Preparation and characterization of waterborne polyurethane/silica hybrid dispersions from castor oil polyols obtained by glycolysis poly(ethylene terephthalate) waste

Castor oil polyols (COLs) have been synthesized from glycolyzed oligoester polyol in order to produce waterborne polyurethane (WPU)/silica hybrid dispersions. Soft drinks poly(ethylene terephthalate) (PET) bottles were depolymerized by glycolysis with different molar ratio of poly(ethylene glycol) ( PEG 400), in the presence of zinc acetate as catalyst. The obtained glycolyzed products were reacted with castor oil (CO) to attain castor oil polyols by the process of transesterification. Five castor oil polyols were used with hydroxyl values of 255, 275, 326, 366 and 426 mg KOH g⁻¹. Several castor oil-based, polyurethane/silica hybrid dispersions having soft segment content of 39.6% to 28.2% and two concentrations of SiO₂ nanoparticles (0.5 and 1.0) have been prepared.The incorporation effect of SiO₂ nanoparticles into the PU matrix and the hydroxyl functionality of the COLs on the thermal and mechanical properties of resulting polyurethane films has been examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TG) and measurement of the mechanical properties. The degree of phase separation (DPS) between oxide nanoparticles and hard segment, and particle size in the polyurethane, depends to some extent on nanosilica content and the hydroxyl functionality of the polyols employed in the polyurethane preparation process.Thermal stability of obtained hybrid materials depends on the hydroxyl functionality of the COLs and nanosilica content. The T_10% and T_50% (the temperature where 10 and 50% weight loss occurred) of WPU films decreased with the rise of OH functionality of castor oil polyols, caused by the increase of hard segment content. Glass transition temperature increased with increasing OH functionality and SiO₂ content. The hardness, adhesion and gloss quality of the polyurethane films were also determined with a view to assessing the effect of mole ratios of PET to glycol in glycolyzed products, the hydroxyl functionality and the SiO₂ content.     

Glycolyzed poly(ethylene terephthalate) waste and castor oil-based polyols for waterborne polyurethane adhesives containing hexamethoxymethyl melamine

Glycolysis of poly(ethylene terephthalate) (PET) waste using different molar ratio of poly(ethylene glycol) (PEG400), was used to produce saturated hydroxyl-functional polyester polyols with castor oil (CO) by transesterification process. The waterborne polyurethane (WBPU) adhesives were synthesized from these saturated polyester polyols, isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), and hexamethoxymethyl melamine (HMMM) as cross-linking agent by a conventional prepolymer process. The glycolyzed polyols and polyester polyos formations were characterized using Fourier transform infrared spectroscopy (FTIR) and the molecular weights were determined using gel permeation chromatography (GPC). The cross-linking reaction between WBPU and HMMM was verified using FTIR and ¹H NMR analysis. Thermal properties were investigated by thermogravimetric analysis (TG). Thermal stability of cross-linked WBPU significantly increased with decreasing castor oil content in the process of transesterification to obtain polyester polyol as a soft segment. The T_15% and T_50% (the temperature where 15 and 50% weight loss occurred) of WBPU increased with the decreasing of castor oil content in the obtained polyester polyols, caused by the steric hindrance of polyester polyol with higher castor oil content, in the process of cross-linking reactions with HMMM. The physico-mechanical properties of WBPU, such as hardness, adhesion test, and gloss of the dried films were also determined considering the effect of participation of HMMM in cross-linking reactions with polyurethane, on coating properties.     

Modified cellulose nanocrystals enhancement to mechanical properties and water resistance of vegetable oil-based waterborne polyurethane

Environmentally friendly and lightweight silylated cellulose nanocrystal (SCNCs)/waterborne polyurethane (WPU) composite films that exhibit excellent mechanical properties and water resistance were prepared. The cellulose nanocrystals (CNCs) of the filamentous structure were surface-modified by γ-aminopropyltriethoxysilane (APTES) and then introduced into a castor oil-based aqueous polyurethane (WPU) matrix by in situ polymerization. The morphology and silylation degree of CNCs were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Fourier infrared transform spectroscopy at different APTES concentrations. The results showed that the surface of the nanocellulose crystal has the best silylation morphology and thermal stability with incorporation of 6 wt % APTES. The thermal stability, mechanical properties, surface morphology, and water resistance of the nanocomposites were investigated by TGA, tensile test, SEM and optical contact angle, water absorption test, and mechanical property test after immersed in water. It was found that the effective introduction of modified CNCs resulted in a significant increase in tensile strength at high levels, and the thermal stability and hydrophobicity of the material were improved simultaneously, reaching the percolation threshold at a 0.50 wt % SCNCs as determined theoretically. This study provided an approach to the design and development of surface-modified CNCs/vegetable oil-based polymer composites by using an appropriate concentration of silane coupling agent to modify CNCs and improve the compatibility between nanocellulose and vegetable oil-based polymer matrices. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48228.     

Synthesis and properties of castor oil-based waterborne polyurethane cloisite 30B nanocomposite coatings

Waterborne polyurethane dispersions (WPUDs) were synthesized successfully from castor oil-based polyol, isophorone diisocyanate and dimethylol propionic acid with NCO/OH ratio of 1.5. Different weight percentages of cloisite 30B (1, 2, and 3 wt%) were loaded with WPUDs to prepare nanocomposite films. Prepared prepolymer and nanocomposite films were characterized using FTIR, XRD, SEM, TEM, DSC, and TGA techniques, and coating properties, such as pencil hardness, abrasion resistance, impact resistance, and contact angle, were evaluated. The results obtained from different amounts of clay loading were compared with the pristine castor oil-based WPUDs. The FTIR spectra deconvolution technique was used to study the hydrogen bonding effect within the polymer with an increase in clay content. TGA analysis showed that the thermal stability of WPUDs increases with cloisite 30B (C30B) content. The surface morphology and hydrophilicity/hydrophobicity nature of the nanocomposite films were characterized using scanning electron microscopy and contact angle measurement. The results obtained from tensile tests indicated that the mechanical property of the dispersion system improved with C30B content. A high-performance castor oil-based nanocomposite coating with low volatile organic component can be targeted as an outcome of this work.     

Effect of nanosilica content on properties of polyurethane/silica hybrid emulsion and its films

Polyurethane/silica hybrid emulsion (PUSi) was synthesized by the reaction of isophorone isocyanate, polyether polyol, hydrophilic nanosilica (A200), dimethylol propionic acid, trimethylol propane, and 3‐aminopropyltriethoxysilane (KH550). The films of the waterborne polyurethane (WPU) were prepared. The structure of the polyurethane was characterized by Fourier transform infrared spectrometer (FTIR), thermogravimetry (TG), and differential scanning calorimetry (DSC). The particle size distribution and morphology of emulsion were examined. Influence of nanosilica content on the mechanical properties and solvent absorption of the cast films were also measured quantificationally. FTIR indicates that  NH₂ of KH550 reacted with  NCO of polyurethane. TG analysis indicates that nanosilica can improve thermal stability of polyurethane. There is no clear effect of nanosilica on the glass transition of soft segments. It was found that greater mechanical properties of WPU were obtained when chemical networks were formed by sol‐gel process. As the nanosilica content increases, water absorption and ethanol absorption decreased. The particle size increases with increase of A200 content. PUSi hybrid emulsions are endowed with pseudoplasticity. The apparent viscosity of emulsions increased and then decreased with addition of A200. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Flame Retardant Modified Bio-Based Waterborne Polyurethane Dispersions Derived from Castor Oil and Soy Polyol

Although tremendous efforts have been dedicated to developing environmentally friendly bio-based waterborne polyurethane (WPU) dispersions from vegetable oil, the fabrication of WPU dispersions solely derived from vegetable oil-based polyol with excellent comprehensive properties is still challenging. In the present work, novel bio-based WPU dispersions derived from castor oil and soy polyol is successfully modified by phosphorus-nitrogen chain extender [bis(2-hydroxyethyl)amino]-methyl-phosphonic acid dimethyl ester (BH). The structure and properties of the dispersions and films are characterized systematically by Fourier transform infrared spectroscopy, thermogravimetric analysis , mechanical test, and limiting oxygen index (LOI), etc. The results indicate that bio-based WPU films display moderate mechanical performance by adjusting BH content, and the WPU film containing 100% BH with 47.8% biobased content has a tensile strength of 8 MPa and the highest Young's modulus of 62.3 MPa. The incorporation of BH can increase the production of char residue. The flame retardancy of WPU films increase gradually with the BH molar content, and the LOI value of the WPU100 with 1.53 wt% phosphorus content can reach as high as 28.1%. This work may provide a new approach to develop high biobased content, eco-friendly, flame retardant WPU for application in the surface coating industry.     

From Castor Oil-Based Multifunctional Polyols to Waterborne Polyurethanes: Synthesis and Properties

A novel castor oil-based multifunctional polyol (CM) is fabricated through mild thiol-ene photo induced reactions using castor oil (CO) and 1-thioglycerol (MPD) as building blocks. The effect of the reaction time, molar ratio of thiol to carbon–carbon double bond, and the loadings of photo-initiator are optimized. The resulting CM is combined with CO and employed as cross-linkers to prepare castor oil-based water-borne polyurethane emulsion with desirable mechanical properties and water resistance. Owing to the incorporation of CM cross-linker with high hydroxyl value of 371 mg KOH/g (which is 2.27 times higher than that of the CO), the prepared castor oil-based waterborne polyurethane (CMWPU) possesses compacted 3D network structure with high cross-linking degree, leading to improved glass transition temperature (45 °C), tensile strength (10.8 MPa), water contact angle (87.4°), and decreased water absorption rate (16.12%) with 20% CM additions. Overall, this work illustrates the feasibility of introducing bio renewable CM combined with CO to develop castor oil-based WPU employing a sustainable development strategy.     

水性聚氨酯包封原生SiO2纳米复合材料的制备及表征

主要研究了SiO2 /水性聚氨酯 (WPU)无机 -有机纳米复合物的制备方法。TEM和动态光散射分析表明 ,SiO2 /WPU纳米复合物粒子分散于WPU胶束内部 ,粒径在 60nm左右 ,具有核 -壳型结构的纳米级微粒。体系有着良好的稳定性和透光性 ,并且其随着SiO2 含量的增加而降低。胶束良好的包覆作用 ,抑制了纳米粒子的团聚 ,是保持其良好的稳定性和较小粒径的原因     

单组分水性聚氨酯复膜胶研制

溶剂型复膜胶一般为双组分,使用不便,而且含大量有机溶剂影响安全和环保。在软包装等领域,已经越来越多地被水性复膜胶产品替代。水性聚氨酯胶粘剂（WPU）为单组分,性能优良。本课题在丙酮法合成水性聚氨酯的技术基础上,分别采用熔融分散法和预聚体分散法合成WPU复膜胶。通过综合比较,性价比较好的预聚体分散法是合成WPU复膜胶的理想方法。用MDI-2460和TDI的混合异氰酸酯、聚酯多元醇PD-56、中和前预聚体一NCO含量在2．5％～30％时,可合成出性能稳定、单组分,对透明PE／PE镀铝、PET镀~／g／BOPP、透明PE／黑白膜等复合性能良好,初粘性可达2N／15mmV＇X上的WPU．基本不用熟化即可直接分切。     

Synthesis and characterizations of waterborne polyurethane modified with 3-aminopropyltriethoxysilane

Waterborne polyurethane (WPU) was prepared by the reaction of isophorone isocyanate (IPDI), polyether polyol (PTMG1000), dimethylol propionic acid (DMPA), and trimethylol propane (TMP) and 3-aminopropyltriethoxysilane (APTES) as coupling agent. The films of the WPU were prepared by casting emulsions on Teflon surfaces. The structure of the polyurethane (PU) was characterized by Fourier transform infrared spectrometer (FT-IR), thermogravimetry (TG), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). The mechanical properties and solvent absorption of the cast films were also measured quantificationally. FT-IR indicates that –NH₂ of APTES reacted with –NCO of PU prepolymer. TG analysis indicates that APTES can improve thermal stability of PU. XRD and DSC show that crystallinity of PU decreased with the increase of w(APTES). It was found that greater mechanical properties of WPU were obtained when chemical networks were formed between PU and APTES. As the mass fraction of APTES increases from 0% to 10%, water absorption decreased from 17% to 8%, ethanol absorption decreased from 46% to 30%. The particle size increases with increase of w(APTES).     

纳米二氧化硅水溶胶改性UWPU的研究

通过丙酮法合成光固化水性聚氨酯丙烯酸酯预聚体,用三乙胺中和后在乳化过程中原位引入纳米二氧化硅水溶胶(Wv33、R900、R301)制备二氧化硅/光固化水性聚氨酯(SiO2/UWPU)纳米复合乳液,并进一步通过紫外光固化制备了SiO2/UWPU复合膜。通过电子扫描显微镜(SEM)和电子拉力机研究了不同纳米二氧化硅水溶胶对UWPU/SiO2复合膜的微观结构和力学性能的影响。SEM分析表明表面有机改性的pH值接近中性的硅溶胶(Wv33)较pH为酸性或碱性的硅溶胶在聚氨酯基体中有较好的分散性;应力-应变曲线分析表明Wv33能有效实现对复合膜的增强,即提高了复合膜的储存模量、拉伸强度和邵A硬度。     

水性聚氮酯的合成及其激活反应研究

聚乙二醇（PEG-1000）与甲基六氢苯酐（MHHPA）在催化剂XCT-cat81的存在下生成聚酯多元醇,再在催化剂XCT-cat57存在下,再与二苯基甲基4,4’-二异氰酸酯（MDI）反应生成聚氨酯预聚体,最后用苯酚封端制得水性聚氨酯。使用FTIR红外光谱仪分别对聚酯多元醇和水性聚氨酯进行了表征。使用大分子聚胺XCT-802及低分子二乙烯三胺（DETA）两种固化剂研究了水性聚氨酯封端基的激活反应,讨论了二种固化剂在不同固化温度与固化时间对水性聚氨酯木材黏结强度的影响。     

蓖麻油改性聚醚型水性聚氨酯乳液的性能

以聚醚、甲苯二异氰酸酯(TDI)、一缩二乙二醇、蓖麻油为主要原料,二羟甲基丙酸(DMPA)为亲水扩链剂,三乙胺为中和剂制备了稳定的阴离子水性聚氨酯乳液(WPU),研究了NCO/OH摩尔比、DMPA及蓖麻油的加入量对WPU的耐水性、稳定性和力学性能的影响,结果表明:改性后的乳液具有较好的稳定性,适量的蓖麻油可提高胶膜的拉伸强度及耐水性。当聚醚与蓖麻油质量比为7︰3、DMPA为5%、NCO与OH摩尔比为1.3时,WPU综合性能最好。     

水性聚氨酯胶粘剂的研究与改性

水性聚氨酯(WPU)胶粘剂在耐水性、力学性能、粘接强度及热稳定性等方面不如溶剂型胶粘剂,故改性WPU势在必行。介绍了WPU胶粘剂的改性方法(包括改变多羟基化合物种类、调节离子中和程度、增加离子含量、形成互穿聚合物网络、选择适量的聚异氰酸酯固化剂和黏土浓度等),评述了WPU胶粘剂的国内外研究现状,指出了WPU胶粘剂的发展趋势。     

蓖麻油硅氧烷双重交联改善水性聚氨酯的耐水性

以苯酐聚酯多元醇、二羟甲基丙酸和甲苯二异氰酸酯为主要原料,选用蓖麻油及3-氨基丙基三乙氧基硅烷(KH-550)为交联剂,通过预聚物的合成和水相扩链两步反应,制备了水性聚氨酯,研究了蓖麻油和KH-550用量对水性聚氨酯力学性能、附着力和吸水率等的影响.结果表明,当蓖麻油质量分数为10%、KH-550质量分数为1%,经过双...     

复合薄膜用双组分水性聚氨酯胶黏剂的制备和性能

制备了复合薄膜用双组分水性聚氨酯胶黏剂,初步研究了两种外加型交联剂环氧树脂6360、三聚氰胺-甲醛树脂对胶黏剂性能的影响。红外谱图和差示扫描量热法分析的结果表明在双组分水性聚氨酯胶黏剂中水性聚氨酯和交联剂发生了交联反应。外加交联剂可增加水性聚氨酯胶黏剂的交联度和黏度,从而有效提高胶黏剂的T型剥离强度和耐溶剂性能。环氧树脂较佳加入量在5%左右而三聚氰胺-甲醛树脂约为10%。由双组分水性聚氨酯胶黏剂黏合的PET/PE薄膜在较高温度下适当处理一段时间,其黏合效果更佳。     

A Review on Waterborne Thermosetting Polyurethane Coatings Based on Castor Oil: Synthesis,Characterization, and Application

Waterborne polyurethane coatings made from castor oil as polyol resource, replacing oil from fossil fuels are attracting lot of recognition during recent decades. In this review, castor oil and its modifications to synthesize various biobased waterborne polyurethane and their nanocomposite systems have been addressed. Various synthesis procedures for waterborne polyurethane dispersions and their applications as a coating material have been described. This review will be helpful to the green research community for selection of monomer and further development of biobased waterborne polyurethane utilizing advanced technology.     

Polydopamine functional reduced graphene oxide for enhanced mechanical and electrical properties of waterborne polyurethane nanocomposites

Waterborne polyurethane/polydopamine (PDA) functional reduced graphene oxide (WPU/PDRGO) nanocomposites were prepared by in situ emulsification method. The presence of a PDA layer and the partial reduction of GO by PDA were confirmed by FTIR, XRD, Raman spectra, and TGA. It was found that the interfacial PDA layers facilitated the dispersion of the PDRGO sheets in the WPU matrix and enhanced mechanical properties of the WPU matrix. The resulting WPU/PDRGO nanocomposite coatings show excellent electrical conductivity (9.9?×?10^?6–1.1?×?10^?4 S cm^?1) corresponding to a PDRGO content of 1–16 wt%. The obtained waterborne polyurethane/graphene nanocomposite dispersions are promising for anticorrosion, antistatic, conductive, and electromagnetic interference shielding coatings.     

Mussel-inspired synthesis of silver nanoparticles as fillers for preparing waterborne polyurethane/Ag nanocomposites with excellent mechanical and antibacterial properties

Silver nanoparticles (AgNPs) were synthesized by a facile, mild and green method using dopamine as a reducing and stabilizing agent and were introduced to waterborne polyurethane (WPU) via an in situ emulsification method to prepare antibacterial nanocomposite films. The formation of AgNPs was characterized by UV–visible spectroscopy and XRD. The dispersion of AgNPs was confirmed by TEM and the thermal stability of WPU/Ag nanocomposites was confirmed by TGA. The results showed that AgNPs were uniformly dispersed in the WPU matrix. The introduction of AgNPs significantly improved the thermal stability of WPU films. With incorporation of 0.1 wt% AgNPs, a five-fold increase in the tensile strength was achieved without sacrificing the ultimate strain. The WPU/Ag nanocomposite films showed antibacterial activity against Escherichia coli and Staphylococcus aureus. © 2021 Society of Industrial Chemistry.     

Effect of silica nanoparticles on structure and properties of waterborne UV-curable polyurethane nanocomposites

UV-curable waterborne polyurethane (WUPU)/silica nanocomposites were prepared using various silica by phase-inversion emulsification method. TEM examinations of nanostructured films indicated that the organic modified nanosilica was well dispersed in the WUPU matrix, while the acid and alkaline silica formed much less compact, or densely aggregated structure. DMA analysis demonstrated that the WUPU/silica nanocomposite films had a broadening of the tanδ peak and shifted to higher temperature. The WUPU/silica nanocomposite films displayed enhanced storage modulus, Shore A hardness, tensile strength without sacrificing high elongation at break compared to that of the pure WUPU film. The resulting nanocomposite films are possibly interesting for the generation of waterborne UV-curable transparent coatings with scratch-resistance.