Production Of Synthetic Fibers Research Articles

PES fabric plasma modification

Polyester ranks the upper position in the world fiber production — nearly 54% of the total production of synthetic fibers. Troubles connected with minimizing of the textile hydrophobicity are usually being solved by the textile fibers’ surface chemical modification, but from ecological point of view modification of fabric with low temperature plasma is superior to classical chemical wet processes. Application of various plasmas for PES treatment has been already described. To compare the effectiveness of different plasma sources we performed a series of experiment both in RF and MW plasmas. For working gas nitrogen, oxygen and their mixtures were employed. Internal plasma control was provided by measurement of optical emission spectra. The hydrophilicity degree was determined by the drop test. Paper discusses optimal conditions of the PES fabric plasma treatment.

From EST sequence to spider silk spinning: identification and molecular characterisation of Nephila senegalensis major ampullate gland peroxidase NsPox

Spider dragline silk is renowned as one of the toughest materials of its kind. In nature, spider silks are spun out of aqueous solutions under environmental conditions. This is in contrast to production of most synthetic fibres, where hazardous solvents, high temperatures and pressure are used. In order to identify some of the chemical processes involved in spider silk spinning, we have produced a collection of cDNA sequences from specific regions of Nephila senegalensis major ampullate gland. We examined in detail the sequence and expression of a putative Nephila senegalensis peroxidase gene ( NsPox) from our EST collection. NsPox encodes a protein with similarity to Drosophila melanogaster and Aedes aegypti peroxidases. Northern analysis and in situ localisation experiments revealed that NsPox is expressed in major and minor ampullate glands of the spider where the main components of the dragline silk are produced. We suggest that NsPox plays a role in dragline silk fibre formation and/or processing.

The Effect of Functional Nanoclays in Enhancing the Fire Performance of Fibre-forming Polymers

This paper reviews the present interest in the use of functionalised nanoclays as additives for improving tensile properties and fire performance in fibre-forming polymers. However, evidence over the last three years suggests that, when present by themselves, they will not be able to fulfil all the required features of an ideal flame-retardant, such as conferring ignition-resistance, self-extinguishability, and char-forming propensity. By using cast films as models for eventual fibre geometries, recent work in our own laboratories suggests that nanoclays may increase the effectiveness of more conventional normal flame-retardants (FRs) and thus enable lower quantities to be used, an especially important requirement in synthetic-fibre production and processing. In this paper, we also extend earlier work and report the effect of introducing two commercial nanoclays of known chemical structure into films of polyamide 6 and 6.6 in combination with selected phosphorus-containing flame-retardants. By using the limiting-oxygen index as a means of measuring increased flame-retardant properties, it is shown that the addition of low levels (2% w/w) of nanoclay does increase the over-all flame-retardant behaviour of films in the presence of defined concentrations (11–27% w/w) of flame-retardant, thus enabling lower concentrations of the latter to be used. As a means of understanding such synergistic activity and in order to be able to develop more effective combined nanoclay-FR systems, a simple model is proposed.

Acrylonitrile is a multisite carcinogen in male and female B6C3F1 mice.

Acrylonitrile is a heavily produced unsaturated nitrile, which is used in the production of synthetic fibers, plastics, resins, and rubber. Acrylonitrile is a multisite carcinogen in rats after exposure via gavage, drinking water, or inhalation. No carcinogenicity studies of acrylonitrile in a second animal species were available. The current studies were designed to assess the carcinogenicity of acrylonitrile in B6C3F1 mice of both sexes. Acrylonitrile was administered by gavage at 0, 2.5, 10, or 20 mg/kg/day, 5 days per week, for 2 years. Urinary thiocyanate and N-acetyl-S-(2-cyanoethyl)-L-cysteine were measured as markers of exposure to acrylonitrile. In general, there were dose-related increases in urinary thiocyanate and N-acetyl-S-(2-cyanoethyl)-L-cysteine concentrations in all dosed groups of mice and at all time points. Survival was significantly (p < 0.001) reduced in the top dose (20 mg/kg) group of male and female mice relative to controls. The incidence of forestomach papillomas and carcinomas was increased in mice of both sexes in association with an increase in forestomach epithelial hyperplasia. The incidence of Harderian gland adenomas and carcinomas was also markedly increased in the acrylonitrile-dosed groups. In female mice, the incidence of benign or malignant granulosa cell tumors (combined) in the ovary in the 10 mg/kg dose group was greater than that in the vehicle control group, but because of a lack of dose response, this was considered an equivocal finding. In addition, the incidences of atrophy and cysts in the ovary of the 10 and 20 mg/kg dose groups were significantly increased. The incidences of alveolar/bronchiolar adenoma or carcinoma (combined) were significantly increased in female mice treated with acrylonitrile at 10 mg/kg/day for 2 years. This was also considered an equivocal result. In conclusion, these studies demonstrated that acrylonitrile causes multiple carcinogenic effects after gavage administration to male and female B6C3F1 mice for 2 years.

Acrylonitrile irreversibly inactivates glyceraldehyde-3-phosphate dehydrogenase by alkylating the catalytically active cysteine 149

Acrylonitrile (AN) is a vinyl monomer used in the production of synthetic fibers, rubber and plastics. AN is acutely toxic but its mechanism of toxicity remains to be established. AN is metabolized to cyanide in vivo but cyanide production alone cannot explain acute AN toxicity. Previous work in our laboratory has shown that AN can alkylate highly reactive cysteine residues in proteins. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a critical enzyme involved in glycolysis, has a catalytically active cysteine 149 in its active site. We report that AN irreversibly inhibits GAPDH with second-order rate constants, at pH 7.4, of 3.7 and 9.2 M −1 s −1 at 25 and 37 °C, respectively. A combination of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) and electrospray ionization–mass spectrometry–mass spectrometry (ESI–MS–MS) was used to show that AN inactivates GAPDH by covalently binding to cysteine 149 in the active site of the enzyme. Inactivation of GAPDH by AN would be expected to impair glycolytic ATP production and when coupled with the inhibition of mitochondrial ATP synthesis by the AN metabolite cyanide would result in metabolic arrest. The brain can withstand metabolic arrest for only a few minutes thus these combined actions may account for the acute toxicity of AN in vivo.

End-User Exposures to Synthetic Vitreous Fibers: II. Fabrication and Installation Fabrication of Commercial Products

This article summarizes the results of exposure monitoring conducted during the installation and fabrication of commercial synthetic vitreous fiber (SVF) products. Included in this investigation were fiberglass duct insulation and construction applications (duct board, duct liner, and duct wrap), pipe and vessel insulation, batt insulation for prefabricated homes, and general fiberglass products. Commercial mineral wool products sampled as a part of this investigation included ceiling tiles, building safing, and loose insulation for prefabricated homes. A total of 520 valid air samples were collected as a part of this investigation and were analyzed using gravimetric, phase contrast microscopy (PCM), or scanning electron microscopy (SEM). Airborne fiber-size distributions were also determined for a subset of samples collected for SEM analysis. As a result of the task-based sampling strategy used in this study, sample times reflect exposures over the time the person was actually engaged in SVF-related work activities, and exposure results are therefore presented as task-length averages (TLAs). Thirty-five total dust samples were collected as a part of this investigation, resulting in 14 TLAs ranging from 0.3 to 7.6 mg/m3. A total of 125 PCM-based TLAs were collected, with the mean TLA time for all product and occupation categories ranging from 277 to 443 minutes. The mean PCM-based TLAs for all product/occupations were below 1.0 f/cm3, ranging from 0.04 to 0.68 f/cm3. A total of 116 SEM TLAs were determined. Average SEM-based TLA concentrations were slightly lower than the PCM-based estimates and ranged from < 0.01 to 0.16 f/cm3

End-user exposures to synthetic vitreous fibers: II. Fabrication and installation fabrication of commercial products.

This article summarizes the results of exposure monitoring conducted during the installation and fabrication of commercial synthetic vitreous fiber (SVF) products. Included in this investigation were fiberglass duct insulation and construction applications (duct board, duct liner, and duct wrap), pipe and vessel insulation, batt insulation for prefabricated homes, and general fiberglass products. Commercial mineral wool products sampled as a part of this investigation included ceiling tiles, building safing, and loose insulation for prefabricated homes. A total of 520 valid air samples were collected as a part of this investigation and were analyzed using gravimetric, phase contrast microscopy (PCM), or scanning electron microscopy (SEM). Airborne fiber-size distributions were also determined for a subset of samples collected for SEM analysis. As a result of the task-based sampling strategy used in this study, sample times reflect exposures over the time the person was actually engaged in SVF-related work activities, and exposure results are therefore presented as task-length averages (TLAs). Thirty-five total dust samples were collected as a part of this investigation, resulting in 14 TLAs ranging from 0.3 to 7.6 mg/m3. A total of 125 PCM-based TLAs were collected, with the mean TLA time for all product and occupation categories ranging from 277 to 443 minutes. The mean PCM-based TLAs for all product/occupations were below 1.0 f/cm3, ranging from 0.04 to 0.68 f/cm3. A total of 116 SEM TLAs were determined. Average SEM-based TLA concentrations were slightly lower than the PCM-based estimates and ranged from <0.01 to 0.16 f/cm3. The geometric mean fiber diameters for commercial products and occupations sampled as a part of the investigation ranged from 0.8 microm to 1.9 microm. Geometric mean fiber length varied by a factor of approximately three, ranging from 9.5 microm to 29.5 microm.

Technology of Strong Fibers: Where are We and Where Should We Direct Our Investigations?

The predictions of future successful technological developments are an important task of research organizations. The extremely poor reliability of these predictions has eroded trust in the efficiency of research laboratories which, in turn, resulted in substantial decreases in and availability of research funding. The causes of poor prediction relability are discussed and ideas are presented on how to minimize this problem. By applying the presented methodology, it is shown that, in the case of strong industrial fibers, we can learn a great deal from evolutionary processes of silk fiber formation and utilize this knowledge to solve some critical environmental problems of current man-made fiber production.

Growth In Polyester Masks Stagnation In Other Hbers

Here's welcome news for the beleaguered fiber industry. In 1999, global man-made fiber production grew 4% from 1998 to reach a total of 29.5 million metric tons of synthetic and cellulosic fibers. What's more, with the world's economic climate looking good for this year, fiber growth likely will continue this year These are the main conclusions in Dutch fiber producer Acordis' annual report on fibers, which formerly was issued by Dutch chemicals and fiber producer Akzo Nobel. The report has been continued by Acordis, which was launched this year as the combined fiber businesses of Akzo Nobel and Courtaulds, acquired by Akzo Nobel in late 1998. According to the report, the growth in production was paced by polyester, which was up 9% from 1998 for staple fiber and 8% for filament yarns. Some 30 years ago, when total man-made fiber production was 8.39 million metric tons, polyester accounted for only about 20% of total production. ...

Flow cytometric measurement of micronuclei induced in a permanent fish cell line as a possible screening test for the genotoxicity of industrial waste waters.

An in vitro micronucleus assay using the permanent fish cell line RTG-2 (rainbow trout gonads) was developed to test industrial waste waters for their genotoxic potential. Comparison of flow cytometric measurement and microscopic scoring of micronucleus frequency with the reference chemicals 1,4-butane sultone (0.2-1 mM), ethylmethane sulphonate (2-10 mM), potassium dichromate (20-100 microM) and benzo[a]pyrene (5-25 microM) showed similar dose-effect relationships. Thirty-eight industrial waste waters from 11 different branches of industry obtained from the Bavarian state office for water research were tested using the flow cytometric method (18 from metal processing, 10 from combined waste water, two from synthetic fibre production, one sample each from settlement wastes, non-iron metal manufacturing, leather production, sulphuric acid production, ore processing, graphite film production, cellulose production and flue gas washing). Fourteen of them showed a significant increase in micronucleus frequency.

Cancer incidence among European man-made vitreous fiber production workers.

This study analyzed cancer incidence among man-made vitreous fiber workers. A cancer incidence follow-up was conducted among 3685 rock-slag wool (RSW) and 2611 glass wool (GW) production workers employed for > or =1 year in Denmark, Finland, Norway, or Sweden, and the standardized incidence ratios (SIR) were calculated on the basis of national incidence rates. Overall cancer incidence was close to expectation. Lung cancer incidence was increased among the RSW [SIR 1.08, 95% confidence interval (95% CI) 0.85-1.36] and GW (SIR 1.28, 95% CI 0.91-1.74) workers. For both subcohorts, a trend was suggested for time since first employment (P-value for linear trend 0.1 and 0.2, respectively). Neither subcohort showed an association with employment during the early technological phase, when fiber exposure was high. The incidence of oral, pharyngeal, and laryngeal cancer was increased among the RSW (SIR 1.46, 95% CI 0.99-2.07) and the GW (SIR 1.41, 95% CI 0.80-2.28) subcohorts. Despite a trend in risk for these neoplasms among the GW workers with time since first employment, the lack of a positive relation with other indirect indicators of fiber exposure points against a causal interpretation. No association between RSW or GW exposure and the risk of other neoplasms was suggested. These lung cancer results are similar to those of a mortality study that included a larger number of factories. For other cancers there was no suggestion of an association with RSW or GW exposure.

A Review of New Technologies in Synthetic Fiber Production

New developments in the areas of the synthetic fiber production of polypropylene, polyesters, polyamides, and acrylics are described. In the area of polypropylene fiber production, the synthesis of metallocene-based polypropylene materials is discussed. The new technologies described for polyesters include ultra-high speed melt spinning, bacterial polyesters, and the thermotropic polyester fiber, Vectran™. Polyamide topics include Nomex™, Kevlar™, and Technora™. The high speed spinning of acrylic fibers is also described.

Acrylonitrile: A Reevaluation of the Database to Support an Inhalation Cancer Risk Assessment

Acrylonitrile (ACN) is a monomer used extensively in the production of plastics, synthetic fibers, and rubber. In previous assessments conducted by IARC and the EPA, ACN was classified as a probable human carcinogen based on limited evidence in humans and sufficient evidence in laboratory animals. Specifically, EPA had determined that there was an association between ACN exposure and lung cancer based on a study by O'Berg (1980,J. Occup. Med.22, 245–252). However, a follow-up of this cohort (O'Berget al.,1985,J. Occup. Med.27, 835–840) shows no statistically significant excess of lung cancer mortality or incidence. Our evaluation of the more recent human database taken as a whole shows that there is not a clear association between ACN exposure and human cancer, yet the studies have insufficient power to be able to rule out a small increase. In laboratory rats, however, ACN has been shown to be clearly carcinogenic by the oral and inhalation routes. Applying the methodology of EPA's proposed 1996 cancer risk assessment guidelines to the rat tumor data, the estimated upper bound on the excess lifetime risk at continuous exposure to 1 μg/m3ACN is calculated to be in the range of 8.2 × 10−6to 1.1 × 10−5.

Supermolecular structure of polymer fibres

The problem of the structure of polymers in general and man-made polymer fibres in particular draws the continuous interest of researchers. The attention to this problem by production engineers who manufacture man-made fibres or process them into final products is based on the necessity of knowing the mechanism of formation of the structure of the polymer during spinning of fibres and predicting their behavior during use. We will limit the discussion here to the principal concepts concerning the organization of the structure of polymers in fibres alone and will cite illustrative and detailed published data to present these concepts. Following this restriction, if we successively examine the factors which determine the structural organization of the starting polymer and the structural features of the fibre manufactured from it, the following basic factors that affect the structure and properties of the fibre can be distinguished. The first factor which greatly determines the structural organiT~tion of the maeromolecules in the fibre, i.e., their reciprocal position and interaction, is the low kinetic mobility of the macromolecule as a whole, caused by the chain structure of the macromolecules, and the unusual mobility of the individual segments in this chain, which is a function of the structure and type of bonds between the elementary units (segments). Characterization of the macromolocules includes their power to form chemical or crystallization bonds between neighboring macromolecules. Continuous cross-linked structures in which the individual macromolecules have no kinetic independence can be created as a result. The next feature of polymers consists of their polydispersity with respect to the molecular weight, which in many cases makes the behavior of the polymers dependent on their fractional composition. Their phase inhomogeneity, related to both the regularity of the chemical structure of the macromolecules and noncompletion of phase transitions of the polymers both in the stage of synthesis and in the concrete conditions of technological operations in spinning of fibres (the.role of the "history" of the polymer materials), is an important property of polymers. Another important property of polymers is the heterogeneity of the maerostructure. It consists of the formation of both manifest, in the form of open or closed pores, and latent (hidden) boundaries between phase particles, which affects the kinetics of absorption of liquids and their vapors by the polymer. Finally, another main characteristic of polymers with respect to their structural organization is the presence of unrelaxed internal stresses in polymer materials. These stresses alter the structural organization of the polymer due to external mechanical effects, temperature conditions, and contacts with liquids or vapors which affect the glass transition temperature of the polymer and the appearance of segmental mobility in the macromolecules. As the list of the basic factors that determine the overall behavior of polymers (and thus the fibres made from them) and their structural organization indicates, there are two aspects of this problem. The first aspect concerns the molecular properties of the polymer which forms the fibre. The second aspect should be called the supermolecular structure. Although both aspects are closely correlated, it is nevertheless expedient to discuss them separately. The first aspect of the problem can be characterized as consideration of factors whose role is preferably determined by the chemical structure of the polymer, primarily the presence and structure of functional groups in the macromolecule, and *This article is a continuation of a series of reviews on physicochemical problems of the production and properties of manmade polymer fibres. Previous articles in this series were: "Problems of transport of solvents to polymers in production and use of chemical fibres" [No. 6, 9-13 (1993)] and "Swelling of man-made fibres as an important characteristic of their properties" [No. 3, 29-35 (1997)]. tDeceased.

Environmental aspects of photodegradable plastics

AbstractDuring the latter half of this century the production of synthetic plastics and fibers has grown so that the total volume of plastics produced world–wide now exceeds that of steel. This paper is concerned with theoretical and experimental studies relating to the environmental consequences of such a rapid shift from a technology based primarily on agriculture, forestry and metallurgy to one based on chemical raw materials such as oil, coal and natural gas. It is shown that plastics and synthetic fibers have the lowest energy costs of all comparable materials and cause less environmental pollution in their production and fabrication. They are easily recycled when not contaminated with other materials and can be manufactured in photo‐or biodegradable modifications tailored to highly litter–prone applications. The topics covered include sections on resource costs and renewal, environmental considerations, the technology and role of photodegradable plastics, and experimental studies of the biodegradation of conventional and photodegradable polyethylene, polypropylene and poly(ethylene terephthalate).

Cancer mortality among man-made vitreous fiber production workers.

We have updated the follow-up of cancer mortality for a cohort study of man-made vitreous fiber production workers from Denmark, Finland, Norway, Sweden, United Kingdom, Germany, and Italy, from 1982 to 1990. In the mortality analysis, 22,002 production workers contributed 489,551 person-years, during which there were 4,521 deaths. Workers with less than 1 year of employment had an increased mortality [standardized mortality ratio (SMR) = 1.45; 95% confidence interval (CI) = 1.37-1.53]. Workers with 1 year or more of employment, contributing 65% of person-years, had an SMR of 1.05 (95% CI = 1.02-1.09). The SMR for lung cancer was 1.34 (95% CI = 1.08-1.63, 97 deaths) among rock/slag wool workers and 1.27 (95% CI = 1.07-1.50, 140 deaths) among glass wool workers. In the latter group, no increase was present when local mortality rates were used. Among rock/slag wool workers, the risk of lung cancer increased with time-since-first-employment and duration of employment. The trend in lung cancer mortality according to technologic phase at first employment was less marked than in the previous follow-up. We obtained similar results from a Poisson regression analysis limited to rock/slag wool workers. Five deaths from pleural mesothelioma were reported, which may not represent an excess. There was no apparent excess for other categories of neoplasm. Tobacco smoking and other factors linked to social class, as well as exposures in other industries, appear unlikely to explain the whole increase in lung cancer mortality among rock/slag wool workers. Limited data on other agents do not indicate an important role of asbestos, slag, or bitumen. These results are not sufficient to conclude that the increased lung cancer risk is the result of exposure to rock/slag wool; however, insofar as respirable fibers were an important component of the ambient pollution of the working environment, they may have contributed to the increased risk.

Dose Dependence of Covalent Binding of Acrylonitrile to Tissue Protein and Globin in Rats

LI, J., AND CORBETT, D. (1997). Fundam. Appl. ToxicoL 36, 149-156. The dose dependence of acrylonitrile (AN) covalent binding to tissue protein, following a single acute exposure over a 100-fold range in dose, was measured. Covalent binding was a linear function of AN dose in the lower dose range (0.02-0.95 mmol AN/ kg). The slopes of the dose-response curves indicated that tissues varied by nearly 10-fold in their reactivity with AN. The relative order of covalent binding was as follows: blood S> kidney = liver > forestomach = brain > glandular stomach *> muscle. Similar dose-response behavior was observed for globin total covalent binding and for globin N-(2-cyanoethyl)valine (CEValine) adduct formation. The latter adduct was found to represent only 0.2% of the total AN adduction to globin. Regression of tissue protein binding versus globin total covalent binding or globin CEValine adduct indicated that both globin biomarkers could be used as surrogates to estimate the amount of AN bound to tissue protein. At higher AN doses, above approximately 1 mmol/kg, a sharp break in the covalent binding dose-response curve was observed. This knot value is explained by the nearly complete depletion of liver glutathione and the resultant termination of AN detoxification. The toxicity of AN is known to increase sharply above this dose. The data suggest that a comparison of specific tissue proteins labeled by AN above and below this threshold dose may provide some insight into the mechanism of AN-induced toxicity. O 1997 Soctety of Toxicology. Acrylonitrile (AN) is a vinyl monomer used in the production of synthetic fibers, rubber, and plastics. The estimated production of AN in the United States in 1995 was 3.21 billion pounds, ranking it 40th among manufactured chemicals (Kirschner, 1996).

Modeling and Simulation of Combined Continuous and Discrete Systems: Case Study of Spinning Process.

In the previous paper, we proposed fundamental techniques to model and simulate combined continuous processes and discrete event systems, including sequential control, and developed a simulation program package for general use. In this paper, we apply the combined simulation method to analyze a proposed design of spinning processes in the synthetic fiber production plant. Repeated simulation is effectively used to make an appropriate decision on the number of equipment items. This case study includes various concrete techniques for modeling and simulation, and will help the process designer to model large-scale and complicated systems, and to analyze system performances.

Expression and Purification of a Spider Silk Protein: A New Strategy for Producing Repetitive Proteins

Synthetic genes were constructed based on the known sequence of the spider dragline silk protein MaSp 2. The genes had 8, 16, or 32 contiguous units of the consensus repeat sequence of the protein. These artificial genes were constructed using a strategy involving compatible but nonregenerable restriction sites, which allowed construction of very large inserts in a precisely controlled manner. This strategy should have general utility in the controlled construction of repetitive proteins composed of identical or different repeat units. The protein from the 16-unit repeat was produced inEscherichia coliat levels up to 10 mg/g wet wt of cells although yields of 1–2 mg/g were more typical. The protein was easily purified with high recovery using an affinity column. The purified protein had the predicted amino acid composition and N-terminal sequence after cleavage of a leader sequence. The methodology described will allow production of sufficient quantities of protein for basic structure/function studies including production of synthetic fibers.

High-Performance Acrylic Fibers

Abstract Acrylic fibers are among the most important man-made fibers. They rank third after polyesters and nylons [1]. The first commercially available acrylic fiber was orlon, introduced by DuPont in 1943. Soon thereafter, other companies introduced new acrylic fibers, such as Acrilan, Dralon, and so forth. During the 1950s, the acrylic fiber industry experienced a rapid growth, with 18 companies introducing acrylic fiber products into the market. In 1970 21% of the synthetic fibers produced were acrylic fiber, whereas this figure fell to about 14% in 1992. In the corresponding period, the actual production of acrylic fibers increased from 809,890 tons to 2,410,520 tons. However, the overall production of synthetic fibers increased from 4.809 million tons to 17.218 million tons (Fig. 1). Interestingly, in 1970 only 12% of the acrylic fibers were produced in Third World countries (countries other than the United States, Japan, and western Europe) whereas this figure increased to 46% in 1989 and was expected to go still higher by 1995 [2–4] indicating a remarkable growth in the expansion of the acrylic fiber industry especially in the developing countries (Fig. 2). In India also there has been a considerable increase in the production of acrylic fibers as three new companies -Pasupati Acrylon Ltd., Indian Acrylics, and Consolidated Fibres—have started producing acrylic fibers of different denier range. In China, the acrylic fiber industry has made rapid progress. The total production of acrylic fiber in 1970 was about 5100 tons, whereas the production had increased to more than 140,000 tons in 1993.