基于反应成膜技术的水基丙烯酸酯乳液包衣控释肥料的研制(英文)

Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release pro-files of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate so-dium could not improve water resistance performance and glass transition temperature Tg of coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and Tg. Incorpo-ration of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated con-trol ed release fertilizer, with the 30-day cumulative nutrient release reduced to 16%and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.     

Application of waterborne acrylic emulsions in coated controlled release fertilizer using reacted layer technology

Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and th...     

聚氨酯缓/控释肥制备与膜层表征

利用多亚甲基多苯基异氰酸酯与蓖麻油在尿素表面反应成膜,制备了聚氨酯包覆的尿素缓/控释肥,通过红外光谱和扫描电镜研究了聚氨酯包覆量对膜层结构的影响,采用凯氏定氮法测定了尿素的溶出曲线。结果表明,不同包膜量聚氨酯膜层的反应程度存在差异;随着包膜量的增加,膜层的厚度增加;当聚氨酯的包覆质量分数为3.3%时,25℃下尿素的缓释期达到40～50 d;根据尿素的溶出曲线推测该缓/控释肥的释放为扩散机制。     

Structure and properties of bio-based polyurethane coatings for controlled-release fertilizer

Two kinds of bio-based polyurethane coatings for controlled-release urea were prepared by in-situ polymerization used castor oil and liquefied starch as raw materials, respectively. Scanning electron microscopy (SEM) showed that the section morphology of castor oil based polyurethane (Castor-PU) coating was uniform and dense, and that of liquefied starch based polyurethane (Starch-PU) coating had certain proportion of microporous. Infrared spectroscopy (IR) showed that the two coatings had typical urethane characteristic structure, but the difference was that the Starch-PU had obvious unreacted isocyanate structure. Differential scanning calorimetry (DSC) showed that the glass transition temperature of the two coatings was around 58°C, but the Castor-PU had a crystallization domain with obvious crystallization melting peak at 130°C. Thermogravimetric analysis (TG) showed that the thermal stability of Castor-PU was significantly higher than that of Starch-PU. The controlled-release property test showed that when the coating ratio was 2.8%, the nutrient release longevity of urea coated with Castor-PU was 49 days and that of urea coated with Starch-PU was 14 days. The reasons for the poor controlled-release performance of Starch-PU were analyzed, which probably caused by concentrated sulfuric acid and hydrophilic dispersant added in the liquefied starch.     

包膜尿素控制释放过程传质模型

根据质量守衡定律和F ick扩散定律建立了包膜尿素控制释放过程的传质模型,并用3种新颖的石蜡-松香混合物包膜尿素在蒸馏水中的释放数据和扫描电镜照片对模型进行了验证。结果表明,该模型能有效地描述和预测由扩散机制控制的包膜尿素的养分释放行为,拟合的相关系数R2分别为0.997 6,0.997 3和0.998 4。模型显示,包膜尿素的养分释放速率与膜的有效扩散系数Deff成正比,与尿素粒径的平方及膜的厚度成反比。     

Effect of annealing time and addition of lactose on release of a model substance from Eudragit RS coated pellets produced by a fluidized bed coater

The aim of this study was to investigate the effects of annealing time and addition of lactose in coating liquid formulations on the release of a model substance, methylene blue (MB), from pellets coated with Eudragit^® RS 30 D. The microcrystalline cellulose pellets were layered with MB before coating with aqueous dispersions of Eudragit^® RS 30 D using a Wurster-type fluidized bed coater. The coating processes and conditions were validated and optimized before the final coating. The uncoated and coated pellets were characterized for their size, MB content, morphology and MB release. The results demonstrated that a stable coating process can be developed to produce repeatable batches of pellets. The film thickness was calculated and found to be similar to those observed from scanning electron microscope. The increased annealing time led to a more coherent film. The drug release was found to vary depending on the duration of annealing time and the addition of lactose. Addition of lactose gave a faster MB release and without any initial lag period in the release profile whereas the increased annealing time slowed down the MB release and increased the lag period.     

Carbonaceous microsphere-based superabsorbent polymer as filler for coating of NPK fertilizer: Fabrication,properties, swelling,and nitrogen release characteristics

Recently, the use of controlled release fertilizers in agriculture has resulted in huge benefits in plant growth and cultivation. Superabsorbent polymer (SAP)-coated fertilizers have the added advantage in retaining water in soil after irrigation and also reduce the nutrient release rate from soil in a controlled manner. This study aimed to produce a nitrogen–phosphorus–potassium (NPK) fertilizer coated with superabsorbent carbonaceous microspheres polymer (SPC) by inverse suspension polymerization method with water-retention and controlled release properties. Two sets of experiments were conducted: (1) three different weight percentages and (2) different materials. NPK coated with SPC showed increasing water-retention ability with respect to carbon microsphere percentages and retains >80% water at the 30th day of experiment compared with pure NPK and NPK coated with SAP. The slow release behavior of all samples was investigated by induced coupled plasma mass spectrometry spectrometry and results showed that NPK coated with SAP and SPC has a low release rate with <50% nutrient release compared with uncoated NPK at the 30th day. The release mechanism kinetics of NPK coated with SAP and SPC were studied based on the Kosmeyer–Peppas model. The mechanisms approached Fickian diffusion-controlled release as the n value for both samples was less than 0.5. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48396.     

Preparation and characterization of triple polymer‐coated controlled‐release urea with water‐retention property and enhanced durability

Triple polymer coated with controlled‐release water retention fertilizer (TCWF) and enhanced mechanical property was developed by coating polyethylene (first layer), poly (acrylic acid‐co‐acrylamide) superabsorbent (second layer), and poly (butyl methacrylate) (third layer) consecutively on the granule core urea in the fluidized‐bed coater. The inner layer possessed controlled‐release property, the middle layer had water absorbent characteristic, and the thin outer layer aimed to protect the fragile layer of the superabsorbent. The relationship between the thickness of coating layer and the nutrient releasing properties was established. The effects of polymerization parameters on the water absorbency of the superabsorbent were studied and optimized as well. The nutrients release behaviors of this triple‐coated urea in both water and soil were investigated and compared. The results showed that TCWF not only performed as a good controlled‐release fertilizer but also had excellent water retention capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Diamond coatings for micro end mills: Enabling the dry machining of aluminum at the micro-scale

We show that thin diamond coatings can dramatically enhance the performance of micrometer-scale cutting tools. We present a new approach for coating 300 μm diameter tungsten carbide (WC) micro end mills using a tailored seeding method and hot filament chemical vapor deposition (HFCVD) to obtain uniform, conformal, and continuous diamond coatings less than 2 μm in both thickness and grain size. The performance of the uncoated and coated tools has been evaluated by dry machining channels in 6061-T6 aluminum. The test results demonstrate far lower tool wear and breakage, much lower adhesion of aluminum to the tool, and significantly lower cutting forces for the coated tools. The coatings achieve a more predictable surface finish and enable dry machining at high speeds (40,000 rpm) with little or no burr formation. The improved performance of the coated tools is a result of the superior tribological properties of fine-grained diamond against aluminum, specifically low friction, low adhesion, and low wear of the film. Since the coating allows machining without lubricants and essentially eliminates metal burrs, this approach can reduce the environmental impact of micro-machining processes and offers greatly improved performance for micro and meso-scale manufacturing applications.     

Novel partially bio-based fluorinated polyimides from dimer fatty diamine for UV-cured coating

A series of novel partially bio-based fluorinated polyimides with double-bond end groups (BGPIs) from 4,4′-(hexafluoroisopropylidene) diphthalic anhydride, 4,4′-(hexafluoroisopropylidene) dianiline, Priamine 1074, 4-aminobenzoic acid, and glycidyl methacrylate were synthesized via a copolycondensation method in m-cresol. The chemical structure and performances of BGPIs were fully characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, solubility test, X-ray diffraction, and differential scanning calorimetry. It was determined that the prepared BGPIs were in the amorphous phase and readily soluble in conventional aprotic polar solvents. Additionally, the properties of as-prepared UV-cured coatings based on BGPIs were also evaluated by real-time Fourier transform infrared, thermogravimetric analysis, UV–Vis spectroscopy, and so on. Results revealed that all coatings exhibited satisfactory curing, higher adhesion, lower water uptakes, outstanding optical transparency, and fairly favorable thermal stability under a high content of biomass up to 48.9%. Therefore, these bio-based polymers could be considered as a potential sustainable candidate for high-temperature UV-curable coatings in the microelectronic field.     

Release of urea from cellulosic hydrogel coated urea granule: Modeling effect of crosslink density and pH triggering

ABSTRACT

Urea granules were coated with CMC-g-cl-PAA hydrogel by in situ spraying and polymerization technique with mean thickness of 0.24 mm. Water absorption capacity of hydrogel coated urea granules varied from 18.67 to 217.33 g/g depending on pH. Urea release was extended due to hydrogel coating and kinetic analysis at different pH (4.0, 7.0 and 9.2) revealed a sigmoid function as best fit model. The coated urea granules showed pH triggered release property with higher rate in alkaline medium and slower in acidic medium. The prepared hydrogel coated urea granules may find its application in integrated water and nutrient management strategies in agriculture.     

Characterization of TiCN and TiCN/ZrN coatings for cutting tool application

Coating a cutting tool improves wear resistance and prolongs tool life. Coating performance strongly depends on the mechanical and chemical properties of the coating material. In a machining process, the type of selected coating depends on the cutting condition because of the properties of the applied coating material. In addition, many factors, such as coating thickness, composition ratio, sequences of layers in multilayer coatings, and the deposition method influence the performance of a coating. In this study, the mechanical properties of TiCN and TiCN/ZrN were investigated using a ball on disk test. The substrate material made from a carbide-based cutting tool was also developed in-house. The analysis performed shows that the performances of TiCN and TiCN/ZrN coatings were found to be comparable to that of the commercial TiN-coated carbide-based cutting tool. Both the in-house and commercial coated inserts had significantly lower coefficient of friction than uncoated inserts, and the friction coefficient of TiCN coatings was constantly slightly lower than that of TiN coatings. Moreover, the coefficient of friction of the in-house developed TiCN was slightly lower than that of commercial TiN coating. However, the coefficient of friction of the in-house developed uncoated carbide inserts was slightly higher than that of commercial uncoated carbide inserts.     

Tribomechanical and microstructural properties of cathodic arc-deposited ternary nitride coatings

Sintered carbides are promising materials for surfaces that are exposed to extreme wear. Owing to their high service load, ceramic-based thin films are coated on carbides using different techniques. In this study, non-toxic and cobalt-free powder metallurgy-sintered carbide samples were coated with TiN, TiAlN, CrAlN, and TiSiN ceramic-based thin film coatings by cathodic arc physical vapor deposition. The microstructure (phase formation, coating thickness, surface roughness, and topography), mechanical properties (hardness, modulus of elasticity, and plasticity indices), and tribological properties (nanoscratch and wear behavior) of the thin film coatings were investigated. No cracks or defects were detected in these layers. The ceramic-based ternary nitride thin film coatings exhibited better mechanical performance than the TiN coating. The TiN thin film coating had the highest average surface roughness, which deteriorated its tribological performance. The ternary nitride thin film coatings exhibited high toughness, while the TiN thin film coating exhibited brittle behavior under applied loads when subjected to nanoscratch tests. The wear resistance of the ternary nitride coatings increased by nearly 9–17 times as compared to that of the TiN coating and substrate. Among all the samples investigated, the substrate showed the highest coefficient of friction (COF), while the TiSiN coating exhibited the lowest COF. The TiSiN thin film coating showed improved mechanical and tribological properties as compared to other binary and ternary nitride thin film coatings.     

Novel bi-layered nanostructured SiO2/Ag-FHAp coating on biodegradable magnesium alloy for biomedical applications

In this study, a novel bi-layered nanostructured silica (SiO₂)/ silver-doped fluorohydroxyapatite (Ag-FHAp) coating was deposited on biodegradable Mg-1.2Ca-4.5Zn alloy via physical vapor deposition (PVD) combined with electrodeposition (ED). The nano-SiO₂ underlayer had a compact columnar microstructure with thickness of around 1 µm while the Ag-FHAp overlayer presented large plate-like crystals accompanied with small rounded particles with thickness about 10 µm. Potentiodynamic polarization test exhibited that the double layer SiO₂/Ag-FHAp coated Mg alloy has superior corrosion resistance compared to uncoated and single layer SiO₂ coated samples. Contact angle measurement showed that Ag-FHAp coating over nano-SiO₂ layers significantly increased surface wettability which is favorable for the attachment of cells. Cytotoxicity tests indicated that the nanostructured SiO₂/Ag-FHAp coating enabled higher cell viability compared to nano-SiO₂ coating and uncoated samples. In addition, bi-layer and single-layer coatings considerably improved the ability of cell attachment than that of the uncoated samples. The cell viability of coated and uncoated samples increased with increasing incubation time. The double layer SiO₂/Ag-FHAp coated biodegradable Mg alloy possessed high corrosion resistance and cytocompatibility and can be considered as a promising material for implant applications.     

Controlled release of nitrogen‐source fertilizers by natural‐oil‐based poly(urethane) coatings: The kinetic aspects of urea release

Urea is the most common source of nitrogen fertilizer, but it has serious disadvantages with respect to volatilization and leaching; these can be controlled by polymeric coatings on the granules. However, the effectiveness of this strategy depends on the formed polymer presenting good adhesion, reactivity with the urea surface, uniformity, and efficient release kinetics control. Therefore, in this study, we evaluated the release kinetics of urea coated by polyurethane produced from two oils (soybean and castor) by analyzing the influence of the thickness, coating stability, deposition interface, and total release time. The results demonstrate that castor oil produced superior materials, which achieved a total release time in water immersion of over 40 days with a total coating mass of less than 4% of the total mass. The good interface suggested that this material may produce coatings of good quality and long release times with minimum thickness, and this will maximize the total nitrogen present in the granule. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43790.     

松香包膜尿素的释放特性研究

以松香为成膜物质,制备了一系列的包膜尿素,利用扫描电子显微镜研究了包膜尿素的表面形貌,用浸泡溶解法表征了所得包膜尿素的释放特性,讨论了包覆量与操作条件对包膜尿素释放特性的影响。结果表明,松香是一种优良的尿素包膜材料,包覆量在5%以上时,松香包膜尿素具有显著缓释性能,包覆量越大,缓释效果越好。     

新型增值速效肥料养分释放效果及大田试验对比研究

利用水浸法试验对磷酸二铵、颗粒磷酸一铵、氯化钾3种外包硫锌营养元素肥料养分释放情况进行对比。结果表明,浸泡4 h后,外包肥料与空白肥料养分释放量基本一致;在养分最开始释放阶段(浸泡时间1 h),包裹S+Zn比例越大的肥料与空白肥料相比,养分释放越慢;颗粒钾肥包裹S+Zn,与空白肥料相比,差异较稳定,说明钾肥颗粒包裹S+Zn后对养分释放没有太大影响。在大田试验中,富邦硫锌包膜磷铵肥料与美可辛均比不加硫锌的磷酸一铵效果好,说明硫锌能提高作物产量。     

磷酸二铵包膜缓释肥料的性能研究

以玉米淀粉、聚乙烯醇、二氧化硅（湿法磷酸脱氟制备氟化钾时的副产物）、丙三醇和膨润土为主要原料,以水作为溶剂制备包膜乳液,以高压喷枪将包膜乳液多次雾化对磷酸二铵颗粒（DAP）进行喷涂,成功制备了一种磷酸二铵缓释肥。研究了不同金属离子种类、不同离子浓度对其缓释性的影响;金属离子种类对土壤持水性能的影响;包膜肥料对土壤保水性和持水性能的影响。结果表明：磷酸二铵包膜肥料的缓释性能随金属离子浓度的增加而增加,多价金属阳离子对包膜肥料缓释性能的影响大于单价金属阳离子;土壤的持水性能会受金属离子种类的影响;包膜肥料能提高土壤的保水性能和持水性能。     

Mechanism and evaluation in electroinitiated copolymerization coatings of acrylonitrile and acrylic acid

Adherent films of copolymers on different metal surfaces were formed by an electrolytically initiated polymerization of acrylonitrile (AN) and acrylic acid (AA) in 0.05N H₂SO₄ aqueous solution. The electrolysis was carried out under a constant current. Hydrogen overvoltages for five different metals used as the cathode were measured in order to interpret the nature and quality of the coating. Solutions containing varying volume fractions of AN and containing different electrolytes gave rise to coatings of varying film thickness. Based on the analyses of copolymer compositions, it is believed that the polymer was formed at the cathode by a free-radical propagation mechanism. The film hardness and the adhesion between the polymer and the metal surface were measured with an Arco microknife. Furthermore, the scanning electron microscope (SEM) was used to examine the structure of the film surface and cross section. The corrosion rates of the coated and uncoated metals in substitute ocean water were also measured for purposes of evaluation of the coatings.     

聚合物硫包尿素的养分释放特征

对聚合物硫包尿素(简称PSCU)产品的养分释放特性进行了试验研究。试验结果表明,PSCU在抗冲击性和耐磨性上均明显优于硫包尿素(简称SCU);PSCU能明显克服SCU的“破裂释放”模式的缺点,使养分释放更加平缓;硫膜的厚度对PSCU的养分释放期起决定性作用,养分初期溶出率随着硫膜厚度的增加而降低, 养分释放期相对延长;在相同涂硫量的条件下,PSCU养分初期溶出率随着外层聚合物用量的增加而降低,养分释放期相对延长。因而可以通过改变硫膜和聚合物的厚度来调节其养分释放特性,生产具有不同养分释放特性的控释肥料。