| 查看: 778 | 回复: 7 | |||
| 当前主题已经存档。 | |||
| 【有奖交流】积极回复本帖子，参与交流，就有机会分得作者 lumeng 的 2 个金币 | |||
| 当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖 | |||
[交流]
【求助】NCO基团测定
|
|||
| 如何监测反应液中的异氰酸根的所剩含量啊？滴定法用什么滴定？谢谢大家！ |
回复此楼» 猜你喜欢
材料调剂
已经有7人回复
-
化学工程085602 305分求调剂
已经有10人回复
-
289求调剂
已经有15人回复
-
291 求调剂
已经有7人回复
-
274求调剂
已经有14人回复
-
北京林业大学硕导招生广告
已经有3人回复
-
309求调剂
已经有5人回复
-
292求调剂
已经有8人回复
-
求调剂
已经有4人回复
-
一志愿 西北大学 总分282 英语一62 求调剂
已经有3人回复
china_rocket
木虫 (小有名气)
- 应助: 0 (幼儿园)
- 金币: 3759.5
- 帖子: 159
- 在线: 140.9小时
- 虫号: 424104
- 注册: 2007-07-21
- 性别: GG
- 专业: 高分子
8楼2010-03-23 20:46:31
蓝色游鱼归情
铁杆木虫 (著名写手)
鱼
- 应助: 1 (幼儿园)
- 贵宾: 0.03
- 金币: 8379.9
- 散金: 6
- 红花: 25
- 帖子: 1211
- 在线: 434.3小时
- 虫号: 943848
- 注册: 2010-01-17
- 专业: 高分子合成化学
3楼2010-03-22 20:09:05
4楼2010-03-22 21:10:50
zyming20051
铁杆木虫 (正式写手)
- 应助: 1 (幼儿园)
- 金币: 12498.7
- 帖子: 386
- 在线: 499.9小时
- 虫号: 343106
- 注册: 2007-04-11
- 性别: MM
- 专业: 功能与智能高分子
★
lumeng(金币+2): 2010-03-23 09:00
薰衣草儿(金币+1):版内奖励 2010-03-23 09:24
lumeng(金币+2): 2010-03-23 09:00
薰衣草儿(金币+1):版内奖励 2010-03-23 09:24
|
Determination of % NCO in Prepolymer The method for the determination of the isocyanate level is based on that given by Wright and Cummins (1969). The NCO content of diisocyanates can be determined by the reaction with an excess of a standard solution of dibutylamine in chlorobenzene (or dry toluene) and titration of the excess with hydrochloric acid. The dibutylamine is prepared by dissolving 129 g of freshly distilled dibutylamine in 871 g of redistilled chlorobenzene and storing the resultant solution in the dark. The solution is relatively stable, but it is advisable to determine the amine content weekly by titration with 1 N hydrochloric acid in methanol. In the determination, 2 g of the diisocyanate should be accurately weighed out into a conical flask and 5 ml of chlorobenzene added. In the case of naphthalene diisocyanate, it is recommended that the mixture be warmed slightly to assist dissolution. To this mixture there is then added 25 ml of the standard dibutylamine solution. The reaction is rapid and takes only a few minutes for completion, when a clear solution is obtained. After adding 2 or 3 drops of a 1% alcoholic solution of bromophenol blue and 100 ml of methanol, the excess dibutylamine can be titrated with 1 N hydrochloric acid. If W = weight of sample in grams V1 = volume in ml of HCl solution required for titration of the sample V2 = volume in ml of HCl solution required for 25 ml of dibutylamine solution (blank) %NCO={[4.2*（v2-V1）*N]/1000W}*100 贴上一段 |
6楼2010-03-23 08:52:53
