The in vitro degradation rate of polyanhydride （poly（sebacic acid）, diacetoxy terminated）, also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding...The in vitro degradation rate of polyanhydride （poly（sebacic acid）, diacetoxy terminated）, also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline （PBS） for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy （SEM）. The experimental results showed that PSADT exhibited sur^hce erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.展开更多
Two-dimensional(2D)boron nitride nanosheet(BNNS)is promising in polymer-based thermal management materials(TMMs)by pre-constructing three-dimensional(3D)thermally conductive skeleton,but it yet suffers from the challe...Two-dimensional(2D)boron nitride nanosheet(BNNS)is promising in polymer-based thermal management materials(TMMs)by pre-constructing three-dimensional(3D)thermally conductive skeleton,but it yet suffers from the challenges of higheffective exfoliation and affinitive compatibility with matrix.In this work,we developed a one-step exfoliation and deprotonation approach by the high-effective ball milling technique to prepare aramid nanofiber(ANF)/BNNS suspension.Under the strong collision/shear effect of ball-milling,micron-level h BN sheets were exfoliated into smaller and thinner BNNS with edge functional groups,meanwhile,poly-p-phenylene terephthalamide(PPTA)fibers were split into ANF by dissociating the intermolecular hydrogen bonds.More importantly,both the exfoliation and deprotonation could be accelerated by each other to achieve a 100%yield of ANF/BNNS suspension with strong hydrogen/covalent bonding interactions between them.Subsequently,the prepared ANF/BNNS suspension was used to construct 3D vertically aligned ANF/BNNS skeleton by the unidirectional freezing method.The obtained epoxy-based composite(EP/ANF/BNNS)revealed excellent thermal conductivity of 2.41 W m^(-1)K^(-1) at 14.9 vol%BNNS loading due to the vertically oriented heat conduction paths and low interfacial thermal resistance in the skeleton.Moreover,EP/ANF/BNNS composite showed high thermal stability and extraordinary fire retardancy with dramatically decreased heat release rate(265 W g^(-1)) and total heat release(20.6 kJ g^(-1)).Therefore,this work demonstrates a high-efficient one-step ball-milling exfoliation and deprotonation technique for preparing ANF/BNNS suspension,which reveals an enormous potential in preparing advanced TMMs by constructing 3D thermally conductive skeletons.展开更多
On November 30,2020,the Political Bureau of the 19th CPC Central Committee held a collective study session on strengthening protection of intellectual property(IP).President Xi Jinping chaired the session and gave an ...On November 30,2020,the Political Bureau of the 19th CPC Central Committee held a collective study session on strengthening protection of intellectual property(IP).President Xi Jinping chaired the session and gave an important speech in which he affirmed China’s historic achievements in,and elaborated on the great significance of,IP protection,discussed the current situation and tasks facing such work,and the Party’s main policies aimed at strengthening IP protection.展开更多
基金Funded by the China Scholarship Council and Wisconsin Institute for Discovery(WID)the Scientific Research Staring Foundation,Fujian University of Technology,China(No.GY-Z13028)+1 种基金the Programfor New Century Excellent Talents in Fujian Province University(NCETFJ-2010)the Research Fund for Fujian Provincial University(JK-2010038)
文摘The in vitro degradation rate of polyanhydride （poly（sebacic acid）, diacetoxy terminated）, also known as PSADT, was investigated. PSADT tablets with a circular cross-section were formed using a compression molding device, and then immersed into phosphate buffer saline （PBS） for in vitro degradation experiments. The mechanisms of degradation and the degradation rate were characterized by the change in molecular weight and reduction in specimen mass. In addition, the effects of processing temperature and the geometry of the formed PSADT tablets on the rate of degradation were studied. The surface morphology at different degradation times was observed by scanning electron microscopy （SEM）. The experimental results showed that PSADT exhibited sur^hce erosion due to the fact that near zero-order degradation kinetics was observed during its degradation process. Moreover, it is found that the geometry of tablets played an important role on the rate of degradation, while the processing temperature had no significant effect on the PSADT degradation rate.
基金supported by the National Key R&D Program of China(Grant No. 2019YFA0706802)the National Natural Science Foundation of China (Grant Nos. 51903223 and 12072325)+2 种基金the Natural Science Foundation of Henan Province (Grant No. 222300420541)the Key Technologies R&D Program of Henan Province (Grant No. 212102210302)。
文摘Two-dimensional(2D)boron nitride nanosheet(BNNS)is promising in polymer-based thermal management materials(TMMs)by pre-constructing three-dimensional(3D)thermally conductive skeleton,but it yet suffers from the challenges of higheffective exfoliation and affinitive compatibility with matrix.In this work,we developed a one-step exfoliation and deprotonation approach by the high-effective ball milling technique to prepare aramid nanofiber(ANF)/BNNS suspension.Under the strong collision/shear effect of ball-milling,micron-level h BN sheets were exfoliated into smaller and thinner BNNS with edge functional groups,meanwhile,poly-p-phenylene terephthalamide(PPTA)fibers were split into ANF by dissociating the intermolecular hydrogen bonds.More importantly,both the exfoliation and deprotonation could be accelerated by each other to achieve a 100%yield of ANF/BNNS suspension with strong hydrogen/covalent bonding interactions between them.Subsequently,the prepared ANF/BNNS suspension was used to construct 3D vertically aligned ANF/BNNS skeleton by the unidirectional freezing method.The obtained epoxy-based composite(EP/ANF/BNNS)revealed excellent thermal conductivity of 2.41 W m^(-1)K^(-1) at 14.9 vol%BNNS loading due to the vertically oriented heat conduction paths and low interfacial thermal resistance in the skeleton.Moreover,EP/ANF/BNNS composite showed high thermal stability and extraordinary fire retardancy with dramatically decreased heat release rate(265 W g^(-1)) and total heat release(20.6 kJ g^(-1)).Therefore,this work demonstrates a high-efficient one-step ball-milling exfoliation and deprotonation technique for preparing ANF/BNNS suspension,which reveals an enormous potential in preparing advanced TMMs by constructing 3D thermally conductive skeletons.
文摘On November 30,2020,the Political Bureau of the 19th CPC Central Committee held a collective study session on strengthening protection of intellectual property(IP).President Xi Jinping chaired the session and gave an important speech in which he affirmed China’s historic achievements in,and elaborated on the great significance of,IP protection,discussed the current situation and tasks facing such work,and the Party’s main policies aimed at strengthening IP protection.
