attained when 50% of the CF gasifies, BO is the fractional burn-off at a given temperature, T, and R max is the maximum rate ( R) of oxidation mg/g starting CF.min. These eqns can predict the recession of a carbon fiber component without the need to include a surface area term in the analysis. The technique and proposed analysis, which can be used to screen a vast number of CF in a relatively short time, yield information on oxidation kinetics, activation energy, and the rate-determining step.

Morphological observation of natural fibers exposed to NO2 gas and ambient air.

Morphological changes of wool, silk, cotton and rayon fabrics exposed to NO2 gas and the ambient air were observed by the electron microscope. Both the samples exposed to 100ppm NO2 gas for 100h and to the ambient air for 18 months showed the changes on the fiber surfaces which could be recognized under the electron microscope. Cellulosic fibers are more damaged by NO2 gas than protein fibers. The difference would be connected with the existance of the amino groups in the protein fibers.

On the reactivity, structure, and porosity of carbon fibers and fabrics

Carbon fibers and fabrics have been used extensively in fabricating carbon composites. From the perspective of the fiber, the adhesion between a fiber and matrix is controlled by the type of fiber, its heat-treatment temperature and its surface properties. This article summarizes these properties on selected carbon fibers and fabrics; including the total surface area as determined by gas adsorption at 77 K, the active surface area as determined by oxygen chemisorption at 573 K and microporosity as measured by CO 2 adsorption at 298 K. The carbonized polyacrylonitrile (PAN) fiber and the graphitized rayon fabric as well as pitch fiber have small surface area (<1.0 m 2/g) and insignificant open porosity. By contrast, most of the carbonized rayon fabrics, at least the samples examined, have considerable micropore volumes. Oxidation rates of the fibers and fabrics in air have been measured at isothermal temperatures in the range 773–1223 K. With the PAN fiber, the oxidation process instantaneously opens the pores and the reaction is controlled by diffusion of O 2 into the pores and of gasification products in the opposite direction. With the graphitized pitch fiber and rayon fabric, the reaction is controlled by the chemical reactivity of the surface below 1123 K, and by the diffusion limitation at higher temperatures. At 773 K, the catalytic effect of sodium on oxidation rates of carbonized rayon fabrics has been established and a maximum concentration of the alkalis (1200 ppm) in the fabrics has been proposed.

Surface characterization of a graphitized rayon fabric

The surface characteristics of an unsized graphitized rayon fabric, WCA, were studied. The “true” and apparent active surface areas, ASA, were determined by volumetric oxygen chemisorption at 573 K and starting oxygen pressures of 5, 50, or 200 Torr. The apparent ASA of the fabric is substantially dependent on exposure time, sample size, reactor pressure, and the time selected to evacuate the sample after the chemisorption step. The normal procedure developed for measuring the ASA of graphitized carbon blacks is not applicable to the fabric; the procedure substantially underestimates the ASA of the fabric. From the present and previous work, it is concluded that for each carbon fiber or fabric, the experimental parameters for measuring ASA have to be tailored differently to yield a true value of ASA. The adsorption of Kr at 76.6 K on three fabric samples was performed to determine the surface area and elucidate the effect of heat treatment and length of oxidation on the nature of the surface and on developing porosity. Evacuating the surface of the as-received fabric successively at 373, 473, 573, and 673 K slightly increased the surface area but substantially changed the surface characteristic from nongraphitic to graphitic. Oxidation of the fabric at 573 K for extended periods of time removed a surface layer, developed some porosity, and revealed a less graphitic structure. Evacuation of the sample from 373 to 773 K in 100 K increments opened the porosity. Further evacuation of the sample from 773 K to 1273 K lowered the surface area, closed the porosity, and started changing the surface from nongraphitic to graphitic.

The Management of Large Soft-tissue Defects following Close-range Shotgun Injury

Large soft-tissue defects following close-range shotgun blasts remain a major technical challenge to trauma surgeons. During the period 1980 through 1988, 43 patients who survived greater than 48 hours following this injury were managed in our center. The locations of their soft-tissue defects were: extremity, 22; abdomen/chest, 18; and head/neck, three. All patients underwent immediate surgical exploration and wide debridement of all devitalized tissue along with repair of associated injuries. Management included mandatory frequent dressing changes, debridement, irrigation in the operating room, and the perioperative administration of broad-spectrum antibiotics. Four patients whose abdominal wall defects could not be initially closed had temporary placement of rayon cloth to prevent evisceration. Overall, four patients underwent delayed primary closure, eight were covered with split-thickness skin grafts, nine had closure with myocutaneous flaps, and 19 closed by secondary intent. Two patients, who were transferred to us following initial management, developed wound sepsis due to inadequate debridement and both eventually required amputation as did one patient who developed early myonecrosis following lengthy arterial repair. Frequent operative dressing changes, adequate debridement, and irrigation minimize sepsis following close-range shotgun blasts and should be the treatment of choice for this devastating injury. Techniques of wound closure need to be individualized to the particular situation.

A Review of Polymer Interfaces in Tyre Technology

AbstractThe study of polymer interfaces is of prime importance in the field of tyre technology due to the critical role these contribute to tyre operation. The paper reviews the main polymer interfaces present in a tyre—(1) tyre/road (tyre wear or abrasion; tyre traction/skid resistance); (2) polymer/filler (carbon black; silica); (3) polymer/cord (brass coated steel wire; textile—rayon, nylon, polyester, aramid); (4) compound/compound (tack); (5) tyre/air (oxygen/ozone protection)—with respect to the criteria required, physical and chemical, to achieve optimum performance.

Oxidation of rayon fabrics in atomic and molecular oxygen

Samples of WCA rayon carbon fabrics have been activated either isothermally in air at 773 and 873 K or in an oxygen plasma to different levels of burn-off (B.O.). From the data of krypton and nitrogen adsorption at 77 K, the surface area of the activated samples has been determined using the BET equation. The t-plot method has been selected to analyze the nitrogen isotherms and to estimate the micropore volumes developed upon oxidation. Activating the samples at 773 K develops only microporosity up to 2% B.O., but develops micro- and meso-porosity above this level. Activating the samples at 873 K develops only microporosity up to 2% B.O. However, between 2 and 70% B.O., the surface area, as well as micro- and meso-pore volumes, remain unchanged and are independent of B.O. At any given B.O. level, the surface area and pore volumes of the sample activated at 773 K are higher than at 873 K. The samples activated inside the plasma have a fragile structure and narrower pore entrances than those activated at high temperatures. Variation of surface morphology with B.O., as examined by scanning electron microscopy, are discussed.

Usage of personal protective devices among Egyptian industrial workers.

A systematic random sample of 405 workers from metal, asbestos cement pipes, textile, and viscose rayon industries were interviewed using a prepared and tested questionnaire. Personal Protective Devices (PPDs), namely goggles, gloves, respirators, and ear defenders, had been distributed to all workers on the payroll and were used by 31.4%. Usage of PPDs was associated with the educational level, duration of occupation, awareness of the work hazards, and knowledge about the purpose of PPDs. Marked association was found between nonusage of PPDs and discomfort, interference with job performance, and the psychological feeling of lowering the person's prestige by the wearing of PPDs. Nonusage was also associated with lack of maintenance of the device and absence of supervision of its usage. Users were more numerous among married workers and workers with urban residence than among unmarried workers and those with rural residence, respectively. No association could be found between the rate of usage and the worker's age except for ear plugs, for which nonusage was proportional to the worker's age. The most important factors were those related to the role of the safety staff and the discomfort of the devices. Recommendations for occupational health authorities on the basis of the above evaluation are suggested.

Studies of activated charcoal cloth. III. Mesopore development induced by phosphate impregnants

Nitrogen adsorption isotherms have been determined at 77 K on samples of activated charcoal cloth prepared from viscose rayon cloth after impregnation of the latter with aqueous solutions containing various phosphate compounds. The results obtained indicate that a much wider range of isotherm type and hysteresis loop may be achieved with phosphate impregnants than with the borates studied previously. Analyses of the isotherms employing the α s method indicate that although all the adsorbents were highly microporous (pore width <2 nm), an appreciable mesoporosity (pore width 2–50 nm) could be superimposed upon the micropore structure by employing suitable combinations of phosphate salts. The addition of 3-3-3 mix (3% w/v AlCl 3 + 3% w/v ZnCl 2 + 3% w/v NH 4Cl) to the impregnating solution led to better control in the development of the mesopore volume at higher degrees of burnoff when 5% w/v sodium dihydrogen phosphate was employed. A comparison of the α s plots obtained with those reported for charcoal cloths derived from borate-impregnated precursors suggests that the mesopore structure developed in the presence of phosphate impregnants is better defined and more rigid. Reasons for this are advanced in terms of a model for mesopore development suggested by us previously.

Studies of activated charcoal cloth. I. Modification of adsorptive properties by impregnation with boron-containing compounds

Adsorption isotherms of nitrogen have been determined at 77 K on samples of activated charcoal cloth prepared from viscose rayon cloth after impregnation of the latter with aqueous solutions of various boron-containing compounds. Application of the α s -method of isotherm analysis revealed that all the adsorbents were highly microporous but, in addition, some possessed an appreciable surface area located outside the micropore structure. This “external” area was especially large (200–300 m 2 g −1) in the case of activated charcoal cloths derived from samples initially impregnated with aqueous solutions containing boric acid/Nacl or boric acid/borax.

The interaction of mechanically generated turbulence and interfacial films with a liquid phase controlled gaslliquid transport process

The liquid phase rate-controlled transport of C0 2 across a gas/liquid interface into water was studied using a non-invasive laser-induced fluorescence (LIF) technique. Turbulence in the liquid layer was generated by a vertically-oscillating grid. The CO 2 /water interface was cleaned by removal of surface water with additive-free lens paper, or 100% rayon cloth followed by surface vacuuming with a glass Pasteur pipette. The liquid phase mass transfer coefficient k L was measured under conditions of varying turbulence intensity and scale for each surface cleaning procedure. Transport rates were also measured for an uncleaned surface and in the presence of a deliberately created organic monolayer. All of the results were used to test the surface renewal models of Fortescue and Pearson and Lamont and Scott. A model for wind-dominated gasiliquid transfer developed by Cohen was used to relate the present data to k L measurements for gas exchange in wind tunnels. This comparison indicates that wind tunnel results may be related to stirred-tank experiments using the turbulent dissipation rate Ԑ and a surface renewal model. DOI: 10.1111/j.1600-0889.1986.tb00256.x

EFFECT OF INORGANIC COMPOUNDS ON YIELD AND TENSILE STRENGTH OF PYROLYSED RAYON FABRICS

Rayon fabrics, untreated or treated with sulfur-containing acids, nitrogen-containing bases and their salts or mixtures, were pyrolysed at 300°C in air, and the yields and the tensile strengths of charred rayon fabrics were measured. For the comparison, the salts of phosphoric acid, hydrochloric acid or nitric acid were also examined as treating agents.All of the compounds investigated, except ammonium nitrate, act to increase yield of charred fabrics. On the other hand, the compounds remarkably increasing tensile strength of charred fabrics seem to be restricted to the combinations of following acids and bases; Acid: surfuric acid, sulfurous acid, sulfamic acid and thiosulfuric acid Base: ammonia, urea, guanidine triethanolamine and anilineThe results are discussed in relation to the flameproofing mechanisms of cellulose.

CHANGES IN THE PHYSICAL PROPERTIES WITH HEAT TREATMENT OF A RAYON FABRIC TREATED WITH AMMONIUM SULFATE

Rayon fabrics treated with ammonium sulfate were heated in the temperature range of 120 to 340°C in air and in nitrogen atmosphere, and the changes in the physical properties were investigated.The results show that the temperature dependencies of the physical properties have inflections near 180°C. In the range of 120 to 180°C, dehydration and depolymerization seem to mainly proceed, being accompanied with weight loss as well as decrease in tensile strength. However, above around 180°C, the different but noteworthy changes were observed, namely, 1) marked increase in tensile strength, 2) release of carbon and introduction of nitrogen, 3) loss of solubility and changes in density. These may suggest that the introduced nitrogen plays an important role in recombining the splitted denatured molecules and hence in tightening the structure of the char.Furthermore, an excellent flame-resistant fabric has been prepared by application of the procedure above mentioned. This fabric has a high L. O. I. value of 47, unmeltability, high hygro-scopicity and also excellent thermal and electrical insulatabilities, so that it seems to be useful in the fields where hazardous thermal environments exist.

Characteristics of Liquid Ammonia Treated and Sodium Hydroxide Mercerized High Wet Modulus Rayon and Cotton Fabrics

Dyeing characteristics of Avril IHWM Rayon, Avril III HWM rayon and of cotton fabrics were compared. Although there was little difference in the quantity of dye exhausted onto fabrics of the three fibers, the Avril I fabrics appeared to be darker than the Avril III or cotton fabrics, while the fabrics of Avril III were deeper in shade than the cotton fabrics. The higher visual color yield of the HWM rayon fabrics was attributed to differences in the morphological structures of the fibers. Mercerization and liquid ammonia treatment were shown to improve the dyeability of all three fibers. While mercerization had adverse effects on performance characteristics such as dry and wet breaking strength, tear strength, and flex abrasion resistance of HWM rayon fabrics, liquid ammonia treatment did not degrade these fabrics. Cotton fabric properties were improved by application of both treatments. Implications of the study are that HWM rayon fabrics can be safely treated with liquid ammonia but that mercerization is not an appropriate treatment for such fabrics.

Performance Characteristics and Applications of Flame Resistant Rayon Fabrics

A brief background of flame resistant rayon is presented, including alternative retardants. The paper covers performance data of flame resistant rayon made from poly(propoxyphosphazene) including vertical flame test results, heat shrinkage, smoke density, and thermal convective test results. Some toxicological data are also covered. Several applications in the institutional market are discussed.

Effect of Preheating and Alkali Treatment on Crease Recovery of Rayon Fabrics

The effect of various pretreatments on rayon fabrics before resin finishing was studied to clarify the mechanism of improvement in dry and wet crease recovery given by resin finishing. Preheating or alkali pretreatment enhanced dry crease recovery when using a reactant-type resin, but at the expense of improvement in wet crease recovery. To clarify the mechanism of improvement in dry and wet crease recovery by these pretreatments, infrared deuteration, x-ray diffraction, and lateral order distribution were carried out. Results are discussed taking into consideration the distribution of resin in the fibers and the water sensitive hydrogen bonds, which were effective only in dry crease recovery.