Waterborne polyurethane wood coatings based on rapeseed fatty acid methyl esters

Trends in wood coatings are driven to waterborne systems and to renewable resources. Vegetable oils are well known for wood coatings, e.g. alkyds or polyurethane dispersions. In this context, fatty acid methyl esters turn out to be an alternative to technical fatty acids and vegetable oils. High contents of hydrophobic oil-based monomers require a sufficient understanding of the dispersion stability. This study shows the influence of hydrophobic monomers, ionic centers, degree of neutralization, and stirring procedure to the particle size distribution and dispersion stability. Furthermore, the impact of these parameters on the resulting coating film properties was investigated.     

Biobased dimer fatty acid containing two pack polyurethane for wood finished coatings

Novel two pack polyurethane wood finished coatings are prepared from renewable sources, such as vegetable oil based fatty acid and dimer fatty acid. In actual experimental part oleic acid was reacted with diethanolamine to obtain amide which was on condensation polymerization with dimer fatty acid converted into the polyesteramide polyol. These are all being used to prepare polyurethanes. The functional and structural elucidation of dimer fatty acid based polyesteramide and diethanolamide were carried out by end group analysis, spectral studies such as FTIR and ¹H NMR. Average molar masses of the polyesteramide were estimated by gel permeation chromatography (GPC). The polyesteramide was used in the preparation of wood finished polyurethane coatings by reacting it with aromatic diisocyanates. Thermogravimetric analysis (TGA) was used to study the thermal behavior of coatings. Physico-chemical and coating properties of the coatings were investigated by using standard methods. The results indicated that the bio-based wood finished PU coatings provided good mechanical, weather resistance as well possessed adequate coating properties for wood surface protections.     

Air-drying bio-based polyurethane dispersion from cardanol: Synthesis and characterization of coatings

Exploring bio-renewable materials to replace petroleum-based building blocks for advanced coatings has been a major thrust area for researchers for the development of eco-friendly and sustainable products. For the last few decades, there has been significant interest among coating researchers around the world to design water-based polyurethane dispersions (PUDs) that can be cured at ambient conditions. In the present work we synthesized auto-oxidizable PUDs based on cardanol as sustainable material that also provides self-crosslinking attribute to the PUDs. Such types of PUDs are expected to be suitable for water-based industrial protective primers. The cardanol-based intermediates and final products are characterized by FTIR spectroscopy for conformation of synthesis reaction and their structures. The dried films of the coatings, formulated using a suitable drier catalyst, exhibited improvement in mechanical properties and solvent resistance. The oxidative curing has also been investigated by FTIR and differential scanning calorimetry (DSC). The corrosion resistance properties of the coatings on steel substrate, as studied by using electrochemical impedance spectroscopy (EIS) technique also showed better performance for cross-linked films.     

Effect of silane modified nano ZnO on UV degradation of polyurethane coatings

Nanosized ZnO modified by 2-aminoethyl-3-aminopropyltrimethoxysilane (APS) was prepared using the precipitation method. Modified nano ZnO by silane (ZnO-APS) was characterized by XRD, SEM, TEM and UV–vis measurements. The degradation of the polyurethane coating, the polyurethane coatings containing 0.1 wt% nano ZnO and the polyurethane coatings containing nano ZnO-APS at two concentrations (0.1 and 0.5 wt%) during QUV test was evaluated by gloss measurement and electrochemical impedance spectroscopy. The coating surface after QUV test was observed with SEM. The results show that nano ZnO-APS has spherical structure with particle size around 10–15 nm. Nano ZnO improved the UV resistance of the PU coating and surface treatment by APS enhanced the effect of nano ZnO. The presence of nano ZnO-APS at 0.1 wt% concentration significantly improved the UV resistance of polyurethane coating.     

用二聚酸聚酯二元醇制备高固体物含量聚氨酯分散体

以二聚酸聚酯二元醇、二羟甲基丙酸、三羟甲基丙烷及异佛尔酮二异氰酸酯等为原料,用预聚法合成了固体物质量分数50%以上的聚氨酯分散体(PUD).PUD的平均粒径在90～150 nm,12 r/min搅拌速率下的剪切黏度绝大多数在500 mPa·s以下.透射电镜分析显示PUD呈现胶粒间大小和形状互不相同的多分散体系.动态力学分析表明试样胶膜的玻璃化转变温度在-40～-35℃,NCO/OH(摩尔比)的增大使PUD胶膜的玻璃化转变温度升高.热重分析显示PUD胶膜在280℃开始分解,其拉伸强度为14.1～25.0 MPa,扯断伸长率为508%～716%,吸水率为2.44%～4.56%.     

Synthesis and characterization of polyurethane coatings derived from polyols synthesized with glycerol, phthalic anhydride and oleic acid

Polyester polyols, with various oleic acid contents were used in the preparation of polyurethane (PUR) coatings. The polyols were designated as Alk28, Alk40 and Alk65, in which 28, 40 and 65 represents the percentages of oleic acid in the respective formulations. The physical properties of the polyols such as acid value and hydroxyl value have been determined and the infrared (IR) spectroscopic analysis of the polyols is reported. The polyols were reacted with aromatic isocyanate (toluene 2,4-diisocyanate, TDI) to form PUR coatings. The effects of varied NCO/OH ratio and oleic acid content of polyols on physical properties of PUR coatings on mild steel panel were determined. The characterization of PUR coatings carried out by IR spectroscopic analysis and physico-chemical properties such as drying time, pencil hardness, adhesion properties, solvent resistance and corrosion/chemical resistant determination were reported. The coatings obtained from polyol Alk28, exhibits the best overall properties followed by Alk40. PUR coatings from Alk65 were softer. As the NCO/OH ratio of the coatings increased, there were progressive increases in mechanical and anticorrosive properties for all the coatings. Overall, these studies showed that the material holds promise for use as effective surface coating compound by designing the formulation of the desired performance.     

Effect of incorporation of surface treated zinc oxide on non-isocyanate polyurethane based nano-composite coatings

Non-isocyanate polyurethanes (NIPUs) based on cyclic carbonate-amine chemistry are an emerging area for polymer synthesis and is being extensively studied for various applications. A successful utilization of this technology can eliminate many of the issues associated with conventional polyurethane chemistry. While these polymers have not yet achieved commercial significance, research is being devoted to methods for synthesizing polymers or oligomers containing cyclic carbonate groups as well as studying their applications in thermoplastic and thermosetting systems.     

Solid polymer electrolytes of blends of polyurethane and polyether modified polysiloxane and their ionic conductivity

Polymer electrolytes based on thermoplastic polyurethane (TPU) and polyether modified polysiloxane (PEMPS) blend with lithium salts were developed via an in-situ polymerization of TPU with the presence of PEMPS and salts. Morphological study of TPU/PEMPS electrolytes showed that TPU and PEMPS were immiscible and TPU/PEMPS electrolytes had a multiphase morphology. The lithium salt enhanced the interfacial compatibilization between TPU and PEMPS via the interaction of lithium ions with different phases. Three lithium salts with different interaction strengths with TPU and PEMPS were used to prepare TPU/PEMPS electrolytes with different levels of phase compatibilization: LiCl, LiClO₄, and LiN(SO₂CF₃)₂ (LiTFSI). The effect of PEMPS on ionic conductivity, dimensional stability and thermal stability of TPU/PEMPS electrolytes and their relationship with the blend morphology were investigated. TPU/PEMPS electrolytes showed good dimensional stability and thermal stability. The addition of PEMPS to TPU increased the ionic conductivity of TPU/PEMPS electrolytes. The room temperature ionic conductivity of TPU/PEMPS electrolytes with LiTFSI can reach up to 2.49 × 10⁻⁵ S/cm.     

Synthesis and characterization of novel hyperbranched alkyd and isocyanate trimer based high solid polyurethane coatings

In the present work, hyperbranched urethane alkyd high solid coatings were formulated by mixing hyperbranched alkyd and isocyanate trimer. Initially, a second generation hyperbranched polyol (HBP) was synthesized using dipentaerythritol (DPE) as a core material and 2,2-bis(methylol)propionic acid (BMPA) as a chain extender. This was reacted with varying concentrations of linseed oil fatty acid (LOFA) to make a series of hyperbranched alkyd (HBA) resins. Viscosity and volume solid of the HBA resins were measured. The resins were characterized by Fourier transform infrared (FTIR), and ¹³C Nuclear magnetic resonance (¹³C NMR) spectroscopic techniques. The hyperbranched alkyd resins containing varying amount unreacted hydroxyl groups were cured with hexamethylene diisocyanate (HDI) trimer (Desmodur N 3390) depending on their NCO: OH ratio to make hyperbranched urethane alkyd coatings. A series of such coatings were made by mixing HBA/isocyanate trimer (Desmodur N 3390) ratio with respect to the hydroxyl group present on the HBA. The performance of the coated specimens was evaluated by various techniques such as pull-off adhesion strength, tensile strength, abrasion resistance, scratch resistance, flexibility, and impact resistance tests. The weathering properties of the coated specimens were evaluated by UV-Weatherometer. Corrosion resistance of the coated specimens was evaluated by electrochemical impedance spectroscopy (EIS), salt spray, seawater immersion and humidity tests. It was observed that, there exists an optimum coating composition in terms of NCO: OH (HBA: Desmodur N 3390) ratio which showed excellent enhancement in terms of the mechanical, weathering and corrosion resistance properties than remaining coating compositions.     

Preparation and characterization of polyurethane based on dimer acid for environment-friendly controlled release fertilizers

ABSTRACT

The paper presents a new controlled release fertilizer coated by dimer acid-based polyurethane (PU). The structure and property of the sample were characterized. Results indicated that the polyether polyol modified PU (MPU) coating reduced water absorption rate by 72.1% after 29 d, and increased the cross-linking density by 23%, and decreased the coating porosity by 26%, Moreover, MPUFs and PUFs both exhibited excellent nutrient controlled release abilities, especially the MPUF possessed longer nitrogen release longevity (118 d,131%) compared with PUF (51 d). Thus, the high-performance MPUFs with environmentally friendly and excellent controlled release could be widely applied to agricultural fields.     

丙烯酸/蓖麻油聚氨酯耐磨涂料的研究

介绍了丙烯酸/聚氨酯涂料的制备和性能测试工艺流程以及蓖麻油改性TDI制备聚氨酯、丙烯酸树脂和丙烯酸改性聚氨酯涂料的合成步骤。通过正交实验对羟基丙烯酸树脂和耐磨性填料———二硫化钼、氧化铬和聚四氟乙烯的用量进行了优化,获得了涂料的最优化配方(用质量分数表示):A组分:聚氨酯3%,醋酸丁酯3%;B组分:羟基丙烯酸1.5%,二硫化钼0.3%,三氧化二铬0.4%,聚四氟乙烯0.6%,混合溶剂5%,十二烷基硫酸钠0.12%,KH-5500.025%,二丁基二月桂酸锡0.0125%。所得涂膜的表干时间约为30min,实干时间约为36h。涂层的附着力1级,硬度1B。在3.3kg的载荷下,磨轮旋转1500圈后,涂层磨痕弦长6.5mm,说明涂料耐磨性优良。试样在质量分数分别为5%和15%的盐酸、氢氧化钠溶液中浸泡一周后,涂层无起泡、润胀和脱落现象,说明涂层耐蚀性优良。     

Genetic diversity for lipid content and fatty acid profile in rice bran

Rice (Oryza sativa L.) bran contains valuable nutritional constituents, which include lipids with health benefits. A germplasm collection consisting of 204 genetically diverse rice accessions was grown under field conditions and evaluated for total oil content and fatty acid (FA) composition. Genotype effects were highly statistically significant for lipid content and FA profile (P<0.001). Environment (year) significantly affected oil content (P<0.05), as well as stearic, oleic, linoleic, and linolenic acids (all with P<0.01 or lower), but not palmitic acid. The oil content in rice bran varied relatively strongly, ranging from 17.3 to 27.4% (w/w). The major FA in bran oil were palmitic, oleic, and linoleic acids, which were in the ranges of 13.9–22.1, 35.9–49.2, and 27.3–41.0%, respectively. The ratio of saturated to unsaturated FA (S/U ratio) was highly related to the palmitic acid content (r ²=0.97). Japonica lines were characterized by a low palmitic acid content and S/U ratio, whereas Indica lines showed a high palmitic acid content and a high S/U ratio. The variation found suggests it is possible to select for both oil content and FA profile in rice bran.     

Near‐infrared spectroscopy for analysis of oil content and fatty acid profile in almond flour

Almond kernels show large variability for oil content and fatty acid profile. The objective of this research was to evaluate the potential of near infrared (NIR) reflectance spectroscopy (NIRS) for the analysis of these traits in almond flour. Ground kernels of 181 accessions collected in 2009 were used for developing calibration equations for oil content and concentrations of individual fatty acids. Calibration equations were developed using second derivative transformation and modified partial least squares regression. They were validated with samples from 179 accessions collected in 2010. The accuracy of calibration equations was measured through the coefficient of determination (r²) in external validation and the ratio of the SD in the validation set to the standard error of prediction (RPD). Both r² and RPD were high for oil content (r² = 0.99; RPD = 9.24) and concentrations of oleic (r² = 0.97; RPD = 5.37) and linoleic acids (r² = 0.98; RPD = 7.35), revealing that calibration equations for these traits are highly accurate. Conversely, the accuracy of the calibration equations for palmitic (r² = 0.54; RPD = 1.41) and stearic acids (r² = 0.52; RPD = 1.44) was too low for allowing their application in practice. NIRS discrimination of oil content and concentrations of oleic and linoleic acids was mainly based on the spectral region from 2240 to 2380 nm. Practical applications : NIRS is a high‐throughput analytical technique that allows fast measurement of several traits in a single analysis without using chemical reagents. We evaluated the feasibility of analyzing oil content and concentrations of palmitic, stearic, oleic, and linoleic acids in almond flour using fruits collected during 2 years from a world germplasm collection. The fruits collected in 2009 were used for NIRS calibration, whereas the fruits collected in 2010 were used for validation. NIRS equations were highly accurate for measuring oil content and concentrations of oleic and linoleic acids, which are important traits defining the quality of almond flour for specific uses in the food industry. These results have applications both in the research laboratory and the food industry, where NIRS is becoming a widely used technique for quality control.     

Preparation and characterization of UV-cured polyurethane acrylate/ZnO nanocomposite films based on surface modified ZnO

A series of polyurethane acrylate (PUA)/ZnO nanocomposite films with different ZnO contents were prepared via a UV-curing system. To ensure good dispersion in the PUA matrix, ZnO nanoparticles were modified with a silane coupling agent and confirmed by FT-IR analysis. The morphological structures, thermal properties, mechanical properties and water transfer properties of the prepared films were investigated as a function of their ZnO concentration. WAXD and SEM analyses showed that the surface-modified ZnO nanoparticles were homogeneously dispersed in the PUA matrix and the molecular ordering increased with increasing ZnO content. Compared with neat PUA, the hardness and elastic modulus in films increased from 0.03 to 0.056 GPa and from 2.75 to 3.55 GPa, respectively. Additionally, the water uptake and WVTR in the PUA/ZnO nanocomposite films decreased as the ZnO content nanoparticles increased, which may come from enhanced molecular ordering and hydrophobicity in films. UV light below approximately 450 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PUA matrix, indicating that these composite films exhibit good weather ability and UV-shielding effects. The enhanced physical properties achieved by incorporating modified ZnO nanoparticles can be advantageous in various applications, whereas the thermal stability of the composite films should be increased.     

Mechanical and dynamic mechanical properties of polyurethane/Fe-octacarboxyl acid phthalocyanine blends

In this paper, Fe-octacarboxyl acid phthalocyanine (Fe-OCAP)/polyurethane (PU) blends were prepared by solution blending. The mechanical and dynamic mechanical properties of the samples were evaluated by tensile tests and dynamic mechanical analysis. The results showed that incorporation of Fe-OCAP significantly improved the tensile strength, elongation at break, and thermal deformation property of PU matrix. The interaction between Fe-OCAP and PU was investigated by infrared analysis. The result indicated that strong hydrogen bond was formed between Fe-OCAP and hard segments of PU and increased with increasing Fe-OCAP content. Quantitive evaluations of the interaction between Fe-OCAP and PU were conducted by analyzing the physical cross-linking density in samples. The results indicated that the physical cross-linking density of the samples was increased with increasing Fe-OCAP content.