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Joh Lackwell - One of the best experts on this subject based on the ideXlab platform.
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effect of thermal annealing on the structure of Technora and kevlar polyamide fibers
Journal of Polymer Research, 1997Co-Authors: Joh LackwellAbstract:This paper describes X-ray diffraction analysis for the structural changes of Technora and Kevlar polyaramid fibers as a result of thermal annealing. Technora fibers are based on the aromatic copolyamide prepared by reaction of terephthaloyl chloride (TPA) with a 50/50 mole ratio of p-phenylene diamine (PPD) and 3,4′-diaminodiphenyl ether (DPE); Kevlar is the alternating copolymer prepared from TPA and DPE. X-ray fiber diagrams of Technora contain a series of non-periodic layer lines that are characteristic of a completely random comonomer sequence. The structure consists of ordered arrays of chain segments that have extended but sinuous conformations. By matching the profiles of the meridional peaks with those predicted for molecular models, the segment length in unannealed Technora is determined to be 300 ± 15 A with a sinuosity g of 1.52 ± 0.05 %, where g is analogous to the paracrystallinity parameter for homopolymer structures. The segment length is similar to that for unannealed Kevlar 29 fiber (350 ± 10 A) and the sinuosity is lower than that for thermally annealed Kevlar 149 (g = 1.69 ± 0.08 %), for which the crystallite size has increased to 440 ± 10 A. On annealing Technora fibers at 300 °C for 48 hours, both the chain segment length and chain sinuosity remain essentially the same. In contrast, annealing Kevlar 29 under the same directions results in an increase in the crystallite size along the fiber direction to 410 ± 10 A with g declining to 2.05 ± 0.06 %. Both polymers show evidence for improved perfection in the lateral packing as a result of annealing. The g values determined for Technora indicate that despite the random copolymer sequence, the chain conformation is straighter in the Kevlar homopolymer. This linearity is probably maximized during spinning and is not improved by annealing, whereas the ordering of the homopolymer increases due to crystal growth along all three axes.
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comparison of the axial correlation lengths and paracrystalline distortion for Technora and kevlar aromatic polyamide fibers
Macromolecules, 1996Co-Authors: Joh LackwellAbstract:X-ray fiber diagrams of the aromatic copolyamide Technora, prepared from terephthaloyl chloride and equimolar proportions of p-phenylenediamine and 3,4'-diaminodiphenyl ether, contain a series of nonperiodic layer lines that point to a structure consisting of parallel chains of random comonomer sequence. The meridional peak positions are predicted accurately for fully extended, infinite chains, and the observed and calculated peak intensities are also in reasonably good agreement. However, there is a less adequate match between the observed and calculated peak profiles, which are predicted to be very much sharper than those observed. The latter agreement is improved by using a model consisting of finite chain segments with a slightly nonlinear (sinuous) conformation. The best agreement for unannealed Technora is obtained with an ordered segment length of 300 ( 15 A and sinuosity of g ) 1.52 ( 0.05%, where g is analogous to the index of paracrystalline distortion in a homopolymer structure. Very similar results are obtained for fibers that have been thermally annealed. These data are strikingly similar to those for Kevlar fibers (poly(p-phenylene terephthalamide)), for which the crystallite size along the fiber axis direction is 350 ( 10 A with a paracrystalline distortion of 2.32 ( 0.08% for Kevlar 29, increasing to 400 ( 12 A with a paracrystalline distortion of 1.71 ( 0.06% for Kevlar 149. Consequently, although Technora is a random copolymer and the presence of the random diaminodiphenyl ether leads to a more distorted lateral packing of the chains than occurs in Kevlar, the fibers produced by the dry-jet wet-spinning process have extended conformations that are very similar in linearity to those for Kevlar, which probably account for the analogous high tensile strengths and moduli.
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chain conformation of the Technora copolyamide
Macromolecules, 1990Co-Authors: Ronald A Cageao, Andreaingrid Schneide, Ami Iswas, Joh LackwellAbstract:The structure of the copolyamide prepared from terephthaloyl chloride phenylenediamine and 3,4'-diaminodiphenyl ether is studied using X-ray fiber diffraction
Muneaki Yamaguchi - One of the best experts on this subject based on the ideXlab platform.
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influence of aging and wetting on dynamic mechanical properties of multi functional epoxy resins filled with aramid short fibers
Journal of the Japan Society for Composite Materials, 1997Co-Authors: Muneaki Yamaguchi, Yuko Tanaka, Katsutoshi TanakaAbstract:The composite materials were made from three multi-functional epoxy resins (EP) cured with five hardeners and filled with aramid (Technora®) short fibers (AFP) by 2.44 wt%. Effects of aging (heat-treated) at 130°C for 5, 000 h and wetting at 21°C for 5, 000 h in distilled water on the dynamic mechanical properties were studied. The morphology of the fiber dispersion in AFP-filled specimens did not change during the aging. Weight of the aged specimens decreased for a prolonged aging time. The maximum decrease during the aging for 5, 000h was 3.5wt%. The glass transition temperature (Tg) of all the specimens shifted to higher temperature by the aging. The dynamic storage moduli (E') of most of aged specimens decreased at lower temperature (-140°C) and room temperature (25°C) compared with those of unaged specimens. At higher temperature (200°C), the moduli of specimens almost increased and in particularly those of the specimens cured with diamines increased significantly. Absorbed water of wet specimens reached a maximum value of 5.0wt%, and values of the specimens cured with diamines were larger than those of the specimens cured with acid anhydrides. The Tgof all the specimens shifted to lower temperature by the absorption of water. E' of many wet specimens increased in the range of lower temperature to room temperature, but E' of all the specimens at higher temperature extremely fell down.
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dynamic mechanical properties of multi functional epoxy resin filled with aramid short fibers
Advanced Composite Materials, 1994Co-Authors: Katsutoshi Tanaka, Muneaki YamaguchiAbstract:Three heat resistant multi-functional epoxy resin were filled with Aramid (Technora®) short fibers (AFP) by 2.4 wt% using four kinds of hardeners. AFPs observed by SEM on the fracture surface were dispersed randomly. Dynamic mechanical properties and flexural strength of those composites were measured. Although the glass transition temperatures Tg of the multi-functional epoxy resin matrix varied when combined with different hardeners, they were all high (over 200° C) and the highest temperature reached 260° C. The storage modulus E' of the material increased when AFP was added and remained at over 2 GPa even at 150° C. The value of E' in the glassy region was higher than the estimated value by the rule of mixtures which shows that the effect of AFP filling was remarkable. The relative modulus at Tg and the ratio of the peak height of tan δ implied that the affinity of epoxy resin with AFPs was large. The flexural strength of the matrix (epoxy resin) for less tough materials was larger than that for tough...
Katsutoshi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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influence of aging and wetting on dynamic mechanical properties of multi functional epoxy resins filled with aramid short fibers
Journal of the Japan Society for Composite Materials, 1997Co-Authors: Muneaki Yamaguchi, Yuko Tanaka, Katsutoshi TanakaAbstract:The composite materials were made from three multi-functional epoxy resins (EP) cured with five hardeners and filled with aramid (Technora®) short fibers (AFP) by 2.44 wt%. Effects of aging (heat-treated) at 130°C for 5, 000 h and wetting at 21°C for 5, 000 h in distilled water on the dynamic mechanical properties were studied. The morphology of the fiber dispersion in AFP-filled specimens did not change during the aging. Weight of the aged specimens decreased for a prolonged aging time. The maximum decrease during the aging for 5, 000h was 3.5wt%. The glass transition temperature (Tg) of all the specimens shifted to higher temperature by the aging. The dynamic storage moduli (E') of most of aged specimens decreased at lower temperature (-140°C) and room temperature (25°C) compared with those of unaged specimens. At higher temperature (200°C), the moduli of specimens almost increased and in particularly those of the specimens cured with diamines increased significantly. Absorbed water of wet specimens reached a maximum value of 5.0wt%, and values of the specimens cured with diamines were larger than those of the specimens cured with acid anhydrides. The Tgof all the specimens shifted to lower temperature by the absorption of water. E' of many wet specimens increased in the range of lower temperature to room temperature, but E' of all the specimens at higher temperature extremely fell down.
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dynamic mechanical properties of multi functional epoxy resin filled with aramid short fibers
Advanced Composite Materials, 1994Co-Authors: Katsutoshi Tanaka, Muneaki YamaguchiAbstract:Three heat resistant multi-functional epoxy resin were filled with Aramid (Technora®) short fibers (AFP) by 2.4 wt% using four kinds of hardeners. AFPs observed by SEM on the fracture surface were dispersed randomly. Dynamic mechanical properties and flexural strength of those composites were measured. Although the glass transition temperatures Tg of the multi-functional epoxy resin matrix varied when combined with different hardeners, they were all high (over 200° C) and the highest temperature reached 260° C. The storage modulus E' of the material increased when AFP was added and remained at over 2 GPa even at 150° C. The value of E' in the glassy region was higher than the estimated value by the rule of mixtures which shows that the effect of AFP filling was remarkable. The relative modulus at Tg and the ratio of the peak height of tan δ implied that the affinity of epoxy resin with AFPs was large. The flexural strength of the matrix (epoxy resin) for less tough materials was larger than that for tough...
Derombise Guillaume - One of the best experts on this subject based on the ideXlab platform.
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Influence of finish treatment on the durability of aramid fibres aged under an alkaline environment
Wiley, 2010Co-Authors: Derombise Guillaume, Vouyovitch Van Schoors, Laetitia, Messou, Marie Fleu, Davies PeteAbstract:Aramid fibres are high performance materials which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for ground reinforcement. The influence of the surface finish composition and content has been studied in the field of cables and textiles, but there is no published data concerning the effect of a finish treatment on the hydrolytic degradation. Aramid fibres with different finish contents have been aged in an alkaline environment. The degradation has been identified by FTIR, viscosimetry, TGA, SEM and tensile tests. For Technora fibres, the presence of finish appears to limit the tensile strength loss of aramid fibres at pH11 by limiting abrasion, as well as bulk and surface degradation. For Twaron fibres, higher finish content only has a slight influence on the fibres durability at pH11 and pH9, by limiting abrasion and bulk degradation
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Degradation of Technora fibres in alkaline and neutral environments
Elsevier, 2009Co-Authors: Derombise Guillaume, Vouyovitch Van Schoors, Laetitia, Davies PeteAbstract:Technora fibres are high performance aramid fibres which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for soil reinforcement. However, there is a lack of experience on the long-term behaviour of Technora fibres in an alkaline environment (lime-treated grounds). Consequently, aging studies have been performed under different conditions (deionised water, pH9 and pH11). Hydrolytic degradation has been evaluated by FTIR, viscosimetry, TGA, density measurements, SEM, and by tensile tests measurements. Some chain degradation and finish rearrangements have been highlighted, but Technora fibres retain their mechanical properties for all conditions considered here
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Comportement à long terme des fibres aramides en milieux neutres et alcalins
HAL CCSD, 2009Co-Authors: Derombise GuillaumeAbstract:Aramid fibres are high-performance fibres proposed in geotextiles for treated ground reinforcement and in ropes and cables for marine applications. This work aims at answering the durability issues raised by a prolonged exposure in alkaline grounds (pH9-pH11) or in sea water, and at giving a better insight into the degradation mechanisms. For that purpose, accelerated agings in laboratory have been performed for three types of aramid fibres in different environments. First, the fibres have been characterized at the macromolecular, structural, morphological and macroscopic scales. Some strength losses mainly associated to chain scissions phenomena have been highlighted for Twaron 1000 fibres aged in tap water, in sea water, at pH9 and at pH11. However, the tensile modulus remains stable in these conditions. The same multi-scales approach has been adopted for Technora T240 fibres which appear to be very stable in these aggressive environments. Then, the influence of the finish on the fibres durability has been shown: not only the finish limits the surface abrasion between fibres, but it can protect the fibres towards hydrolysis as well. Finally, the comparison of the mechanical properties evolutions of polyesters and aramid fibres aged in an alkaline environment reveals that the Technora T240 fibres are well-suited for alkaline ground reinforcement, because of their high stability towards hydrolysis. The second part of this work is dedicated to the study of viscoelastic and viscoplastic behaviour of Twaron 1000 and Technora T200w fibres. The results indicate a significant influence of sea water immersion on the creep-recovery deformation, but the influence of aging on this behaviour is not obvious.Les fibres aramides sont des fibres à hautes performances mécaniques utilisées dans les géotextiles pour le renforcement des sols traités ou dans les câbles et cordages à applications maritimes. L'objectif de ce travail consiste à répondre aux problématiques de durabilité posées dans le cadre d'une exposition prolongée en sols alcalins (pH9-pH11) ou dans l'eau de mer, et à améliorer la compréhension des mécanismes de dégradation mis en jeu. Des vieillissements accélérés en laboratoire ont donc été réalisés sur trois types de fibres aramides dans différents milieux. Dans un premier temps, les fibres ont été caractérisées à l'échelle macromoléculaire, structurale, morphologique et macroscopique. Ainsi, des chutes de résistance mécanique associées principalement à des phénomènes de coupures des chaînes ont été mises en évidence pour les fibres Twaron 1000 vieillies dans l'eau douce, dans l'eau de mer, à pH9 et à pH11. Cependant, aucune évolution du module de traction n'a été observée dans ces conditions. Cette même approche multi-échelles a mis en évidence la grande stabilité des fibres Technora T240 dans ces environnements pourtant agressifs. Ensuite, l'étude de l'influence de l'ensimage sur le vieillissement en environnement alcalin révèle que non-seulement la présence d'ensimage permettait de limiter l'abrasion entre les fibres, mais pouvait également jouer un rôle de protection vis-à-vis de l'hydrolyse. Enfin, la comparaison de l'évolution des propriétés mécaniques des fibres aramides et polyesters vieillies en milieu basique a révélé que les fibres Technora T240 semblent être très bien adaptées au renforcement des sols traités compte-tenu de leur grande stabilité vis-à-vis de l'hydrolyse. La deuxième partie de ce travail est consacrée à l'étude du comportement viscoélastique et viscoplastique des fibres Twaron 1000 et Technora T200w. Les résultats ont révélé une influence significative de l'eau de mer sur la déformation en fluage-recouvrance, mais l'influence du vieillissement sur ce comportement n'a pas clairement été établie
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Comportement à long terme des fibres aramides en milieux neutres et alcalins
2009Co-Authors: Derombise Guillaume, Davies Pete, Chaussade ThierryAbstract:Les fibres aramides sont des fibres à hautes performances mécaniques utilisées dans les géotextiles pour le renforcement des sols traités ou dans les câbles et cordages à applications maritimes. L'objectif de ce travail consiste à répondre aux problématiques de durabilité posées dans le cadre d'une exposition prolongée en sols alcalins (pH9-pH11) ou dans l'eau de mer, et à améliorer la compréhension des mécanismes de dégradation mis en jeu. Des vieillissements accélérés en laboratoire ont donc été réalisés sur trois types de fibres aramides dans différents milieux. Dans un premier temps, les fibres ont été caractérisées à l'échelle macromoléculaire, structurale, morphologique et macroscopique. Ainsi, des chutes de résistance mécanique associées principalement à des phénomènes de coupures des chaînes ont été mises en évidence pour les fibres Twaron 1000 vieillies dans l'eau douce, dans l'eau de mer, à pH9 et à pH11. Cependant, aucune évolution du module de traction n'a été observée dans ces conditions. Cette même approche multi-échelles a mis en évidence la grande stabilité des fibres Technora T240 dans ces environnements pourtant agressifs. Ensuite, l'étude de l'influence de l'ensimage sur le vieillissement en environnement alcalin révèle que non-seulement la présence d'ensimage permettait de limiter l'abrasion entre les fibres, mais pouvait également jouer un rôle de protection vis-à-vis de l'hydrolyse. Enfin, la comparaison de l'évolution des propriétés mécaniques des fibres aramides et polyesters vieillies en milieu basique a révélé que les fibres Technora T240 semblent être très bien adaptées au renforcement des sols traités compte-tenu de leur grande stabilité vis-à-vis de l'hydrolyse. La deuxième partie de ce travail est consacrée à l'étude du comportement viscoélastique et viscoplastique des fibres Twaron 1000 et Technora T200w. Les résultats ont révélé une influence significative de l'eau de mer sur la déformation en fluage-recouvrance, mais l'influence du vieillissement sur ce comportement n'a pas clairement été établie.Aramid fibres are high-performance fibres proposed in geotextiles for treated ground reinforcement and in ropes and cables for marine applications. This work aims at answering the durability issues raised by a prolonged exposure in alkaline grounds (pH9-pH11) or in sea water, and at giving a better insight into the degradation mechanisms. For that purpose, accelerated agings in laboratory have been performed for three types of aramid fibres in different environments. First, the fibres have been characterized at the macromolecular, structural, morphological and macroscopic scales. Some strength losses mainly associated to chain scissions phenomena have been highlighted for Twaron 1000 fibres aged in tap water, in sea water, at pH9 and at pH11. However, the tensile modulus remains stable in these conditions. The same multi-scales approach has been adopted for Technora T240 fibres which appear to be very stable in these aggressive environments. Then, the influence of the finish on the fibres durability has been shown: not only the finish limits the surface abrasion between fibres, but it can protect the fibres towards hydrolysis as well. Finally, the comparison of the mechanical properties evolutions of polyesters and aramid fibres aged in an alkaline environment reveals that the Technora T240 fibres are well-suited for alkaline ground reinforcement, because of their high stability towards hydrolysis. The second part of this work is dedicated to the study of viscoelastic and viscoplastic behaviour of Twaron 1000 and Technora T200w fibres. The results indicate a significant influence of sea water immersion on the creep-recovery deformation, but the influence of aging on this behaviour is not obvious.MARNE-LA-VALLEE-ENPC-BIBL. (774682303) / SudocSudocFranceF
Davies Pete - One of the best experts on this subject based on the ideXlab platform.
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Influence of finish treatment on the durability of aramid fibres aged under an alkaline environment
Wiley, 2010Co-Authors: Derombise Guillaume, Vouyovitch Van Schoors, Laetitia, Messou, Marie Fleu, Davies PeteAbstract:Aramid fibres are high performance materials which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for ground reinforcement. The influence of the surface finish composition and content has been studied in the field of cables and textiles, but there is no published data concerning the effect of a finish treatment on the hydrolytic degradation. Aramid fibres with different finish contents have been aged in an alkaline environment. The degradation has been identified by FTIR, viscosimetry, TGA, SEM and tensile tests. For Technora fibres, the presence of finish appears to limit the tensile strength loss of aramid fibres at pH11 by limiting abrasion, as well as bulk and surface degradation. For Twaron fibres, higher finish content only has a slight influence on the fibres durability at pH11 and pH9, by limiting abrasion and bulk degradation
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Degradation of Technora fibres in alkaline and neutral environments
Elsevier, 2009Co-Authors: Derombise Guillaume, Vouyovitch Van Schoors, Laetitia, Davies PeteAbstract:Technora fibres are high performance aramid fibres which have been used in ropes and protective clothing for many years. They are also now being proposed in geotextiles for soil reinforcement. However, there is a lack of experience on the long-term behaviour of Technora fibres in an alkaline environment (lime-treated grounds). Consequently, aging studies have been performed under different conditions (deionised water, pH9 and pH11). Hydrolytic degradation has been evaluated by FTIR, viscosimetry, TGA, density measurements, SEM, and by tensile tests measurements. Some chain degradation and finish rearrangements have been highlighted, but Technora fibres retain their mechanical properties for all conditions considered here
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Comportement à long terme des fibres aramides en milieux neutres et alcalins
2009Co-Authors: Derombise Guillaume, Davies Pete, Chaussade ThierryAbstract:Les fibres aramides sont des fibres à hautes performances mécaniques utilisées dans les géotextiles pour le renforcement des sols traités ou dans les câbles et cordages à applications maritimes. L'objectif de ce travail consiste à répondre aux problématiques de durabilité posées dans le cadre d'une exposition prolongée en sols alcalins (pH9-pH11) ou dans l'eau de mer, et à améliorer la compréhension des mécanismes de dégradation mis en jeu. Des vieillissements accélérés en laboratoire ont donc été réalisés sur trois types de fibres aramides dans différents milieux. Dans un premier temps, les fibres ont été caractérisées à l'échelle macromoléculaire, structurale, morphologique et macroscopique. Ainsi, des chutes de résistance mécanique associées principalement à des phénomènes de coupures des chaînes ont été mises en évidence pour les fibres Twaron 1000 vieillies dans l'eau douce, dans l'eau de mer, à pH9 et à pH11. Cependant, aucune évolution du module de traction n'a été observée dans ces conditions. Cette même approche multi-échelles a mis en évidence la grande stabilité des fibres Technora T240 dans ces environnements pourtant agressifs. Ensuite, l'étude de l'influence de l'ensimage sur le vieillissement en environnement alcalin révèle que non-seulement la présence d'ensimage permettait de limiter l'abrasion entre les fibres, mais pouvait également jouer un rôle de protection vis-à-vis de l'hydrolyse. Enfin, la comparaison de l'évolution des propriétés mécaniques des fibres aramides et polyesters vieillies en milieu basique a révélé que les fibres Technora T240 semblent être très bien adaptées au renforcement des sols traités compte-tenu de leur grande stabilité vis-à-vis de l'hydrolyse. La deuxième partie de ce travail est consacrée à l'étude du comportement viscoélastique et viscoplastique des fibres Twaron 1000 et Technora T200w. Les résultats ont révélé une influence significative de l'eau de mer sur la déformation en fluage-recouvrance, mais l'influence du vieillissement sur ce comportement n'a pas clairement été établie.Aramid fibres are high-performance fibres proposed in geotextiles for treated ground reinforcement and in ropes and cables for marine applications. This work aims at answering the durability issues raised by a prolonged exposure in alkaline grounds (pH9-pH11) or in sea water, and at giving a better insight into the degradation mechanisms. For that purpose, accelerated agings in laboratory have been performed for three types of aramid fibres in different environments. First, the fibres have been characterized at the macromolecular, structural, morphological and macroscopic scales. Some strength losses mainly associated to chain scissions phenomena have been highlighted for Twaron 1000 fibres aged in tap water, in sea water, at pH9 and at pH11. However, the tensile modulus remains stable in these conditions. The same multi-scales approach has been adopted for Technora T240 fibres which appear to be very stable in these aggressive environments. Then, the influence of the finish on the fibres durability has been shown: not only the finish limits the surface abrasion between fibres, but it can protect the fibres towards hydrolysis as well. Finally, the comparison of the mechanical properties evolutions of polyesters and aramid fibres aged in an alkaline environment reveals that the Technora T240 fibres are well-suited for alkaline ground reinforcement, because of their high stability towards hydrolysis. The second part of this work is dedicated to the study of viscoelastic and viscoplastic behaviour of Twaron 1000 and Technora T200w fibres. The results indicate a significant influence of sea water immersion on the creep-recovery deformation, but the influence of aging on this behaviour is not obvious.MARNE-LA-VALLEE-ENPC-BIBL. (774682303) / SudocSudocFranceF