Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy s...Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .展开更多
This experimental study investigates the friction and wear of three coatings commonly used in industrial applications,particularly in hydrodynamic bearings.The three materials under investigation were Babbitt,polyethe...This experimental study investigates the friction and wear of three coatings commonly used in industrial applications,particularly in hydrodynamic bearings.The three materials under investigation were Babbitt,polyether ether ketone(PEEK)reinforced with 15%carbon fibers,and PEEK reinforced with 20%carbon fibers.The first polymer material was extruded,while the other was produced by fused deposition modelling(FDM).The materials were subjected to sliding tests in a pin-on-disc configuration,with a steel ball serving as the counter surface.The tests were conducted at room temperature,with a load of 10 N and under three different lubrication conditions:dry,grease,and oil.The linear speed was set at 0.3 m/s for the dry and semi-solid lubrication tests,while for the oil tests,the speed was set at 0.25 m/s.The greases used had consistency grades of NGLI 000 and NGLI 2.An ISO VG 68 circulation oil was used for the oil lubrication tests.Additionally,thermodynamic analyses were performed under the most severe conditions(i.e.,dry)to investigate the steel-Babbitt and steel-PEEK contact.展开更多
Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistanc...Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and biocompatibility.PEEK and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal structures.Nevertheless,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic properties.In this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D printing.We also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its composites.Additionally,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural adjustments.Finally,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.展开更多
Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly（ether ether ketone） （PEEK） with the aim of extending its applications to biological fields. PEEK sheets were surface modified by...Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly（ether ether ketone） （PEEK） with the aim of extending its applications to biological fields. PEEK sheets were surface modified by grafting of acrylamide（AAm） with ultraviolet（UV） irradiation in the presence or absence of benzophenone（BP）. The effects of BP, irradiation time and monomer concentration on the surface wettability of PEEK were investigated. Characteriza tion of modified PEEK using scanning electron microscopy（SEM）, energy-disperse spectrometer（EDS） and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP. With the increase in irradiation time and monomer concentration, contact angles decrease to as low as 30°, demonstrating a significant improvement of surface hydrophilicity. In agreement with the decrease in contact angle, under identical conditions, the nitrogen concentration increases, suggesting the increase in grafting degree of the grafting polymerization. This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer. Though the graft polymerization proceeds more readily in the presence of BP, the self-initiated graft polymerization is clearly observed.展开更多
UV-induced graft polymerization of acrylic acid（AA） on poly（ether ether ketone）（PEEK） films was carried out to introduce ―COOH for the subsequent immobilization of bovine serum albumin（BSA）.BSA was introduced...UV-induced graft polymerization of acrylic acid（AA） on poly（ether ether ketone）（PEEK） films was carried out to introduce ―COOH for the subsequent immobilization of bovine serum albumin（BSA）.BSA was introduced on PEEK surface based on the condensation reaction between ―NH 2 and ―COOH.The modified surface（PEEK-BSA） was characterized by energy-disperse spectrometry（EDS）,X-ray photoelectron spectroscopy（XPS）,water contact angle measurement and UV spectrum analysis.The contact angle was found to decrease from 104° for the virgin PEEK films to 63° for the BSA-immobilized PEEK films,demonstrating a significant improvement of surface hydrophilicity.Moreover,the appearance of nitrogen on PEEK film confirmed by XPS and EDS indicates the immobilization of BSA on PEEK surface.展开更多
文摘Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .
基金The present work was undertaken under the support of the Italian Ministry for Education,University and Research by means of the project Department of Excellence LIS4.0(Integrated Laboratory for Lightweight e Smart Structures).We acknowledge Marco Lattuada(Eni SpA)for providing grease data and Davide Scaglia(Eurobearings S.R.L.)for providing disc specimens.
文摘This experimental study investigates the friction and wear of three coatings commonly used in industrial applications,particularly in hydrodynamic bearings.The three materials under investigation were Babbitt,polyether ether ketone(PEEK)reinforced with 15%carbon fibers,and PEEK reinforced with 20%carbon fibers.The first polymer material was extruded,while the other was produced by fused deposition modelling(FDM).The materials were subjected to sliding tests in a pin-on-disc configuration,with a steel ball serving as the counter surface.The tests were conducted at room temperature,with a load of 10 N and under three different lubrication conditions:dry,grease,and oil.The linear speed was set at 0.3 m/s for the dry and semi-solid lubrication tests,while for the oil tests,the speed was set at 0.25 m/s.The greases used had consistency grades of NGLI 000 and NGLI 2.An ISO VG 68 circulation oil was used for the oil lubrication tests.Additionally,thermodynamic analyses were performed under the most severe conditions(i.e.,dry)to investigate the steel-Babbitt and steel-PEEK contact.
基金supported by the National Key R&D Program of China(No.2022YFC2401903)the“Pioneer”and the“Leading Goose”R&D Program of Zhejiang Province(No.2023C01170)+1 种基金the National Natural Science Foundation of China(No.52205424)the Key Project of Science and Technology Innovation 2025 of Ningbo(No.2023Z029),China.
文摘Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and biocompatibility.PEEK and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal structures.Nevertheless,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic properties.In this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D printing.We also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its composites.Additionally,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural adjustments.Finally,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.
基金Supported by the Scientific and Technological Development Programs of Beijing Municipal Education Commission, China (No.KM201010011004)the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education, China, the 2011 Merit-based Research Funding for Picked Returned Overseas Scholars, Beijing Municipality, ChinaBeijing Technology and Business University Through a Research Project Approved for Undergraduates
文摘Photo-grafting of hydrophilic monomer was used to enhance the hydrophilicity of poly（ether ether ketone） （PEEK） with the aim of extending its applications to biological fields. PEEK sheets were surface modified by grafting of acrylamide（AAm） with ultraviolet（UV） irradiation in the presence or absence of benzophenone（BP）. The effects of BP, irradiation time and monomer concentration on the surface wettability of PEEK were investigated. Characteriza tion of modified PEEK using scanning electron microscopy（SEM）, energy-disperse spectrometer（EDS） and water contact angle measurements shows that AAm was successfully grafted on PEEK surface both in presence and absence of BP. With the increase in irradiation time and monomer concentration, contact angles decrease to as low as 30°, demonstrating a significant improvement of surface hydrophilicity. In agreement with the decrease in contact angle, under identical conditions, the nitrogen concentration increases, suggesting the increase in grafting degree of the grafting polymerization. This investigation demonstrates a self-initiation of PEEK due to its BP-like structure in the backbone of the polymer. Though the graft polymerization proceeds more readily in the presence of BP, the self-initiated graft polymerization is clearly observed.
基金Supported by the Scientific and Technological Development Programs of Beijing Municipal Education Commission,China(No.KM201010011004)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education,China,the 2011 Merit-based Research Funding for Picked Returned Overseas Scholars,Beijing Municipality(China)the Research Project Approved for Graduate Students of Beijing Technology and Business University,China(No.19000101026)
文摘UV-induced graft polymerization of acrylic acid（AA） on poly（ether ether ketone）（PEEK） films was carried out to introduce ―COOH for the subsequent immobilization of bovine serum albumin（BSA）.BSA was introduced on PEEK surface based on the condensation reaction between ―NH 2 and ―COOH.The modified surface（PEEK-BSA） was characterized by energy-disperse spectrometry（EDS）,X-ray photoelectron spectroscopy（XPS）,water contact angle measurement and UV spectrum analysis.The contact angle was found to decrease from 104° for the virgin PEEK films to 63° for the BSA-immobilized PEEK films,demonstrating a significant improvement of surface hydrophilicity.Moreover,the appearance of nitrogen on PEEK film confirmed by XPS and EDS indicates the immobilization of BSA on PEEK surface.
