k**3
发帖数: 917 | 1 【 以下文字转载自 Macromolecules 讨论区 】
发信人: kna3 (骨头), 信区: Macromolecules
标 题: 请问:天然纤维遇水变软是什么原因
发信站: BBS 未名空间站 (Wed Jan 16 08:31:01 2013, 美东)
比如羊毛之类，谢谢。 |
k**3
发帖数: 917 | 2 放在学术版，看的人不少就是没有人解答。还是转到佛版请教一下吧。 |
l****n
发帖数: 768 | |
l*****e
发帖数: 8596 | 4 也不是所有天然纤维都会遇水变软吧。
会变软的，具体是persistence length 减小。能想到几个原因
1 觉得可能跟表面的带电有关系。 水的dielectric constant比空气大，会screen一些
电荷作用。 而且如果不是纯水，ionic strength也会further screen
2 亲水的分子和水分子作用，如果作用能比较大，接近甚至达到theta condition，就
会很软 |
k**3
发帖数: 917 | 5
感谢牛牛！
我现在天天写毛笔字，毛笔干的时候弹力很容易感觉到，但沾了墨以后，弹力感觉就减
小了。所以好奇为什么。
请问大拿有何高见？
【在 l*****e 的大作中提到】
: 也不是所有天然纤维都会遇水变软吧。
: 会变软的，具体是persistence length 减小。能想到几个原因
: 1 觉得可能跟表面的带电有关系。 水的dielectric constant比空气大，会screen一些
: 电荷作用。 而且如果不是纯水，ionic strength也会further screen
: 2 亲水的分子和水分子作用，如果作用能比较大，接近甚至达到theta condition，就
: 会很软
|
p******r
发帖数: 6213 | 6 表面吸附＋氢键？
【在 k**3 的大作中提到】
:
: 感谢牛牛！
: 我现在天天写毛笔字，毛笔干的时候弹力很容易感觉到，但沾了墨以后，弹力感觉就减
: 小了。所以好奇为什么。
: 请问大拿有何高见？
|
t*d
发帖数: 1290 | 7 润滑。
【在 p******r 的大作中提到】
: 表面吸附＋氢键？
|
k**3
发帖数: 917 | 8 多谢楼上两位。
表面吸附我有点印象，氢键就不懂了。
润滑好像和吸附有关系，是不是润滑之后，纤维之间的摩擦力减小了，所以感觉笔软？ |
q********1
发帖数: 860 | |
A********o
发帖数: 1307 | 10 天然纤维里的植物纤维和动物纤维都易吸水。当回搬运工：
"The reason why wetting your hair or cotton destroys any shape you've given
it is precisely because it absorbs water. The water then chemically bonds to
the molecular chains, effectively partially dissolving them. Because the
atoms within the chains are now bonded to the water, the links between them
become weakened. That allows them to start slipping past one another again.
In the case of hair, it has a natural shape that is a result of the precise
chemicals it is made of. That is the lowest energy state for the hair. If
the molecular chains are free to slip around they will eventually "fall"
into that shape, and because it is a low energy shape you then need to put a
lot of energy in to get them back out of it. That energy normally comes on
the form of pressure, but if you aren't applying pressure to the hair while
it is wet it's just gonna stay in the low energy natural shape, the way
nature intended it." |
k**3
发帖数: 917 | 11 多谢多谢！
given
to
them
.
precise
a
【在 A********o 的大作中提到】
: 天然纤维里的植物纤维和动物纤维都易吸水。当回搬运工：
: "The reason why wetting your hair or cotton destroys any shape you've given
: it is precisely because it absorbs water. The water then chemically bonds to
: the molecular chains, effectively partially dissolving them. Because the
: atoms within the chains are now bonded to the water, the links between them
: become weakened. That allows them to start slipping past one another again.
: In the case of hair, it has a natural shape that is a result of the precise
: chemicals it is made of. That is the lowest energy state for the hair. If
: the molecular chains are free to slip around they will eventually "fall"
: into that shape, and because it is a low energy shape you then need to put a
|
