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lumeng

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[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!
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fangxingbaixue

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gxgm111

lumeng(金币+1):红外麻烦 不太方便 2010-03-23 08:59
红外~~~~·
love my guamei forever
2楼2010-03-22 18:56:51
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蓝色游鱼归情

铁杆木虫 (著名写手)

lumeng(金币+2): 2010-03-23 08:59
用HCl-水滴定,朽甲酚绿做指示剂
据说鱼只有七秒的记忆。。。
3楼2010-03-22 20:09:05
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spspmrmr

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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
你去查二正丁胺滴定NCO的方法吧,就是用二正丁胺的醇溶液去滴定含NCO的样品,用溴甲酚绿做指示剂。
4楼2010-03-22 21:10:50
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562408134

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lumeng(金币+1): 2010-03-23 09:00
楼上说的很大
5楼2010-03-22 22:52:29
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zyming20051

铁杆木虫 (正式写手)


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
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sharecool

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对吻鱼(金币+1):鼓励交流~~~ 2010-03-24 18:28
你去查二正丁胺滴定NCO的方法吧,就是用二正丁胺的醇溶液去滴定含NCO的样品,用溴甲酚绿做指示剂。
貌似以前做的时候用定量的二正丁胺来反应,然后用酸来反滴定。网上或者书上可以查到现成的做法。
7楼2010-03-23 09:12:25
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china_rocket

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用二正丁胺反应,用盐酸反滴定
8楼2010-03-23 20:46:31
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