The purpose of this research study was to investigate the properties of polyurethane coatings based on lignin nano-particles.For this purpose,the prepared coatings were applied to pine wood surfaces and weathered arti...The purpose of this research study was to investigate the properties of polyurethane coatings based on lignin nano-particles.For this purpose,the prepared coatings were applied to pine wood surfaces and weathered artificially.Subsequently,color and gloss of the coatings were measured before and after the weathering test.Field emission scanning electron microscopy(FE-SEM)micrographs prepared from the coatings showed that the average size of nano-particles in the polyurethane substrate was approximately 500 nm.Nuclear magnetic resonance(13C-NMR)spectroscopy showed that strong urethane bonds were formed in the nano-lignin-based polyurethane.Differential calorimetric analysis(DSC)test revealed that the glass-transition temperature(Tg)of lignin nanoparticles modified with diethylenetriamine(DETA)was 112.8℃ and Tg of lignin nano-particles modified with ethylenediamine(EDA)was 102.5℃,which is lower than the Tg of un-modified lignin(114.6℃)and lignin modified with DETA(126.8℃)and lignin modified with EDA(131.3℃).The coatings modified with lignin nano-particles had a greater change in gloss.The lignin nano-particles in the modified coating are trapping hydroxyl radicals which reduces photoactivity and yellowing of the polyurethane by about 3 times compared to unmodified polyurethane coatings.After weathering test,the nano-lignin-based coating had a rougher surface with a lower contact angle(0.78°)compared to the unmodified polyurethane coating(0.85°).展开更多
By using HDI and TMP as the main raw materials,polyethylene glycol 400(PEG400)is used as a non-ionic hydrophilic modifier,and sodium hydroxyethyl sulfonate is used as an ionic hydrophilic modifier to synthesize a dual...By using HDI and TMP as the main raw materials,polyethylene glycol 400(PEG400)is used as a non-ionic hydrophilic modifier,and sodium hydroxyethyl sulfonate is used as an ionic hydrophilic modifier to synthesize a dual hydrophilic modified polyurethane curing agent.Research revealed that introducing PEG400 for hydrophilic chain segments and sodium hydroxyethyl sulfonate for hydrophilic ionic groups in the polyurethane curing agent component leads to a uniform distribution of hydrophilic components,significantly enhancing compatibility with the aqueous polyol component,and results in excellent film performance.The synthesis process and film were characterized using Fourier transform infrared spectroscopy and high-resolution scanning electron microscopy in the study.展开更多
A polyacrylate/polyurethane (P(A)/P(U)) composite coating has been prepared by crosslinking an acetoacetylated polyacrylate with a vinylic group terminated polyurethane at room temperature. A model Michael reaction be...A polyacrylate/polyurethane (P(A)/P(U)) composite coating has been prepared by crosslinking an acetoacetylated polyacrylate with a vinylic group terminated polyurethane at room temperature. A model Michael reaction between ethyl acetoacetate (EAA) and methyl acrylate (MA) was designed to study the crosslinking mechanism. It was found that the two active hydrogen atoms in acetoacetyl group can both add to vinylic groups and the yield of mono-and bis-adducts are much affected by the molar ratio of acetoacetyl to vinylic groups. Higher crosslinking degree and better properties could be obtained with decreasing the molar ratio of the two active groups from 1/1 to 0.6/1 in the composite coatings.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
A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched....A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched. It was then analyzed in what ways the technical parameters, such as temperature and pressure, influence the coat quality. The results showed that the molar ratio and synthesizing conditions must be strictly controlled to obtain suitable pre-polymer viscosity by adjusting the formula ratio of the B component, satisfactory mechanical properties and cure rate can be obtained and bubbles in the coat can be avoided.展开更多
This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substit...This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substituted by wollastonite, and an optimal substitution ratio was obtained. Analyses based on scanning electron microscope, powder X-ray diffraction, and Raman scattering measurements demonstrated that the addition of wollastonite caused nearly no change in the basic structure of the coating. Coating with a substitution ratio of 25% showed high thermal stability, good cover effect, considerable moisture-proof and water resistance ability, great acidic and basic resistance, and improved performance and hardness in performance tests. Furthermore, the production cost was reduced significantly at this substitution ratio.展开更多
Neural electrodes,the core component of neural prostheses,are usually encapsulated in polydimethylsiloxane(PDMS).However,PDMS can generate a tissue response after implantation.Based on the physicochemical properties...Neural electrodes,the core component of neural prostheses,are usually encapsulated in polydimethylsiloxane(PDMS).However,PDMS can generate a tissue response after implantation.Based on the physicochemical properties and excellent biocompatibility of polyurethane(PU)and poly(vinyl alcohol)(PVA)when used as coating materials,we synthesized PU/PVA hydrogel coatings and coated the surface of PDMS using plasma treatment,and the cytocompatibility to rat pheochromocytoma(PC12)cells was assessed.Protein adsorption tests indicated that the amount of protein adsorption onto the PDMS substrate was reduced by 92%after coating with the hydrogel.Moreover,the PC12 cells on the PU/PVA-coated PDMS showed higher cell density and longer and more numerous neurites than those on the uncoated PDMS.These results indicate that the PU/PVA hydrogel is cytocompatible and a promising coating material for neural electrodes to improve their biocompatibility.展开更多
In this technical paper,we will discuss polyurethane linings and coatings to ductile iron pipe for transporting corrosive and abrasive fluids in a sub soil,that is extremely corrosive in nature.The capabilities of ECL...In this technical paper,we will discuss polyurethane linings and coatings to ductile iron pipe for transporting corrosive and abrasive fluids in a sub soil,that is extremely corrosive in nature.The capabilities of ECL(Electrosteel Castings Limited)in this regard will be discussed.展开更多
In order to improve the adhesion of the middle frequency magnetic sputtered zirconium coating on a polyurethane film,an anode layer source was used to pretreat the polyurethane film with nitrogen and oxygen ions.SEMs ...In order to improve the adhesion of the middle frequency magnetic sputtered zirconium coating on a polyurethane film,an anode layer source was used to pretreat the polyurethane film with nitrogen and oxygen ions.SEMs and AFM roughness profiles of treated samples and the contrast groups were obtained.Besides,XPS survey spectrums and high resolution spectrums were also investigated.The adhesion test revealed that ion bombardment could improve the adhesion to the polyurethane coating substrate.A better etching result of oxygen ions versus nitrogen predicts a higher bonding strength of zirconium coating on polyurethane and,indeed,the highest bonding strengths are for oxygen ion bombardment upto 13.3 MPa.As demonstrated in X-ray photoelectron spectroscopy,the oxygen ion also helps to introduce more active groups,and,therefore,it achieves a high value of adhesion strength.展开更多
Investigated systems of acrylic-polyurethane coatings consisted of three kinds of coatings: base coat (acrylic), intermediate (polyurethane) and top coat (acrylic);each made up of two layers. Mean thickness of the coa...Investigated systems of acrylic-polyurethane coatings consisted of three kinds of coatings: base coat (acrylic), intermediate (polyurethane) and top coat (acrylic);each made up of two layers. Mean thickness of the coating system was equal (145 ± 1) μm. In time of accelerated UV ageing, electromagnetic radiation was emitted of wave length in the range (300 - 400) nm which was progressively inducing a destruction of coatings chemical structure, especially photooxidation and photolysis of coating material. Carried out X-ray investigations revealed increased contents of oxygen in aged coatings due to their photooxidation which resulted in increased tendency of coating microfragments to chip off from surface layer with the ageing time flow. The hardness increase of UV aged coatings was also observed which intensified their surface layer brittleness. This contributed to their thickness decrease by more than 10% after 2016 h of ageing. Photodestruction of UV aged coatings was documented as well by characteristics obtained during investigations carried out with DMA method use. A noticeable physical destruction of the coatings was observed in the form of silver cracks, etchings and grooves in surface layer as well as craters extending also into interlayer. Processes of physical and chemical destruction undergoing in aged coatings influenced roughness profile change and coatings surface topography shaping. After 2016 h of UV ageing, the roughness parameters (Ra, Rz, Rt) increased several times. Long-lasting UV radiation influence on the surface of investigated acrylic-polyurethane coating systems contributed to their decorativeness loss. Microscopic examinations revealed colour change (yellowing) of blue pigment contained in polyurethane interlayer. Decline in coating gloss was also observed as the result of surface roughness increase.展开更多
Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea gran...Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.展开更多
A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamin...A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.展开更多
UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly(urea-formaldehyde) shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water e...UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly(urea-formaldehyde) shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water emulsion. The diameters of the microcapsules ranged from 118 μm to 663 μm depending on agitation speed, and were obtained via optical mi-croscopy and scanning electron microscopy analyses. The encapsulation percent and the yield of microcapsules prepared at the agitation speed of 600 r/min can reach 97.52wt% and 65.23wt%, respectively. When the water-borne polyurethane (WPU) coating embedded with the prepared microcapsules were scratched, the healing agent could be released from rup-tured microcapsules and lled the scribed region. The excellent anticorrosion properties of the WPU coating embedded with the prepared microcapsules were con rmed by the results obtained from both electrochemical impedance spectroscopy and Tafel curves.展开更多
Three kinds of UV-curable self-emulsified polyurethane-acrylate (PUA) prepolymer, i.e., conventional, chain extended and grafted PUAs, were prepared. The relatively small particle size of the PUA dispersions indicates...Three kinds of UV-curable self-emulsified polyurethane-acrylate (PUA) prepolymer, i.e., conventional, chain extended and grafted PUAs, were prepared. The relatively small particle size of the PUA dispersions indicates that the PUA prepolymers exhibit sufficient aqueous dispersibility. The PUA prepolymers can substantially lower the interfacial tension of water. Chain-extended PUA dispersions exhibit pseudoplastic behavior and thixotropy to a greater extent than do their conventional counterpart. The chain-extended and grafted PUA photocure to higher conversion than do the conventional PU equivalent. The results of DSC measurement suggest that there exists phase mixing between the hard and the soft segment phases for the PUAs based on PEG 400 that is the comparatively short soft segment in the prepolymer. For the PUA prepolymers based on PEG having higher M-n values, chain-extending and grafting could impede the phase separation between the hard and the soft segment domains. The adhesion, impact strength and flexibility of the photocured films were tested.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
The relation between structures and properties of polyurethane are investigated by modern physical and chemical methods.The results obtained are as follows:the effects of the content of self-crosslinking agent on the ...The relation between structures and properties of polyurethane are investigated by modern physical and chemical methods.The results obtained are as follows:the effects of the content of self-crosslinking agent on the properties of polyurethane,i.e.,dispersion stability,dynamical viscoelasticity and mechanical properties are discussed.It is found that the optimum molar ratio of epichlorohydrin and diethylenetriamine is 1:2.A mois-展开更多
A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water a...A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water addition procedure by in situ generated water to react with polyurethane prepolymer instead of the external water addition process.As a comparison,waterborne polyurethane was synthesized through the external water addition process.According to the characterization methods including FTIR,1H-NMR,TEM and water swelling experiments,it is suggested there are two kinds of hydrogen bonds interactions in hard/soft domain of the novel polyurethane,and the phase separation of hard/soft domains increases significantly.The morphology of the two polyurethanes was quite different(nanorods and spherical particles,respectively),presenting a different surface property.In addition,the water swelling of the novel polyurethane indicates that it holds significant potential application as degradable material.展开更多
Tung oil-based polyols were synthesized by the esterification and transesterification between Tung oilbased anhydride and butanediol. The hydroxyl values of the polyols prepared were tested and discussed. Polyurethane...Tung oil-based polyols were synthesized by the esterification and transesterification between Tung oilbased anhydride and butanediol. The hydroxyl values of the polyols prepared were tested and discussed. Polyurethane was prepared by using Tung oil-based polyols and/or poly(propylene glycol) as polyols and by using isophorone diisocyanate as isocyanate. The effect of the ratio of Tung oil-based polyols to poly(propylene glycol) on the properties of polyurethane prepared was investigated by the water resistance, alcohol resistance and hardness tests. The results show that Tung oil-based polyols are effective to improve the hardness, water resistance and alcohol resistance of polyurethane.展开更多
Silane terminated prepolymers for adhesives, sealants and coatings are of </span></span><span><span><span style="font-family:"">great <span>industrial importance. The...Silane terminated prepolymers for adhesives, sealants and coatings are of </span></span><span><span><span style="font-family:"">great <span>industrial importance. They are very important because of their low toxicity</span><span> over polyurethanes, silicones, and solvent-based products. Hence</span>, many pieces of literature which deal with the synthesis, properties and applications of this Si<span>lane terminated polymers hybrid system exist. Silylated polyether (MS polymers) </span>and Silylated Polyurethane Polymers (SPUR) are the bases for nu<span>merous sealants, adhesives and coatings used worldwide. A hybrid system mixed with </span><span>organic-polyurethane proportion and inorganic-alkoxysilane proportion</span> <span>com</span>bines the benefits of conventional polyurethane and silicone-based products.<span> This article reviews the chemistry of MS polymers and SPUR and their</span> <span>ad</span><span>vantages and disadvantages in silyl terminated prepolymer-based adhesives</span>, sea<span>lants and coatings as well as provides information on different end applications.展开更多
文摘The purpose of this research study was to investigate the properties of polyurethane coatings based on lignin nano-particles.For this purpose,the prepared coatings were applied to pine wood surfaces and weathered artificially.Subsequently,color and gloss of the coatings were measured before and after the weathering test.Field emission scanning electron microscopy(FE-SEM)micrographs prepared from the coatings showed that the average size of nano-particles in the polyurethane substrate was approximately 500 nm.Nuclear magnetic resonance(13C-NMR)spectroscopy showed that strong urethane bonds were formed in the nano-lignin-based polyurethane.Differential calorimetric analysis(DSC)test revealed that the glass-transition temperature(Tg)of lignin nanoparticles modified with diethylenetriamine(DETA)was 112.8℃ and Tg of lignin nano-particles modified with ethylenediamine(EDA)was 102.5℃,which is lower than the Tg of un-modified lignin(114.6℃)and lignin modified with DETA(126.8℃)and lignin modified with EDA(131.3℃).The coatings modified with lignin nano-particles had a greater change in gloss.The lignin nano-particles in the modified coating are trapping hydroxyl radicals which reduces photoactivity and yellowing of the polyurethane by about 3 times compared to unmodified polyurethane coatings.After weathering test,the nano-lignin-based coating had a rougher surface with a lower contact angle(0.78°)compared to the unmodified polyurethane coating(0.85°).
文摘By using HDI and TMP as the main raw materials,polyethylene glycol 400(PEG400)is used as a non-ionic hydrophilic modifier,and sodium hydroxyethyl sulfonate is used as an ionic hydrophilic modifier to synthesize a dual hydrophilic modified polyurethane curing agent.Research revealed that introducing PEG400 for hydrophilic chain segments and sodium hydroxyethyl sulfonate for hydrophilic ionic groups in the polyurethane curing agent component leads to a uniform distribution of hydrophilic components,significantly enhancing compatibility with the aqueous polyol component,and results in excellent film performance.The synthesis process and film were characterized using Fourier transform infrared spectroscopy and high-resolution scanning electron microscopy in the study.
文摘A polyacrylate/polyurethane (P(A)/P(U)) composite coating has been prepared by crosslinking an acetoacetylated polyacrylate with a vinylic group terminated polyurethane at room temperature. A model Michael reaction between ethyl acetoacetate (EAA) and methyl acrylate (MA) was designed to study the crosslinking mechanism. It was found that the two active hydrogen atoms in acetoacetyl group can both add to vinylic groups and the yield of mono-and bis-adducts are much affected by the molar ratio of acetoacetyl to vinylic groups. Higher crosslinking degree and better properties could be obtained with decreasing the molar ratio of the two active groups from 1/1 to 0.6/1 in the composite coatings.
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.
文摘A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched. It was then analyzed in what ways the technical parameters, such as temperature and pressure, influence the coat quality. The results showed that the molar ratio and synthesizing conditions must be strictly controlled to obtain suitable pre-polymer viscosity by adjusting the formula ratio of the B component, satisfactory mechanical properties and cure rate can be obtained and bubbles in the coat can be avoided.
文摘This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substituted by wollastonite, and an optimal substitution ratio was obtained. Analyses based on scanning electron microscope, powder X-ray diffraction, and Raman scattering measurements demonstrated that the addition of wollastonite caused nearly no change in the basic structure of the coating. Coating with a substitution ratio of 25% showed high thermal stability, good cover effect, considerable moisture-proof and water resistance ability, great acidic and basic resistance, and improved performance and hardness in performance tests. Furthermore, the production cost was reduced significantly at this substitution ratio.
基金supported by the National Natural Science Foundation of China,No.81170768grant from the Fundamental Research Project of Shanxi Province of China,No.2015021079
文摘Neural electrodes,the core component of neural prostheses,are usually encapsulated in polydimethylsiloxane(PDMS).However,PDMS can generate a tissue response after implantation.Based on the physicochemical properties and excellent biocompatibility of polyurethane(PU)and poly(vinyl alcohol)(PVA)when used as coating materials,we synthesized PU/PVA hydrogel coatings and coated the surface of PDMS using plasma treatment,and the cytocompatibility to rat pheochromocytoma(PC12)cells was assessed.Protein adsorption tests indicated that the amount of protein adsorption onto the PDMS substrate was reduced by 92%after coating with the hydrogel.Moreover,the PC12 cells on the PU/PVA-coated PDMS showed higher cell density and longer and more numerous neurites than those on the uncoated PDMS.These results indicate that the PU/PVA hydrogel is cytocompatible and a promising coating material for neural electrodes to improve their biocompatibility.
文摘In this technical paper,we will discuss polyurethane linings and coatings to ductile iron pipe for transporting corrosive and abrasive fluids in a sub soil,that is extremely corrosive in nature.The capabilities of ECL(Electrosteel Castings Limited)in this regard will be discussed.
文摘In order to improve the adhesion of the middle frequency magnetic sputtered zirconium coating on a polyurethane film,an anode layer source was used to pretreat the polyurethane film with nitrogen and oxygen ions.SEMs and AFM roughness profiles of treated samples and the contrast groups were obtained.Besides,XPS survey spectrums and high resolution spectrums were also investigated.The adhesion test revealed that ion bombardment could improve the adhesion to the polyurethane coating substrate.A better etching result of oxygen ions versus nitrogen predicts a higher bonding strength of zirconium coating on polyurethane and,indeed,the highest bonding strengths are for oxygen ion bombardment upto 13.3 MPa.As demonstrated in X-ray photoelectron spectroscopy,the oxygen ion also helps to introduce more active groups,and,therefore,it achieves a high value of adhesion strength.
文摘Investigated systems of acrylic-polyurethane coatings consisted of three kinds of coatings: base coat (acrylic), intermediate (polyurethane) and top coat (acrylic);each made up of two layers. Mean thickness of the coating system was equal (145 ± 1) μm. In time of accelerated UV ageing, electromagnetic radiation was emitted of wave length in the range (300 - 400) nm which was progressively inducing a destruction of coatings chemical structure, especially photooxidation and photolysis of coating material. Carried out X-ray investigations revealed increased contents of oxygen in aged coatings due to their photooxidation which resulted in increased tendency of coating microfragments to chip off from surface layer with the ageing time flow. The hardness increase of UV aged coatings was also observed which intensified their surface layer brittleness. This contributed to their thickness decrease by more than 10% after 2016 h of ageing. Photodestruction of UV aged coatings was documented as well by characteristics obtained during investigations carried out with DMA method use. A noticeable physical destruction of the coatings was observed in the form of silver cracks, etchings and grooves in surface layer as well as craters extending also into interlayer. Processes of physical and chemical destruction undergoing in aged coatings influenced roughness profile change and coatings surface topography shaping. After 2016 h of UV ageing, the roughness parameters (Ra, Rz, Rt) increased several times. Long-lasting UV radiation influence on the surface of investigated acrylic-polyurethane coating systems contributed to their decorativeness loss. Microscopic examinations revealed colour change (yellowing) of blue pigment contained in polyurethane interlayer. Decline in coating gloss was also observed as the result of surface roughness increase.
基金the National Key Technology R&D Program of the 11th Five-Year Period (No.2006BAD10B08)
文摘Polyurethane coated urea slow/controlled release fertilizer was prepared based on urea granules, isocyanate, polyols and paraffin. Isocyanate reacted with polyols to synthesize the polyurethane skin layer on urea granules surface. Paraffin serves as a lubricant during syntheses of polyurethane skin layers. The structure and nutrient release characteristics of the polyurethane skin layers were investigated by FTIR, SEM and TG. Urea nitrogen slow-release behavior of the polyurethane coated urea was tested. The experimental results indicated that compact and dense polyurethane skin layers with a thickness of 10-15 lam were formed on urea surface, the urea nitrogen slow-release time can reach 40-50 days. Paraffin proves to play a key role in inhibiting water to penetrate into urea, but excessive addition would decrease the polyurethane crosslinking density.
基金the financial support by the National Natural Science Foundation of China(No.20973022 and No.11472048)
文摘A series of nano silica/silicone modified waterborne polyurethane(WPU) have been synthesized from polytetramethylene glycol and isophorone diisocyanate, dihydroxymethyl propionic acid and triethylamine, ethylenediamine, trimethylolpropane, nano-SiO2 and the silane coupling agent KH550. The effect of the dosage of nano-SiO2 on the WPU-Si membrane and the coated RDX(cyclotrimethylenetrinitramine) particles have been studied in terms of their surface properties, mechanical properties, and thermal stability. The results showed that with the increase of Si content, the stability of the emulsion reduced gradually. The material with more Si content displayed an increased thermodynamic stability, an increased high temperature resistance, an increased tensile strength and a decreased elongation at break. With the increase of Si content, the surface tension of the material decreased, the bibulous rate reduced, and the contact angle increased gradually, so that the surface tension of the polyurethane and RDX are close to each other which could improve the performance of coating.
文摘UV-curable polyurethane prepolymer and photoinitiator 1173 were facilely encapsulated in a poly(urea-formaldehyde) shell, which was in situ formed by the polymerization of formalde-hyde and urea in an oil-in-water emulsion. The diameters of the microcapsules ranged from 118 μm to 663 μm depending on agitation speed, and were obtained via optical mi-croscopy and scanning electron microscopy analyses. The encapsulation percent and the yield of microcapsules prepared at the agitation speed of 600 r/min can reach 97.52wt% and 65.23wt%, respectively. When the water-borne polyurethane (WPU) coating embedded with the prepared microcapsules were scratched, the healing agent could be released from rup-tured microcapsules and lled the scribed region. The excellent anticorrosion properties of the WPU coating embedded with the prepared microcapsules were con rmed by the results obtained from both electrochemical impedance spectroscopy and Tafel curves.
基金Project supported by Guangdong Natural Science Foundation(No. 960019)
文摘Three kinds of UV-curable self-emulsified polyurethane-acrylate (PUA) prepolymer, i.e., conventional, chain extended and grafted PUAs, were prepared. The relatively small particle size of the PUA dispersions indicates that the PUA prepolymers exhibit sufficient aqueous dispersibility. The PUA prepolymers can substantially lower the interfacial tension of water. Chain-extended PUA dispersions exhibit pseudoplastic behavior and thixotropy to a greater extent than do their conventional counterpart. The chain-extended and grafted PUA photocure to higher conversion than do the conventional PU equivalent. The results of DSC measurement suggest that there exists phase mixing between the hard and the soft segment phases for the PUAs based on PEG 400 that is the comparatively short soft segment in the prepolymer. For the PUA prepolymers based on PEG having higher M-n values, chain-extending and grafting could impede the phase separation between the hard and the soft segment domains. The adhesion, impact strength and flexibility of the photocured films were tested.
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The relation between structures and properties of polyurethane are investigated by modern physical and chemical methods.The results obtained are as follows:the effects of the content of self-crosslinking agent on the properties of polyurethane,i.e.,dispersion stability,dynamical viscoelasticity and mechanical properties are discussed.It is found that the optimum molar ratio of epichlorohydrin and diethylenetriamine is 1:2.A mois-
基金The author acknowledges the financial support provided by the National Natural Science Foundation of China[Grant No.51802259]China Postdoctoral Science Foundation Funded Project[Grant No.2019M663785]+6 种基金the Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Technology[Grant No.XJZZ202001]the Scientific Research Project of Shaanxi Education Department[Grant No.20JS108]the Promotion Program for Youth of Shaanxi University science and technology association[Grant No.20190415]Fund of Key Laboratory of Processing and Quality Evaluation Technology of Green Plastics of China National Light Industry council[Grant No.PQETGP2019003]the Innovation Guidance of Technology Program of Shaanxi Province[Grant No.2020CGXNG-022]Xi’an Programs for Science and Technology Plan[Grant No.2020KJRC0090]The author also acknowledges the previous work[https://www.sciencedirect.com/science/article/pii/S030094401630323X].
文摘A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water addition procedure by in situ generated water to react with polyurethane prepolymer instead of the external water addition process.As a comparison,waterborne polyurethane was synthesized through the external water addition process.According to the characterization methods including FTIR,1H-NMR,TEM and water swelling experiments,it is suggested there are two kinds of hydrogen bonds interactions in hard/soft domain of the novel polyurethane,and the phase separation of hard/soft domains increases significantly.The morphology of the two polyurethanes was quite different(nanorods and spherical particles,respectively),presenting a different surface property.In addition,the water swelling of the novel polyurethane indicates that it holds significant potential application as degradable material.
文摘Tung oil-based polyols were synthesized by the esterification and transesterification between Tung oilbased anhydride and butanediol. The hydroxyl values of the polyols prepared were tested and discussed. Polyurethane was prepared by using Tung oil-based polyols and/or poly(propylene glycol) as polyols and by using isophorone diisocyanate as isocyanate. The effect of the ratio of Tung oil-based polyols to poly(propylene glycol) on the properties of polyurethane prepared was investigated by the water resistance, alcohol resistance and hardness tests. The results show that Tung oil-based polyols are effective to improve the hardness, water resistance and alcohol resistance of polyurethane.
文摘Silane terminated prepolymers for adhesives, sealants and coatings are of </span></span><span><span><span style="font-family:"">great <span>industrial importance. They are very important because of their low toxicity</span><span> over polyurethanes, silicones, and solvent-based products. Hence</span>, many pieces of literature which deal with the synthesis, properties and applications of this Si<span>lane terminated polymers hybrid system exist. Silylated polyether (MS polymers) </span>and Silylated Polyurethane Polymers (SPUR) are the bases for nu<span>merous sealants, adhesives and coatings used worldwide. A hybrid system mixed with </span><span>organic-polyurethane proportion and inorganic-alkoxysilane proportion</span> <span>com</span>bines the benefits of conventional polyurethane and silicone-based products.<span> This article reviews the chemistry of MS polymers and SPUR and their</span> <span>ad</span><span>vantages and disadvantages in silyl terminated prepolymer-based adhesives</span>, sea<span>lants and coatings as well as provides information on different end applications.