Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for...Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for blending with TcC.An oxidative thermal stabilisation step was used prior to carbonisation in an inert atmosphere to prevent the fusion of the filaments during the latter step.Thermal stabilisation was not possible using a one-step stabilisation process reported in the literature for lignin and other lignin/synthetic polymer blends.As a consequence,a cyclic process involving an additional isothermal phase at a lower temperature than the precursor filaments’melting point,was introduced to increase the cross-linking reactions between the lignin and polyamide.Thermally stabilised filaments were characterised by DSC,TGA,TGA-FTIR,ATR,and SEM techniques.Polymer rheology and heating rate used during thermal stabilisation influenced the thermal stabilisation process and mechanical properties of the derived filaments.Thermally stabilised filaments using optimised conditions(heating in the air atmosphere at 0.25℃/min to 180℃;isothermal for 1 h,cooling back down to ambient at 5℃/min;heating to 250℃ at 0.25℃/min,isothermal for 2 h)could be successfully carbonised.Carbon fibres pro-duced had void-free morphologies and mechanical properties comparable to similarly thermally stabilised and carbonised polyacrylonitrile(PAN)filaments.展开更多
Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membrane...Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membranes were prepared by using a non-conventional phase separation approach,namely,mixed‘non-solvents’evaporation induced phase separation(MNEIPS).PA1012 can be dissolved in a mixture of polar and non-polar solvents,both of which are non-solvents of PA1012.During the sequential evaporation of the two solvents,the phase separation of PA1012 occurred,inducing the formation of porous structures.We investigated the process of membrane formation in detail,with a specific focus on the liquid-liquid and liquid-solid phase transitions involved.Moreover,we studied the influence of critical factors,such as polymer concentration and mixed-solvent ratio,on the morphologies and properties of PA1012 membranes.This study provides new insights into the development of porous materials based on long-chain polycondensates.展开更多
Side-by-side bicomponent fibers have a spring-like three-dimensional spiral crimp structure and are widely used in elastic fabric.The difference in thermal shrinkage between different polymers can produce an unbalance...Side-by-side bicomponent fibers have a spring-like three-dimensional spiral crimp structure and are widely used in elastic fabric.The difference in thermal shrinkage between different polymers can produce an unbalanced stress during the cooling process,and this unbalanced stress can be exploited to prepare naturally crimped fibers by spinning design.In this work,different types of polyamides(PAs)were selected for fabrication of the PA-based side-by-side bicomponent elastic fibers using melt spinning,and the structure development and performance of such bicomponent elastic fibers were studied.Meanwhile,thermoplastic PA elastomer(TPAE)with intrinsic elasticity was also used as one of the comparative materials.The block structure of the PA segment and the polyether segment in the TPAE molecule is the key to providing thermal shrinkage differences and forming a good interface structure.As a result,the crimp ratio of PA6/TPAE bicomponent elastic fiber is 7.23%,which is better than that of the currently commercialized T400 fiber(6.72%).The excellent crimp performance of PA6/TPAE bicomponent elastic fibers comes from the asymmetric distribution of the stress along the radial direction of the fibers during the cooling process,which is caused by the difference in thermal shrinkage between PA6 and TPAE.In addition,the crimp formability of the PA-based bicomponent elastic fibers could be improved by expanding the shrinkage stress through wet-heat treatment.The crimp ratio of PA6/TPAE bicomponent elastic fibers reaches the maximum(33.08%)after treatment at 100℃.At the same time,the fabric made of PA6/TPAE bicomponent elastic fibers has the excellent air and water vapor permeability,with an air permeability of 272.76 mm/s and a water vapor transmission rate of 406.71 g/(m^(2)·h).展开更多
Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photod...Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photodegradation behavior of polyamide microplastics is studied by using polyamide 6(PA6)as model microplastics and FeCl_(3) as catalyst.It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl_(3) is irradiated in water.The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl_(3) aqueous solution,indicating that it is promising to use this new method to solve the problem of PA6type microplastics.In addition,the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS),which provides a new insight for the study of polymer degradation mechanism.展开更多
Zeolitic imidazolate framework-8(ZIF-8)is a typical filler used to fabricate mixed matrix membranes(MMMs)on account of its attractive advantage of high selective permeability for gas separation.However,the performance...Zeolitic imidazolate framework-8(ZIF-8)is a typical filler used to fabricate mixed matrix membranes(MMMs)on account of its attractive advantage of high selective permeability for gas separation.However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,which will lead to a decrease of selectivity and the performance of gas separation will be strongly influenced.Herein,we modified ZIF-8 with 3-amino-1,2,4-triazole to obtain ZIF-8-NH_(2),Kapton polyamide acid was selected as the polymer matrix.Results showed that the ZIF-8-NH_(2)/Kapton MMMs has a good compatibility interface between ZIF-8 and Kapton because of the covalent bridging,even the filler loading up to 45%(mass).The 45%(mass)of ZIF-8-NH_(2)/Kapton membrane showed 297 barrer(1 barrer=10^(-10)10 cm^(3)·cm·cm^(-2)·s^(-1)·cmHg^(-1),1 cmHg=1333.22 Pa,standard temperature and pressure)of the permeability of H_(2)and 43.9 and 62.2 of selectivities for H_(2)/N_(2)and for H_(2)/CH_(4),respectively,which are beyond the upper limit of Robeson 2008.展开更多
Polyamide(PA)is a widely utilized engineering polymer,and its thermal and mechanical properties can be further improved by adding nanofillers.However,adding inorganic fullerene-like tungsten disulfide(IF-WS_(2))nanopa...Polyamide(PA)is a widely utilized engineering polymer,and its thermal and mechanical properties can be further improved by adding nanofillers.However,adding inorganic fullerene-like tungsten disulfide(IF-WS_(2))nanoparticles(NPs)to PA to produce composite precursor powders for additive manufacturing is challenging.Here,we report a novel and cost-effective method for fabricating PA-12 based nanocomposite(NC)powders with fixed/partially encapsulated IF-WS_(2) nanoparticulate fillers utilizing an advanced mixing technique because simple wet mixing(WM)can only attach fillers weakly to the powder surfaces when compared to the proposed method.The resulting nanocomposite powders maintained nearly the original particle size distribution of PA-12.They also exhibited improved rheological properties,melting,and crystallization behaviors compared with those prepared by the WM method.The laser-sintered PA-12 nanocomposite specimens revealed enhanced pow-der thermal stability and higher tensile strengths than pristine PA-12,validating the advantages of the novel technique for the fabrication of polyamide nanocomposite powders and their suitability for utilization in laser sintering additive manufacturing.These results demonstrate that high-performance engineered PA-12 nanocom-posite components can be directly laser sintered,and this technique can potentially be extended to fabricate other engineered polymeric nanocomposite powders.展开更多
以己二胺为原料利用界面反应制备了双氟酰胺单体1,6-N,N′-双(4-氟苯甲酰胺)己烷(BFBH),并与硫化钠、二氯二苯砜通过溶液缩聚制备了一系列新型半芳族聚酰胺共聚改性聚芳硫醚砜(Semi-PASS/A)树脂。通过核磁氢谱(1 H NMR)和红外光谱(FTIR...以己二胺为原料利用界面反应制备了双氟酰胺单体1,6-N,N′-双(4-氟苯甲酰胺)己烷(BFBH),并与硫化钠、二氯二苯砜通过溶液缩聚制备了一系列新型半芳族聚酰胺共聚改性聚芳硫醚砜(Semi-PASS/A)树脂。通过核磁氢谱(1 H NMR)和红外光谱(FTIR)表征了单体及聚合物的化学结构。结果表明,新型单体及聚合物成功制备。Semi-PASS/A树脂的特性黏度范围为0.43~0.55 dL/g,该共聚物具有优异的热性能,其玻璃化转变温度范围为202~215℃,5%热分解温度范围为396~429℃。玻璃化转变温度、热分解温度均随着聚合物中半芳族酰胺含量的增加而下降。平板流变结果表明,Semi-PASS/A的复数黏度相比于聚芳硫醚砜树脂(PASS)下降显著,PASS树脂的25470 Pa·s降低至Semi-PASS/A-10树脂(BFBH的摩尔分数为10%)的36.9 Pa·s。随着半芳族聚酰胺含量的增加,共聚物的复数黏度降低。此外,Semi-PASS/A树脂在高温(310℃)下的时间测试中,其熔体复数黏度随时间增加基本保持稳定,表明半芳族聚酰胺引入PASS树脂结构中不仅降低了聚合物的熔体黏度,同时还有效改善了PASS的熔体稳定性,极大地改善了PASS的熔体加工性能。展开更多
文摘Carbon fibres have been produced from hydroxypropyl-modified lignin(TcC)/bio-based polyamide 1010(PA1010)blended filaments.Two grades of PA1010,with different molecular weights and rheological properties,were used for blending with TcC.An oxidative thermal stabilisation step was used prior to carbonisation in an inert atmosphere to prevent the fusion of the filaments during the latter step.Thermal stabilisation was not possible using a one-step stabilisation process reported in the literature for lignin and other lignin/synthetic polymer blends.As a consequence,a cyclic process involving an additional isothermal phase at a lower temperature than the precursor filaments’melting point,was introduced to increase the cross-linking reactions between the lignin and polyamide.Thermally stabilised filaments were characterised by DSC,TGA,TGA-FTIR,ATR,and SEM techniques.Polymer rheology and heating rate used during thermal stabilisation influenced the thermal stabilisation process and mechanical properties of the derived filaments.Thermally stabilised filaments using optimised conditions(heating in the air atmosphere at 0.25℃/min to 180℃;isothermal for 1 h,cooling back down to ambient at 5℃/min;heating to 250℃ at 0.25℃/min,isothermal for 2 h)could be successfully carbonised.Carbon fibres pro-duced had void-free morphologies and mechanical properties comparable to similarly thermally stabilised and carbonised polyacrylonitrile(PAN)filaments.
基金supported by the Fundamental Research Funds for the Central Universities(No.2023ZYGXZR107)the TCL Science and Technology Innovation Fund。
文摘Long-chain polyamides(LCPAs)are a class of bio-based polymers that can bridge conventional polyolefins and polycondensates.In this work,taking the advantage of the amphiphilic nature of polyamide 1012(PA1012),membranes were prepared by using a non-conventional phase separation approach,namely,mixed‘non-solvents’evaporation induced phase separation(MNEIPS).PA1012 can be dissolved in a mixture of polar and non-polar solvents,both of which are non-solvents of PA1012.During the sequential evaporation of the two solvents,the phase separation of PA1012 occurred,inducing the formation of porous structures.We investigated the process of membrane formation in detail,with a specific focus on the liquid-liquid and liquid-solid phase transitions involved.Moreover,we studied the influence of critical factors,such as polymer concentration and mixed-solvent ratio,on the morphologies and properties of PA1012 membranes.This study provides new insights into the development of porous materials based on long-chain polycondensates.
基金Fundamental Research Funds for the Central Universities of China(No.2232022D-10)Open Fund of State Key Laboratory of Biobased Fiber Manufacturing Technology,China(No.SKL202306)。
文摘Side-by-side bicomponent fibers have a spring-like three-dimensional spiral crimp structure and are widely used in elastic fabric.The difference in thermal shrinkage between different polymers can produce an unbalanced stress during the cooling process,and this unbalanced stress can be exploited to prepare naturally crimped fibers by spinning design.In this work,different types of polyamides(PAs)were selected for fabrication of the PA-based side-by-side bicomponent elastic fibers using melt spinning,and the structure development and performance of such bicomponent elastic fibers were studied.Meanwhile,thermoplastic PA elastomer(TPAE)with intrinsic elasticity was also used as one of the comparative materials.The block structure of the PA segment and the polyether segment in the TPAE molecule is the key to providing thermal shrinkage differences and forming a good interface structure.As a result,the crimp ratio of PA6/TPAE bicomponent elastic fiber is 7.23%,which is better than that of the currently commercialized T400 fiber(6.72%).The excellent crimp performance of PA6/TPAE bicomponent elastic fibers comes from the asymmetric distribution of the stress along the radial direction of the fibers during the cooling process,which is caused by the difference in thermal shrinkage between PA6 and TPAE.In addition,the crimp formability of the PA-based bicomponent elastic fibers could be improved by expanding the shrinkage stress through wet-heat treatment.The crimp ratio of PA6/TPAE bicomponent elastic fibers reaches the maximum(33.08%)after treatment at 100℃.At the same time,the fabric made of PA6/TPAE bicomponent elastic fibers has the excellent air and water vapor permeability,with an air permeability of 272.76 mm/s and a water vapor transmission rate of 406.71 g/(m^(2)·h).
基金supported by the Natural Science Foundation of Zhejiang Province(No.LDQ23E030001)。
文摘Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photodegradation behavior of polyamide microplastics is studied by using polyamide 6(PA6)as model microplastics and FeCl_(3) as catalyst.It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl_(3) is irradiated in water.The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl_(3) aqueous solution,indicating that it is promising to use this new method to solve the problem of PA6type microplastics.In addition,the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS),which provides a new insight for the study of polymer degradation mechanism.
基金funded by National Natural Science Foundation of China(22278023)Beijing Municipal Science and Technology Planning Project(Z221100002722002)+1 种基金Beijing Natural Science Foundation(2222015)the long-term from the Ministry of Finance and the Ministry of Education of China.
文摘Zeolitic imidazolate framework-8(ZIF-8)is a typical filler used to fabricate mixed matrix membranes(MMMs)on account of its attractive advantage of high selective permeability for gas separation.However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,However,the performance is usually affected by filler aggregation due to strong interactions among fillers and weak interactions between the polymer and fillers,which will lead to a decrease of selectivity and the performance of gas separation will be strongly influenced.Herein,we modified ZIF-8 with 3-amino-1,2,4-triazole to obtain ZIF-8-NH_(2),Kapton polyamide acid was selected as the polymer matrix.Results showed that the ZIF-8-NH_(2)/Kapton MMMs has a good compatibility interface between ZIF-8 and Kapton because of the covalent bridging,even the filler loading up to 45%(mass).The 45%(mass)of ZIF-8-NH_(2)/Kapton membrane showed 297 barrer(1 barrer=10^(-10)10 cm^(3)·cm·cm^(-2)·s^(-1)·cmHg^(-1),1 cmHg=1333.22 Pa,standard temperature and pressure)of the permeability of H_(2)and 43.9 and 62.2 of selectivities for H_(2)/N_(2)and for H_(2)/CH_(4),respectively,which are beyond the upper limit of Robeson 2008.
基金supported by National Natural Science Foundation(Grant.Nos.12205056,51972068)Natural Science Foundation of Guangxi Province in China(Grant.No.2021GXNSFBA076003)the UK Engineering and Physical Science Research Council(EPSRC)for funding(EPSRC Grant:Novel high-performance polymeric composite materials for additive manufacturing of multifunctional components,EP/N034627/1).
文摘Polyamide(PA)is a widely utilized engineering polymer,and its thermal and mechanical properties can be further improved by adding nanofillers.However,adding inorganic fullerene-like tungsten disulfide(IF-WS_(2))nanoparticles(NPs)to PA to produce composite precursor powders for additive manufacturing is challenging.Here,we report a novel and cost-effective method for fabricating PA-12 based nanocomposite(NC)powders with fixed/partially encapsulated IF-WS_(2) nanoparticulate fillers utilizing an advanced mixing technique because simple wet mixing(WM)can only attach fillers weakly to the powder surfaces when compared to the proposed method.The resulting nanocomposite powders maintained nearly the original particle size distribution of PA-12.They also exhibited improved rheological properties,melting,and crystallization behaviors compared with those prepared by the WM method.The laser-sintered PA-12 nanocomposite specimens revealed enhanced pow-der thermal stability and higher tensile strengths than pristine PA-12,validating the advantages of the novel technique for the fabrication of polyamide nanocomposite powders and their suitability for utilization in laser sintering additive manufacturing.These results demonstrate that high-performance engineered PA-12 nanocom-posite components can be directly laser sintered,and this technique can potentially be extended to fabricate other engineered polymeric nanocomposite powders.
