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71.
料温对RIM交联型聚氨酯脲结构与性能的影响 总被引:1,自引:0,他引:1
采用便携式微型反应注射成型机制备了一组料温分别为30,40,50,60℃的交联型聚氨酯脲。用DSC和力学性能对试样进行表征的结果表明:料温提高有利于软、硬微相的混合,而硬链段微区的有序性变差。反映在宏观力学性能上则表现为:试样的拉伸强度提高,伸长率在50℃料温时出现极大值,弯曲强度和弯曲模量则出现最小值。料温为30℃时,物料混合不充分,随着料温升高,混合逐渐均匀,试样透明度提高。 相似文献
72.
介绍中石油宁夏石化分公司二化肥尿素装置的现状,拟采用二氧化碳汽提法对装置进行50%扩能改造,分析改造方案的可行性。 相似文献
73.
Toshihiro Nagao Yuji Shimada Yoshie Yamauchi-Sato Takaya Yamamoto Masaaki Kasai Kentaro Tsutsumi Akio Sugihara Yoshio Tominaga 《Journal of the American Oil Chemists' Society》2002,79(3):303-308
A commercial product of CLA contains almost equal amounts of cis-9,trans-11 (c9,t11)-CLA and trans-10,cis-12 (t10,c12)-CLA. We attempted to enrich the two isomers by a two-step selective esterification using Candida rugosa lipase that acted on c9,t11-CLA more strongly than on t10,c12-CLA. An FFA mixture containing CLA isomers was esterified with an equimolar amount of lauryl alcohol in a mixture of 20%
water and the lipase. When the esterification of total FA reached 50%, two isomers were fractionated in a good yield: t10,c12-CLA was enriched in FFA, and c9,t11-CLA was recovered in lauryl esters. The FFA were esterified again to enrich t10,c12-CLA. At 27.3% esterification of total FA, the t10,c12-CLA content in FFA increased to 64.8 wt% with 89.3% recovery: The ratio of the content of t10,c12-CLA to that of two isomers was 95.9%. Lauryl esters obtained by the single esterification were employed for enrichment
of c9,t11-CLA. After the esters were hydrolyzed, the resulting FFA were esterified again with lauryl alcohol. At 62.0% esterification
of total FA, the c9,t11-CLA content in lauryl esters increased to 73.3 wt% with 79.4% recovery: The ratio of the content of c9,t11-CLA to that of two isomers was 95.6%. In a 600-g-scale purification, molecular distillation was effective in separating
the reaction mixture into lauryl alcohol, FFA, and lauryl ester fractions. 相似文献
74.
Field studies were conducted for two years on a rapidly percolating loamy sand (Typic Ustochrept) to evaluate the effect of green manure (GM) on the yield,15N recovery from urea applied to flooded rice, the potential for ammonia loss and uptake of residual fertilizer N by succeeding crops. The GM crop ofSesbania aculeata was grownin situ and incorporated one day before transplanting rice. Urea was broadcast in 0.05 m deep floodwater, and incorporated with a harrow. Green manure significantly increased the yield and N uptake by rice and substituted for a minimum of 60 kg fertilizer N ha–1. The recovery of fertilizer N as indicated by15N recovery was higher in the GM + urea treatments. The grain yield and N uptake by succeeding wheat in the rotation was slightly higher with GM. The recovery of residual fertilizer N as indicated by the15N recovery in the second, third and fourth crops of wheat, rice and wheat was only 3, 1 and 1 per cent of the urea fertilizer applied to the preceding rice crop. Floodwater chemistry parameters showed that the combined use of the GM and 40 kg N ha–1 as urea applied at transplanting resulted in a comparatively higher potential for NH3 loss immediately after fertilizer application. The actual ammonia loss as suggested by the15N recoveries in the rice crop, however, did not appear to be appreciably larger in the GM treatment. It appeared the ammonia loss was restricted by low ammoniacal-N concentration maintained in the floodwater after 2 to 3 days of fertilizer application. 相似文献
75.
论述了我国发展高浓度复合型肥料的必要性,介绍了以尿素为氮源生产复合肥的特点,以团粒法、料浆法、熔体法和掺混法为代表,介绍了尿基复混肥的生产方法和工艺技术特征。 相似文献
76.
77.
对严重影响大颗粒尿素流化床造粒机尿液喷射系统正常运行的多项故障进行了剖析,从生产技术改造及操作管理方面提出了改进和防范措施,结果表明,改进后装置运行周期从不足10天延长到40天。 相似文献
78.
Christine Baatz Nadine Thielecke Ulf Prüße 《Applied catalysis. B, Environmental》2007,70(1-4):653-660
In this work, two deposition–precipitation methods for the preparation of gold catalysts for glucose oxidation were investigated. Thus far, gold colloids immobilized on carbon have been used for catalytic glucose oxidation, but the long-term stability of these systems was not sufficient. To improve the long-term stability we used the deposition–precipitation methods using NaOH (DP NaOH) or urea (DP urea) as precipitation agents as they were described by Haruta and Dekkers, respectively, using alumina as a support material. With these methods, it was possible to prepare highly active and selective catalysts which showed an excellent long-term stability. DP urea was found to be the preferred method, because in contrast to DP NaOH, no losses of gold occurred during the preparation, and it was possible to adjust various gold contents up to 10 wt% Au. 相似文献
79.
介绍了我国尿素合成在线分析的现状及在取样技术上遇到的困难,针对这一难点,研究设计了旋液分离器及成套系统,经实际应用,效果较好。 相似文献
80.
介绍在团粒法工艺的基础上 ,将尿素熔融成尿液或用尿素车间二段蒸发器的尿液进行喷浆造粒生产复合肥的改造方案、改造内容、改造效果和投资情况。 相似文献