共查询到19条相似文献,搜索用时 171 毫秒
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采用MDI、PAPI和大豆多元醇为原料,制备包膜尿素肥料.探索并确定了该工艺路线的可行性,研究了树脂型包膜材料,并使用包膜剂对尿素进行了包膜,开展了包膜尿素释放率试验.结果表明,包膜尿素在前15 d尿素没有释放,到30 d的时候,尿素释放率为70%.该包膜材料具有明显的缓释作用,且包膜材料对尿素的物理性能和机械性能有一... 相似文献
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缓释肥料国家标准(GB/T 23348-2009)中规定用25℃静水浸提凯氏定氮法测定包膜型控释尿素释放率[1]。用凯氏定氮仪法测其养分释放率相对繁琐耗时。用对二甲氨基苯甲醛分光光度法测定包膜型控释尿素养分释放率,分别用该法与25℃静水浸提凯氏定氮法测定了同一批次的包膜型控释尿素养分释放率。结果表明,两种方法测定结果之间的相关性极显著。在25℃浸提下用对二甲氨基苯甲醛分光光度法可以准确、较快地测定包膜型控释尿素养分释放率和养分释放期。 相似文献
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聚氨酯/氧化锌复合控释材料对包膜尿素控释性能的影响 总被引:2,自引:0,他引:2
采用折光率法测定包膜控释尿素在水中养分释放特性,以普通聚氨酯包膜尿素为对照,通过研究聚氨酯/氧化锌复合材料包膜尿素的控释性能,探究聚氨酯/氧化锌复合控释材料应用于控释肥料的效果及其可行性。结果表明:聚氨酯/氧化锌复合材料包膜尿素控释性能优于普通聚氨酯包膜尿素,且以氧化锌质量分数为5%复合材料包膜尿素控释性能最佳,适合于作为控释肥料的包膜材料。 相似文献
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The photodegradation of raw natural rubber and natural rubber compound film were studied using an artificial solar energy simulator. The properties of degraded rubber sheets containing benzophenone (BP) were determined by solution viscosity, 1H‐NMR, and FTIR analyses. In the case of rubber compounds containing BP, the changes of tensile strength and crosslinking density were determined. It was found that BP could amply accelerate the photodegradation of rubber. To control the release rate of BP, it was necessary to encapsulate BP with urea–formaldehyde as a matrix. The encapsulated BP or capsule was formed by an interfacial polycondensation reaction between formaldehyde and urea. The kinetic of release rate of BP from urea–formaldehyde capsule was markedly observed within 15 days of release time; after that the rate of BP released from urea–formaldehyde microcapsule was very slow. At the same concentration of BP, the degradation rate of rubber compound by adding BP directly was faster than that of the rubber containing encapsulated BP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 297–305, 2003 相似文献
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包醛酶淀粉吸附性能的研究 总被引:5,自引:0,他引:5
本文介绍了肠溶制剂包醛酶淀粉在尿素溶液中的吸附性能,以及溶液的浓度,pH值,吸附剂用量对吸附性能的影响。结果表明,包醛酶淀粉的吸附速度大于包醛氧淀粉,吸附容量大约是包醛氧淀粉的4倍,当溶液pH〈4时,随着pH值减小,对溶液中尿素的吸附力迅速降低。 相似文献
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《国际聚合物材料杂志》2012,61(14):755-762
The controlled release of urea through mesoporous methylcellulose (MPMC) films with varying concentration of urea (10, 20, 40, and 50 wt%) was studied. It was found that the release of urea from methyl cellulose (MC) films take place through pores as well as through bulk of the MC matrix. The release of urea through MPMC film is independent of the initial concentration of urea. The mass of diffused urea is well fitted to the transport equations. The transport of urea is pseudo-Fickian. The optical study exhibits the compactness of the MC film at the high percentage of urea. 相似文献
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Feng Chen Li Yuan Aijuan Gu Chao Lin Guozheng Liang 《Polymer Engineering and Science》2013,53(9):1871-1877
The encapsulated catalyst can be released under stimulation conditions to control the polymerization reaction. In this study, poly(urea‐formaldehyde) (PUF) microcapsules (MCs) filled with dibutyltin dilaurate (DBTDL) catalyst (PUF/DBTDL MCs) were applied to bisphenol A dicyanate ester (BADCy) resins to develop a novel low temperature cure high performance BADCy/MCs systems. The effect of PUF/DBTDL MCs on the reactivity of BADCy was investigated. The mechanical property, the thermal property, the water uptake, and the dielectric property of cured BADCy/MCs resin systems were discussed in detail. Results indicate that roughly varying the content of the encapsulated DBTDL can easily and safely adjust the polymerization temperature. The BADCy systems with proper content of MCs cured at low temperature show excellent mechanical property, good thermal property, low water uptake, and low dielectric property. When the content of MCs is 0.125 wt%, the cured BADCy/MCs system has the optimal integrated properties owing to the formation of more uniform crosslinked structure and high conversion of cyanate ester (? OCN) groups resulting from the slow release of DBTDL catalyst through the wall shell under heating condition. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers 相似文献
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An efficient method for the prediction of the release characteristics of film‐coated urea from its film structure is proposed. A model spray‐coating apparatus was built to prepare a plane film to directly measure the film permeability coefficients by simulating the characteristics of randomness, intermittence and multiple layers of the coating, and eliminating particle collision effects. From analysis, the spray‐coated film structure can be modeled as comprising a dense structure and a defect structure. Both structures contributed to the penetration flux and the apparent permeability coefficients of the film for water and urea diffusion. The permeability coefficients of the plane films were calculated from the film structure model, and were shown to be close to the measured values. 相似文献