The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. Brazilian test is used to study the tensile propert...The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. Brazilian test is used to study the tensile properties. The microstructure of polymer bonded explosives and its evolution are studied by use of scanning electronic microscopy and polarized light microscopy. Polishing techniques have been developed to prepare samples for microscopic examination. The failure mechanisms of polymer bonded explosives under different loads are analyzed. The results show that interfacial debonding is the predominant failure mode in quasi-static tension, while extensive crystal fractures are induced in compression. With the increase of strain rate, more crystal fractures occur. Low velocity impact also induces extensive crystal fractures.展开更多
A thermoviscoelastic modeling approach is developed to predict the recovery behaviors of the thermally activated amorphous shape memory polymers(SMPs)based on the generalized finite deformation viscoelasticity theory....A thermoviscoelastic modeling approach is developed to predict the recovery behaviors of the thermally activated amorphous shape memory polymers(SMPs)based on the generalized finite deformation viscoelasticity theory.In this paper,a series of moduli and relaxation times of the generalized Maxwell model is estimated from the stress relaxation master curve by using the nonlinear regression(NLREG)method.Assuming that the amorphous SMPs are approximately incompressible isotropic elastomers in the rubbery state,the hyperelastic response of the materials is well modeled with a hyperelastic model in Ogden form.In addition,the Williams-Landel-Ferry(WLF)equation is used to describe the horizontal shift factor obtained with time-temperature superposition principle(TTSP).The finite element simulations show good agreement with the experimental thermomechanical behaviors.Moreover,the possibility of developing a temperature-responsive intravascular stent with the SMP studied here is investigated in terms of its thermomechanical property.Therefore,it can be concluded that the model has good prediction capabilities for the recovery behaviors of amorphous SMPs.展开更多
Crosslinked liquid crystalline polymers（CLCPs） are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks.The anisotropic deformation of the CLCPs takes pl...Crosslinked liquid crystalline polymers（CLCPs） are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks.The anisotropic deformation of the CLCPs takes place when the mesogens experience order to disorder change in response to external stimuli; therefore,they can be utilized to fabricate smart actuators,which have potential applications in artificial muscles,micro-optomechanical systems,optics,and energyharvesting fields.In this review the recent development of thermo-and photo-driven soft actuators based on the CLCPs are summarized.展开更多
聚合物砂浆(polymer mortar,PM)因其良好的气密性、抗裂性和变形适应性被认为是一种极具发展潜力的建造压缩空气储能(compressed air energy storage,CAES)人工硐室储气库密封层的可选材料之一。为探究聚氨酯类聚合物砂浆(polyurethane ...聚合物砂浆(polymer mortar,PM)因其良好的气密性、抗裂性和变形适应性被认为是一种极具发展潜力的建造压缩空气储能(compressed air energy storage,CAES)人工硐室储气库密封层的可选材料之一。为探究聚氨酯类聚合物砂浆(polyurethane polymer mortar,PPM)与人工硐室储气库衬砌混凝土之间的黏结性能和变形适应性,采用室内试验和数值模拟方法,研究了PPM中粉料和聚合物含量以及配比变化对PPM-混凝土界面的黏结性能和变形性能的影响规律,并分析了界面的破坏特征和破坏机制。研究结果表明:PPM-混凝土界面破坏型式主要表现为界面两侧材料的分离;界面剪应力-位移关系在应力峰值前呈现两阶段近似线性变形特征,界面破坏剪切应变最大值可达11.05%;粉料和聚合物含量以及配比变化对界面黏结强度都有重要的影响,最高黏结强度约为1.21MPa,最低平均黏结强度为0.237MPa。PPM-混凝土界面强度和变形性能可满足CAES地下储气库的建库要求。展开更多
The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-fi...The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-field and high-field NMR,while the timedomain NMR is normally applied in the former case and the frequency-domain NMR is adopted in the latter one.Depending on different rheometer cells,it can be further divided into tensile and shear mode Rheo-NMR.The combination of various rheometer cells and NMR facility guarantees our acquisition of molecular level structure and dynamics information under flow conditions,which is crucial for our understanding of the molecular origin of complex fluids.A personal perspective is also presented at last to highlight possible development in this direction.展开更多
文摘The deformation and failure of pressed polymer bonded explosives under different types of loads including tension, compression and low velocity impact are presented. Brazilian test is used to study the tensile properties. The microstructure of polymer bonded explosives and its evolution are studied by use of scanning electronic microscopy and polarized light microscopy. Polishing techniques have been developed to prepare samples for microscopic examination. The failure mechanisms of polymer bonded explosives under different loads are analyzed. The results show that interfacial debonding is the predominant failure mode in quasi-static tension, while extensive crystal fractures are induced in compression. With the increase of strain rate, more crystal fractures occur. Low velocity impact also induces extensive crystal fractures.
基金supported by the Natural Science Foundation of Jiangsu Province of China (No. BK20170759)the National Natural Science Foundation of China (No. 11572153)+3 种基金Jiangsu Government Scholarship for Overseas Studiesa project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu Provincethe Doctor Special Foundation and the Research Fund of Nanjing Institute of Technology (Nos. ZKJ201603, YKJ201312)
文摘A thermoviscoelastic modeling approach is developed to predict the recovery behaviors of the thermally activated amorphous shape memory polymers(SMPs)based on the generalized finite deformation viscoelasticity theory.In this paper,a series of moduli and relaxation times of the generalized Maxwell model is estimated from the stress relaxation master curve by using the nonlinear regression(NLREG)method.Assuming that the amorphous SMPs are approximately incompressible isotropic elastomers in the rubbery state,the hyperelastic response of the materials is well modeled with a hyperelastic model in Ogden form.In addition,the Williams-Landel-Ferry(WLF)equation is used to describe the horizontal shift factor obtained with time-temperature superposition principle(TTSP).The finite element simulations show good agreement with the experimental thermomechanical behaviors.Moreover,the possibility of developing a temperature-responsive intravascular stent with the SMP studied here is investigated in terms of its thermomechanical property.Therefore,it can be concluded that the model has good prediction capabilities for the recovery behaviors of amorphous SMPs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21134003,21273048,51225304,and 51203023)Shanghai Outstanding Academic Leader Program,China(Grant No.15XD1500600)
文摘Crosslinked liquid crystalline polymers（CLCPs） are a type of promising material that possess both the order of liquid crystals and the properties of polymer networks.The anisotropic deformation of the CLCPs takes place when the mesogens experience order to disorder change in response to external stimuli; therefore,they can be utilized to fabricate smart actuators,which have potential applications in artificial muscles,micro-optomechanical systems,optics,and energyharvesting fields.In this review the recent development of thermo-and photo-driven soft actuators based on the CLCPs are summarized.
文摘聚合物砂浆(polymer mortar,PM)因其良好的气密性、抗裂性和变形适应性被认为是一种极具发展潜力的建造压缩空气储能(compressed air energy storage,CAES)人工硐室储气库密封层的可选材料之一。为探究聚氨酯类聚合物砂浆(polyurethane polymer mortar,PPM)与人工硐室储气库衬砌混凝土之间的黏结性能和变形适应性,采用室内试验和数值模拟方法,研究了PPM中粉料和聚合物含量以及配比变化对PPM-混凝土界面的黏结性能和变形性能的影响规律,并分析了界面的破坏特征和破坏机制。研究结果表明:PPM-混凝土界面破坏型式主要表现为界面两侧材料的分离;界面剪应力-位移关系在应力峰值前呈现两阶段近似线性变形特征,界面破坏剪切应变最大值可达11.05%;粉料和聚合物含量以及配比变化对界面黏结强度都有重要的影响,最高黏结强度约为1.21MPa,最低平均黏结强度为0.237MPa。PPM-混凝土界面强度和变形性能可满足CAES地下储气库的建库要求。
基金This work was financially supported by the National Natural Science Foundation of China(U20A20256,51973207)the NSAF Joint Fund(U2030203).
文摘The general development of Rheo-NMR during the last four decades as well as selective hyphenated apparatuses is presented.Based on different magnet types,the current review is divided into two categories,namely low-field and high-field NMR,while the timedomain NMR is normally applied in the former case and the frequency-domain NMR is adopted in the latter one.Depending on different rheometer cells,it can be further divided into tensile and shear mode Rheo-NMR.The combination of various rheometer cells and NMR facility guarantees our acquisition of molecular level structure and dynamics information under flow conditions,which is crucial for our understanding of the molecular origin of complex fluids.A personal perspective is also presented at last to highlight possible development in this direction.
