This study presents the development of high-performance,solvent-free polyurethane-urea(PU)elastomeric coatings engineered for rapid curing and precise sprayability.Utilizing polyoxytetramethylene glycol(PTMG)as the pr...This study presents the development of high-performance,solvent-free polyurethane-urea(PU)elastomeric coatings engineered for rapid curing and precise sprayability.Utilizing polyoxytetramethylene glycol(PTMG)as the primary polyol and a static-mixing spraying technique,the formulations were systematically optimized.It was found that a soft-segment content of 64% yields optimalmechanical properties,achieving a remarkable tensile strength exceeding 30 MPa.Crucially,the incorporation of an ultra-low concentration(0.002 wt%)of dibutyltin dilaurate catalyst was sufficient to enhance curing completeness and mechanical performance while effectively eliminating moisture-induced foaming,a common challenge in solvent-free spray applications.The gel and tack-free times were successfully reduced to the order of minutes through strategic formulation with the chain extender dimethylsulfidetoluene diamine,minimizing reliance on high catalyst loadings.Theresultant PTMG-based coatings exhibit exceptional comprehensive properties,including a tensile strength>30 MPa,elongation at break>400%,and a tear strength of 66 N/mm,significantly surpassing conventional polypropylene-diamine-based polyurea systems.Furthermore,the coatings demonstrated superior low-temperature flexibility,evidenced by a glass transition temperature of-53℃,and suppressed soft-segment crystallinity.The solvent-free nature and tunable curing kinetics of this system enable precise spraying on complex geometries,effectively overcoming thickness-control limitations for small-object applications.This work establishes a sustainable and high-performance coating solution ideal for demanding impact-and corrosionresistant protective layers.展开更多
A non-reacting system and a reacting system are run with an on-line slit rheometer devel-oped by the authors.It is found that the polyurethane-urea system behaves slightly elastic and theZaremba-Fromm-Dewitt model may...A non-reacting system and a reacting system are run with an on-line slit rheometer devel-oped by the authors.It is found that the polyurethane-urea system behaves slightly elastic and theZaremba-Fromm-Dewitt model may be employed to describe its rheological behaviors.After the geltime,the inside pressure of the testing materials varies dramatically.Reports in this respect have notbeen found in literature,as yet its mechanism warrants further studies.展开更多
In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the r...In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure.The prepolymers were characterized fully by various techniques.Then,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and compared.Different from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property.Furthermore,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their nanocomposites.The influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then decreased.The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample.In addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.展开更多
With ultrasonic assistant mixing way, an intercalated mixture of polyol/ organo reactive montmorillonite （ORMMT） was pretreated. The prepolymer composed MMT clay was prepared by reaction of polyol/ORMMT mixture with...With ultrasonic assistant mixing way, an intercalated mixture of polyol/ organo reactive montmorillonite （ORMMT） was pretreated. The prepolymer composed MMT clay was prepared by reaction of polyol/ORMMT mixture with toluene diisocyanate （TDI）. The resultant prepolymer reacted with extender （DMTDA） and then the polyur- ethane-urealorgano reactive montmorillonite （PUUIORMMT） nanocomposites were obtained. The structure, morphology and properties of PUU/ORMMT nanocomposites were characterized by FT-IR, TEM, AFM, strain-stress machine, TGA, and dynamic mechanical analysis （DMA）. The results showed that when tl-m OMMT content is 3%, the PUU/ORMMT nanocomposities performed super mechanical properties. Because of the presence of ORMMT, both Tg of the soft segment and tan5 of the PUU increased, and the decomposition temperature for the first step and the second step increased respectively. TEM images showed that the organophilic MMT particles in the PUU composite exhibit a high degree of intercalation and exfoliation.展开更多
基金funded by the National Natural Science Foundation of China(No.U2330207)the presidential foundation of China Academy of Engineering Physics(No.YZJJZQ2024004).
文摘This study presents the development of high-performance,solvent-free polyurethane-urea(PU)elastomeric coatings engineered for rapid curing and precise sprayability.Utilizing polyoxytetramethylene glycol(PTMG)as the primary polyol and a static-mixing spraying technique,the formulations were systematically optimized.It was found that a soft-segment content of 64% yields optimalmechanical properties,achieving a remarkable tensile strength exceeding 30 MPa.Crucially,the incorporation of an ultra-low concentration(0.002 wt%)of dibutyltin dilaurate catalyst was sufficient to enhance curing completeness and mechanical performance while effectively eliminating moisture-induced foaming,a common challenge in solvent-free spray applications.The gel and tack-free times were successfully reduced to the order of minutes through strategic formulation with the chain extender dimethylsulfidetoluene diamine,minimizing reliance on high catalyst loadings.Theresultant PTMG-based coatings exhibit exceptional comprehensive properties,including a tensile strength>30 MPa,elongation at break>400%,and a tear strength of 66 N/mm,significantly surpassing conventional polypropylene-diamine-based polyurea systems.Furthermore,the coatings demonstrated superior low-temperature flexibility,evidenced by a glass transition temperature of-53℃,and suppressed soft-segment crystallinity.The solvent-free nature and tunable curing kinetics of this system enable precise spraying on complex geometries,effectively overcoming thickness-control limitations for small-object applications.This work establishes a sustainable and high-performance coating solution ideal for demanding impact-and corrosionresistant protective layers.
基金Supported by the National Natural Science Foundation of China.
文摘A non-reacting system and a reacting system are run with an on-line slit rheometer devel-oped by the authors.It is found that the polyurethane-urea system behaves slightly elastic and theZaremba-Fromm-Dewitt model may be employed to describe its rheological behaviors.After the geltime,the inside pressure of the testing materials varies dramatically.Reports in this respect have notbeen found in literature,as yet its mechanism warrants further studies.
文摘In this study,a series of hindered urea bond(HUB)containing polyurethane-urea methacrylate prepolymers and a none HUB containing polyurethane methacrylate prepolymer were prepared using isobornyl methacrylate as the reactive diluent via one-pot procedure.The prepolymers were characterized fully by various techniques.Then,their thermosets were fabricated via UV curing in presence of a photo initiator,and their mechanical property and thermal behavior were investigated and compared.Different from the none HUB containing thermoset,the HUB containing thermosets(defined as PUT)could be recycled and reprocessed by hot press under relatively mild conditions with high recovery ratio of mechanical property.Furthermore,zinc oxide(ZnO)nanoparticles were modified with 3-(trimethoxysilyl)propyl methacrylate and the modified ZnO(defined as ZnO-TPM)was dispersed and polymerized into PUT matrix to prepare their nanocomposites.The influence of ZnO-TPM on the mechanical performance of the composites was evaluated,which indicated that the Young’s modulus and tensile strength increased gradually to the maximum values at ZnO-TPM content of 1 wt%and then decreased.The composites also displayed good reprocessability with improved recovery ratio compared to the pure PUT sample.In addition,the composite materials exhibited strong UV absorption capacity,implying their potential application in the circumstance where UV-shielding was required.
文摘With ultrasonic assistant mixing way, an intercalated mixture of polyol/ organo reactive montmorillonite （ORMMT） was pretreated. The prepolymer composed MMT clay was prepared by reaction of polyol/ORMMT mixture with toluene diisocyanate （TDI）. The resultant prepolymer reacted with extender （DMTDA） and then the polyur- ethane-urealorgano reactive montmorillonite （PUUIORMMT） nanocomposites were obtained. The structure, morphology and properties of PUU/ORMMT nanocomposites were characterized by FT-IR, TEM, AFM, strain-stress machine, TGA, and dynamic mechanical analysis （DMA）. The results showed that when tl-m OMMT content is 3%, the PUU/ORMMT nanocomposities performed super mechanical properties. Because of the presence of ORMMT, both Tg of the soft segment and tan5 of the PUU increased, and the decomposition temperature for the first step and the second step increased respectively. TEM images showed that the organophilic MMT particles in the PUU composite exhibit a high degree of intercalation and exfoliation.
