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Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 'm. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ~40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from $8 to ~$3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly(acrylonitri

Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 'm. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ~40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from $8 to ~$3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly(acrylonitri

Se ha aplicado el ensayo de solubilidad diferencial a grupos de sustratos de fibras de poliéster, poliamida, acrílicas y fibras químicas celulósicas. Se ha puesto de manifiesto su sensibilidad para detectar diferencias de estructura fina en grupos de sustratos fabricados o procesados en diferentes condiciones, o procedentes de diferentes productoras., Postprint (published version)

English: Silk occupies a unique position as a textile fibre with a rare combination of beauty and strength. Production and processing of silk is labour intensive which leads to high cost and limited production of the silk fibre. Unfortunately the high cost of silk makes it unaffordable for many consumers; therefore mixed yarn fabrics could be constructed in order to lower the price of the fabric, without changing the unique properties of the silk negatively. The aim of this study was to evaluate and compare the properties of Gonometa postica silk fabric with the properties of mixed yarn fabrics consisting of Gonometa postica silk weft on a wool warp, and Gonometa postica silk weft on an acrylic warp. This is done in order to determine which of the wool or the acrylic create a more suitable mixed yarn fabric with the Gonometa postica silk. Standard methods were used to evaluate the abrasion resistance (ASTM 4966), tensile strength and elongation (ISO 13934), stiffness (BS 3356 ), crease recovery (AATCC 66), fabric thickness (BS 2544), dimensional change (AATCC 99) and moisture regain (ASTM 2654). Analysis of variance supported the interpretation of the results of the tests. The Gonometa postica silk textile fabric has relatively good abrasion resistance, with a mean value of 28 750 rubs necessary to break two yarns. The Gonometa postica silk weft/wool warp test fabric showed very good abrasion resistance with a mean value of 51 000 rubs required to break two yarns. And the Gonometa postica silk weft/acrylic warp test fabric also showed relatively good abrasion resistance, although it was lower than the other test fabrics with a mean value of 25 197 rubs needed to break two yarns. The Gonometa postica silk test fabric had the largest weight loss, while the Gonometa postica silk weft/wool warp fabric had the smallest weight loss. Tensile strength and displacement were measured and the Gonometa postica silk fabric had the highest mean maximum load necessary to break the, Afrikaans: Sy beslaan ‘n unieke posisie as tekstielvesel met ‘n skaars kombinasie van skoonheid en sterkte. Produksie en prosessering van sy is arbeids-intensief en dit lei tot hoë koste en beperkte produksie van sy. Ongelukkig lei hierdie hoë pryse daartoe dat dit onbekostigbaar is vir baie verbruikers, aarom kan gemengde garing stowwe gemaak word om die prys van die tekstielstof te verlaag, sonder om die unieke eienskappe van die sy negatief te beïnvloed. Die doel van hierdie studie was om die eienskappe van die tekstielstowwe wat bestaan uit Gonometa postica-sy-inslag op wol-skering en Gonometa postica-sy-inslag op akriel-skering te evalueer en dit dan met Gonometa postica-sy- ekstielstof te vergelyk. Dit word gedoen om te kan bepaal watter van die wol of akriel geskik sal wees om met die Gonometa postica-sy te meng. Standaard metodes was gebruik om slytweerstand (ASTM 4966), breek sterkte (ISO 13934), styfheid (BS3356), kreukelherstel (AATCC 66), material dikte (BS2544), krimping (AATCC 99) en vogbyslag (ASTM 2654) te evalueer. Variansie analise was aangewend met die interpretasie van die resultate. Die Gonometa postica-sy-inslag/Gonometa postica-sy-skering tekstielstof het goeie slytweerstand getoon, met ‘n gemiddeld van 28 750 vrywe nodig om twee drade te breek. 195 Die Gonometa postica-sy-inslag/wol-skering tekstielstof toon baie goeie slytweerstand met ‘n gemiddeld van 51 000 vrywe nodig om twee drade te breek. Die Gonometa postica-sy-inslag/akriel-skering tekstielstof het ook goeie slytweerstand alhoewel dit laer as die ander tekstielstowwe was met ‘n gemiddeld van 25 197 vrywe voor twee drade gebreek het. Die Gonometa postica-sy-tekstielstof het die meeste gewigsverlies gehad terwyl die Gonometa postica-sy-inslag/wol-skering tekstielstof die minste gewigsverlies gehad het. Breeksterkte en verplasing was geëvalueer en die Gonometa postica-sytekstielstof het die grootste gemiddelde maksimum vrag van 492.317 N gedra voordat dit gebreek het, met ‘n verplasing

En el presente estudio se consideran las propiedades físico-mecánicas de los hilos paralelos con alma de lana y de acrilica-poliamida (90/10) recubiertos con mono o polifilamento de poliamida y se relacionan las mencionadas propiedades con los parámetros del hilo tales como la masa lineal, la torsión del filamento, la proporción del mismo y su masa lineal. El diseño experimental utilizado permite repasar y reconocer los factores estadísticamente significativos y el establecimiento, por regresión múltiple, de las ecuaciones que ligan las propiedades estudiadas con los parámetros de estructura del hilo, con lo cual pueden escogerse las condiciones experimentales que conducen a la optimización de las propiedades elásticas, el indice de vellosidad, la irregularidad y el coeficiente de rozamiento en sus modalidades hilo/hilo e hilo/cerámica., In this study physico-mechanical properties of wool and acryl-polyamide (90/10) wrap spun yarns are considered. Core fibres were wrapped by four types of polyamide mono and polyfilament and related to yarn parameters such as, linear density, twist yarn, ratio and linear density yarn.The experimental design applied allows to revise the statistically significant factors as well as the establishment, by means of multiple regression, of equations relating the properties studied to the parameters of the yarn structure. This, in turn, will permit to select the optimum experimental conditions leading to the optimization of the elastic properties, hairiness index, uneveness, and the friction coefficient in the aspects of yarn/yarn and yarn/ceramic., Cette étude présente les propriétés physico-mécaniques de fils bicomposés à âme de laine et d'acrylique-polyamide (90/10%) guipés de monofilament ou multifilament de polyamide. Ces propriétés sont mises en relation avec les caractéristiques du fil telles que sa masse linéique ainsi que la torsion, proportion et masse linéique du filament. Le système conçu pour l'expérience permet de passer en revue et d'identifier les facteurs statistiquement significatifs et d'en déduire, par régression multiple, les rapports entre les propriétés étudiées et les caractéristiques structurelles du fil, ce qui permet de choisir les conditions expérimentales qui conduiront à l'optimisation des propriétés élastiques, du taux de formation de duvet, de l'irrégularité et du coefficient de frottement dans ses modalités fil/fíl et fil/céramique., Peer Reviewed

La segunda parte de este tema está relacionada con el comportamiento friccional de hilos de acrílicas con distintos porcentajes de fibras retráctiles en su composición y procedentes de distintas productoras. Estos hilos se distinguen claramente por sus distintas características y como consecuencia las condiciones de tisaje serán diferentes. Se han empleado las mismas técnicas de ensayo descritas en la parte primera., The second part of this article is based on the frictional behaviour of acrylic yarns composed of different percentage of retractile fibres and proceeding from various fibre manufecturers. These yarns are very different from each other and as a result the knitting conditions for each type should be different. The same laboratory techniques described in part I were used for measuring coefficient of friction., La deuxième partie de ce sujet a rapport au comportement frictionnel de fils d'acryliques avec différents pourcentages de fibres rétractiles dans leur composition et procédents de différents producteurs. Ces fils se distinguent clairement de par leurs diverses caractbristiques et par conséquent, les conditions de tissages seront différentes. On a employé les memes techniques d'expériences décrites dans la première parfie., Peer Reviewed

As acrylic fibers are heated in air to induce the stabilization reactions, the tension developed when stabilized at constant length and the instantaneous velocity of stabilizing fibers undergoing continuous processing both depend on the chemical composition, diameter, and orientation of the precursor fiber. An oriented fiber will tend to shrink when heated to the range of 130-160C, and hence will develop tension if restrained at constant length. Although this process has no direct relation to the stabilization process, it will influence the instantaneous velocity of the fiber during the later stages of continuous processing. As a fiber held at constant length is heated above 160C the tension developed by entropic relaxation decreases and the fiber starts to undergo the prefatory and sequent reactions of stabilization described in the first paper in this series. If the prefatory reactions are rapid, a rigid structure is quickly established in the fiber and tension again increases rapidly. However, if the prefatory reactions are slow, select portions of the fiber react preferentially and the unreacted portions tend to relax to maintain a temporary quasi-equilibrium tension level. In both cases the fibers shrink at the later stages of stabilization because of chemical reactions. The shape of the tension-time curve is similar to the oxygen-uptake curves: the diffusion-limited mechanism of stabilization produces parabolic curves whereas the reaction-limited mechanism produces linear curves. Because each element of a fiber undergoing continuous processing is subjected to the same tension at all times, previously oriented fibers first shrink, then stretch, and finally shrink again.

A new model for the structure of oriented acrylic fibers is presented. The polyacrylonitrile molecules (or the acrylic sequences in a copolymer) are suggested to form two distinct regions within a fibril: amorphous (disordered) and partially ordered. In the partially ordered regions, the polymer molecules assume a contorted helical shape to form rods with a diameter averaging about 6.0A in which the nitrile units are oriented at various angles to the rod axis, but are spaced irregularly on or near the surface of the rod. The nitrile groups of adjacent rods can interpenetrate to form dipole pairs. The rods are ordered into a liquid crystal-type array, giving in some cases a lamellar-like texture oriented perpendicular to the fibril axis, with the ordered lamellae regions interspersed with amorphous regions. Evidence for the structure is obtained from transmission electron microscopy observations, a transient peak observed in small angle X-ray scattering when fibers are thermally treated, as well as wide angle X-ray diffraction patterns. The proposed model is consistent with the absence of a periodic repeat unit along the chain direction, with the hkO reflections seen in wide angle X-ray and electron diffraction, with the spherulitic morphology reported in some studies, and with the plate-like morphologies obtained under some conditions of precipitation from dilute solution. (Author), See also report dated 10 Jan 78, AD-A048 746.

This Report describes work on a series of commercially available cordages of nylon, polypropylene, polyester, glass, aramid and acrylic fibers, with the aim of finding the translational effects of yarn and cordage construction on physical properties. It was found that while count and extension increase, breaking strength, tenacity, modulus and energy absorption decrease with increasing complexity of construction. Except for count these properties also vary on translation with fibre type, heat treatment and surface finishing.

This article considers in detail the chemical reactions which occur in acrylonitrile polymers during: (1) the 'low-temperature' thermal (below 150C), oxidative, and nucleophilic induced degradation that is so important to avoid in forming textile fibers; (2) the destructive exotherm which occurs on rapid heating of these polymers; (3) the controlled high-temperature conversion of these polymers to carbon fibers; and (4) a brief consideration of ionizing radiation, photochemical, and mechanical degradations.

Se ha realizado la puesta a punto de la técnica de valoración potenciométrica automática de colorantes catiónicos para fibras acrílicas, en medio no acuoso (anhídrido acético) empleado como reactivo ácido perclórico 0,1 N en ácido acético glacial. Se han determinado los pesos moleculares de varios colorantes catiónicos purificados de fórmula conocida, siendo la concordancia con los valores téóricos bastante aceptable. Asimismo a partir de los potenciales alcanzados al añadir la mitad del reactivo correspondiente a la primera inflexión se ha realizado una clasificación de los colorantes ensayados que da una idea de su reactividad frente al reactivo valorante en medio no acuoso . Dicha reactividad fundamentalmente es debida al anión del colorante., On a réalisé la mise au point de la technique d'évaluation potentiométrique automatique de colorants cationiques pour fibres acryliques, en milieu non-aqueux (anhydride acetique) en employant comete réactif acide perchlorique 0,1 N en acide acétique glacial. On a détetminé les poids moléculaires de plusieurs colorants cationique purifiés, de formule connue, la concordante avec les valeurs théoriques étant assez acceptable, De la mêmes á partir des potentiels atteints en ajoufant la moitié du réactif correspondant à la premiére inflexion, on a réalisé une classification des colorants essayés qui donne une idée de leur réactivité vis-à-vis du réactif évaluant en milieu non-aqueux . Cette réactivité est fondamentalement due à l'anion du colorant., The technique of the automatic potentiometric evaluation of cationic dyes for acrylic fibres in non-aqueous medium (acetic anydride) and using perchloric acid 0,1 N in glacial acetic acid has been developed. The molecular weights of several purified cationic dyes of known formula have been determined; the concordante with the theoretical values being quite acceptable. Besides, from the potentials reached on adding the half of the reactant corresponding to the first inflexion, a classification of the tested dyes has been carried out which gives an idea of their reactivity facing the ecaluating reactant in non-aqueous medium. This reactivity is basically due to the anion of the dye. ., Peer Reviewed

Se ha determinado el tiempo crítico de disolución de diversos hilos acrílicos antes y después de haberlos sometido a diferentes tratamientos térmicos o hidrotérmicos, a efectos de conocer las posibilidades de esta técnica para detectar diferencias de memoria térmica en las fibras acrílicas. Como sustratos, se ha partido de hilo continuo acrílico texturado, hilos relax, hilos encogibles e hilos con potencial HB preparados con diferentes proporciones de los componentes relax y retráctil. También se ha determinado el TCD de sustratos de diferente estructura fina que se han teñido con diferente intensidad, así como el de las zonas diferentemente teñidas de seis casos reales sobre los que en su día se estudiaron las causas de las irregularidades tintóreas., The dissolution critical time of some acrylic spun yarns has been studied before and after having submitted them to different hydrothermical or thermical treatments in order to find the ability of this technique to detect come differences of the thermal memory in the acrylic fibres. Texturized acrylic continuous filament, relax yarns, shrink-yarns as well as HB potencial yarns prepared with different proportions of relax and retractable components have been used as sustrates. The DCT of sustrates of different fine structure, dyed at different shades, as well as that of the areas of six real cases have been equally determined., On a determiné le temps de diddolution critique de divers filas acryliques avant et apres avoir subi différents traitements thermiques ou hydrothermiques, a effet de connaitre les possibilités de cette technique pour la detection de différences de mémoire thermique dans les fibres acryliques. Comme substrats, on a utilicé un fil continu acrylique texturé, des fils relax, des fils rétrécissables et des fils a un potentiel HB préparés avec des taux différents des composants relax et rétractile. On a déterminé aussi le TCD de substrats a structure fine différente, qui ont été teints a intensité différente, ainsi que celui des zones différemment teintes pour six cas réels sur lesquels en une autre occasion avaient été étudiées les causes des irrégularités tinctoriales., Peer Reviewed

Se estudia la influencia de la temperatura de la zona de transición vítrea y el número de grupos aniónicos de las fibras Dralón, Courtelle y Euroacril en las constantes de velocidad de tintura, energía de activación de Arrhenius y configuración del ciclo tiempo-temperatura de un sistema de tintura isorractivo. Se aprecia que los valores de las constantes de velocidad de tintura dependen en mayor grado de la temperatura de la zona de transición vítrea que del número de grupos aniónicos, si bien éstos también influyen. La ley de Arrhenius se cumple durante la zona de transición vítrea de la fibra, sin embargo, la energía de activación experimental no es un parámetro adecuado para valorar la rapidez del proceso tintóreo porque está influenciada por la apertura de la fibra. Mediante la ecuación de isorreactividad se obtiene, para unas condiciones dadas, la tabulación tiempo-temperatura a fin de lograr un agotamiento lineal durante todo el proceso tintóreo y obtener las mejores condiciones, para conseguir una tintura igualada sobre dichas fibras mediante control de la temperatura., Peer Reviewed

Tres fibras acrilicas de tipo retrdctil de 2'9, 4'7 y 10 dtex fueron sometidas a tratamientos termicos con aire caliente a distintas temperaturas y distintos tiempos de acción. Se han comparado sus características físico-mecánicas con las de otras fibras tratadas por el procedimiento clásico de vapor. Se han establecido condiciones 6ptimas de tratamiento, considerando las mejoras obtenidas., Three acrylic retractile fibres of 2'9, 4'7 and 10 dtex were subjected to heat treatments by hot air at different temperatures and treatment times. Their physico-mechanical caracteristics are compared with those of fibres treated by stearn. Optimum test conditions are established taking into consideration improvernents achieved., Trois fibres acryliques de type retractil de 2'9,4'7 et 10 dtex, on été soumisses à des traitements thermiques a l'air chaud, A differentes temperatures et à differents temps d'action. On a cornparé leurs caractéristiques physico-mécaniques avec celles des autres fibres quiont été traitées par la méthode clasique de la vapeur. On a établi les conditions optimum des traitements, tenant compte des améliorations obténues., Peer Reviewed

Se ha realizado un estudio comparativo sobre la determinación de los grupos ácidos de las fibras acrilicas Drnlón, Courtelle y Euroacril, por los métodos potenciométrico y tintóreo, habiéndose encontrado valores diferentes tanto en grupos totales como en grupos débiles y fuertes. Cuando se tiñe a pH 1,6 los miliequivalentes de colorante fijados en la fibra superan a los rniliequivalentes de grupos ácidos fuertes determinados por potenciometria, interpretando que este exceso se fija a la fibra por disolución., On a réalisé une étude comparative sur la détermination des groupes acides des fibres acryliques Dralon, Courtelle et Euroacryl par les méthodes potentiométrique et tinctoriale; on a trouvé des valeurs différentes en groupes totaux aussi bien qu'en groupes faibles et forts. Lorsqu'on teint a pH 1,6, les milliéquivalents de colorant fixés sur la fibre dépassent les milliéquivalents de groupes acides forts déterminés par potentiométrie; on interprete que cet exces se fixe d la fibre par dissolution., A comparative study on determining the acid groups of the acrylic fibres Dralon, Courtelle and Euroacryl by the potentiometric and the tinctorial methods has been carried out. Different values have been found in total groups as well as in weak and strong groups. When dyeing at pH 1.6 the milliequivalents of dye set on the fibre are higher than the milliequivalents of strong acid groups determined by potentiometry; it has been interpreted that this excess is set on the fibre by dissolution., Peer Reviewed

The friction-reducing properties of fiber suspensions were investigated. Fibers of asbestos, glass, and acrylic were found to greatly reduce the turbulent-flow resistance of both aqueous and non-aqueous suspending fluids. Pipe-flow and rotating-disk experiments show that fibers having the smallest diameter, and substantial length-to-diameter ratio gave the most friction reduction at the smallest weight concentration of fiber. An asbestos fiber gave 65 percent friction reduction in a small pipe-flow apparatus and 48 percent in the rotating-disk equipment (both being the maximum obtainable in the devices) at a suspension concentration of 500 ppm. (Author)

A fast heating rate DTA TECHNIQUE HAS BEEN APPLIED TO VARIOUS COMMERCIAL ACRYLIC FIBRES (Acrilan, Courtelle, Orlon, Cashmillon, Exlan, Creslan, and Acribel). Their melting points, which may otherwise be obscured by exothermic decomposition, can be reliably determined, and the patterns of thermal events obtained by this method can be used to afford some discrimination between commercial acrylic fibres. (Author)

The abrasion resistance of 15 prototype fabrics representing single fiber constructions and blends of 12 different fibers is measured. The purpose of evaluating this group of fabrics was to obtain a pattern of performance which may be relatable to inherent properties such as work-to-rupture, melting point, and friction. The report presents an interesting by-product of the study, which demonstrates the relatedness of some laboratory instruments for evaluating wear.

En el presente estudio, vamos a tratar de diferenciar entre sí, mediante el método de la espectroscopía infrarroja, diversas fibras acrílicas, basándonos para ello en el reconocimiento de algunos de los comonómeros indicados., Peer Reviewed

Vamos a intentar llegar al tema de esta charla, "Estado actual y futuro del mercado de Fibras Acrílicas", efectuando una rápida visión scbre la forma en que se han desarrollado el conjunto de fibras sintéticas y artificiales, dentro del consumo mundial de fibras textiles. Posteriormente, pasaremos a centrarnos sobre el lugar que ocupan hoy las fibras acrílicas, dentro del consumo de fibras sintéticas, así como de sus aplicaciones principales., Peer Reviewed