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     

Synthesis and characterization of bio‐based PA/EP interpenetrating network polymer as coating material for controlled release fertilizers

A novel controlled release fertilizer was developed using interpenetrating polymer network (IPN) as the coating material. The IPN was successfully sprayed on the surface of the urea particles to form IPN‐coated fertilizers (IPNCU) for controlled nitrogen release. The IPN was synthesized by bio‐based polyamide (PA) from d ‐glucaric acid and epoxy (EP) through network interpenetrating. The chemical structure and microscopic morphology characteristics of IPN were examined by Fourier transform infrared spectroscopy, ¹H‐nuclear magnetic resonance, and scanning electron microscopy. The property of IPN with the different PA/EP mass ratios were investigated and compared with that of EP‐coated fertilizers (EPCU). The nutrient release behaviors of IPNCU in water and soil were detected. The results showed that the IPNCU with 5% PA content increased the nitrogen release longevity by 41 days, raised the water contact angle of surface by 23.9°, and then significantly slowed the nitrogen release rate of the IPNCU. The nutrient release mechanism of IPNCU was discussed in detail. This work indicated that the environment‐friendly IPN with superior controlled release properties could be especially useful in horticultural and agricultural applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46052.     

Preparation and properties of a degradable interpenetrating polymer networks based on starch with water retention,amelioration of soil,and slow release of nitrogen and phosphorus fertilizer

In this study, we aimed to develop a degradable nitrogen and phosphorus (NP) fertilizer with properties of slow release, water retention, and remediation of saline soil; the nitrogen and phosphorus was coated with starch/poly(acrylic acid‐co‐acrylamide) [poly(AA‐co‐AM)] superabsorbent (SAAmF) by reverse suspension radical copolymerization. The variable influences on the water absorbency were investigated and optimized. The results of the structure and morphology characterization of SAAmF show that poly(AA‐co‐AM) was grafted partly from the chain of starch, and the different contents of starch brought about a difference in the size of the three‐dimensional net hole of the coating polymer. The property of water retention, the behaviors of slow release of nutrient, and the degradation of the SAAmF were evaluated, respectively, and the results revealed that the water transpiration ratio of soil with SAAmF was lower by approximately 8 percentage points than that of the blank test, about 60% nutrient was released from SAAmF by the 30th day, and 32 wt % of SAAmF with a content of starch of 20% was degraded after 55 days. Moreover, a considerable decrease in the conductivity was observed, which revealed a sharp reduction in the concentration of residual ions for the soil mixed with SAAmF. It may be inferred from these that the product seems to be a promising vehicle for the management of soils, including saline soils. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of temperature on nutrient release from slow-release fertilizers

We studied the effect of temperature on the release of N, P, and K from slow-release fertilizers (SRF). The study was conducted in micro-lysimeters filled with moist peat medium. Increasing the temperature from 4 to 12°C slightly increased N release from three different slow-release N (SRN) carriers with different particle sizes and coating thicknesses. At 21°C the rate of release was significantly different than the other two temperatures. Urea formaldehyde (UF), sulphur coated urea (SCU) and coated calcium nitrate (CCN), incubated in sphagnum moss peat, released between 3 and 20% of the applied N in six weeks. For eight synthetic and organic NPK carriers, the release pattern was similar to UF and SCU. However, the leaching losses of N from the NPK fertilizers were up to twenty times more than for the SRN products. Except for Osmocote^® and Duna, which released 30–40% of the applied N as mineral-N within six weeks, all other slow-release and slowly mineralized NPK carriers acted like readily water-soluble compound NPK. Temperature did not affect the nutrient release from NPK fertilizers.     

PAA-AM-AMPS与PAA-AM高吸水性树脂的合成及保水性能

利用水溶液聚合法合成了聚丙烯酸系高吸水性高保水性树脂,其吸水倍率均在800 g/g以上,且在50 min内吸水饱和。研究了共聚单体和交联剂用量对树脂加压保水能力和恒温保水能力的影响。研究结果表明,树脂恒压放置7 d后保水率均在30%以上,保水能力随丙烯酰胺用量增加先增大后减小,随交联剂MBA用量增加先增大后减小。同时,PAA-AM-AMPS在沙土中恒温50℃时放置7 h后,保水率为75.5%,说明树脂能提高沙土的饱和含水量,有效地改良沙土的保水能力,为沙漠保水提供有效的保水剂。     

聚合物乳液包膜控释肥料技术研究进展

综述了包膜控释肥料聚合物乳液包膜剂的研究现状和基本特性,分析了流化床和转鼓流化床包膜过程中的主要影响因素,对目前聚合物乳液包膜控释肥料的释放性能进行了评述,分析了乳液包膜控释肥料研发中的关键问题,并对其发展前景进行了展望。     

黄原胶/膨润土复合高吸水性树脂的制备与性能研究

采用水溶液聚合法制备了黄原胶(XG)/膨润土有机-无机复合SAP(高吸水性树脂)。通过单因素试验法和正交试验法优选出制备复合SAP的最佳工艺条件。结果表明:丙烯酸(AA)、丙烯酰胺(AM)、XG与膨润土之间发生了接枝共聚反应;当m(AA)∶m(AM)=5∶1、AA中和度为75%、w(膨润土)=5%、w(引发剂)=1.0%和w(交联剂)=0.08%时,相应的复合SAP具有最大的吸水倍率(863.8 g/g)和吸盐水倍率(109.4 g/g)。     

大颗粒包膜肥料是包膜肥料发展的方向

大颗粒包膜肥料比小颗粒包膜肥料有更高的肥效和养分利用率;大颗粒包膜肥料的比表面积减小,可大量节省包膜材料,降低生产成本和应用成本;大颗粒包膜肥料还具有减少土壤污染和方便使用等特点。发展大颗粒包膜肥料是解决缓/控释肥料难以推广应用问题的重要途径。     

Preparation of a monolithic and macroporous superabsorbent polymer via a high internal phase Pickering emulsion template

A superabsorbent polymer (SAP) possesses an ability to absorb an aqueous solution up to several hundred times its own weight. To utilize a SAP effectively, a high absorption rate is also essential in addition to a high absorption capability. Herein, using a template based on a high internal phase Pickering emulsion (HIPPE) stabilized by aluminum oxide (Al₂O₃) nanoparticles, we synthesize a SAP with a high absorption rate by forming macropores. In particular, by adjusting three different parameters, the concentration of the crosslinker, the internal volume fraction of the emulsion, and the particle concentration, we successfully formed a HIPPE-templated SAP with a high absorption rate for a saline solution, which was 51.6 g g⁻¹ of the absorbency within 10 s. We confirm that the swelling kinetics is mainly determined by the interconnectivity between the internal macro-pores. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48133.     

桐油成膜材料的生物降解性研究

以土壤和活性污泥中的微生物来降解桐油缓(控)释肥料的成膜材料,通过测定试样在降解过程中的CO2释放量、质量损失百分率和表面形貌来综合评价成膜材料的生物降解性能。结果表明,用桐油作为成膜材料制备缓(控)释肥料,养分释放后残留在土壤中的包膜肥料壳囊可以被生物降解,对环境友好。     

Conversion of Fine Particle Waste of Water-Absorbents to Value-Added Oil-Absorbents

This is a preliminary report on conversion of fine particle waste of superabsorbent polymer (SAP) hydrogels to value-added oil-absorbing organogels via a facile and green approach. Thus, SAP was hydrophobically modified with different contents of an R₄N⁺Br^– to incorporate long alkyl groups to the polymer structure. FTIR and DSC were employed to study the structural and thermal characteristics of the product. Swelling measurements verified that the SAP could be easily converted to efficient organophilic samples with absorption capacity up to 6 g/g in toluene and 4 g/g in crude oil media. Therefore, the product may be employed in environmental decontamination.     

缓释／控释包膜肥料的研究现状与发展

缓释腔释包膜肥料具有重要的经济效益和生态效益,因而成为目前肥料研究与发展的热点之一.简述了缓释腔释肥料的特点和分类,回顾了国内外缓释/控释包膜肥料发展和研究现状,总结了其养分释放机理和养分释放影响因素,论述了其发展前景,并分析了进一步研究和开发的方向.     

包膜肥料控制释放速率的测定

分别用水浸泡法和土壤溶出率法测定了3种包膜肥料氮素的释放速率,研究了这两种测试方法的特点以及应用范围。结果表明：同一肥料在水中以及土壤中氮素的释放速率和释放模式有所不同;水浸泡法适用于水田用或者释放速率小的包膜肥料释放速率的测定,而土壤溶出率法适用于旱地上用或者释放速率大的包膜肥料释放速率的测定;水浸泡法可以快速比较不同包膜肥料的缓／控释性能,但与肥料在土壤中的实际释放期有偏差;土壤溶出率法能较好地模拟施肥的情况,但测试时间长。     

Use of polyolefin-coated fertilizers for increasing fertilizer efficiency and reducing nitrate leaching and nitrous oxide emissions

This paper reviews some of the benefits of polyolefin-coated fertilizers (POCFs) with accurate controlled release properties. They are helpful in developing innovative rice farming systems, such as no-till direct seeded rice with single basal fertilization and transplanting of rice seedlings with single basal fertilization. These new cultivation systems can increase fertilizer efficiency and reduce farming costs. The recovery of basal N can be increased from 22–23% with conventional broadcast application of ammonium sulfate or urea to 79% withco-situs application of polyolefin-coated urea. The no-till rice cultivation of transplanting of rice seedlings with single basal application of POCFs decreased the farming cost by 65% as compared to that of the conventional rice cultivation. Theco-situs application of POCFs containing NPK reduced nitrate leaching and nitrous oxide emissions from cultivated soils with heavy fertilization. Since POCFs have various nutrient composition and release types, a variety of application methods to agricultural and horticultural plants are being developed in Japan.     

高吸水性树脂的性能与应用

介绍了高吸水性树脂的概况及应用 ,对高吸水性树脂的吸水原理和性能进行了论述 ,并结合目前实际状况对高吸水性树脂的今后发展提出了建议。     

Soil organic matter dynamics as affected by long-term use of organic and inorganic fertilizers under maize–wheat cropping system

Understanding the effects of long-term use of fertilizers on soil carbon and nitrogen pools and their activities is essential for sustaining soil productivity. Our objectives were to quantify long-term changes in soil organic carbon (SOC), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN) and mineralizable C in maize–wheat cropping sequence in fertilized and unfertilized plots (control, N, NP, NPK, and NPK + FYM). Continuous application of fertilizers increased SOC over its initial content. Active fractions of SOC, i.e., water-soluble carbon, hydrolysable carbohydrates, SMBC, SMBN and dehydrogenase activity, improved significantly with an application of NPK and NPK + FYM. A general increase in carbon mineralization with time period was observed throughout the experiment and was maximum in 100% NPK + FYM treated plots. The estimated annual C input value in NPK + FYM treatment was 1.05 MgC ha⁻¹ year⁻¹. The overall net change in organic carbon was maximum in treatment receiving FYM along with inorganic fertilizers. Therefore, these results suggest that the integrated use of NPK and FYM is an important nutrient management option for sustaining maize–wheat cropping system.     

Aqueous polyacrylate/poly(silicone‐co‐acrylate) emulsion coated fertilizers for slow nutrient‐release application

Waterborne polyacrylate/poly(silicone‐co‐acrylate) emulsions were synthesized to develop coated fertilizers. The effects of the n‐butyl acrylate (BA)/methyl methacrylate (MMA) ratio, vinyltriethoxysilane, and synthesis method on the water resistance, glass‐transition temperature, mechanical properties, and nutrient‐release profiles were investigated. The results show that miniemulsion polymerization with a BA/MMA ratio of 55:45 was the most suitable for slow nutrient‐release applications. Under these conditions, the preliminary solubility rate of the nutrient was about 3%, and the 30‐day cumulative nutrient release was 15% at 25°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40369.     

缓释/控释肥料用包膜材料的现状及发展探讨

缓释／控释包膜肥料具有提高肥料利用率、降低环境污染、提高作物产量等特点,因而成为目前肥料研究与开发的热点之一,包膜材料则是影响肥料释放速率的关键。本文简要介绍缓释／控释包膜肥料的研究现状、讨论了若干目前已被采用包膜材料的特点、并对包膜材料的发展前景进行了初步探讨。     

脲醛缓释肥料红外光谱分析及养分释放特性研究

采用红外光谱分析法、水中溶出法和土壤培养法,探讨了4种不同种类的脲醛缓释肥料的结构特性及养分释放特性。结果表明:2种脲甲醛(UF和MU)肥料的红外光谱图相似,异丁叉二脲(IBDU)和丁烯叉二脲(CDU)的红外光谱图可反映其结构特征,用红外光谱法可以对脲醛缓释肥料进行定性分析。4种脲醛缓释肥料在水、土两种介质中的养分释放特性有较大的差异。可以用冷水不溶性氮、热水不溶性氮以及活性指数来表征脲甲醛的释放性能,并且活性指数越高,释放速率越快。     

Supercritical carbon dioxide–assisted synthesis of stimuli-responsive magnetic poly(N-isopropylacrylamide)–ferrite biocompatible nanocomposites for targeted and controlled drug delivery

Supercritical carbon dioxide–assisted synthesis of poly(N-isopropylacrylamide)–ferrite nanocomposites was carried out by polymerization reaction of N-isopropyl acrylamide monomer in the presence of ferrite nanoparticles. They were characterized by Fourier transform infrared, X-ray diffraction, transmission electron microscopy, atomic force microscopy, and vibrating sample magnetometry analysis. Drug loading and release profiles were studied. Nanomaterials showed pH-dependent drug release profile. Polymer nanocomposites in comparison to ferrite nanoparticles showed impressive drug release activity, with a release percent of 20.98–76.54%, and greater biocompatibility in breast cancer cells, with a cell viability of 81–93%. This pH-dependent drug release activity and magnetic property of polymer nanocomposites can be used for controlled and targeted drug delivery.