A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc b...A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc borate(ZB)as flame retardant.The tribological property,mechanical property,flame retardant property and the flame retardant mechanism were investigated.The tests show that the formula of the wear resistant PA6 composite(WRPA 6)is PA6/GF/T/PTFE/Gr in the ratio of 100/15/5/10/5 by mass.Because this composite exhibits the lowest friction coefficient(0.1429)and no wear mass loss,the introduction of RP and ZB can increase the flame resistance of WRPA6,and the synergistic effect of RP and ZB is obtained.Detailedly,the composite with 4 parts of ZB and 12 parts of RP shows the best flame retardant property,achieving the highest limiting oxygen index(LOI)(30.2 vol%)and a UL94 V-0 rating,and the flame retardant mechanisms may be gas phase along with condense phase mechanism.展开更多
We report on the synthesis and characterizations of TiO2 nanoparticles embedded in polyamide-6composite nanofibers by using electrospinning technique. The influence of substrate on the electrical characteristics of po...We report on the synthesis and characterizations of TiO2 nanoparticles embedded in polyamide-6composite nanofibers by using electrospinning technique. The influence of substrate on the electrical characteristics of polyamide-6/TiO2 composite nanofibers was investigated. The resultant nanofibers exhibit good incorporation of TiO2 nanoparticles. The doping of TiO2 nanoparticles into the polyamide-6 nanofibers were confirmed by high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Photoluminescence（PL） and cathodoluminescence（CL） spectroscopy were also used to characterize the samples.The PL and CL spectra reveal that the as-spun polyamide-6/TiO2 composite nanofibers consisted of overlapping of two broad emission bands due to the contribution of polyamide-6（centered at about 475 nm）, which might originate from organic functional groups of polyamide-6 and TiO2 nanoparticles（centered around 550 nm）. The electrical conductivity of the polyamide-6/TiO2 composite nanofibers on different substrates was carried out.It was found that the electrical conductivity of the polyamide-6/TiO2 composite nanofibers on silicon substrate was in the range of 13 μA, and about 1 to 20 p A for the paper and glass substrates.展开更多
Sulphur hexafluoride(SF6)decomposed products analysis is highly critical in the earlystage fault diagnosis of gas-insulated switchgear(GIS).Spectrum technology outperforms traditional methods on non-invasiveness,no sa...Sulphur hexafluoride(SF6)decomposed products analysis is highly critical in the earlystage fault diagnosis of gas-insulated switchgear(GIS).Spectrum technology outperforms traditional methods on non-invasiveness,no sample preparation,and no consumption.Here,the authors present an improved fibre-enhanced Raman spectroscopy(FERS)as a comprehensive analytical tool to detect a suite of SF_(6)decomposed products(SO_(2)F_(2),SOF_(2),SO_(2),H_(2)S,CF_(4),OCS,CO_(2),and CO).The FERS approach is combined with two iris diaphragms for spatial filtering and a rear-end reflector for additional Raman signal enhancement.Limits of detection down to 1×10^(−6)–8×10^(−6)are achieved for different SF6 decompositions,and quantification of an undefined multigas,sampled from an 800 kV GIS in service,is realised utilising SF6 as the internal standard gas and with a maximum error of 5.5%.The GIS is diagnosed according to the results and confirmed by an on-site check.The authors foresee that this technique will provide a route for trace gas analysis in the power industry.展开更多
The effect of blending routes on the morphology and properties of Polyamide-6 (PA-6)/nano-CaCO3/Maleated ethylene-octane copolymer (MA-POE) ternary composite was analyzed using static mechanical test (DMA), TEM (trans...The effect of blending routes on the morphology and properties of Polyamide-6 (PA-6)/nano-CaCO3/Maleated ethylene-octane copolymer (MA-POE) ternary composite was analyzed using static mechanical test (DMA), TEM (transmission electronic microscope) and SEM (scanning electron microscope). It was found that MA-POE, as an impact modifier, had a profound effect upon the toughness of the PA-6/nano-CaCO3 composite. In particular, by adopting two-stage blending route, the microstructure of the ternary composites turned to core-shell structure, and the impact toughness was improved greatly. At the same time, tensile strength and dynamic storage modulus (E1) were higher than those with one-stage blending route processed ternary composite. The results suggest that blending routes may improve the properties of PA-6/nano-CaCO3/MA-POE ternary composites.展开更多
In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and ...In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and the composition dependence of Tg for these blends was well described by the Kwei equation. The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression. The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach. A linear increase in the radii of the spherulites with time was observed for all compositions. All the spherulites continued to grow at nearly identical growth rates. With increasing polyamide-6 content, the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased, and the number of spherulites in the blends increased.展开更多
A statistical approach is developed, based on a Monte Carlo method, in order to determine the statistical composition of a polyamide-6 sample composed of caprolactam （an AB-type monomer） and of a di-acid （A2 type）...A statistical approach is developed, based on a Monte Carlo method, in order to determine the statistical composition of a polyamide-6 sample composed of caprolactam （an AB-type monomer） and of a di-acid （A2 type） or a tri- acid （A3 type） as coupling agents. For this composition, the linear theological behavior of these systems is predicted using a tube-based theory. This allows us to show that while coupling agents of type A2 can be seen as flow improver, the effect of branching agents of type A3, depending on the synthesis recipe and the conversion level, can lead either to an increase or to a decrease of the viscosity. By adding specific amount of these agents, we also show that it is possible to obtain materials with the same zero-shear viscosity but with different shear thinning behavior. Furthermore, the polydispersity of linear samples of the same average number molecular weight, Mn, is discussed in function of the amount of A2 monomers they contain. Ranging from 2 to 1.5, this difference in polydispersity is expected to have a significant influence on the processing behavior of such materials.展开更多
The asymmetric polyamide-6 （PA6） membranes were prepared by thermally induced phase separation. From the scanning electron microscopy （SEM） images, it is observed that with the increase of silicon dioxide （SiO2）...The asymmetric polyamide-6 （PA6） membranes were prepared by thermally induced phase separation. From the scanning electron microscopy （SEM） images, it is observed that with the increase of silicon dioxide （SiO2） content the structure of obtained membranes gradually varied from cellular structure to large ball-shaped cluster aggregates. Subsequently, with the addition of SiO2, pure water flux increased first and then decreased, while rejection showed the opposite trend. Besides, raising the coagulation bath temperature was favorable to increase pure water flux. Consequently, different membrane morphologies and performance were obtained by changing SiO2 content and coagulation bath temperature.展开更多
L-Arginine (L-Arg), the precursor of nitric oxide (NO), plays an important role in muscle function. Fasttwitchglycolytic fibres are more susceptible to age-related atrophy than slow-twitch oxidative fibres.The effect ...L-Arginine (L-Arg), the precursor of nitric oxide (NO), plays an important role in muscle function. Fasttwitchglycolytic fibres are more susceptible to age-related atrophy than slow-twitch oxidative fibres.The effect of L-Arg/NO on protein metabolism of fast- and slow-twitch muscle fibres was evaluated inchickens. In Exp. 1, 48 chicks at 1 day old were divided into 4 groups of 12 birds and subjected to 4treatments: basal diet without supplementation or supplemented with 1% L-Arg, and water supplementedwith or without L-nitro-arginine methyl ester (L-NAME, 18.5 mM). In Exp. 2, 48 chicks weredivided into 4 groups of 12 birds fed with the basal diet and subjected to the following treatments: tapwater (control), tap water supplemented with L-NAME (18.5 mM), or molsidomine (MS, 0.1 mM), or18.5 mM L-NAME t 0.1 mM MS (NAMS). The regulatory effect of L-Arg/NO was further investigatedin vitro with myoblasts obtained from chicken embryo pectoralis major (PM) and biceps femoris (BF).In vivo, dietary L-Arg supplementation increased breast (t14.94%, P < 0.05) and thigh muscle mass(t23.40%, P < 0.05);whereas, MS treatment had no detectable influence. However, L-NAME treatmentblocked the beneficial influence of L-Arg on muscle development. L-Arg decreased (P < 0.05) proteinsynthesis rate, phosphorylated mTOR and ribosomal protein S6 kinase beta-1 (p70S6K) levels in breastmuscle, which was recovered by L-NAME treatment. In vitro, L-Arg or sodium nitroprusside (SNP)reduced protein synthesis rate, suppressed phosphorylated mTOR/p70S6K and decreased atrogin-1 andmuscle RING finger 1 (MuRF1) in myoblasts from PM muscle (P < 0.05). L-NAME abolished the inhibitoryeffect of L-Arg on protein synthesis and the mTOR/p70S6K pathway. However, myoblasts from BF muscleshowed the weak influence. Moreover, blocking the mTOR/p70S6K pathway with rapamycin suppressedprotein synthesis of the 2 types of myoblasts;whereas, the protein expression of atrogin-1 and MuRF1levels were restricted only in myoblasts from PM muscle. In conclusion, L-Arg/NO/mTOR/p70S6Kpathway enhances protein accumulation and muscle development in fast-twitch glycolytic muscle inchickens. L-Arg/NO regulates protein turnover in a muscle fibre specific way, which highlights the potentialclinical application in fast-twitch glycolytic muscle fibres.展开更多
基金Project(149929)supported by the Postdoctoral Fund of Central South University,ChinaProject(16C0292)supported by the Hunan Education Department,ChinaProject(2016TP1022)supported by the Hunan Provincial Key Lab of Dark Tea and Jin-hua,China
文摘A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc borate(ZB)as flame retardant.The tribological property,mechanical property,flame retardant property and the flame retardant mechanism were investigated.The tests show that the formula of the wear resistant PA6 composite(WRPA 6)is PA6/GF/T/PTFE/Gr in the ratio of 100/15/5/10/5 by mass.Because this composite exhibits the lowest friction coefficient(0.1429)and no wear mass loss,the introduction of RP and ZB can increase the flame resistance of WRPA6,and the synergistic effect of RP and ZB is obtained.Detailedly,the composite with 4 parts of ZB and 12 parts of RP shows the best flame retardant property,achieving the highest limiting oxygen index(LOI)(30.2 vol%)and a UL94 V-0 rating,and the flame retardant mechanisms may be gas phase along with condense phase mechanism.
基金supported by a grant from the Korean Ministry of Education,Science and Technology(The Regional Core Research Program/Center for Healthcare Technology&Development,Chonbuk National University,Jeonju 561-756 Republic of Korea)
文摘We report on the synthesis and characterizations of TiO2 nanoparticles embedded in polyamide-6composite nanofibers by using electrospinning technique. The influence of substrate on the electrical characteristics of polyamide-6/TiO2 composite nanofibers was investigated. The resultant nanofibers exhibit good incorporation of TiO2 nanoparticles. The doping of TiO2 nanoparticles into the polyamide-6 nanofibers were confirmed by high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Photoluminescence（PL） and cathodoluminescence（CL） spectroscopy were also used to characterize the samples.The PL and CL spectra reveal that the as-spun polyamide-6/TiO2 composite nanofibers consisted of overlapping of two broad emission bands due to the contribution of polyamide-6（centered at about 475 nm）, which might originate from organic functional groups of polyamide-6 and TiO2 nanoparticles（centered around 550 nm）. The electrical conductivity of the polyamide-6/TiO2 composite nanofibers on different substrates was carried out.It was found that the electrical conductivity of the polyamide-6/TiO2 composite nanofibers on silicon substrate was in the range of 13 μA, and about 1 to 20 p A for the paper and glass substrates.
基金National Natural Science Foundation of China,Grant/Award Number:U1766217Fundamental Research Funds for the Central Universities,Grant/Award Number:2022CDJKYJH027CSC Scholarship。
文摘Sulphur hexafluoride(SF6)decomposed products analysis is highly critical in the earlystage fault diagnosis of gas-insulated switchgear(GIS).Spectrum technology outperforms traditional methods on non-invasiveness,no sample preparation,and no consumption.Here,the authors present an improved fibre-enhanced Raman spectroscopy(FERS)as a comprehensive analytical tool to detect a suite of SF_(6)decomposed products(SO_(2)F_(2),SOF_(2),SO_(2),H_(2)S,CF_(4),OCS,CO_(2),and CO).The FERS approach is combined with two iris diaphragms for spatial filtering and a rear-end reflector for additional Raman signal enhancement.Limits of detection down to 1×10^(−6)–8×10^(−6)are achieved for different SF6 decompositions,and quantification of an undefined multigas,sampled from an 800 kV GIS in service,is realised utilising SF6 as the internal standard gas and with a maximum error of 5.5%.The GIS is diagnosed according to the results and confirmed by an on-site check.The authors foresee that this technique will provide a route for trace gas analysis in the power industry.
基金This work was financially supported by the National Natural Science Foundation of China under grant No.29934070.
文摘The effect of blending routes on the morphology and properties of Polyamide-6 (PA-6)/nano-CaCO3/Maleated ethylene-octane copolymer (MA-POE) ternary composite was analyzed using static mechanical test (DMA), TEM (transmission electronic microscope) and SEM (scanning electron microscope). It was found that MA-POE, as an impact modifier, had a profound effect upon the toughness of the PA-6/nano-CaCO3 composite. In particular, by adopting two-stage blending route, the microstructure of the ternary composites turned to core-shell structure, and the impact toughness was improved greatly. At the same time, tensile strength and dynamic storage modulus (E1) were higher than those with one-stage blending route processed ternary composite. The results suggest that blending routes may improve the properties of PA-6/nano-CaCO3/MA-POE ternary composites.
文摘In this research, the morphologies, isothermal-crystallization kinetics, and spherulite growth of aliphatic polyketone/polyamide-6 blends were studied. A single glass-transition temperature （Tg） was determined, and the composition dependence of Tg for these blends was well described by the Kwei equation. The strong intermolecular interaction between the two polymer components was confirmed by melting-point depression. The isothermal-crystallization kinetics were analyzed on the basis of the Avrami approach. A linear increase in the radii of the spherulites with time was observed for all compositions. All the spherulites continued to grow at nearly identical growth rates. With increasing polyamide-6 content, the size of the spherulites in the polyketone/polyamide-6 blends gradually decreased, and the number of spherulites in the blends increased.
文摘A statistical approach is developed, based on a Monte Carlo method, in order to determine the statistical composition of a polyamide-6 sample composed of caprolactam （an AB-type monomer） and of a di-acid （A2 type） or a tri- acid （A3 type） as coupling agents. For this composition, the linear theological behavior of these systems is predicted using a tube-based theory. This allows us to show that while coupling agents of type A2 can be seen as flow improver, the effect of branching agents of type A3, depending on the synthesis recipe and the conversion level, can lead either to an increase or to a decrease of the viscosity. By adding specific amount of these agents, we also show that it is possible to obtain materials with the same zero-shear viscosity but with different shear thinning behavior. Furthermore, the polydispersity of linear samples of the same average number molecular weight, Mn, is discussed in function of the amount of A2 monomers they contain. Ranging from 2 to 1.5, this difference in polydispersity is expected to have a significant influence on the processing behavior of such materials.
基金supported by the National Natural Science Foundation of China(No.20874073)National 863(high-tech research and development) Program of China(No.2007AA030304)Tianjin Science and Technology Key Support Plan (No.08ZCGYGX03700).
文摘The asymmetric polyamide-6 （PA6） membranes were prepared by thermally induced phase separation. From the scanning electron microscopy （SEM） images, it is observed that with the increase of silicon dioxide （SiO2） content the structure of obtained membranes gradually varied from cellular structure to large ball-shaped cluster aggregates. Subsequently, with the addition of SiO2, pure water flux increased first and then decreased, while rejection showed the opposite trend. Besides, raising the coagulation bath temperature was favorable to increase pure water flux. Consequently, different membrane morphologies and performance were obtained by changing SiO2 content and coagulation bath temperature.
基金the Key Technologies Research and Development Programof China(2021YFD1300405)the Earmarked Fund for China Agriculture Research System(CARS-40-K09)+1 种基金National Natural Science Foundation of China(31772619)Key Technology Research and Development Program of Shandong Province(2019JZZY020602).
文摘L-Arginine (L-Arg), the precursor of nitric oxide (NO), plays an important role in muscle function. Fasttwitchglycolytic fibres are more susceptible to age-related atrophy than slow-twitch oxidative fibres.The effect of L-Arg/NO on protein metabolism of fast- and slow-twitch muscle fibres was evaluated inchickens. In Exp. 1, 48 chicks at 1 day old were divided into 4 groups of 12 birds and subjected to 4treatments: basal diet without supplementation or supplemented with 1% L-Arg, and water supplementedwith or without L-nitro-arginine methyl ester (L-NAME, 18.5 mM). In Exp. 2, 48 chicks weredivided into 4 groups of 12 birds fed with the basal diet and subjected to the following treatments: tapwater (control), tap water supplemented with L-NAME (18.5 mM), or molsidomine (MS, 0.1 mM), or18.5 mM L-NAME t 0.1 mM MS (NAMS). The regulatory effect of L-Arg/NO was further investigatedin vitro with myoblasts obtained from chicken embryo pectoralis major (PM) and biceps femoris (BF).In vivo, dietary L-Arg supplementation increased breast (t14.94%, P < 0.05) and thigh muscle mass(t23.40%, P < 0.05);whereas, MS treatment had no detectable influence. However, L-NAME treatmentblocked the beneficial influence of L-Arg on muscle development. L-Arg decreased (P < 0.05) proteinsynthesis rate, phosphorylated mTOR and ribosomal protein S6 kinase beta-1 (p70S6K) levels in breastmuscle, which was recovered by L-NAME treatment. In vitro, L-Arg or sodium nitroprusside (SNP)reduced protein synthesis rate, suppressed phosphorylated mTOR/p70S6K and decreased atrogin-1 andmuscle RING finger 1 (MuRF1) in myoblasts from PM muscle (P < 0.05). L-NAME abolished the inhibitoryeffect of L-Arg on protein synthesis and the mTOR/p70S6K pathway. However, myoblasts from BF muscleshowed the weak influence. Moreover, blocking the mTOR/p70S6K pathway with rapamycin suppressedprotein synthesis of the 2 types of myoblasts;whereas, the protein expression of atrogin-1 and MuRF1levels were restricted only in myoblasts from PM muscle. In conclusion, L-Arg/NO/mTOR/p70S6Kpathway enhances protein accumulation and muscle development in fast-twitch glycolytic muscle inchickens. L-Arg/NO regulates protein turnover in a muscle fibre specific way, which highlights the potentialclinical application in fast-twitch glycolytic muscle fibres.
