A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble ac...A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.展开更多
The rheological properties of two specific waterborne polyurethane （PU） paints were studied by both macrorheological and microrheological methods. During the macrorheological measurement on a rotary rheometer, evapo...The rheological properties of two specific waterborne polyurethane （PU） paints were studied by both macrorheological and microrheological methods. During the macrorheological measurement on a rotary rheometer, evaporation of solvent cannot be totally excluded, which has an influence on the reliability of rheological results. So, the linear oscillatory frequency sweep results （storage and loss modulus versus frequency） and steady shear results （viscosity versus shear rate） got from the rotary rheometer measurement are only used for qualitative analysis. As the evaporation of solvent can be neglected during microrheological measurements on a diffusing wave spectroscope （DWS）, the results of storage modulus （G3 and loss modulus （G＇~） versus frequency are more credible than the results obtained from the rotary rheometer measurement. Thus, the results of G＇ and G＂ versus frequency from DWS measurements are used for quantitative analysis in this work. The G＇ for both of the waterborne PU paints are larger than G＂ at low frequency and that is opposite at high frequency in the experimental angular frequency range. The values of modulus at same frequency and viscosity at low shear rate for the two PU paints have apparent difference, which determines the difference of their application.展开更多
In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyuretha...In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose(CMC)and silicon oxide(SiO2)nanoparticles to the paint.The first function of CMC and SiO_(2) is to improve rheological properties of the polyurethane paint for making a printable precursor,which improves the printing resolution and enhances additive manufacturability.Second,the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties.Third,the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane.Finally,the 3D printedpolyurethane-CMCandSiO_(2) parts exhibit time-resolved shape transformation upon heat stimulation.To the best of our knowledge,this is the first study of using the polyurethane paint as the precursor for 4D printing,which would open new possibilities in future applications in biomedical engineering,soft robotics and so on.展开更多
文摘A two-component waterborne polyurethane(2K-WPU) was prepared by mixing water-soluble acrylic resin and hexamethylene diisocyanate biuret, and then diluted for phase inversion with water. Compared with water-soluble acrylic resin, the phase inversion of 2K-WPU occurs at lower water content. It is indicated by TEM that 2K-WPU parti-cles show a core-shell structure, in which HDI biuret is encapsulated by hydrophilic acrylic resin. 2K-WPU emulsion with HDI biuret has larger particle size and narrower distribution index, while for 2K-WPU emulsion with HDI iso-cyanurate, the latex not only has large particle size, but also has two-peak distribution. FTIR shows that the reaction be-tween HDI biuret and acrylic resin can complete in 12h. In addition, studies on effect of composition of acrylic resin on performance of 2K-WPU show that narrowing the polar difference between water-soluble acrylic resin and HDI biuret and improving the miscibility of two components are the key to prepare the transparent and high gloss films with high crosslinking density.
基金financially supported by the National Natural Science Foundation of China(Nos.2127415251473168 an21234007)
文摘The rheological properties of two specific waterborne polyurethane （PU） paints were studied by both macrorheological and microrheological methods. During the macrorheological measurement on a rotary rheometer, evaporation of solvent cannot be totally excluded, which has an influence on the reliability of rheological results. So, the linear oscillatory frequency sweep results （storage and loss modulus versus frequency） and steady shear results （viscosity versus shear rate） got from the rotary rheometer measurement are only used for qualitative analysis. As the evaporation of solvent can be neglected during microrheological measurements on a diffusing wave spectroscope （DWS）, the results of storage modulus （G3 and loss modulus （G＇~） versus frequency are more credible than the results obtained from the rotary rheometer measurement. Thus, the results of G＇ and G＂ versus frequency from DWS measurements are used for quantitative analysis in this work. The G＇ for both of the waterborne PU paints are larger than G＂ at low frequency and that is opposite at high frequency in the experimental angular frequency range. The values of modulus at same frequency and viscosity at low shear rate for the two PU paints have apparent difference, which determines the difference of their application.
基金supported by the NASA Missouri Space Consortium[00049784]U.S.Department of Agriculture[2018-67017-27880]+1 种基金U.S.Department of Energy[DE-FE0031645]National Science Foundation[0054237,EAR 1220051].
文摘In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose(CMC)and silicon oxide(SiO2)nanoparticles to the paint.The first function of CMC and SiO_(2) is to improve rheological properties of the polyurethane paint for making a printable precursor,which improves the printing resolution and enhances additive manufacturability.Second,the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties.Third,the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane.Finally,the 3D printedpolyurethane-CMCandSiO_(2) parts exhibit time-resolved shape transformation upon heat stimulation.To the best of our knowledge,this is the first study of using the polyurethane paint as the precursor for 4D printing,which would open new possibilities in future applications in biomedical engineering,soft robotics and so on.
