Stiffened thermosetting composite panels were fabricated with co-curing processing.In the co-curing processing,the temperature distribution in the composite panels was nonuniform.An investigation into the threedimensi...Stiffened thermosetting composite panels were fabricated with co-curing processing.In the co-curing processing,the temperature distribution in the composite panels was nonuniform.An investigation into the threedimensional cure simulation of T-shape stiffened thermosetting composite panels was presented.Flexible tools and locating tools were considered in the cure simulation.Temperature distribution in the composites was predicted as a function of the autoclave temperature history.A nonlinear transient heat transfer finite element model was developed to simulate the curing process of stiffened thermosetting composite panels.And a simulation example was presented to demonstrate the use of the present finite element procedure for analyzing composite curing process.The glass/polyester structure was investigated to provide insight into the nonuniform cure process and the effect of flexible tools and locating tools on temperature distribution.Temperature gradient in the intersection between the skin and the flange was shown to be strongly dependent on the structure of the flexible tools and the thickness of the skin.展开更多
A glass fiber(GF)/polydicyclopentadiene(PDCPD)composite impact simulation model was established based on LS-DYNA(the finite element analysis software peroduced by Livermore Software Technology Corporation)simulation.A...A glass fiber(GF)/polydicyclopentadiene(PDCPD)composite impact simulation model was established based on LS-DYNA(the finite element analysis software peroduced by Livermore Software Technology Corporation)simulation.An optimal ply thickness of the composite GF/PDCPD was determined as 3.0 mm,and thus the final intrusion depth was controlled within 8.8 mm,meeting the performance standards for battery electric vehicle protection materials.A comparative analysis of failure modes during impacts was conducted for composites GF/PDCPD,GF/polypropylene(PP)and GF/polyamide(PA).The results indicated that GF/PDCPD exhibited compressive failure modes and ductile fractures,resulting in smaller damage areas.In contrast,GF/PP and GF/PA showed fiber fracture failures,leading to larger damage areas.The molding process and impact resistance of GF/PDCPD were investigated.By comparing the impact performance of GF/PDCPD with that of GF/PP and GF/PA,it was concluded that GF/PDCPD demonstrated superior performance and better alignment with the performance standards of battery electric vehicle protective materials.The predictability and accuracy of LS-DYNA simulation was verified,providing a theoretical foundation for further in-depth research.展开更多
Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials ...Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials with thermally cross-linked molecular structures has become a daunting challenge.Here,we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high-performance material.Different particle size of waste epoxy micro-spheres(100–600μm)with core-shell structure is obtained through simple mechanical crushing and boron nitride surface treatment.By using smattering epoxy monomer as an adhesive,an eco-friendly composite material with a“brick-wall structure”can be formed.The continuous boron nitride pathway with efficient thermal conductivity endows eco-friendly composite materials with a preeminent thermal conductivity of 3.71 W m^(−1)K^(−1) at a low content of 8.5 vol%h-BN,superior to pure epoxy resin(0.21 W m^(−1)K^(−1)).The composite,after secondary recycling and reuse,still maintains a thermal conductivity of 2.12 W m^(−1)K^(−1) and has mechanical and insulation properties comparable to the new epoxy resin(energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm^(−1)).This strategy expands the sustainable application prospects of thermosetting polymers,offering extremely high economic and environmental value.展开更多
Thermosetting materials are widely used as encapsulation in the electrical packaging to protect the core electronic components from external force, moisture, dust, and other factors. However, the spreading and curing ...Thermosetting materials are widely used as encapsulation in the electrical packaging to protect the core electronic components from external force, moisture, dust, and other factors. However, the spreading and curing behaviors of such kind of fluid on a heated surface have been rarely explored. In this study, we experimentally and numerically investigated the spreading and curing behaviors of the silicone(OE6550 A/B, which is widely used in the light-emitting diode packaging) droplet with diameter of ~2.2 mm on a heated surface with temperature ranging from 25 ℃ to 250 ℃. For the experiments, we established a setup with high-speed camera and heating unit to capture the fast spreading process of the silicone droplet on the heated surface. For the numerical simulation, we built a viscosity model of the silicone by using the Kiuna’s model and combined the viscosity model with the Volume of Fluid(VOF) model by the User Defined Function(UDF) method. The results show that the surface temperature significantly affected the spreading behaviors of the silicone droplet since it determines the temperature and viscosity distribution inside the droplet. For surface temperature varied from 25 ℃ to 250 ℃, the final contact radius changed from ~2.95 mm to ~1.78 mm and the total spreading time changed from ~511 s to ~0.15 s. By further analyzing the viscosity evolution of the droplet, we found that the decreasing of the total spreading time was caused by the decrease of the viscosity under high surface temperature at initial spreading stage, while the reduction of the final contact radius was caused by the curing of the precursor film. This study supplies a strategy to tuning the spreading and curing behavior of silicone by imposing high surface temperature, which is of great importance to the electronic packaging.展开更多
Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability o...Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability of the titanium-oxo-cluster was examined using a microdielectric analytical(DEA)curing monitor,Fourier transformed infrared spectroscopy(FTIR),and Soxhlet extraction experiments,and the properties of the resulted coatings were investigated with pendulum hardness tester,dynamic mechanical analysis(DMA),thermogravimetric analysis(TGA)and ultraviolet-visible spectrometer.The effect of titania-oxo-cluster in leading acrylic oligomers to form thermosetting acrylic coatings was confirmed.An increasing pendulum hardness and modulus of acrylic coatings with increasing titania content was observed, which resulted from the increment of crosslinking degree rather than of the titania content.The thermosetting acrylic/titania coatings also showed better thermal stability and higher UV-blocking properties than those coatings using organic curing agent.展开更多
Designing and synthesizing crystalline porous thermosetting polymers(CPTPs)with ordered porous structures remains a significant challenge.Herein,we create a strategy to prepare CPTPs by synthesizing covalent organic f...Designing and synthesizing crystalline porous thermosetting polymers(CPTPs)with ordered porous structures remains a significant challenge.Herein,we create a strategy to prepare CPTPs by synthesizing covalent organic framework(COF)monoliths using the solvent-free flux synthesis method.An olefin-linked COF with an ultramicroporous structure is fabricated,exhibiting good crystallites,excellent chemical stability,and periodic ultramicroporous structures.Similar to traditional thermosetting polymers,the COF undergoes a melt→curing process that generates robust monoliths with good mechanical properties.Impressively,this COF monolith exhibits outstanding thermal insulation and flame-retardancy properties.Moreover,the distinctive pore environment and optimal pore dimensions of the COF facilitate a pronounced separation effect for C_(3)H_(4)/C_(3)H_(6).Gas mixture breakthrough experiments confirm that this COF can efficiently remove trace amounts of C_(3)H_(4)from C_(3)H_(4)/C_(3)H_(6)(0.1/99.9 and 1/99,v/v)mixtures to produce highly pure propylene.This work bridges the gap between thermosetting polymers and COFs,and points out a new direction for thermosetting polymers.展开更多
Glassy thermosetting polymers,which possess excellent mechanical properties,structural stability,and solvent resistance,cannot be healed and recycled due to the irreversible crosslinking network.Covalent adaptive netw...Glassy thermosetting polymers,which possess excellent mechanical properties,structural stability,and solvent resistance,cannot be healed and recycled due to the irreversible crosslinking network.Covalent adaptive networks could address these drawbacks,as their chemical networks are able to shuffle dynamic covalent bonds through exchange reactions,which nevertheless need high temperature or solvent assistance.Here we report a room-temperature self-healing glassy thermoset enabled by designing a disulfide-bond and H-bond hybridized network carrying abundant dangling chains,which are commonly known as network“defects.”However,the“defects”do not plasticize the polymer,as they are bound to network chains through H-bonds.Therefore,the polymer possesses high modulus and strength at room temperature.Importantly,the“defects”can drive the metathesis reaction of disulfide bonds and the rearrangement of H-bonds in the glassy state,enabling the thermosetting network to self-heal at and even below room temperature.展开更多
Conventional thermosetting plastics have faced the dilemma of non-degradability and recycling,leading to waste accumulation and a huge burden on the global environment and economy.Realizing recycling,reusing and repur...Conventional thermosetting plastics have faced the dilemma of non-degradability and recycling,leading to waste accumulation and a huge burden on the global environment and economy.Realizing recycling,reusing and repurposing plastics is a meaningful mileage for the development of sustainable ecological energy.Closed-loop recycling represents an emerging strategy for achieving the circular“waste-to-starting value-to-polymeric plastics”in recent years.Dynamic covalent chemistry(DCC)offers an attractive and efficient targeted design concept for closed-loop recyclable thermosetting polymers.In this review,the features and mechanisms of various DCC including Schiff bases,B-O bonds,sulfide-or selenide-based linkages,acetal linkages,etc.,are discussed in the construction of recyclable polymers.Based on the reversible cleavage and reformation of dynamic covalent bonds,chemically closed-loop recyclable polymers with multi-functions have been raised and developed as promising circular materials.Furthermore,we highlight and analyze the process,conditions and mechanisms of the depolymerization of polymers and recovery of monomers,as well as the remanufacture of cycled polymer networks.Significantly,the reported closed-loop recyclable thermosetting polymers exhibit potential applications in multiple fields,while providing an advanced aspect for resolving plastic waste pollution and promoting the circularity in polymeric materials.Finally,existing challenges and opportunities such as the limited production process,high costs,harsh recycling conditions,and the maintenance of comprehensive performance of thermosetting polymers in the process of implementing the practical use are proposed and discussed.展开更多
Thermosetting resins have advantages such as high strength,corrosion resistance,and aging resistance,and have excellent prospects for practical application as asphalt modifiers.In order to promote the research of ther...Thermosetting resins have advantages such as high strength,corrosion resistance,and aging resistance,and have excellent prospects for practical application as asphalt modifiers.In order to promote the research of thermosetting resin modified asphalt,to provide direction for its further research,this paper reviews the research progress of thermosetting resin modified asphalt in recent years.The material composition,modification mechanism,and curing behavior of epoxy asphalt,thermosetting polyurethane modified asphalt,unsaturated polyester modified asphalt,and other thermosetting resin modified asphalts are overviewed.Different types of thermosetting resin modified asphalt have different performances,the performance advantages of different thermosetting resin modified asphalts are summarized.At the same time,the existing problems in thermosetting resin modified asphalt and further research directions are provided.Encouraging researchers to produce thermosetting resin modified asphalts using waste or bio-based materials,and to study the recycling technologies and life cycle assessment of thermosetting resin modified asphalt.This paper provides a reference for the study of thermosetting resin modified asphalt.展开更多
Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were...Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were successfully synthesized.The tensile strength,elongation at break,and Young’s modulus of PI are 108.70±7.29 MPa,19.35%±3.89%,and 2336.42±128.00 MPa,respectively.The addition of reduced graphene oxide(RGO)not only enhances the mechanical properties of PI but also endows it with excellent tribological properties.The PI illustrates a high recycling efficiency of 94.15%,but the recycled composite exhibits inferior mechanical properties.The recycling and utilization of PI and its composite are realized through imine bonds(-C=N),which provides new guidance for solving the problem of environmental pollution and resource waste and is potential application in the field of sustainable tribology.展开更多
The advancement of photo-curing three-dimensional(3D)printing technology has significantly enhanced the capabilities of advanced manufacturing across various fields.However,the robust cross-linking network of photopol...The advancement of photo-curing three-dimensional(3D)printing technology has significantly enhanced the capabilities of advanced manufacturing across various fields.However,the robust cross-linking network of photopolymers limits its application in information encryption and exacerbates environmental issues.In this study,a degradable thermosetting photopolymer platform for information encryption was proposed by incorporating sulfite bonds into the polymer structure.Due to the autocatalytic behavior of sulfite bonds during hydrolysis under acidic conditions,the photopolymer can achieve complete degradation at 50℃ within 45 min.Based on the degradability of the developed photopolymers,a highly secure degradation-UV dual information encryption system has been established using photo-curing-based 3D printing technology.Furthermore,the degradation products of these photopolymers,generated during the information decryption process,can be utilized to prepare high-performance solar thermoelectric generators with a power density of 325.7µW cm^(−2)(under one sun)after a simple one-step modification.This work not only inspires the development of multiple information encryption methods based on 3D printing but also provides a practical solution to address environmental challenges associated with plastic pollution.展开更多
The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature(UCST)or lower critical solution temperature(LCST)were studied wit...The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature(UCST)or lower critical solution temperature(LCST)were studied with emphasis on the temperature dependency of the phase separation time and its potential application in the cure time-temperature processing window.We found that the phase separation time/temperature relationship follows the simple Arrhenius equation.The cure-induced phase separation activation energy E_(a)(ps)generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time.We also found that E_(a)(ps)is insensitive to TP content,TP molecular weight and curing rate,but it changes with the cure reaction kinetics and the chemical environment of the systems.With the established phase separation time-temperature dependence relation,we can easily establish the whole cure time-temperature transformation(TTT)diagram with morphology information which is a useful map for the TP/TS composites processing industry.展开更多
Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic comp...Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic components.However,the majority of commercial thiol curing agents contain hydrolysable ester bonds and lack rigid structures,which induces most of thiol/epoxy systems still suffering from unsatisfactory heat resistance and hygrothermal resistance,significantly hindering their application in electronic packaging.In this study,we synthesized a tetrafunctional thiol compound,bis[3-(3-sulfanylpropyl)-4-(3-sulfanylpropoxy)phenyl]sulfone(TMBPS)with rigid and ester-free structures to replace traditional commercial thiol curing agents,pentaerythritol tetra(3-mercaptopropionate)(PETMP).Compared to the PETMP/epoxy system,the TMBPS/epoxy system exhibited superior comprehensive properties.The rigid structures of bisphenol S-type tetrathiol enhanced the heat resistance and mechanical properties of TMBPS/epoxy resin cured products,outperforming those of PETMP/epoxy resin cured products.Notably,the glass transition temperature of TMBPS/epoxy resin cured products was 74.2℃which was 11.8°C higher than that of PETMP cured products.Moreover,the ester-free structure in TMBPS contributed to its enhanced resistance to chemicals and hygrothermal conditions.After undergoing 1000 h of hightemperature and high-humidity aging,the tensile strength and adhesion strength of TMBPS-cured products were 73.33 MPa and 3.39 MPa,respectively exceeding 100%and 40%of their initial values,while PETMP-cured products exhibited a complete loss of both tensile strength and adhesion strength.This study provides a strategy for obtaining thermosetting polymers that can be cured at low temperatures and exhibit excellent comprehensive properties.展开更多
Thermosets are indispensable to our daily life,but their crosslinked structures make them unable to be processed by the melt processing like thermoplastics,which greatly limits their shape designs and applications.Her...Thermosets are indispensable to our daily life,but their crosslinked structures make them unable to be processed by the melt processing like thermoplastics,which greatly limits their shape designs and applications.Herein,we address this challenge via an in situ self-growing strategy,i.e.utilizing the dynamic imidazole-urea moiety to suck up and integrate epoxy into the materials and making the thermoplastics grow in situ into thermosets.With this strategy,thermosets can be readily processed via hot-melt extrusion molding,including melt spinning and fused deposition modeling 3D printing.More importantly,this strategy simultaneously integrates the flexibility of polyurethane and the robustness of epoxy resin into the resulting thermosets,yielding a mechanical-reinforcing effect to make the material not only strong but also tough(toughness:99.3 MJ·m^(-3),tensile strength:38.8 MPa).Moreover,the crosslinking density and modulus of the as-prepared thermosets(from 34.1 MPa to613.7 MPa)can be readily tuned on demand by changing the growth index.Furthermore,these thermosets exhibited excellent thermal stability and chemical resistance.展开更多
In this study,epoxidized soybean oil(ESO)and ricinoleic acid(RA)were used to synthesize polyol esters,designated ESO-RA(ER)resin.The esters were further crosslinked with 4,4-diphenylmethane diisocyanate(PMDI)to create...In this study,epoxidized soybean oil(ESO)and ricinoleic acid(RA)were used to synthesize polyol esters,designated ESO-RA(ER)resin.The esters were further crosslinked with 4,4-diphenylmethane diisocyanate(PMDI)to create a biodegradable flame-retardant thermoset foam,referred to as ESO-RA-PMDI(ERP)foam,using water as a foaming agent.Additionally,flame retardants such as triethyl phosphate(TEP)and expanded graphite(EG)have been combined for foam preparation without the need for catalysts or foaming agents.The study findings showed that the incorporation of TEP and EG diminished the pulverization ratio while augmenting the compressive strength and shore hardness.Furthermore,the ERP foam exhibited exceptional flame retardant characteristics,as evidenced by a reported limiting oxygen index(LOI)value of 30.6vol%.A peak heat release rate of 97.12 kW/m^(2)was reported during the fire test.Significantly,a low peak smoke production rate(pSPR)of 0.026m^(2)/s and a total smoke production(TSP)of 0.62 m^(2)were achieved.In addition,ERP foam exhibited exceptional ultraviolet(UV)resistance,thermal insulation,and biodegradability.After 60 days of exposure to Penicillium sp.,foam containing both TEP and EG exhibited a mass loss of 9.39%,indicating that the incorporation of flame retardants did not negatively impact its biodegradability.展开更多
Thermosetting polyurethanes are widely used in various fields owing to their excellent elasticity,strength and solvent resistance.Three environmental friendly propyl gallate-based self-healing polyurethanes were prepa...Thermosetting polyurethanes are widely used in various fields owing to their excellent elasticity,strength and solvent resistance.Three environmental friendly propyl gallate-based self-healing polyurethanes were prepared from polyurethane prepolymers with varying isocyanate content.The thermal stabilities of the polyurethanes were tested using thermogravimetric analysis.Their self-healing and mechanical properties were analyzed using a universal testing machine and dynamic thermomechanical analysis.The polyurethanes were found with high self-healing ability and excellent mechanical properties due to the absence of phenolic carbamate.These qualities improved with increased isocyanate content and the prolonged selfhealing time.We found,therefore,that the propyl gallate-based polyurethane has potential for use in industrial applications as self-healing materials.展开更多
A facile scalable synthesis of hierarchical Sb/C micro-/nanohybrid has been addressed in this work, which possesses the advantages of both micrometer and nanometer scale structures as lithium-ion battery anode. Difunc...A facile scalable synthesis of hierarchical Sb/C micro-/nanohybrid has been addressed in this work, which possesses the advantages of both micrometer and nanometer scale structures as lithium-ion battery anode. Difunctional methacrylate monomers are used as solvent and carbon source as well. Liquid precursor of antimony（III） n-butoxide is dissolved in the resin monomer solution, and further incorporated into the cross-linking polymer network via photo polymerization. Through calcination in argon/hydrogen atmosphere, antimony nanoparticles are in situ formed by carbothermal reduction, and homogeneously embedded in the in situ formed micrometer sized carbon matrix. The morphology, structure, crys- tallinity, spatial dispersion, composition, and electrochemical performance of the Sb/C micro-/nanohybrid are systemati- cally investigated. The cyclic and rate performance of the Sb/C micro-/nanohybrid anode have been effectively improved compared to the pure carbon anode. A reversible capacity of 362 mAh g-1 is achieved with a reasonable mass loading density after 300 cycles at 66 mA g-1, corresponding to capacity retention of 79%. With reducing mass loading density, the reversible capacity reaches 793 mAh g-1 after 100 cycles. Moreover, the electrochemical performance of Sb/C micro-/nanohybrid as sodium-ion battery anode is also investigated in this study.展开更多
This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy (CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic ...This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy (CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin (GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.展开更多
Dye-sensitized solar cells （DSSCs） are the most promising, low cost and most extensively investigated solar cells. They are famous for their clean and efficient solar energy conversion. Nevertheless this, long-time ...Dye-sensitized solar cells （DSSCs） are the most promising, low cost and most extensively investigated solar cells. They are famous for their clean and efficient solar energy conversion. Nevertheless this, long-time sta- bility is still to be acquired. In recent years research on solid and quasi-solid state electrolytes is extensively in- creased. Various quasi-solid electrolytes, including composites polymer electrolytes, ionic liquid electrolytes, thermoplastic polymer electrolytes and thermosetting polymer electrolytes have been used. Performance and stability of a quasi-solid state electrolyte are between liquid and solid electrolytes. High photovoltaic performances of QS-DSSCs along better long-term stability can be obtained by designing and optimizing quasi-solid electrolytes. It is a prospective candidate for highly efficient and stable DSSCs.展开更多
Cure and decomposition reaction kinetics of typical organic materials in aerospace applications are introduced.From the data of dynamic differential scanning calorimetry(DSC)experiments,and based on changes of the pea...Cure and decomposition reaction kinetics of typical organic materials in aerospace applications are introduced.From the data of dynamic differential scanning calorimetry(DSC)experiments,and based on changes of the peak temperatures(T_(p))with different heating rates(β),a linear equation,T_(p)=T_(1)+△Tlnβ,has been obtained more reasonably.The above equation can be used to explain some laws of higher or lower of apparent activation energies(E_(a)),by which the apparent activation energy(E_(a))is nearly equal to RT^(2)_(1)/△T.A number of kinetic investigations of typical thermosetting resins and energetic materials in aerospace applications were chosen to validate the above equations.展开更多
文摘Stiffened thermosetting composite panels were fabricated with co-curing processing.In the co-curing processing,the temperature distribution in the composite panels was nonuniform.An investigation into the threedimensional cure simulation of T-shape stiffened thermosetting composite panels was presented.Flexible tools and locating tools were considered in the cure simulation.Temperature distribution in the composites was predicted as a function of the autoclave temperature history.A nonlinear transient heat transfer finite element model was developed to simulate the curing process of stiffened thermosetting composite panels.And a simulation example was presented to demonstrate the use of the present finite element procedure for analyzing composite curing process.The glass/polyester structure was investigated to provide insight into the nonuniform cure process and the effect of flexible tools and locating tools on temperature distribution.Temperature gradient in the intersection between the skin and the flange was shown to be strongly dependent on the structure of the flexible tools and the thickness of the skin.
文摘A glass fiber(GF)/polydicyclopentadiene(PDCPD)composite impact simulation model was established based on LS-DYNA(the finite element analysis software peroduced by Livermore Software Technology Corporation)simulation.An optimal ply thickness of the composite GF/PDCPD was determined as 3.0 mm,and thus the final intrusion depth was controlled within 8.8 mm,meeting the performance standards for battery electric vehicle protection materials.A comparative analysis of failure modes during impacts was conducted for composites GF/PDCPD,GF/polypropylene(PP)and GF/polyamide(PA).The results indicated that GF/PDCPD exhibited compressive failure modes and ductile fractures,resulting in smaller damage areas.In contrast,GF/PP and GF/PA showed fiber fracture failures,leading to larger damage areas.The molding process and impact resistance of GF/PDCPD were investigated.By comparing the impact performance of GF/PDCPD with that of GF/PP and GF/PA,it was concluded that GF/PDCPD demonstrated superior performance and better alignment with the performance standards of battery electric vehicle protective materials.The predictability and accuracy of LS-DYNA simulation was verified,providing a theoretical foundation for further in-depth research.
基金supported by the National Natural Science Foundation of China(Nos.51977084 and 52307025).
文摘Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials with thermally cross-linked molecular structures has become a daunting challenge.Here,we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high-performance material.Different particle size of waste epoxy micro-spheres(100–600μm)with core-shell structure is obtained through simple mechanical crushing and boron nitride surface treatment.By using smattering epoxy monomer as an adhesive,an eco-friendly composite material with a“brick-wall structure”can be formed.The continuous boron nitride pathway with efficient thermal conductivity endows eco-friendly composite materials with a preeminent thermal conductivity of 3.71 W m^(−1)K^(−1) at a low content of 8.5 vol%h-BN,superior to pure epoxy resin(0.21 W m^(−1)K^(−1)).The composite,after secondary recycling and reuse,still maintains a thermal conductivity of 2.12 W m^(−1)K^(−1) and has mechanical and insulation properties comparable to the new epoxy resin(energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm^(−1)).This strategy expands the sustainable application prospects of thermosetting polymers,offering extremely high economic and environmental value.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51606074,51625601,and 51576078)the Ministry of Science and Technology of the People’s Republic of China(Grant No.2017YFE0100600)the Creative Research Groups Funding of Hubei Province(Grant No.2018CFA001)
文摘Thermosetting materials are widely used as encapsulation in the electrical packaging to protect the core electronic components from external force, moisture, dust, and other factors. However, the spreading and curing behaviors of such kind of fluid on a heated surface have been rarely explored. In this study, we experimentally and numerically investigated the spreading and curing behaviors of the silicone(OE6550 A/B, which is widely used in the light-emitting diode packaging) droplet with diameter of ~2.2 mm on a heated surface with temperature ranging from 25 ℃ to 250 ℃. For the experiments, we established a setup with high-speed camera and heating unit to capture the fast spreading process of the silicone droplet on the heated surface. For the numerical simulation, we built a viscosity model of the silicone by using the Kiuna’s model and combined the viscosity model with the Volume of Fluid(VOF) model by the User Defined Function(UDF) method. The results show that the surface temperature significantly affected the spreading behaviors of the silicone droplet since it determines the temperature and viscosity distribution inside the droplet. For surface temperature varied from 25 ℃ to 250 ℃, the final contact radius changed from ~2.95 mm to ~1.78 mm and the total spreading time changed from ~511 s to ~0.15 s. By further analyzing the viscosity evolution of the droplet, we found that the decreasing of the total spreading time was caused by the decrease of the viscosity under high surface temperature at initial spreading stage, while the reduction of the final contact radius was caused by the curing of the precursor film. This study supplies a strategy to tuning the spreading and curing behavior of silicone by imposing high surface temperature, which is of great importance to the electronic packaging.
基金supported by the National Natural Science Foundation of China(No.20774023)Shanghai Leading Academic Discipline Project(No.B113).
文摘Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability of the titanium-oxo-cluster was examined using a microdielectric analytical(DEA)curing monitor,Fourier transformed infrared spectroscopy(FTIR),and Soxhlet extraction experiments,and the properties of the resulted coatings were investigated with pendulum hardness tester,dynamic mechanical analysis(DMA),thermogravimetric analysis(TGA)and ultraviolet-visible spectrometer.The effect of titania-oxo-cluster in leading acrylic oligomers to form thermosetting acrylic coatings was confirmed.An increasing pendulum hardness and modulus of acrylic coatings with increasing titania content was observed, which resulted from the increment of crosslinking degree rather than of the titania content.The thermosetting acrylic/titania coatings also showed better thermal stability and higher UV-blocking properties than those coatings using organic curing agent.
基金supported by the National Natural Science Foundation of China(22205116)Nankai University Cangzhou Bohai New Area Green Chemical Research Institute Fund Project(NCC2022PY04)。
文摘Designing and synthesizing crystalline porous thermosetting polymers(CPTPs)with ordered porous structures remains a significant challenge.Herein,we create a strategy to prepare CPTPs by synthesizing covalent organic framework(COF)monoliths using the solvent-free flux synthesis method.An olefin-linked COF with an ultramicroporous structure is fabricated,exhibiting good crystallites,excellent chemical stability,and periodic ultramicroporous structures.Similar to traditional thermosetting polymers,the COF undergoes a melt→curing process that generates robust monoliths with good mechanical properties.Impressively,this COF monolith exhibits outstanding thermal insulation and flame-retardancy properties.Moreover,the distinctive pore environment and optimal pore dimensions of the COF facilitate a pronounced separation effect for C_(3)H_(4)/C_(3)H_(6).Gas mixture breakthrough experiments confirm that this COF can efficiently remove trace amounts of C_(3)H_(4)from C_(3)H_(4)/C_(3)H_(6)(0.1/99.9 and 1/99,v/v)mixtures to produce highly pure propylene.This work bridges the gap between thermosetting polymers and COFs,and points out a new direction for thermosetting polymers.
基金supported by National Natural Science Foundation of China(grant nos.51873110 and 51673120)State Key Laboratory of Polymer Materials Engineering.
文摘Glassy thermosetting polymers,which possess excellent mechanical properties,structural stability,and solvent resistance,cannot be healed and recycled due to the irreversible crosslinking network.Covalent adaptive networks could address these drawbacks,as their chemical networks are able to shuffle dynamic covalent bonds through exchange reactions,which nevertheless need high temperature or solvent assistance.Here we report a room-temperature self-healing glassy thermoset enabled by designing a disulfide-bond and H-bond hybridized network carrying abundant dangling chains,which are commonly known as network“defects.”However,the“defects”do not plasticize the polymer,as they are bound to network chains through H-bonds.Therefore,the polymer possesses high modulus and strength at room temperature.Importantly,the“defects”can drive the metathesis reaction of disulfide bonds and the rearrangement of H-bonds in the glassy state,enabling the thermosetting network to self-heal at and even below room temperature.
基金supported by the National Key Research and Development Program of China(2022YFB3808800)the National Natural Science Foundation of China(52272084,52072177,22401150)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20241448)the Fundamental Research Funds for the Central Universities(2023102003,30924010811).
文摘Conventional thermosetting plastics have faced the dilemma of non-degradability and recycling,leading to waste accumulation and a huge burden on the global environment and economy.Realizing recycling,reusing and repurposing plastics is a meaningful mileage for the development of sustainable ecological energy.Closed-loop recycling represents an emerging strategy for achieving the circular“waste-to-starting value-to-polymeric plastics”in recent years.Dynamic covalent chemistry(DCC)offers an attractive and efficient targeted design concept for closed-loop recyclable thermosetting polymers.In this review,the features and mechanisms of various DCC including Schiff bases,B-O bonds,sulfide-or selenide-based linkages,acetal linkages,etc.,are discussed in the construction of recyclable polymers.Based on the reversible cleavage and reformation of dynamic covalent bonds,chemically closed-loop recyclable polymers with multi-functions have been raised and developed as promising circular materials.Furthermore,we highlight and analyze the process,conditions and mechanisms of the depolymerization of polymers and recovery of monomers,as well as the remanufacture of cycled polymer networks.Significantly,the reported closed-loop recyclable thermosetting polymers exhibit potential applications in multiple fields,while providing an advanced aspect for resolving plastic waste pollution and promoting the circularity in polymeric materials.Finally,existing challenges and opportunities such as the limited production process,high costs,harsh recycling conditions,and the maintenance of comprehensive performance of thermosetting polymers in the process of implementing the practical use are proposed and discussed.
基金supported by the Fundamental Research Funds for the Central Universities,CHD (300102213708)the Shaanxi Provincial Communication Construction Group (No.17-06K)。
文摘Thermosetting resins have advantages such as high strength,corrosion resistance,and aging resistance,and have excellent prospects for practical application as asphalt modifiers.In order to promote the research of thermosetting resin modified asphalt,to provide direction for its further research,this paper reviews the research progress of thermosetting resin modified asphalt in recent years.The material composition,modification mechanism,and curing behavior of epoxy asphalt,thermosetting polyurethane modified asphalt,unsaturated polyester modified asphalt,and other thermosetting resin modified asphalts are overviewed.Different types of thermosetting resin modified asphalt have different performances,the performance advantages of different thermosetting resin modified asphalts are summarized.At the same time,the existing problems in thermosetting resin modified asphalt and further research directions are provided.Encouraging researchers to produce thermosetting resin modified asphalts using waste or bio-based materials,and to study the recycling technologies and life cycle assessment of thermosetting resin modified asphalt.This paper provides a reference for the study of thermosetting resin modified asphalt.
基金financially supported by the Natural Science Foundation of Gansu Province(Grant No.22JR5RA108)the National Natural Science Foundation of China(Grant No.52205234)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y2018457)the Key Program of the Lanzhou Institute of Chemical Physics,CAS(Grant No.KJZLZD-3).
文摘Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were successfully synthesized.The tensile strength,elongation at break,and Young’s modulus of PI are 108.70±7.29 MPa,19.35%±3.89%,and 2336.42±128.00 MPa,respectively.The addition of reduced graphene oxide(RGO)not only enhances the mechanical properties of PI but also endows it with excellent tribological properties.The PI illustrates a high recycling efficiency of 94.15%,but the recycled composite exhibits inferior mechanical properties.The recycling and utilization of PI and its composite are realized through imine bonds(-C=N),which provides new guidance for solving the problem of environmental pollution and resource waste and is potential application in the field of sustainable tribology.
基金supported by the National Natural Science Foundation of China(52073038 and 51873027)the National Key R&D Program of China(2022YFB3704600)the Fundamental Research Funds for the Central Universities(DUT22LAB605)。
文摘The advancement of photo-curing three-dimensional(3D)printing technology has significantly enhanced the capabilities of advanced manufacturing across various fields.However,the robust cross-linking network of photopolymers limits its application in information encryption and exacerbates environmental issues.In this study,a degradable thermosetting photopolymer platform for information encryption was proposed by incorporating sulfite bonds into the polymer structure.Due to the autocatalytic behavior of sulfite bonds during hydrolysis under acidic conditions,the photopolymer can achieve complete degradation at 50℃ within 45 min.Based on the degradability of the developed photopolymers,a highly secure degradation-UV dual information encryption system has been established using photo-curing-based 3D printing technology.Furthermore,the degradation products of these photopolymers,generated during the information decryption process,can be utilized to prepare high-performance solar thermoelectric generators with a power density of 325.7µW cm^(−2)(under one sun)after a simple one-step modification.This work not only inspires the development of multiple information encryption methods based on 3D printing but also provides a practical solution to address environmental challenges associated with plastic pollution.
文摘The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature(UCST)or lower critical solution temperature(LCST)were studied with emphasis on the temperature dependency of the phase separation time and its potential application in the cure time-temperature processing window.We found that the phase separation time/temperature relationship follows the simple Arrhenius equation.The cure-induced phase separation activation energy E_(a)(ps)generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time.We also found that E_(a)(ps)is insensitive to TP content,TP molecular weight and curing rate,but it changes with the cure reaction kinetics and the chemical environment of the systems.With the established phase separation time-temperature dependence relation,we can easily establish the whole cure time-temperature transformation(TTT)diagram with morphology information which is a useful map for the TP/TS composites processing industry.
基金the support of the Science and Technology Commission of Shanghai Municipality(STCSM,No.20dz1203600)the Experimental Center of Materials Science and Engineering in Tongji University。
文摘Epoxy resin is widely used in electronic packaging due to its exceptional performance,particularly the low-temperature curable thiol/epoxy system,which effectively minimizes thermal damage to sensitive electronic components.However,the majority of commercial thiol curing agents contain hydrolysable ester bonds and lack rigid structures,which induces most of thiol/epoxy systems still suffering from unsatisfactory heat resistance and hygrothermal resistance,significantly hindering their application in electronic packaging.In this study,we synthesized a tetrafunctional thiol compound,bis[3-(3-sulfanylpropyl)-4-(3-sulfanylpropoxy)phenyl]sulfone(TMBPS)with rigid and ester-free structures to replace traditional commercial thiol curing agents,pentaerythritol tetra(3-mercaptopropionate)(PETMP).Compared to the PETMP/epoxy system,the TMBPS/epoxy system exhibited superior comprehensive properties.The rigid structures of bisphenol S-type tetrathiol enhanced the heat resistance and mechanical properties of TMBPS/epoxy resin cured products,outperforming those of PETMP/epoxy resin cured products.Notably,the glass transition temperature of TMBPS/epoxy resin cured products was 74.2℃which was 11.8°C higher than that of PETMP cured products.Moreover,the ester-free structure in TMBPS contributed to its enhanced resistance to chemicals and hygrothermal conditions.After undergoing 1000 h of hightemperature and high-humidity aging,the tensile strength and adhesion strength of TMBPS-cured products were 73.33 MPa and 3.39 MPa,respectively exceeding 100%and 40%of their initial values,while PETMP-cured products exhibited a complete loss of both tensile strength and adhesion strength.This study provides a strategy for obtaining thermosetting polymers that can be cured at low temperatures and exhibit excellent comprehensive properties.
基金financially supported by the Natural Science Foundation of Zhejiang Province(No.LQ24B040004)。
文摘Thermosets are indispensable to our daily life,but their crosslinked structures make them unable to be processed by the melt processing like thermoplastics,which greatly limits their shape designs and applications.Herein,we address this challenge via an in situ self-growing strategy,i.e.utilizing the dynamic imidazole-urea moiety to suck up and integrate epoxy into the materials and making the thermoplastics grow in situ into thermosets.With this strategy,thermosets can be readily processed via hot-melt extrusion molding,including melt spinning and fused deposition modeling 3D printing.More importantly,this strategy simultaneously integrates the flexibility of polyurethane and the robustness of epoxy resin into the resulting thermosets,yielding a mechanical-reinforcing effect to make the material not only strong but also tough(toughness:99.3 MJ·m^(-3),tensile strength:38.8 MPa).Moreover,the crosslinking density and modulus of the as-prepared thermosets(from 34.1 MPa to613.7 MPa)can be readily tuned on demand by changing the growth index.Furthermore,these thermosets exhibited excellent thermal stability and chemical resistance.
基金financially supported by the National Natural Science Foundation of China(No.32460363)Yunnan Province Agricultural Joint Key Foundation(No.202401BD070001-029)+3 种基金as well as the Yunnan Provincial Youth top talent project(No.YNWR-QNBJ-2020-166)Foreign Expert Workstation(No.202305 AF150006)111 project(No.D21027)Yunnan Province Natural Science Key Foundation(No.202301AS070043)。
文摘In this study,epoxidized soybean oil(ESO)and ricinoleic acid(RA)were used to synthesize polyol esters,designated ESO-RA(ER)resin.The esters were further crosslinked with 4,4-diphenylmethane diisocyanate(PMDI)to create a biodegradable flame-retardant thermoset foam,referred to as ESO-RA-PMDI(ERP)foam,using water as a foaming agent.Additionally,flame retardants such as triethyl phosphate(TEP)and expanded graphite(EG)have been combined for foam preparation without the need for catalysts or foaming agents.The study findings showed that the incorporation of TEP and EG diminished the pulverization ratio while augmenting the compressive strength and shore hardness.Furthermore,the ERP foam exhibited exceptional flame retardant characteristics,as evidenced by a reported limiting oxygen index(LOI)value of 30.6vol%.A peak heat release rate of 97.12 kW/m^(2)was reported during the fire test.Significantly,a low peak smoke production rate(pSPR)of 0.026m^(2)/s and a total smoke production(TSP)of 0.62 m^(2)were achieved.In addition,ERP foam exhibited exceptional ultraviolet(UV)resistance,thermal insulation,and biodegradability.After 60 days of exposure to Penicillium sp.,foam containing both TEP and EG exhibited a mass loss of 9.39%,indicating that the incorporation of flame retardants did not negatively impact its biodegradability.
基金supported by the National Natural Science Foundation of China.(Grand No.31570563)Jiangsu Province Biomass Energy and Materials Laboratory,China(Grant No.JSBEM-S-201807)Fundamental Research Funds of Chinese academy of forestry(CAFYBB2017MB017).
文摘Thermosetting polyurethanes are widely used in various fields owing to their excellent elasticity,strength and solvent resistance.Three environmental friendly propyl gallate-based self-healing polyurethanes were prepared from polyurethane prepolymers with varying isocyanate content.The thermal stabilities of the polyurethanes were tested using thermogravimetric analysis.Their self-healing and mechanical properties were analyzed using a universal testing machine and dynamic thermomechanical analysis.The polyurethanes were found with high self-healing ability and excellent mechanical properties due to the absence of phenolic carbamate.These qualities improved with increased isocyanate content and the prolonged selfhealing time.We found,therefore,that the propyl gallate-based polyurethane has potential for use in industrial applications as self-healing materials.
基金funded by the Natural Science Foundation of China(No.51702335)open project of the Beijing National Laboratory for Molecular Science(No.20140138)+1 种基金the CASEU S&T cooperation partner program(No.174433KYSB20150013)the Key Laboratory of Bio-based Polymeric Materials of Zhejiang Province
文摘A facile scalable synthesis of hierarchical Sb/C micro-/nanohybrid has been addressed in this work, which possesses the advantages of both micrometer and nanometer scale structures as lithium-ion battery anode. Difunctional methacrylate monomers are used as solvent and carbon source as well. Liquid precursor of antimony（III） n-butoxide is dissolved in the resin monomer solution, and further incorporated into the cross-linking polymer network via photo polymerization. Through calcination in argon/hydrogen atmosphere, antimony nanoparticles are in situ formed by carbothermal reduction, and homogeneously embedded in the in situ formed micrometer sized carbon matrix. The morphology, structure, crys- tallinity, spatial dispersion, composition, and electrochemical performance of the Sb/C micro-/nanohybrid are systemati- cally investigated. The cyclic and rate performance of the Sb/C micro-/nanohybrid anode have been effectively improved compared to the pure carbon anode. A reversible capacity of 362 mAh g-1 is achieved with a reasonable mass loading density after 300 cycles at 66 mA g-1, corresponding to capacity retention of 79%. With reducing mass loading density, the reversible capacity reaches 793 mAh g-1 after 100 cycles. Moreover, the electrochemical performance of Sb/C micro-/nanohybrid as sodium-ion battery anode is also investigated in this study.
文摘This study focuses on the insert-injection molding process. The thermoset composite inserts in this study were carbon fiber/epoxy (CF/Epoxy) prepreg sheets. The injected molded part was glass fiber contained phenolic resin (GF/PF). The CF/Epoxy was placed in the mold cavity prior to injecting GF/PF onto the inserted injection molded CF/Epoxy specimens. The role of adhesion between the inserted part and injected resin on the mechanical properties was evaluated by 3 point bending and impact tests. In addition, the effect of prepreg orientation on the mechanical properties of the prepreg inserted-injection molding system was investigated. It was found that the prepreg with unidirectional orientation significantly improved flexural and impact strength of the inserted injection molding composites, providing better support and resistance to bending and impact loading. The main failure modes of the specimens were structural and adhesive failure.
文摘Dye-sensitized solar cells （DSSCs） are the most promising, low cost and most extensively investigated solar cells. They are famous for their clean and efficient solar energy conversion. Nevertheless this, long-time sta- bility is still to be acquired. In recent years research on solid and quasi-solid state electrolytes is extensively in- creased. Various quasi-solid electrolytes, including composites polymer electrolytes, ionic liquid electrolytes, thermoplastic polymer electrolytes and thermosetting polymer electrolytes have been used. Performance and stability of a quasi-solid state electrolyte are between liquid and solid electrolytes. High photovoltaic performances of QS-DSSCs along better long-term stability can be obtained by designing and optimizing quasi-solid electrolytes. It is a prospective candidate for highly efficient and stable DSSCs.
文摘Cure and decomposition reaction kinetics of typical organic materials in aerospace applications are introduced.From the data of dynamic differential scanning calorimetry(DSC)experiments,and based on changes of the peak temperatures(T_(p))with different heating rates(β),a linear equation,T_(p)=T_(1)+△Tlnβ,has been obtained more reasonably.The above equation can be used to explain some laws of higher or lower of apparent activation energies(E_(a)),by which the apparent activation energy(E_(a))is nearly equal to RT^(2)_(1)/△T.A number of kinetic investigations of typical thermosetting resins and energetic materials in aerospace applications were chosen to validate the above equations.
