Influences of polymer-based grinding aid(PGA) on the damage process of concrete exposed to sulfate attack under dry-wet cycles were investigated. The mass loss, dynamic modulus of elasticity(Erd), and S and Ca ele...Influences of polymer-based grinding aid(PGA) on the damage process of concrete exposed to sulfate attack under dry-wet cycles were investigated. The mass loss, dynamic modulus of elasticity(Erd), and S and Ca element contents of concrete specimens were measured. Scanning electron microscopy(SEM), mercury intrusion porosimetry(MIP), and X-ray diffractometry(XRD) were used to investigate the changing of microstructure of interior concrete. The results indicated that PGA was capable of reducing the mass loss and improving the sulfate attack resistance of concrete. X-ray fluorescence(XRF) analysis revealed that PGA delayed the transport process of sulfate ions and Ca ions. In addition, MIP analysis disclosed that the micropores of concrete with PGA increased in the fraction of 20-100 nm and decreased in the residues of 200 nm. Compared with the blank sample, concrete with PGA had more slender and well-organized hydration products, and no changes in hydration products ratio or type were observed.展开更多
High-power capacitors are highly demanded in advanced electronics and power systems,where rising concerns on the operating temperatures have evoked the attention on developing highly reliable high-temperature dielectr...High-power capacitors are highly demanded in advanced electronics and power systems,where rising concerns on the operating temperatures have evoked the attention on developing highly reliable high-temperature dielectric polymers.Herein,polyetherimide(PEI)filled with highly insulating Al_(2)O_(3)(AO)nanoparticles dielectric composite films have been fabricated aiming for high thermal stability and reliability operated under high cycling electric field and elevated temperature.At room temperature,incorporating a small fraction of 0.5 vol%AO nanoparticles gives rise to a highest discharged energy density(U_(e))of 5.57 J·cm^(-3)and efficiency(η)of 90.9%at650 MV·m^(-1),and a robust cycling stability up to 10^(7) cycles at 400 MV·m^(-1).Due to the substantially reduced dielectric loss,2.0 vol%AO/PEI nanocomposite film exhibits excellent high-temperature capacitive performances,delivering U_(e)~7.33 J·cm^(-3)withη~88.8%under 700 MV·m^(-1),and cycling stability up to 10^(6) cycles under 400 MV·m^(-1)at 100℃,and U_(e)~5.57 J·cm^(-3)withη~84.7%under 620 MV·m^(-1)at 150℃.Molecular dynamic simulations are performed to understand the microscopic mechanism via revealing the polymer relaxation process in the AO/PEI composite at elevated temperatures.Our results are therefore very encouraging for high-temperature high-power capacitor application.展开更多
High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the norma...High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.展开更多
Biomaterials and medical devices are broadly used in the diagnosis,treatment,repair,replacement or enhancing functions of human tissues or organs.Although the living conditions of human beings have been steadily impro...Biomaterials and medical devices are broadly used in the diagnosis,treatment,repair,replacement or enhancing functions of human tissues or organs.Although the living conditions of human beings have been steadily improved in most parts of the world,the incidence of major human’s diseases is still rapidly growing mainly because of the growth and aging of population.The compound annual growth rate of biomaterials and medical devices is projected to maintain around 10%in the next 10 years;and the global market sale of biomaterials and medical devices is estimated to reach$400 billion in 2020.In particular,the annual consumption of polymeric biomaterials is tremendous,more than 8000 kilotons.The compound annual growth rate of polymeric biomaterials and medical devices will be up to 15-30%.As a result,it is critical to address some widespread concerns that are associated with the biosafety of the polymer-based biomaterials and medical devices.Our group has been actively worked in this direction for the past two decades.In this review,some key research results will be highlighted.展开更多
Hydrogel is a polymer network system that can form a hydrophilic three-dimensional network structure through different cross-linking methods.In recent years,hydrogels have received considerable attention due to their ...Hydrogel is a polymer network system that can form a hydrophilic three-dimensional network structure through different cross-linking methods.In recent years,hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross-linking mechanisms and functional components.Compared with synthetic hydrogels,natural polymer-based hydrogels have low biotoxicity,high cell affinity,and great potential for biomedical fields;however,their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements.In recent years,many efforts have been made to solve these issues.In this review,the recent progress in the field of natural polymer-based adhesive hydrogels is highlighted.The authors first introduce the general design principles for the natural polymer-based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design.Next,their usages in biomedical applications are summarised,such as wound healing,haemostasis,nerve repair,bone tissue repair,cartilage tissue repair,electronic devices,and other tissue repairs.Finally,the potential challenges of natural polymer-based adhesive hydrogels are presented.展开更多
基金Funded by National Natural Science Foundation of China(No.51578141)National Program on Key Basic Research Project(973 Program)(No.2015CB655102)Ministry of Science and Technology of China(No.2016YFE011820)
文摘Influences of polymer-based grinding aid(PGA) on the damage process of concrete exposed to sulfate attack under dry-wet cycles were investigated. The mass loss, dynamic modulus of elasticity(Erd), and S and Ca element contents of concrete specimens were measured. Scanning electron microscopy(SEM), mercury intrusion porosimetry(MIP), and X-ray diffractometry(XRD) were used to investigate the changing of microstructure of interior concrete. The results indicated that PGA was capable of reducing the mass loss and improving the sulfate attack resistance of concrete. X-ray fluorescence(XRF) analysis revealed that PGA delayed the transport process of sulfate ions and Ca ions. In addition, MIP analysis disclosed that the micropores of concrete with PGA increased in the fraction of 20-100 nm and decreased in the residues of 200 nm. Compared with the blank sample, concrete with PGA had more slender and well-organized hydration products, and no changes in hydration products ratio or type were observed.
基金financially supported by the National Natural Science Foundation of China (Nos.92066203 and51872009)the Fundamental Research Funds for the Central Universities。
文摘High-power capacitors are highly demanded in advanced electronics and power systems,where rising concerns on the operating temperatures have evoked the attention on developing highly reliable high-temperature dielectric polymers.Herein,polyetherimide(PEI)filled with highly insulating Al_(2)O_(3)(AO)nanoparticles dielectric composite films have been fabricated aiming for high thermal stability and reliability operated under high cycling electric field and elevated temperature.At room temperature,incorporating a small fraction of 0.5 vol%AO nanoparticles gives rise to a highest discharged energy density(U_(e))of 5.57 J·cm^(-3)and efficiency(η)of 90.9%at650 MV·m^(-1),and a robust cycling stability up to 10^(7) cycles at 400 MV·m^(-1).Due to the substantially reduced dielectric loss,2.0 vol%AO/PEI nanocomposite film exhibits excellent high-temperature capacitive performances,delivering U_(e)~7.33 J·cm^(-3)withη~88.8%under 700 MV·m^(-1),and cycling stability up to 10^(6) cycles under 400 MV·m^(-1)at 100℃,and U_(e)~5.57 J·cm^(-3)withη~84.7%under 620 MV·m^(-1)at 150℃.Molecular dynamic simulations are performed to understand the microscopic mechanism via revealing the polymer relaxation process in the AO/PEI composite at elevated temperatures.Our results are therefore very encouraging for high-temperature high-power capacitor application.
基金Foundation of National Natural Science Foundation of China,Grant/Award Number:51903145Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province of China,Grant/Award Number:2019JC-11Wang L.would like to thank the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,Grant/Award Number:CX202053。
文摘High-frequency electromagnetic waves and electronic products can bring great convenience to people’s life,but lead to a series of electromagnetic interference(EMI)problems,such as great potential dangers to the normal operation of elec-tronic components and human safety.Therefore,the research of EMI shield-ing materials has attracted extensive attention by the scholars.Among them,polymer-based EMI shielding materials with light weight,high specific strength,and stable properties have become the current mainstream.The construction of 3D conductive networks has proved to be an effective method for the prepara-tion of polymer-based EMI shielding materials with excellent shielding effective-ness(SE).In this paper,the shielding mechanism of polymer-based EMI shield-ing materials with 3D conductive networks is briefly introduced,with emphasis on the preparation methods and latest research progress of polymer-based EMI shielding materials with different 3D conductive networks.The key scientific and technical problems to be solved in the field of polymer-based EMI shielding materials are also put forward.Finally,the development trend and application prospects of polymer-based EMI shielding materials are prospected.
基金This work was supported by the National Natural Science Foundation of China(Project Numbers:21274150,51473167 and 51273200)Chinese Academy of Sciences-WEGO Group High-Tech Research&Development Program and Scientific Development Program of Jilin Province(20130102064JC).
文摘Biomaterials and medical devices are broadly used in the diagnosis,treatment,repair,replacement or enhancing functions of human tissues or organs.Although the living conditions of human beings have been steadily improved in most parts of the world,the incidence of major human’s diseases is still rapidly growing mainly because of the growth and aging of population.The compound annual growth rate of biomaterials and medical devices is projected to maintain around 10%in the next 10 years;and the global market sale of biomaterials and medical devices is estimated to reach$400 billion in 2020.In particular,the annual consumption of polymeric biomaterials is tremendous,more than 8000 kilotons.The compound annual growth rate of polymeric biomaterials and medical devices will be up to 15-30%.As a result,it is critical to address some widespread concerns that are associated with the biosafety of the polymer-based biomaterials and medical devices.Our group has been actively worked in this direction for the past two decades.In this review,some key research results will be highlighted.
基金supported by grants from the Sichuan Key Research and Development Program of China(22ZDYF2034)the National Natural Science Foundation of China(grant no.82,072,071,82,072,073)+2 种基金the Key-Area Research and Development Program of Guang Dong Province(2019B010941002)Shenzhen Funds of the Central Government to Guide Local Scientific and Technological Development(2021SZVUP123)Fundamental Research Funds for Central Universities(2682021CX109).
文摘Hydrogel is a polymer network system that can form a hydrophilic three-dimensional network structure through different cross-linking methods.In recent years,hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross-linking mechanisms and functional components.Compared with synthetic hydrogels,natural polymer-based hydrogels have low biotoxicity,high cell affinity,and great potential for biomedical fields;however,their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements.In recent years,many efforts have been made to solve these issues.In this review,the recent progress in the field of natural polymer-based adhesive hydrogels is highlighted.The authors first introduce the general design principles for the natural polymer-based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design.Next,their usages in biomedical applications are summarised,such as wound healing,haemostasis,nerve repair,bone tissue repair,cartilage tissue repair,electronic devices,and other tissue repairs.Finally,the potential challenges of natural polymer-based adhesive hydrogels are presented.