| 查看: 724 | 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 | |||
[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
不自信的我
已经有11人回复
-
北核录用
已经有3人回复
-
要不要辞职读博？
已经有6人回复
-
实验室接单子
已经有3人回复
-
磺酰氟产物，毕不了业了！
已经有8人回复
-
求助:我三月中下旬出站，青基依托单位怎么办？
已经有10人回复
-
26申博（荧光探针方向，有机合成）
已经有4人回复
-
论文终于录用啦！满足毕业条件了
已经有26人回复
-
2026年机械制造与材料应用国际会议 （ICMMMA 2026）
已经有4人回复
-
Cas 72-43-5需要30g，定制合成，能接单的留言
已经有8人回复
fangxingbaixue
木虫 (知名作家)
gxgm111
- 应助: 1 (幼儿园)
- 金币: 3786.3
- 散金: 263
- 红花: 3
- 帖子: 8385
- 在线: 320.1小时
- 虫号: 324877
- 注册: 2007-03-16
- 性别: GG
- 专业: 催化化学
2楼2010-03-22 18:56:51
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
5楼2010-03-22 22:52:29
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
7楼2010-03-23 09:12:25
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