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。     

以松香和桐油为成膜物质的包膜尿素的释放特性和表面形貌

以松香和桐油为成膜物质制备了一系列包膜尿素,用浸泡溶解法和无土柱淋溶法表征了所得包膜尿素的释放特性,用扫描电子显微镜研究了包膜尿素的表面形貌,讨论了涂覆成分、涂覆层数、密封层对包膜尿素释放特性的影响。采用双层涂覆和单层外密封工艺制备的包膜尿素其一天溶解释放率为12.7％,释放周期大于11天,累积释放率为80％。     

肥料用聚苯乙烯包覆膜的制备及其性能的研究

利用废弃聚苯乙烯泡沫塑料为主要材料,对尿素进行包膜来生产缓释化肥。筛选乙酸乙酯或甲苯为溶剂,邻苯二甲酸二丁酯为的增塑剂降低聚苯乙烯的脆性,SBS树脂为增强剂提高聚苯乙烯膜的附着力。结果表明,包膜液的浓度12 %,增塑剂的用量3 %,增强剂用量1 %,包膜肥料的包膜量为10 %。用氮素水中溶出率法和土壤淋溶法研究包膜尿素缓释效果,肥料初期溶出率均低于40 %,在土壤中累计溶出率比普通尿素有大幅降低。说明聚苯乙烯经过改性后对尿素包膜,制得缓释肥的缓释性能良好。     

用聚合物乳液为包膜剂制备缓释尿素

介绍了采用聚合物乳液作为包膜剂制备包膜缓释尿素,具有工艺简洁和包膜过程绿色的特点,能够根本解决现有包膜过程中毒性有机溶剂的污染和回收问题。实验考察了聚合物乳液包膜剂平板成膜时的渗透系数,表明聚合物乳液是良好的缓释包膜剂。实验采用转鼓流化床工艺制备包膜尿素,测定了包膜尿素在水中的释放特性。通过扫描电镜检测包膜尿素和膜层的形貌特征。结果表明,采用聚合物乳液直接对尿素颗粒包膜时,在颗粒表面形成的高湿性环境容易导致尿素表面溶解,水分蒸发后形成针状尿素结晶,复合在聚合物膜层中,包膜尿素进入水中时,针状尿素快速溶出,造成膜层多孔性渗漏,降低了包膜尿素的缓释性能。在聚合物乳液包膜前,先在尿素颗粒表面包覆一层硫磺阻隔层或石蜡疏水层,能有效抑制尿素在包膜时的溶出过程。     

调理剂对醇酸树脂包膜尿素缓释性能的影响

以颗粒尿素为核心,醇酸树脂为膜材料,淀粉、高岭土、硅藻土、松香、氧化钙等为调理剂,制备了一系列不同膜厚度的包膜尿素。利用水浸泡法考察了调理剂种类及包覆量对包膜尿素的缓释性能的影响,并利用SEM对包膜尿素的表面及界面进行了观察。结果表明,醇酸树脂是一种良好的膜材料,实验所选用的几种调理剂中以高岭土的效果最好,淀粉的效果最差;粒尿素膜的包覆量的增加,缓释性能也逐渐加强。     

肥料用聚苯乙烯包覆膜的制备及其性能研究

利用废旧聚苯乙烯泡沫塑料为主要材料,对尿素进行包膜来制备缓释化肥。筛选乙酸乙酯或甲苯为溶剂,邻苯二甲酸二丁酯为增塑剂来降低聚苯乙烯的脆性,苯乙烯-丁二烯-苯乙烯(SBS)树脂为增强剂来提高聚苯乙烯膜的附着力。结果表明,包膜液的浓度为12%,增塑剂的用量为3%,增强剂用量为1%,包膜肥料的包膜量为10%。用氮素水中溶出率法和土壤淋溶法研究包膜尿素缓释效果,肥料初期溶出率均低于40%,在土壤中累计溶出率比普通尿素有大幅降低。说明聚苯乙烯经过改性后对尿素包膜,制得缓释肥的缓释性能良好。     

具有吸水保水功能的改性魔芋共聚物包膜缓释尿素的制备及其性能研究

以烯丙基硫脲改性魔芋葡甘聚糖为包膜剂制备包膜缓释尿素。对包膜缓释材料进行扫描电子显微镜(SEM)表征,并分析其吸水性能;评价温度及土壤水含量对包膜缓释尿素氮素溶出率的影响,利用土柱淋溶法检测包膜缓释尿素的缓释效果,并分析缓释尿素对白菜的生长影响。结果表明,烯丙基硫脲接枝魔芋葡甘聚糖在接枝率为35%~45%时,吸水性能最好,吸水量高达794 g/g;随着温度和土壤水含量的升高,包膜缓释尿素氮素溶出率逐渐增加;氮素溶出具有典型的缓释肥溶出特征,表现出良好的缓释效果;白菜对缓释尿素中氮素的利用率提高。     

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。     

具有吸水保水功能的缓释尿素的制备及其性能

以丙烯酸、丙烯酰胺、氨水,尿素、磷酸镁铵和腐殖酸钠等为主要原料,制备了一种既具有缓释性又可吸水保水的双层包膜尿素.对其制备条件进行了优化,得产品含氮量为26.3%,常压下吸自来水95倍;研究了产品在土壤中的吸水保水性和缓释性,推测了其释放过程机理;并通过扫描电镜检测了包膜尿素和膜层的形貌特征.结果表明:试验土壤中加入1%本产品,最大持水率提高14.3%,水分蒸发率明显降低,土壤具有很好的吸水保水性能,养分释放率在一个月内不超过80%.     

聚氨酯包膜缓释肥的制备及性能的研究

采用无溶剂喷涂成型法制备了聚氨酯包膜缓释肥,讨论了喷涂比例对包膜量和耐磨性的影响以及不同包膜量对缓释性能的影响。结果表明,聚氨酯预聚体与扩链剂的喷涂比例为7.50∶1、实际包覆量为7.23%时,包膜缓释肥的初溶率范围在10.00%~12.50%、微溶率范围在1.80%~2.40%,包膜效果最好;包覆肥颗粒的表面光滑度、均匀度和耐磨性能好,优于日本产包膜肥。     

Encapsulation of aliphatic amines into nanoparticles for self-healing corrosion protection of steel sheets

A noble approach based on the encapsulation of corrosion inhibitors has been presented, which are capable of improving the active corrosion protection without negatively influencing the barrier properties of the coating layers. Polymeric nanocapsules loaded with six types of amine corrosion inhibitors were synthesized by multi-stage emulsion polymerization. Depending on the basicity and water solubility of amines, different amounts of releasable corrosion inhibitors were encapsulated into the polymer capsules. Encapsulated organic amines were generally well released under alkaline conditions, and linear amines were more easily released from inside capsules than branched ones. The nanocapsules were incorporated into the coating resin and were coated on cold-rolled steel sheets to investigate corrosion protection efficiencies. The corrosion inhibitive efficiencies of the nanocapsule-containing coating layers were evaluated by electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). In this study, it was revealed that the intrinsic properties of the amines as well as their encapsulation/release behaviors determined the barrier property and self-healing protection capability of the coating layer.     

Determining permeability of coatings of polymer-coated urea

Permeability of polymer coatings on urea varies greatly with the type of polymer. A conventional test of measuring the effectiveness of coating involves a 7d static dissolution rate of coated urea into concentrated urea solution, but the results are only qualitative. Our approach was, instead, to make quantitative measurements of permeability, and so make more accurate predictions of release rate of urea across a membrane. A simple device, consisting of a container attached to vertical pipes at the bottom, was constructed to determine permeability of coats on urea granules. A turbulent flow of water ran over a 2 cm pack of coated-urea granules so urea did not accumulate at the outer surface of the coated granules. Separate determinations with two thicknesses of coats (8.8 and 14.7µm) were conducted with water at 12 or 31°C. Permeability and activation energy of permeability were calculated. A comparison was also made between release rate of urea calculated from permeability and that determined by 7d dissolution rate method at 23°C. Nearly 100 h were required for 100% release with the thick coating, but only 20% urea was released after 168 h with the 7d dissolution rate method.     

改性聚乙烯醇添加酒糟制备缓释肥包膜材料的表征及其性能

采用聚乙烯吡咯烷酮（PVP）,通过溶液共混的方式对聚乙烯醇（PVA）进行改性,添加酒糟（JZ）制备复合包膜材料,并对氮肥进行包膜制备缓释肥料。研究了JZ的添加量对复合包膜材料性能以及包膜肥料缓释性能的影响。结果表明：JZ与各组分之间通过氢键作用相互结合,相容性良好;JZ的添加使复合膜材料热稳定性得到了显著提高;120d PUPZ5复合包膜材料降解率相比未添加JZ提高了20.11%;随着JZ的加入,复合包膜材料的机械性能先增加后下降,当JZ与PVA的质量比为15∶100时复合膜材料的力学性能达到了20.75MPa,比未添加酒糟提高了528.79%,且缓释肥料具有良好的缓释性能,可以通过调节JZ在复合包膜材料中的含量来控制缓释肥料中N的释放速率。     

可生物降解PBAT包膜尿素缓释肥料的制备与性能研究

以可生物降解PBAT为包膜材料,通过循环流化床工艺制备一系列PBAT包膜尿素缓释肥料,并对制备工艺进行了优化;通过扫描电镜观察包膜肥料表面形态特征,分析缺陷形成原因;通过水中静置法测试PBAT包膜尿素缓释肥料的缓释性能,测定缓释曲线,样品的初期释放率为20%~50%,第28天的累积释放率为70%~90%。     

Prediction of Release Characteristics of Film‐Coated Urea from Structure Characterization Data of the Film

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.     

聚氨酯包膜尿素的制备

用异氰酸酯与聚氧化丙烯二醇(PPG)合成聚氨酯,再以其包裹尿素制成聚氨酯包膜尿素.采用比色法绘制聚氨酯包膜尿素的缓释曲线,讨论了异氰酸酯与羟基摩尔比(NCO/OH)、包膜率、反应方式、异氰酸酯、PPG分子量对包膜尿素缓释性能的影响.结果发现,以丙酮为溶剂,NCO/OH为1.1,在50～60℃的水浴温度下,PPG-300...