The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate...The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.展开更多
Fracture grouting is widely used for building foundation reinforcement,however the underpinning mechanisms are still not clear.Using numerical results about a single-hole fracture grouting process as a basis,a model c...Fracture grouting is widely used for building foundation reinforcement,however the underpinning mechanisms are still not clear.Using numerical results about a single-hole fracture grouting process as a basis,a model composed of soil and grouting veins has been created to analyze the reinforcement mechanism.The influence weights of the grouting vein skeleton and compaction effect have been studied,thereby obtaining relevant information on the compressive modulus of the considered composite soil.The research results show that the compaction effect plays a leading role in the soil fracture grouting reinforcement.The grouting pressure,the hardened grouting vein modulus,and the shape of the grouting veins all influence the compressive modulus of the composite soil.展开更多
Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a serie...Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out.Through setting 5.0 kg TNT charges at different stand-off distances,the damage characteristics of masonry walls at different scaled distances were obtained.The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored.Five failure grades were summarized according to the dynamic response features of masonry walls.Based on the stress wave propagation pattern in multi-media composite structures,the internal stress distribution of masonry walls were analyzed,and the division basis of the masonry walls’ failure grades was then quantified.Combined with Scanning Electron Microscope(SEM)images,the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively,which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.展开更多
Replacing micro-reinforcing fibers with carbon nanotubes(CNTs)is beneficial for improving the impact properties of ultra-high performance concrete(UHPC);however,the weak wettability and dispersibility of CNTs and the ...Replacing micro-reinforcing fibers with carbon nanotubes(CNTs)is beneficial for improving the impact properties of ultra-high performance concrete(UHPC);however,the weak wettability and dispersibility of CNTs and the weakly bonded interface between CNTs and UHPC limit their effectiveness as composites.Therefore,this study aims to enhance the reinforcement effect of CNTs on the impact properties of UHPC via functionalization.Unlike ordinary CNTs,functionalized CNTs with carboxyl or hydroxyl groups can break the Si-O-Ca-O-Si coordination bond in the C-S-H gel and form a new network in the UHPC matrix,effectively inhibiting the dislocation slip inside UHPC matrix.Furthermore,functionalized CNTs,particularly carboxyl-fu nctionalized CNTs,co ntrol the crystallization process and microscopic morphology of the hydration products,significantly decreasing and even eliminating the width of the aggregate-matrix interface transition zone of the UHPC.Moreover,the functionalized CNTs further decrease the attraction of the negatively charged silicate tetrahedron to Ca2+in the C-S-H gel,while modifying the pore structure(particularly the nanoscale pore structure)of UHPC,leading to the expansion of the intermediate CS-H layer.The changes in the microstructures of UHPC brought about by the functionalized CNTs significantly enhance its dynamic compressive strength,peak strain,impact toughness,and impact dissipation energy at strain rates of 200-800 s^(-1).Impact performance of UHPC containing a small amount of carboxyl-functionalized CNTs(especially the short ones)is generally better than that of UHPC containing hydroxyl-functionalized and ordinary CNTs;it is even superior to that of UHPC with a high steel fiber content.展开更多
One-dimensional(1D)SiO_(2) nanofibers(SNFs),one of the most popular inorganic nanomaterials,have aroused widespread attention because of their excellent chemical stability,as well as unique optical and thermal charact...One-dimensional(1D)SiO_(2) nanofibers(SNFs),one of the most popular inorganic nanomaterials,have aroused widespread attention because of their excellent chemical stability,as well as unique optical and thermal characteristics.Electrospinning is a straightforward and versatile method to prepare 1D SNFs with programmable structures,manageable dimensions,and modifiable properties,which hold great potential in many cutting-edge applications including aerospace,nanodevice,and energy.In this review,substantial advances in the structural design,controllable synthesis,and multifunctional applications of electrospun SNFs are highlighted.We begin with a brief introduction to the fundamental principles,available raw materials,and typical apparatus of electrospun SNFs.We then discuss the strategies for preparing SNFs with diverse structures in detail,especially stressing the newly emerging three-dimensional SiO_(2) nanofibrous aerogels.We continue with focus on major breakthroughs about brittleness-to-flexibility transition of SNFs and the means to achieve their mechanical reinforcement.In addition,we showcase recent applications enabled by electrospun SNFs,with particular emphasis on physical protection,health care and water treatment.In the end,we summarize this review and provide some perspectives on the future development direction of electrospun SNFs.展开更多
While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propos...While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propose and demonstrate a strategy to reinforce the mechanical properties of supramolecular hydrogel by introducing polymeric multiple-unit linker(PMUL),which incorporates multiple supramolecular units into a polymeric backbone to crosslink supramolecular hydrogel.We demonstrated that PMUL can effectively improve the kinetic stability of supramolecular crosslinkers through multiple-unit interaction in a DNA supramolecular hydrogel model system,thus leading to higher mechanical strength.Meanwhile,the dynamic features of the supramolecular hydrogels have been well preserved,including shear-thinning,self-healing properties,and reversible thermal responsiveness.This strategy offers a simple but effective way for mechanical reinforcement of supramolecular hydrogels to construct novel biomaterials.展开更多
The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network str...The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques.Herein,small-angle neutron scattering(SANS)and synchrotron radiation X-ray nano-computed tomography(Nano-CT)techniques are employed to explore the evolution of filler networks of fumed,precipitated and sol-gel silica,respectively.Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates.And the silica with highly associated structure,pertaining to amorphous morphology,small size,and large surface area,presents short distance and effective molecular chain bridge between aggregates,thus forming strong and steady filler networks.This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.展开更多
Owing to their inherent semi-solid property and lubricant ability,organogels manifest various unique characteristics and serve as promising candidates for antifouling.However,the poor mechanical properties of organoge...Owing to their inherent semi-solid property and lubricant ability,organogels manifest various unique characteristics and serve as promising candidates for antifouling.However,the poor mechanical properties of organogels often limit their practical applications.Herein,we report a simple and effective method to prepare organogels with reinforced mechanical performance and surface lubricant ability with the synergistic roles played by oleophobic and oleophilic chains.The rigid oleophobic chains have a poor affinity to lubricating solvent,which gives rise to high oleophobic interactions between polymer networks;the soft oleophilic chains possess a high affinity to the low surface energy solvent,which lead to high solvent content to maintain the satisfactory lubricant capacity.The organogel of oleophobic methyl methacrylate(MMA)and oleophilic lauryl methacrylate(LMA)is chosen as a representative example to illustrate this concept.With the optimal composition,the as-prepared organogels offer satisfactory tensile fracture stress,fracture strain,Young’s modulus,toughness,and tearing fracture energy of 480 k Pa,550%,202 k Pa,1.14 MJ m,and 5.14 k J m,respectively,which are far beyond the classical PLMA organogels.Furthermore,the biofouling resistance tests demonstrate 4 to 9-fold reduction of protein and bacteria adhesion on the reinforced organogels surface in comparison to the glass substrate and solvent-free dry organogels.This simple and effective approach to toughen organogels,we hope,can be applied in various fields with different practical functional requirements in the future.展开更多
基金the support of the instrument and equipment fund of the Key Laboratory of Special Energy,Ministry of Education,Nanjing University of Science and Technology,China.
文摘The severe erosion and inadequate mechanical strength are prominent challenges for high-energy gun propellants.To address it,novel PTW@PDA composites was prepared by polydopamine(PDA)-modifying onto potassium titanate whisker(PTW,K_(2)Ti_(6)O_(13)),and after was incorporated into gun propellant as erosion-reducing and mechanical-reinforcing fillers.The interfacial characterizations results indicated that as-prepared PTW@PDA composites exhibits an enhanced surface compatible with propellant matrix,thereby facilitating their dispersion into propellants more effectively than raw PTW materials.Compared to original propellants,PTW@PDA-modified propellants exhibited significant less erosion,with a Ti-Kbased protective coating being detected on the eroded steel.And 0.5 wt%and 1.0 wt%addition of PTW@PDA significantly improved impact,compressive and tensile strength of propellants.Despite the inevitably reduction in relative force,PTW@PDA slightly increase propellant burning rate while exerting little adverse impact on propellant dynamic activity.This strategy can provide a promising alternative to develop high-energy gun propellant with less erosion and more mechanical strength.
基金supported by the National Key R&D Plan of China(No.2017YFC0805400).
文摘Fracture grouting is widely used for building foundation reinforcement,however the underpinning mechanisms are still not clear.Using numerical results about a single-hole fracture grouting process as a basis,a model composed of soil and grouting veins has been created to analyze the reinforcement mechanism.The influence weights of the grouting vein skeleton and compaction effect have been studied,thereby obtaining relevant information on the compressive modulus of the considered composite soil.The research results show that the compaction effect plays a leading role in the soil fracture grouting reinforcement.The grouting pressure,the hardened grouting vein modulus,and the shape of the grouting veins all influence the compressive modulus of the composite soil.
基金supported by the National Natural Science Foundation of China nos.51978660。
文摘Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out.Through setting 5.0 kg TNT charges at different stand-off distances,the damage characteristics of masonry walls at different scaled distances were obtained.The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored.Five failure grades were summarized according to the dynamic response features of masonry walls.Based on the stress wave propagation pattern in multi-media composite structures,the internal stress distribution of masonry walls were analyzed,and the division basis of the masonry walls’ failure grades was then quantified.Combined with Scanning Electron Microscope(SEM)images,the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively,which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.
基金the National Natural Science Foundation of China(51978127 and 51908103)the Fundamental Research Funds for the Central Universities(DUT21RC(3)039)the China Scholarship Council Foundation(202006060103)for providing funding to carry out this investigation。
文摘Replacing micro-reinforcing fibers with carbon nanotubes(CNTs)is beneficial for improving the impact properties of ultra-high performance concrete(UHPC);however,the weak wettability and dispersibility of CNTs and the weakly bonded interface between CNTs and UHPC limit their effectiveness as composites.Therefore,this study aims to enhance the reinforcement effect of CNTs on the impact properties of UHPC via functionalization.Unlike ordinary CNTs,functionalized CNTs with carboxyl or hydroxyl groups can break the Si-O-Ca-O-Si coordination bond in the C-S-H gel and form a new network in the UHPC matrix,effectively inhibiting the dislocation slip inside UHPC matrix.Furthermore,functionalized CNTs,particularly carboxyl-fu nctionalized CNTs,co ntrol the crystallization process and microscopic morphology of the hydration products,significantly decreasing and even eliminating the width of the aggregate-matrix interface transition zone of the UHPC.Moreover,the functionalized CNTs further decrease the attraction of the negatively charged silicate tetrahedron to Ca2+in the C-S-H gel,while modifying the pore structure(particularly the nanoscale pore structure)of UHPC,leading to the expansion of the intermediate CS-H layer.The changes in the microstructures of UHPC brought about by the functionalized CNTs significantly enhance its dynamic compressive strength,peak strain,impact toughness,and impact dissipation energy at strain rates of 200-800 s^(-1).Impact performance of UHPC containing a small amount of carboxyl-functionalized CNTs(especially the short ones)is generally better than that of UHPC containing hydroxyl-functionalized and ordinary CNTs;it is even superior to that of UHPC with a high steel fiber content.
基金This work was supported by the National Natural Science Foundation of China(Nos.21961132024,51925302,and 52173055)the Ministry of Science and Technology of China(No.2021YFE0105100)the Fundamental Research Funds for the Central Universities and the DHU Distinguished Young Professor Program(No.LZA2020001).
文摘One-dimensional(1D)SiO_(2) nanofibers(SNFs),one of the most popular inorganic nanomaterials,have aroused widespread attention because of their excellent chemical stability,as well as unique optical and thermal characteristics.Electrospinning is a straightforward and versatile method to prepare 1D SNFs with programmable structures,manageable dimensions,and modifiable properties,which hold great potential in many cutting-edge applications including aerospace,nanodevice,and energy.In this review,substantial advances in the structural design,controllable synthesis,and multifunctional applications of electrospun SNFs are highlighted.We begin with a brief introduction to the fundamental principles,available raw materials,and typical apparatus of electrospun SNFs.We then discuss the strategies for preparing SNFs with diverse structures in detail,especially stressing the newly emerging three-dimensional SiO_(2) nanofibrous aerogels.We continue with focus on major breakthroughs about brittleness-to-flexibility transition of SNFs and the means to achieve their mechanical reinforcement.In addition,we showcase recent applications enabled by electrospun SNFs,with particular emphasis on physical protection,health care and water treatment.In the end,we summarize this review and provide some perspectives on the future development direction of electrospun SNFs.
基金supported by the National Natural Science Foundation of China(grant nos.21890731,21821001,21534007,21971248,and 21890730)the National Basic Research Plan of China(grant no.2018YFA0208900)the Institute of Chemistry CAS(grant no.C220200701).
文摘While supramolecular hydrogels have received growing interest due to their unique dynamic features,their relatively weak mechanical properties have largely limited their biomedical applications.In this study,we propose and demonstrate a strategy to reinforce the mechanical properties of supramolecular hydrogel by introducing polymeric multiple-unit linker(PMUL),which incorporates multiple supramolecular units into a polymeric backbone to crosslink supramolecular hydrogel.We demonstrated that PMUL can effectively improve the kinetic stability of supramolecular crosslinkers through multiple-unit interaction in a DNA supramolecular hydrogel model system,thus leading to higher mechanical strength.Meanwhile,the dynamic features of the supramolecular hydrogels have been well preserved,including shear-thinning,self-healing properties,and reversible thermal responsiveness.This strategy offers a simple but effective way for mechanical reinforcement of supramolecular hydrogels to construct novel biomaterials.
基金the National Natural Science Foundation of China(Nos.11605171 and 21973076)Sichuan Science and Technology Program(No.2018GZ0155)+2 种基金Ph.D program Foundation of SWUST(No.18ZX7112)Longshan Program for Talents(SWUST,No.I8 LZXT11)the Project of State Key Laboratory of Environment-Friendly Energy Materials(SWUST,No.19FKSY16).
文摘The silicone rubber composites present remarkable mechanical properties due to the double network structure constructed with molecular network of matrix and filler network of silica.Nevertheless,the filler network structure and corresponding reinforcement mechanism are still under debate and need to be further probed with the aid of applicative advanced analysis techniques.Herein,small-angle neutron scattering(SANS)and synchrotron radiation X-ray nano-computed tomography(Nano-CT)techniques are employed to explore the evolution of filler networks of fumed,precipitated and sol-gel silica,respectively.Our studying results reveal the formation of filler network constructed by the interconnecting of branched silica aggregates.And the silica with highly associated structure,pertaining to amorphous morphology,small size,and large surface area,presents short distance and effective molecular chain bridge between aggregates,thus forming strong and steady filler networks.This work would provide deep-seated revisiting of filler networks and corresponding reinforcement mechanism and offer guidance for optimizing the mechanical properties of silicone rubber.
基金the financial support from the National Natural Science Foundation of China(NSFC)(Nos.51903253,51879292)Natural Science Foundation of Guangdong Province of China(No.2019A1515011150)。
文摘Owing to their inherent semi-solid property and lubricant ability,organogels manifest various unique characteristics and serve as promising candidates for antifouling.However,the poor mechanical properties of organogels often limit their practical applications.Herein,we report a simple and effective method to prepare organogels with reinforced mechanical performance and surface lubricant ability with the synergistic roles played by oleophobic and oleophilic chains.The rigid oleophobic chains have a poor affinity to lubricating solvent,which gives rise to high oleophobic interactions between polymer networks;the soft oleophilic chains possess a high affinity to the low surface energy solvent,which lead to high solvent content to maintain the satisfactory lubricant capacity.The organogel of oleophobic methyl methacrylate(MMA)and oleophilic lauryl methacrylate(LMA)is chosen as a representative example to illustrate this concept.With the optimal composition,the as-prepared organogels offer satisfactory tensile fracture stress,fracture strain,Young’s modulus,toughness,and tearing fracture energy of 480 k Pa,550%,202 k Pa,1.14 MJ m,and 5.14 k J m,respectively,which are far beyond the classical PLMA organogels.Furthermore,the biofouling resistance tests demonstrate 4 to 9-fold reduction of protein and bacteria adhesion on the reinforced organogels surface in comparison to the glass substrate and solvent-free dry organogels.This simple and effective approach to toughen organogels,we hope,can be applied in various fields with different practical functional requirements in the future.
