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
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
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
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
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
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
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
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
It is of great significance to design epoxy coatings with superior antibacterial properties and high adhesive properties, as well as excellent processing, superior durability, and high transparency. However, it is sti...It is of great significance to design epoxy coatings with superior antibacterial properties and high adhesive properties, as well as excellent processing, superior durability, and high transparency. However, it is still a challenge because of the common complex design and synthesis. Herein, the bio-based monomer protocatechuic acid(PCA) was used as raw material, the catechol structure with high bonding and antibacterial properties was introduced into the flexible alkane segment of ethylene glycol diglycidyl ether(EGDE) through an efficient, and green method, and it was cured with isophorone diamine(IPDA) to prepare corresponding thermosets. The cured resins exhibited excellent allaround qualities, particularly in bonding and antibacterial. When 30% PCA was added to pure epoxy resin, the adhesion between substrate and coating increased from 4.40 MPa to 13.60 MPa and the antibacterial rate of coating against E. coli and S. aureus could approach 100%. All of this is due to the fact that the catechol structure present in PCA has the ability to interact with various substrates and alter the permeability of bacterial cell membranes. The architecture of this method offers a fresh approach to dealing with the issues of challenging raw material selection and complex synthesis techniques.展开更多
Polymers are indispensable to humans in different applications due to their ease of manufacturing and overall performance.However,after a material lifetime,there is a large amount of polymer-based waste,which greatly ...Polymers are indispensable to humans in different applications due to their ease of manufacturing and overall performance.However,after a material lifetime,there is a large amount of polymer-based waste,which greatly contributes to the loss of valuable resources and environmental pollution.Thermoplastics may be readily recycled,but because of their flammability,large amounts of flame retardant(FR)ad-ditives are required for many applications.This results in a significant volume of FR polymeric wastes too,particularly halogenated plastics,which are subject to severe recycling regulations.In general,ther-moplastics containing FRs are raising concerns,as their effective recycling is strongly influenced by the chemical composition,additive content,and physicochemical characteristics of the waste stream.The recycling of FR thermosets is even more challenging due to their crosslinked and cured nature,which makes them resistant to melting and reprocessing.In many cases,traditional mechanical recycling meth-ods,such as grinding and melting,are not applicable to thermosetting polymers.Current recycling meth-ods do not always consider the recovery of the thermosetting/thermoplastic matrix and the presence of toxic FRs in the polymer network.Sorting and solvent washing treatment are important steps,which are usually performed before recycling the FR polymeric waste to reduce contamination in the following steps.展开更多
The use of CO_(2) as monomer to synthesize polymer materials is an important and potential applications topic from the viewpoint of green and sustainable chemistry.A new kind of CO_(2)-based polyurea(PUa)was synthesiz...The use of CO_(2) as monomer to synthesize polymer materials is an important and potential applications topic from the viewpoint of green and sustainable chemistry.A new kind of CO_(2)-based polyurea(PUa)was synthesized by polycondensation of CO_(2) with 4,7,10-trioxa-1,13-tridecanediamine and tris(2-aminoethyl)amine(TAEA).TAEA was used as cross-link reagent.The mechanical properties of PUa were significantly improved by inserted the crosslink agent of TAEA.The formed slight cross-linked PUa exhibited excellent mechanical properties with tensile strength of 26.8 MPa,elongation at break of 34%and Young’s modulus of 351 MPa.Moreover,it could be remolded for 3 times without obvious change in the mechanical properties,which are ascribed to the hydrogen bonding interaction among the main chains and the slight cross-linked structure.In addition,the synthesized CO_(2)-based PUa is of outstanding thermal performance with an initial decomposition temperature above 300℃,besides it is tolerance for a variety of organic solvents.展开更多
Due to their extraordinary durability and thermal stability,Epoxy Resin Thermosets(ERTs)are essential in various industries.However,their poor recyclability leads to unacceptable environmental pollution.In this study,...Due to their extraordinary durability and thermal stability,Epoxy Resin Thermosets(ERTs)are essential in various industries.However,their poor recyclability leads to unacceptable environmental pollution.In this study,Wu et al.successfully synthesized a completely bio-based ERT using lignocellulose-derived building blocks which exhibit outstanding thermal and mechanical properties.Remarkably,these bio-materials degrade via methanolysis without the need of any catalyst,presenting a smart and cost-effective recycling strategy.Furthermore,this approach could be employed for fabricating reusable composites comprising glass fiber and plant fiber,thereby expanding its applications in sustainable transportation,coatings,paints or biomedical devices.展开更多
The conception of epoxy thermosets with both reprocessability and flame retardancy delineates a new horizon in polymer science,offering a material solution that is not only superior in fire safety but is also environm...The conception of epoxy thermosets with both reprocessability and flame retardancy delineates a new horizon in polymer science,offering a material solution that is not only superior in fire safety but is also environment friendly.Herein,a flame-retardant epoxy vitrimer(EV)was prepared using partially bio-based IADPPO(diphenylphosphine oxide itaconic anhydride)and citric acid as curing reagents via a solvent-free process.Their incorporation created covalent adaptable networks(CANs)in the matrix which promote reprocessability and recyclability.The EV exhibits excellent thermal stability with high initial decomposition temperature(T_(- 5wt%)∼308℃)and high glass transition temperature(T_(g)∼107℃),similar to the blank EV(115℃).The flame retardancy,mechanical properties,transesterification-based reprocessability,and flame-retardant mechanism were investigated.The EV containing 3 wt%phosphorus(EV IADPPO 3P)achieved UL-94 V0 classification with a limiting oxygen index(LOI)of 27%,while the virgin sample Blank EV(without phosphorus)burned completely.Additionally,increased flexural strength of 79%was observed for EV IADPPO 3P compared to Blank EV.Furthermore,the flame-retardant EV showed high malleability and reparability that could be thermomechanically reprocessed without sacrificing the thermal,mechanical,and flame-retardant properties.Thus,the newly developed epoxy vitrimer is not only fire-safe but fulfills the sustainability goals of today’s society.展开更多
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.
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.
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.
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.
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financially supported by the National Natural Science Foundation of China (Nos.U1909220 and 52003283)Science and Technology Innovation 2025 Major Project of Ningbo (Nos.2021Z092, 2022Z111 and 2022Z160)+1 种基金Defense Industrial Technology Development Program (No.JCKY2021513B001)the Research Project of Technology Application for Public Welfare of Ningbo City (No.202002N3122)。
文摘It is of great significance to design epoxy coatings with superior antibacterial properties and high adhesive properties, as well as excellent processing, superior durability, and high transparency. However, it is still a challenge because of the common complex design and synthesis. Herein, the bio-based monomer protocatechuic acid(PCA) was used as raw material, the catechol structure with high bonding and antibacterial properties was introduced into the flexible alkane segment of ethylene glycol diglycidyl ether(EGDE) through an efficient, and green method, and it was cured with isophorone diamine(IPDA) to prepare corresponding thermosets. The cured resins exhibited excellent allaround qualities, particularly in bonding and antibacterial. When 30% PCA was added to pure epoxy resin, the adhesion between substrate and coating increased from 4.40 MPa to 13.60 MPa and the antibacterial rate of coating against E. coli and S. aureus could approach 100%. All of this is due to the fact that the catechol structure present in PCA has the ability to interact with various substrates and alter the permeability of bacterial cell membranes. The architecture of this method offers a fresh approach to dealing with the issues of challenging raw material selection and complex synthesis techniques.
基金the Italian Ministry of Ed-ucation and Research,PON R&I 2014-2020-Asse IV“Istruzione e ricerca per il recupero-REACT-EU”-Azione IV.6-“Contratti di ricerca su tematiche Green”,for the financial support concerning his employment contractThe work was partially supported by funds from the Zuercher Stiftung fuer Textilforshung(Winterthur,Switzerland).
文摘Polymers are indispensable to humans in different applications due to their ease of manufacturing and overall performance.However,after a material lifetime,there is a large amount of polymer-based waste,which greatly contributes to the loss of valuable resources and environmental pollution.Thermoplastics may be readily recycled,but because of their flammability,large amounts of flame retardant(FR)ad-ditives are required for many applications.This results in a significant volume of FR polymeric wastes too,particularly halogenated plastics,which are subject to severe recycling regulations.In general,ther-moplastics containing FRs are raising concerns,as their effective recycling is strongly influenced by the chemical composition,additive content,and physicochemical characteristics of the waste stream.The recycling of FR thermosets is even more challenging due to their crosslinked and cured nature,which makes them resistant to melting and reprocessing.In many cases,traditional mechanical recycling meth-ods,such as grinding and melting,are not applicable to thermosetting polymers.Current recycling meth-ods do not always consider the recovery of the thermosetting/thermoplastic matrix and the presence of toxic FRs in the polymer network.Sorting and solvent washing treatment are important steps,which are usually performed before recycling the FR polymeric waste to reduce contamination in the following steps.
文摘The use of CO_(2) as monomer to synthesize polymer materials is an important and potential applications topic from the viewpoint of green and sustainable chemistry.A new kind of CO_(2)-based polyurea(PUa)was synthesized by polycondensation of CO_(2) with 4,7,10-trioxa-1,13-tridecanediamine and tris(2-aminoethyl)amine(TAEA).TAEA was used as cross-link reagent.The mechanical properties of PUa were significantly improved by inserted the crosslink agent of TAEA.The formed slight cross-linked PUa exhibited excellent mechanical properties with tensile strength of 26.8 MPa,elongation at break of 34%and Young’s modulus of 351 MPa.Moreover,it could be remolded for 3 times without obvious change in the mechanical properties,which are ascribed to the hydrogen bonding interaction among the main chains and the slight cross-linked structure.In addition,the synthesized CO_(2)-based PUa is of outstanding thermal performance with an initial decomposition temperature above 300℃,besides it is tolerance for a variety of organic solvents.
基金the foundational support by the Fundamental Research Funds for the Central Universities(BLX202132)the foundational support by the Beijing Youth Talent Funding Program-Visiting program for young foreign scholars(Q2023043)IIT(BHU)Varanasi.
文摘Due to their extraordinary durability and thermal stability,Epoxy Resin Thermosets(ERTs)are essential in various industries.However,their poor recyclability leads to unacceptable environmental pollution.In this study,Wu et al.successfully synthesized a completely bio-based ERT using lignocellulose-derived building blocks which exhibit outstanding thermal and mechanical properties.Remarkably,these bio-materials degrade via methanolysis without the need of any catalyst,presenting a smart and cost-effective recycling strategy.Furthermore,this approach could be employed for fabricating reusable composites comprising glass fiber and plant fiber,thereby expanding its applications in sustainable transportation,coatings,paints or biomedical devices.
基金partially supported by the Swiss National Sci-ence Foundation(Grant No.200021L_196923)by funds from the Zürcher Stiftung für Textilforschung(Winterthur,Switzerland)supported by the China Scholarship Council(CSC No.202006260103)。
文摘The conception of epoxy thermosets with both reprocessability and flame retardancy delineates a new horizon in polymer science,offering a material solution that is not only superior in fire safety but is also environment friendly.Herein,a flame-retardant epoxy vitrimer(EV)was prepared using partially bio-based IADPPO(diphenylphosphine oxide itaconic anhydride)and citric acid as curing reagents via a solvent-free process.Their incorporation created covalent adaptable networks(CANs)in the matrix which promote reprocessability and recyclability.The EV exhibits excellent thermal stability with high initial decomposition temperature(T_(- 5wt%)∼308℃)and high glass transition temperature(T_(g)∼107℃),similar to the blank EV(115℃).The flame retardancy,mechanical properties,transesterification-based reprocessability,and flame-retardant mechanism were investigated.The EV containing 3 wt%phosphorus(EV IADPPO 3P)achieved UL-94 V0 classification with a limiting oxygen index(LOI)of 27%,while the virgin sample Blank EV(without phosphorus)burned completely.Additionally,increased flexural strength of 79%was observed for EV IADPPO 3P compared to Blank EV.Furthermore,the flame-retardant EV showed high malleability and reparability that could be thermomechanically reprocessed without sacrificing the thermal,mechanical,and flame-retardant properties.Thus,the newly developed epoxy vitrimer is not only fire-safe but fulfills the sustainability goals of today’s society.
