In this paper, isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA) and internal crosslinking agent trimethylolpropane (TMP) were used to prepare waterborne polyurethane. And then...In this paper, isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA) and internal crosslinking agent trimethylolpropane (TMP) were used to prepare waterborne polyurethane. And then double-crosslinked polyurethane-acrylic composite aqueous dispersion was prepared in which polyacrylate was adopted to modify waterborne polyurethane and some special external crosslinking agents were added including silicone and trifunctional aziridine. The influence of the amounts of internal and external crosslinking agents, emulsifier, initiator on the particle size, particle size distribution, viscosity, molecular weight, as well as water adsorption ratio were studied.展开更多
In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical mode...In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical model is proposed which can guide the synthesis of the waterborne dispersions such as polymer/nanoparticle composite dispersion. In the presence of a latent curing catalyst, PIE can give a crosslinkable epoxy resin waterborne dispersion. The dispersions can form cured transparent coatings with some unique properties such as UV shielding. They are promising in functional coatings, waterborne resin matrices for composites, and sizing for high performance fibers.展开更多
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne...The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions by PIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution during phase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well. The deformation and break up of water drops in a shear field were analyzed in terms of micro-theology, while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory, respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress was suggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.展开更多
The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown t...The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown that the concentrated dispersions were highly viscoelastic and pseudoplastic, which was attributed to the formation of a physical network among the waterborne particles via hydrogen bond. The dilute dispersions were Newtonian fluids. The discrete clusters composed of small waterborne particles were found in diluted dispersions. With increasing solid content, there existed a structural transition via percolation through a cluster-cluster aggregation mode to form the physical network, which was qualitatively evidenced by the TEM morphologies.展开更多
Polyurethane dispersions (PUD) have diversified into a myriad of applications over the years. This has led to extensive research on both industrial and laboratory fronts as polyurethane dispersions provide liberty to ...Polyurethane dispersions (PUD) have diversified into a myriad of applications over the years. This has led to extensive research on both industrial and laboratory fronts as polyurethane dispersions provide liberty to interplay at the molecular level to diversify the properties of the product which has also led to the development of eco-friendly waterborne dispersions. Yet, waterborne PUDs are limited in their mechanical and physical properties as compared to solvent-based products. The incorporation of crosslinkers in the PUD further bolsters these properties thus improving water and solvent resistance. The incorporation of silanols increases solvent resistance and adhesion of the resultant PUD. In this work, a post crosslinking system based on the ketone-hydrazine mechanism was incorporated into the PUD thus providing the required structural reinforcement for construction application. The targeted application for this work is the use of PUDs for waterproofing.展开更多
Waterborne nanoscale carbon black dispersion (NCBD) was widely used in inkjet printing, spun-dyeing fibers and coloration fabrics. In this paper, NCBD was prepared using sodium carboxymethyl cellulose (CMC) as dispers...Waterborne nanoscale carbon black dispersion (NCBD) was widely used in inkjet printing, spun-dyeing fibers and coloration fabrics. In this paper, NCBD was prepared using sodium carboxymethyl cellulose (CMC) as dispersant. Effects of CMC viscosity, ultrasonic time and oxidation with hydrogen peroxide on carbon black (CB) particle size were discussed. The results showed that CB particle size decreased by mechanical agitation while it increased by ultrasonic with the increase of CMC viscosity. Ultrasonic is a more effective method to disperse CB particles than that of mechanical agitation. CB particle size obviously decreased with increasing ultrasonic time and arrived at about 160 nm for 60 min. In addition, oxidation with 2 mol/L of H_ 2 O_ 2 and 0.2 wt% of CMC300 reduced CB particle size to 160 nm at 90℃ for 2.5 h.展开更多
The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted ...The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.展开更多
Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was car...Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was carried out in flowing nitrogen atmosphere. The PUD’s preparations are free of NMP (n-methyl pyrrolidone), a toxic processing solvent generally used during the preparation of PUD’s. The performance of the synthesised polyurethane dispersions with varying NCO/OH molar ratio was tested on wood surface. The physical, chemical, thermal and mechanical properties such as viscosity, particle size, chemical resistance, thermal stability and taber abrasion of applied polyurethane dispersion were carried out as a function of NCO/OH molar ratio. The PUD’s preparation with NCO/OH ratio of 1.4 or 1.6 showed better performance as a wood finish and the results are described in the present study.展开更多
Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples posses...Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.展开更多
For the concentrated dispersions of epoxy resin prepared by phase inversion emulsification technique, the effects of solid content and temperature on the rheological behavior are studied. It is found that there exists...For the concentrated dispersions of epoxy resin prepared by phase inversion emulsification technique, the effects of solid content and temperature on the rheological behavior are studied. It is found that there exists reversible structural transition in concentrated dispersions subjected to shearing. The viscosity oscillation correlated with high viscoelasticity at lower stress is remarkable in highly concentrated dispersions. There exists storage modules overshot at higher stress during the dynamic stress time ramp test. This could provide some information on dynamics of structure changes during shear action. Besides, the effects of solid content and temperature on the relationship between tangent delta and frequency are essentially different.展开更多
文摘In this paper, isophorone diisocyanate (IPDI), polyethylene glycol (PEG), dimethylolpropionic acid (DMPA) and internal crosslinking agent trimethylolpropane (TMP) were used to prepare waterborne polyurethane. And then double-crosslinked polyurethane-acrylic composite aqueous dispersion was prepared in which polyacrylate was adopted to modify waterborne polyurethane and some special external crosslinking agents were added including silicone and trifunctional aziridine. The influence of the amounts of internal and external crosslinking agents, emulsifier, initiator on the particle size, particle size distribution, viscosity, molecular weight, as well as water adsorption ratio were studied.
基金This project is supported by NSF of China(Nos. 20104008 and 29774038)State Key Laboratory of Polymer Physics and Chemistry.
文摘In this review, our recent work in phase inversion emulsification （PIE） for polymer （especially epoxy resin） waterborne dispersions is summarized. Based on experimental results about PIE process, the physical model is proposed which can guide the synthesis of the waterborne dispersions such as polymer/nanoparticle composite dispersion. In the presence of a latent curing catalyst, PIE can give a crosslinkable epoxy resin waterborne dispersion. The dispersions can form cured transparent coatings with some unique properties such as UV shielding. They are promising in functional coatings, waterborne resin matrices for composites, and sizing for high performance fibers.
基金This work was supported by the National Key Project for Fundamental Research, "Macromolecular Condensed State" of Ministry of Science and Technology of China and National Natural Science Foundation of China 29774038.
文摘The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterborne dispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions by PIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution during phase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well. The deformation and break up of water drops in a shear field were analyzed in terms of micro-theology, while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory, respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress was suggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 29774038), and 973 project "Fundamental study on enhanced oil recovery" of the Ministry of China Science and Technology.
文摘The waterborne dispersions of epoxy resin were prepared by the phase inversion emulsification technique. Rheological behavior and its relationship with the structural change of the systems were studied. It was shown that the concentrated dispersions were highly viscoelastic and pseudoplastic, which was attributed to the formation of a physical network among the waterborne particles via hydrogen bond. The dilute dispersions were Newtonian fluids. The discrete clusters composed of small waterborne particles were found in diluted dispersions. With increasing solid content, there existed a structural transition via percolation through a cluster-cluster aggregation mode to form the physical network, which was qualitatively evidenced by the TEM morphologies.
文摘Polyurethane dispersions (PUD) have diversified into a myriad of applications over the years. This has led to extensive research on both industrial and laboratory fronts as polyurethane dispersions provide liberty to interplay at the molecular level to diversify the properties of the product which has also led to the development of eco-friendly waterborne dispersions. Yet, waterborne PUDs are limited in their mechanical and physical properties as compared to solvent-based products. The incorporation of crosslinkers in the PUD further bolsters these properties thus improving water and solvent resistance. The incorporation of silanols increases solvent resistance and adhesion of the resultant PUD. In this work, a post crosslinking system based on the ketone-hydrazine mechanism was incorporated into the PUD thus providing the required structural reinforcement for construction application. The targeted application for this work is the use of PUDs for waterproofing.
基金Supported by National Natural Science Foundation of China( No.50173012) and863Hi-tech Research and Development Program ofChina (2002AA327120)
文摘Waterborne nanoscale carbon black dispersion (NCBD) was widely used in inkjet printing, spun-dyeing fibers and coloration fabrics. In this paper, NCBD was prepared using sodium carboxymethyl cellulose (CMC) as dispersant. Effects of CMC viscosity, ultrasonic time and oxidation with hydrogen peroxide on carbon black (CB) particle size were discussed. The results showed that CB particle size decreased by mechanical agitation while it increased by ultrasonic with the increase of CMC viscosity. Ultrasonic is a more effective method to disperse CB particles than that of mechanical agitation. CB particle size obviously decreased with increasing ultrasonic time and arrived at about 160 nm for 60 min. In addition, oxidation with 2 mol/L of H_ 2 O_ 2 and 0.2 wt% of CMC300 reduced CB particle size to 160 nm at 90℃ for 2.5 h.
基金the Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET,Argentina)(PIP 20170100677)the Fondo para la Investigación Científica y Tecnológica(FONCYT)(PICT-2017-1318)the Universidad Nacional de Mar del Plata(UNMdP,15/G557,ING561/19)and to the Comisión de Investigaciones Científicas de la Provincia de Buenos Aires(CIC)and the Universidad Tecnológica Nacional(UTN)for their financial support.
文摘The increasing pressure from consumers and policy makers to reduce the use of synthetic polymers,whose production contributes to the depletion of non-renewable resources and are usually non-biodegradable,has prompted the efforts to find suitable bio-based sources for the production of polymers.Vegetable oils have been a frequently spotted in this search because they are versatile,highly available and a low cost liquid biosource,which can be used in the synthesis of a wide plethora of different polymers and reactive monomers.Following the same idea of reducing the environmental stress,the traditional polyurethanes that are soluble in organic solvents have been targeted for replacement,particularly in applications such as adhesives and coatings,in which the solvent is released to the atmosphere increasing the air pollution.Instead,waterborne polyurethanes(WBPU),which are polyurethane dispersions(PUD)prepared in aqueous media,release benign water to the atmosphere during use as supported or self-standing films for different applications.In this brief review,the contributions to the development of WBPUs based on vegetable oils are discussed,focusing mainly on the contributions of the last decade.The synthesis of ionic and nonionic PUDs,their characterization and the properties of the resulting dried materials,as well as derived composite materials are considered.
文摘Environmentally friendly, polyacrylic-based polyurethane dispersion (PUD) was synthesised using various molar ratios of polycaprolactone, dimethylolpropionic acid and tetramethyl xylene diisocyanate. Synthesis was carried out in flowing nitrogen atmosphere. The PUD’s preparations are free of NMP (n-methyl pyrrolidone), a toxic processing solvent generally used during the preparation of PUD’s. The performance of the synthesised polyurethane dispersions with varying NCO/OH molar ratio was tested on wood surface. The physical, chemical, thermal and mechanical properties such as viscosity, particle size, chemical resistance, thermal stability and taber abrasion of applied polyurethane dispersion were carried out as a function of NCO/OH molar ratio. The PUD’s preparation with NCO/OH ratio of 1.4 or 1.6 showed better performance as a wood finish and the results are described in the present study.
基金This work was financially supported by the National Natural Science Foundation of China(No.20104008).
文摘Sub-micron sized phenolic epoxy resin waterborne particles were prepared by phase inversion emulsification. Micro-phase separation occurred during the curing process at high temperature. The as-prepared samples possessed one glass transition temperature （Tg） and two exothermal processes during DSC heating scannings. After being thermally treated above the exothermal peak temperature, they possessed two glass transition temperatures with the disappearance of exothermal peaks, whilst a core/shell structure was formed. This was likely related with the outward diffusion of reactive oligomers to the outer layer of particles.
文摘For the concentrated dispersions of epoxy resin prepared by phase inversion emulsification technique, the effects of solid content and temperature on the rheological behavior are studied. It is found that there exists reversible structural transition in concentrated dispersions subjected to shearing. The viscosity oscillation correlated with high viscoelasticity at lower stress is remarkable in highly concentrated dispersions. There exists storage modules overshot at higher stress during the dynamic stress time ramp test. This could provide some information on dynamics of structure changes during shear action. Besides, the effects of solid content and temperature on the relationship between tangent delta and frequency are essentially different.
