Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.Th...Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.The microcapsules were directly added to the hydroxyl terminated polybutadiene(HTPB)-polyurethane elastomer system to fabricate the polyurethane elastomer composites.The thermodynamic stability and mechanical properties of the material were then studied.The results show that the thermal stability of the polyurethane elastomer does not decrease after adding paraffin phase change microcapsules,and the thermal stability of the polyurethane elastomer with melamine resin as the wall increases.Tensile strength increased from 367 kPa to 797 kPa,and compression strength increased from 245.9 N to 344.7 N.In addition,capsule walls comprised different monomers/paraffin microcapsules of the copolymer of styrene and divinylbenzene.The optimal mechanical property was obtained at a monomer/paraffin ratio of 1:1.The compression strength increased and the tensile strength decreased.The tensile strength of the microcapsule with melamine resin capsule wall and the compression strength of the microcapsule with polystyrene capsule wall were considerably improved.展开更多
A series of polyurethane elastomers (PUEs) were synthesized by using β-cyclodextrin (β-CD) as cross-linker from aliphatic, alicyclic, aromatic diisocyanates, and polyol. The PUEs were characterized by Fourier Transf...A series of polyurethane elastomers (PUEs) were synthesized by using β-cyclodextrin (β-CD) as cross-linker from aliphatic, alicyclic, aromatic diisocyanates, and polyol. The PUEs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), swelling test, hardness test and tensile test. The influence of diisocyanate on microphase separation and properties of PUEs was evaluated.展开更多
In recent years, sugar-derived polymer materials have been actively investigated. In research of polyurethane (PU), sugar has been used as a raw material because it has properties similar to polyol. However, the elast...In recent years, sugar-derived polymer materials have been actively investigated. In research of polyurethane (PU), sugar has been used as a raw material because it has properties similar to polyol. However, the elastic property of the obtained PU is substantially lost. Hence, the introduction of a sugar unit to PU while maintaining the elastic property remains a challenge in polymer chemistry. Here, we report the synthesis of a polyurethane elastomer (PUE) with a trehalose unit using raw materials such as an aromatic diisocyanate (4,4’-diphenylmethane diisocyanate), polyols including a polyether polyol (polytetramethylene glycol), two polyester polyols (polycaprolactone and polycarbonate diol), and trehalose. Novel PUEs with trehalose units are synthesized by a one-shot method. Trehalose, which has non-reducing properties, is used as sugar. The use of trehalose, which has been scarcely applied to PUE, is essential to obtain the desired PUEs with sugar units.展开更多
A series of PUEs which use β-CD as cross-linker were synthesized. Nanoindentation measurements of mechanical properties of these PUEs were made. Load and depth sensing indentation and nano DMA mode were used to evalu...A series of PUEs which use β-CD as cross-linker were synthesized. Nanoindentation measurements of mechanical properties of these PUEs were made. Load and depth sensing indentation and nano DMA mode were used to evaluate mechanical properties of PUEs in nano-scale. The difference between the results from two modes proved the microphase separation in PUEs and to investigate PUE from hard domains and soft domains was of great significance.展开更多
The hydrogen bond percentage and its temperature dependence of the three TPU samples synthesized from polytetrahydrofuran, 4,4’-diphenylmethane diisocyanate, N -methyl diethanol amine or 1,4-butane diol were studied ...The hydrogen bond percentage and its temperature dependence of the three TPU samples synthesized from polytetrahydrofuran, 4,4’-diphenylmethane diisocyanate, N -methyl diethanol amine or 1,4-butane diol were studied by means of IR thermal analysis. The enthalpy and the entropy of the hydrogen bond dissociation were determined by the Van’t Hoff plot.展开更多
The polyaddition of isocyanate and polyol to form polyurethane elastomers has rarely been applied to the construction of chiral polyurethane elastomers. Hence, the introduction of chiral units via polyaddition remains...The polyaddition of isocyanate and polyol to form polyurethane elastomers has rarely been applied to the construction of chiral polyurethane elastomers. Hence, the introduction of chiral units via polyaddition remains a challenging subject in polymer chemistry. In this study, the synthesis of chiral polyurethane elastomers using an aromatic isocyanate, polyols (polyether and polyester polyols), and L(+)-, D(−)-, or meso-tartaric acid by a one-shot method is investigated. The polymers are characterized using FTIR and NMR spectroscopy, and their thermal properties are investigated by TGA, DMA, and DSC analyses. The optical activities of the polymers are confirmed by rotation. The use of chiral tartaric acids is essential to obtain the desired chiral polyurethane elastomers.展开更多
Thermoplastic polyurethane(PU)elastomers have attracted significant attention because of their many important industrial applications.However,the creation of fire-retardant and anti-dripping PU elastomers has remained...Thermoplastic polyurethane(PU)elastomers have attracted significant attention because of their many important industrial applications.However,the creation of fire-retardant and anti-dripping PU elastomers has remained a grant challenge due to the lack of crosslinking and weak interchain interactions.Herein,we report a mechanically robust,biodegradable,fire-retardant,and anti-dripping biobased PU elastomer with excellent biodegradability using an abietic acid-based compound as hard segments and polycaprolactone diol(PCL)as soft segments,followed by physically crosslinking with cellulose nanocrystals(CNC)through dynamic hydrogen-bonding.The resultant elastomer shows the balanced mechanical and fire-retardant properties,e.g.,a tensile strength and break strain of 9.1 MPa and 560%,a self-extinguishing ability(V-0 rating in UL-94 testing),and an anti-dripping behavior.Moreover,the as-developed PU can be completely degraded in 1.0 wt.%lipase solution at 37℃ in 60 days,arising from the catalytic and wicking effect of CNC on PU chains.This work provides an innovative and versatile strategy for constructing robust,fire-retardant,anti-dripping,and biodegradable PU elastomers,which hold great promise for practical applications in electronic and automobile sectors.展开更多
Bridging the gap between the computation of mechanical properties and the chemical structure of elastomers is a long-standing challenge.To fill the gap,we create a raw dataset and build predictive models for Young’s ...Bridging the gap between the computation of mechanical properties and the chemical structure of elastomers is a long-standing challenge.To fill the gap,we create a raw dataset and build predictive models for Young’s modulus,tensile strength,and elongation at break of polyurethane elastomers(PUEs).We then construct a benchmark dataset with 50.4%samples remained from the raw dataset which suffers from the intrinsic diversity problem,through a newly proposed recursive data elimination protocol.The coefficients of determination(R^(2)s)from predictions are improved from 0.73-0.78 to 0.85-0.91 based on the raw and the benchmark datasets.The fitting of stress-strain curves using the machine learning model shows a slightly better performance than that for one of the well-performed constitutive models(e.g.,the Khiêm-Itskov model).It confirmed that the black-box machine learning models are feasible to bridge the gap between the mechanical properties of PUEs and multiple factors for their chemical structures,composition,processing,and measurement settings.While accurate prediction for these curves is still a challenge.We release the raw dataset and the most representative benchmark dataset so far to call for more attention to tackle the longstanding gap problem.展开更多
In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyuret...In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyurethanes(PU). For the experiments, a series of cerium oxide(CeO_(2))/PUE composites were prepared with different sizes and appearance of CeO_(2), and different mixing methods as well. CeO_(2) particles with different sizes were added into PUs during the formation of urethane linkage and the chain-extend process, respectively. The morphology along with mechanical properties, thermal properties of the composites were studied. The results suggest that the size of CeO_(2) and mixing methods influence the microstructure of PUs which has profound effect on properties of these composites. The composites tend to form more quantity of hard domains(HDs) with small size when CeO_(2) particles were added before the formation of urethane linkage, whereas Ce O2 particles increase the size of HDs when added with chain extender into PU prepolymer.展开更多
Black phosphorus(BP), as one of the most promising fillers for flame retarding polymer, has been seriously limited in practical application, due to the agglomeration and poor structural stability challenges.Here, the ...Black phosphorus(BP), as one of the most promising fillers for flame retarding polymer, has been seriously limited in practical application, due to the agglomeration and poor structural stability challenges.Here, the BP was modified by MXene and polydopamine(PDA) via ultrasonication and dopamine modification strategy to improve the structural stability and dispersibility in the matrix. Then, the obtained(BP-MXene@PDA) nanohybrid was employed to promote the mechanical performance, thermal stability,and flame retardancy of thermoplastic polyurethane elastomer(TPU). The resultant TPU composite containing 2 wt.% of BP1-MXene2@PDA showed a 19.2% improvement in the tensile strength and a 13.8%increase in the elongation at break compared to those of the pure TPU. The thermogravimetric analysis suggested that BP-MXene@PDA clearly enhances the thermal stability of TPU composites. Furthermore,the introduction of the BP-MXene@PDA nanohybrids could considerably improve the flame retardancy of TPU composite, i.e., 64.2% and 27.3% decrease in peak heat release rate and total heat release, respectively. The flame-retardant mechanisms of TPU/BP-MXene@PDA in the gas phase and condensed phase were investigated systematically. This work provides a novel strategy to simultaneously enhance the fire safety and mechanical properties of TPU, thus expanding its industrial applications.展开更多
基金The work is financially supported by the National Natural Science Foundation of China(No.:b030301,a020601)the Foundation project for basic discipline research of Inner Mongolia Agricultural University(jc2017005)the research start project for high level talent of Inner Mongolia Agricultural University(ndgcc2016-17).
文摘Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.The microcapsules were directly added to the hydroxyl terminated polybutadiene(HTPB)-polyurethane elastomer system to fabricate the polyurethane elastomer composites.The thermodynamic stability and mechanical properties of the material were then studied.The results show that the thermal stability of the polyurethane elastomer does not decrease after adding paraffin phase change microcapsules,and the thermal stability of the polyurethane elastomer with melamine resin as the wall increases.Tensile strength increased from 367 kPa to 797 kPa,and compression strength increased from 245.9 N to 344.7 N.In addition,capsule walls comprised different monomers/paraffin microcapsules of the copolymer of styrene and divinylbenzene.The optimal mechanical property was obtained at a monomer/paraffin ratio of 1:1.The compression strength increased and the tensile strength decreased.The tensile strength of the microcapsule with melamine resin capsule wall and the compression strength of the microcapsule with polystyrene capsule wall were considerably improved.
文摘A series of polyurethane elastomers (PUEs) were synthesized by using β-cyclodextrin (β-CD) as cross-linker from aliphatic, alicyclic, aromatic diisocyanates, and polyol. The PUEs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), swelling test, hardness test and tensile test. The influence of diisocyanate on microphase separation and properties of PUEs was evaluated.
文摘In recent years, sugar-derived polymer materials have been actively investigated. In research of polyurethane (PU), sugar has been used as a raw material because it has properties similar to polyol. However, the elastic property of the obtained PU is substantially lost. Hence, the introduction of a sugar unit to PU while maintaining the elastic property remains a challenge in polymer chemistry. Here, we report the synthesis of a polyurethane elastomer (PUE) with a trehalose unit using raw materials such as an aromatic diisocyanate (4,4’-diphenylmethane diisocyanate), polyols including a polyether polyol (polytetramethylene glycol), two polyester polyols (polycaprolactone and polycarbonate diol), and trehalose. Novel PUEs with trehalose units are synthesized by a one-shot method. Trehalose, which has non-reducing properties, is used as sugar. The use of trehalose, which has been scarcely applied to PUE, is essential to obtain the desired PUEs with sugar units.
文摘A series of PUEs which use β-CD as cross-linker were synthesized. Nanoindentation measurements of mechanical properties of these PUEs were made. Load and depth sensing indentation and nano DMA mode were used to evaluate mechanical properties of PUEs in nano-scale. The difference between the results from two modes proved the microphase separation in PUEs and to investigate PUE from hard domains and soft domains was of great significance.
基金Supported by the Key Subject Construction Project of Shanghai Educational Com mittee(No. 13980 70 2 )
文摘The hydrogen bond percentage and its temperature dependence of the three TPU samples synthesized from polytetrahydrofuran, 4,4’-diphenylmethane diisocyanate, N -methyl diethanol amine or 1,4-butane diol were studied by means of IR thermal analysis. The enthalpy and the entropy of the hydrogen bond dissociation were determined by the Van’t Hoff plot.
文摘The polyaddition of isocyanate and polyol to form polyurethane elastomers has rarely been applied to the construction of chiral polyurethane elastomers. Hence, the introduction of chiral units via polyaddition remains a challenging subject in polymer chemistry. In this study, the synthesis of chiral polyurethane elastomers using an aromatic isocyanate, polyols (polyether and polyester polyols), and L(+)-, D(−)-, or meso-tartaric acid by a one-shot method is investigated. The polymers are characterized using FTIR and NMR spectroscopy, and their thermal properties are investigated by TGA, DMA, and DSC analyses. The optical activities of the polymers are confirmed by rotation. The use of chiral tartaric acids is essential to obtain the desired chiral polyurethane elastomers.
基金support of the National Natural Science Foundation of China(Nos.32301545 and 32071712)the Jiangsu Key Laboratory of Biomass Energy and Materials(No.JSBEM-S-202312)the Australian Research Council(Nos.FT190100188 and LP230100278).
文摘Thermoplastic polyurethane(PU)elastomers have attracted significant attention because of their many important industrial applications.However,the creation of fire-retardant and anti-dripping PU elastomers has remained a grant challenge due to the lack of crosslinking and weak interchain interactions.Herein,we report a mechanically robust,biodegradable,fire-retardant,and anti-dripping biobased PU elastomer with excellent biodegradability using an abietic acid-based compound as hard segments and polycaprolactone diol(PCL)as soft segments,followed by physically crosslinking with cellulose nanocrystals(CNC)through dynamic hydrogen-bonding.The resultant elastomer shows the balanced mechanical and fire-retardant properties,e.g.,a tensile strength and break strain of 9.1 MPa and 560%,a self-extinguishing ability(V-0 rating in UL-94 testing),and an anti-dripping behavior.Moreover,the as-developed PU can be completely degraded in 1.0 wt.%lipase solution at 37℃ in 60 days,arising from the catalytic and wicking effect of CNC on PU chains.This work provides an innovative and versatile strategy for constructing robust,fire-retardant,anti-dripping,and biodegradable PU elastomers,which hold great promise for practical applications in electronic and automobile sectors.
基金financially supported by the National Natural Science Foundation of China(Nos.51988102 and 22173094)CAS Key Research Program of Frontier Sciences(No.QYZDYSSW-SLH027)+1 种基金Network and Computing Center,Changchun Institute of Applied Chemistry for essential supportthe financial support of Major Science and Technology Project in Yunnan Province(No.202002AB080001-1)。
文摘Bridging the gap between the computation of mechanical properties and the chemical structure of elastomers is a long-standing challenge.To fill the gap,we create a raw dataset and build predictive models for Young’s modulus,tensile strength,and elongation at break of polyurethane elastomers(PUEs).We then construct a benchmark dataset with 50.4%samples remained from the raw dataset which suffers from the intrinsic diversity problem,through a newly proposed recursive data elimination protocol.The coefficients of determination(R^(2)s)from predictions are improved from 0.73-0.78 to 0.85-0.91 based on the raw and the benchmark datasets.The fitting of stress-strain curves using the machine learning model shows a slightly better performance than that for one of the well-performed constitutive models(e.g.,the Khiêm-Itskov model).It confirmed that the black-box machine learning models are feasible to bridge the gap between the mechanical properties of PUEs and multiple factors for their chemical structures,composition,processing,and measurement settings.While accurate prediction for these curves is still a challenge.We release the raw dataset and the most representative benchmark dataset so far to call for more attention to tackle the longstanding gap problem.
基金financially supported by Funding of Jiangsu Educational Committee (No. 19KJB430042)。
文摘In general, inorganic filler/polyurethane elastomer(PUE) composites possess favorable properties, such as modulus, chemical resistance, and heat stability, are promising for broadening the application area of polyurethanes(PU). For the experiments, a series of cerium oxide(CeO_(2))/PUE composites were prepared with different sizes and appearance of CeO_(2), and different mixing methods as well. CeO_(2) particles with different sizes were added into PUs during the formation of urethane linkage and the chain-extend process, respectively. The morphology along with mechanical properties, thermal properties of the composites were studied. The results suggest that the size of CeO_(2) and mixing methods influence the microstructure of PUs which has profound effect on properties of these composites. The composites tend to form more quantity of hard domains(HDs) with small size when CeO_(2) particles were added before the formation of urethane linkage, whereas Ce O2 particles increase the size of HDs when added with chain extender into PU prepolymer.
基金supported by the National Natural Science Foundation of China(No.21908031)Scientific Research Funds of Yunnan Education Department(No.2021Y111)。
文摘Black phosphorus(BP), as one of the most promising fillers for flame retarding polymer, has been seriously limited in practical application, due to the agglomeration and poor structural stability challenges.Here, the BP was modified by MXene and polydopamine(PDA) via ultrasonication and dopamine modification strategy to improve the structural stability and dispersibility in the matrix. Then, the obtained(BP-MXene@PDA) nanohybrid was employed to promote the mechanical performance, thermal stability,and flame retardancy of thermoplastic polyurethane elastomer(TPU). The resultant TPU composite containing 2 wt.% of BP1-MXene2@PDA showed a 19.2% improvement in the tensile strength and a 13.8%increase in the elongation at break compared to those of the pure TPU. The thermogravimetric analysis suggested that BP-MXene@PDA clearly enhances the thermal stability of TPU composites. Furthermore,the introduction of the BP-MXene@PDA nanohybrids could considerably improve the flame retardancy of TPU composite, i.e., 64.2% and 27.3% decrease in peak heat release rate and total heat release, respectively. The flame-retardant mechanisms of TPU/BP-MXene@PDA in the gas phase and condensed phase were investigated systematically. This work provides a novel strategy to simultaneously enhance the fire safety and mechanical properties of TPU, thus expanding its industrial applications.