a********0
发帖数: 34 | 1 Conceptually, viscosity and internal friction is the same thing. But you can
measure it by different means, resulting in different quantities and units.
Viscosity is a measure of stress at a certain strain rate. Glass's viscosity
may be very high but because it can still flow its viscosity is still
finite. You can directly measure viscosity based on its definition.
I don't know much about "phonon lifetime" but I guess you are talking about
some mechanical relaxation test, probably using acoustic... 阅读全帖 |
|
d*****i
发帖数: 213 | 2 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
d*****i
发帖数: 213 | 3 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
d*****i
发帖数: 213 | 4 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
d*****i
发帖数: 213 | 5 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
d*****i
发帖数: 213 | 6 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
d*****i
发帖数: 213 | 7 按照下面的解释，viscosity的意义仅在于让机油在高温时仍然黏在金属表面上，但跟
lubricity并没有直接关系。那么也就是说我们买机油用来参考的标号其实完全不对应
机油的润滑性能？
那么机油的润滑性能能通过什么方式查到吗？
http://in.answers.yahoo.com/question/index?qid=20110609104051AA
Viscosity is just the thickness of the lubricant. You could have a lubricant
like grease mixed with solid lard and have a very high viscosity, but the
lard would actually reduce the lubricity.
The lubricity just refers to the actual slipperiness of the lubricant. You
could have a solid lubricant like lithium or graphit... 阅读全帖 |
|
c*********e
发帖数: 119 | 8 Are you kidding or donot really know that?
IV=limit((Nr-1)/c),c->0
or, IV=limit(Nsp/c), c->0
Nr---relative viscosity=N/No, where,N--viscosity of solution, No--viscosity of
pure solvent
Nsp--specific viscosity=Nr-1
用 |
|
d*****i
发帖数: 213 | 9 base oil本身有润滑性，然后一些additive增加润滑性。
但我这里问的是这个润滑性为什么不在参数里面。
比如下面是Mobil 1 5W-20的参数，没有一个参数是直接描述lubricity的。
Mobil 1 5W-20
SAE Grade 5W-20
Viscosity @ 100ºC, cSt (ASTM D445) 8.9
Viscosity, @ 40ºC, cSt (ASTM D445) 49.8
Viscosity Index 160
Sulfated Ash, wt%, (ASTM D874) 0.85
HTHS Viscosity, mPa•s @ 150ºC (ASTM D4683) 2.75
Pour Point, ºC (ASTM D97) -43
Flash Point, ºC (ASTM D92) 230
Density @15º C g/ml, (ASTM D4052) 0.852 |
|
h******g
发帖数: 600 | 10 高分子溶液的viscosity会随着浓度上升而上升，小分子溶液的viscosity会不会随着浓
度增加而增加呢？似乎会吧？请高手指点一二，谢谢了。 |
|
h****l
发帖数: 7290 | 11 There are laminar viscosity and Turbulence viscosity.
Laminar viscosity is the same everywhere, but turbulence one
is not, it related to flow condition. |
|
O***e
发帖数: 89 | 12 In liquid, viscosity has the unit of Pa.s, in glasses, there is also
viscosity with a much larger number, but there is also internal friction,
whose unit is Hz to characterize the life time of phonons, some papers
mentioned they are the same thing and I am confused, what is the connection
between them?
In liquid, my boss mentioned Debye model for relaxation time t changing with
temperature,when wt=1, viscosity is the maximum. Anyone know a textbook
about this?
Thanks very much! |
|
w********h
发帖数: 12367 | 13 what you said is very familiar to a polymer scientist like me.
there are indeed several good books on that if one wants to know that better.
Rubinstein and Colby's Polymer Physics and Ferry's Viscoelastic Properties
of Polymers.
I have to point out two things I won't agree:
(1) Maximum G" does not mean maximum viscosity in the spectrum of dynamic
frequency sweep.
(2) Even some items can be correlated, for example, viscosity and relaxation
time,
but they are different quantities with different un... 阅读全帖 |
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T********k
发帖数: 94 | 14 There are two types of viscosity: shear and bulk.
shear viscosity applys to fluids and has units Poise or Pa s
bulk viscosity relates to the energy lost in internal frictions. it should
be used in solid case.
thoughts:
liquid
of |
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t*****e
发帖数: 15794 | 15 昨天看见两件衬衣，一件长袖，一件短袖，
手感很像麻，很垂又透气的感觉，
土人一个，看见写的材料是viscose,也不认识。
就糊涂着买了。
回家查了下：
Viscose in its most commercial form is rayon. It has a silky feel, and is
used extensively for clothing manufacture. Though it breathes like cotton
and has a good drape, it can wrinkle easily and shrink in hot water.
貌似水洗容易起皱，每次还要熨。
有高人指点下吗？
要是真得这么麻烦的伺候，就去退了算了。 |
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l**********g
发帖数: 55 | 16 Given the viscosities and refractive indices of two miscible solvents, and
the volume ratio of the two solvents, how can I calculate the viscosity and
RI of the mixed solvent?
thanks!! |
|
l**********g
发帖数: 55 | 17 Given the viscosities and refractive indices of two miscible solvents, and
the volume ratio of the two solvents, how can I calculate the viscosity and
RI of the mixed solvent?
thanks!! |
|
l**********g
发帖数: 55 | 18 Thanks, so how can I calculate viscosity? mass ratio or?
because when i use DLS for a mixed solvent, i have to enter the viscosity
and RI of the mixed solvent, that is where my question comes from.
thanks again!! |
|
s**********8
发帖数: 25265 | 19 【 以下文字转载自 Chemistry 讨论区 】
发信人: skycaptain08 (太尉), 信区: Chemistry
标 题: 请教polymer inherent viscosity 和 温度。 20bz
发信站: BBS 未名空间站 (Fri Sep 7 13:30:24 2012, 美东)
inherenet viscosity 和温度关系是啥？ sample flow time 和 T0 都随温度变， 是
不是就彼此抵消了， 影响不大？
谢谢。 |
|
c****5
发帖数: 2 | 20 楼主超有钻研精神的！
其实用viscosity表征机油还是比较合理的。因为Viscosity属于机油本身的性质，跟用
在什么发动机上没有关系。Lubricity很少用来表征在机油性质，如果用的话，不光跟
机油的性质有关，还跟什么发动机有关，跟发动机有关就更复杂了，每个牌子的车都不
一样，就算一个牌子，不同年，不同型号，基本上wear也都不一样，所以就很难有统一
标准。
如果楼主想给自己的车选机油，要看目的是啥，是省油呢，还是保护发动机呢，还是别
的。一般来说按照车本省推荐的机油来选是比较安全的。 |
|
k*******n
发帖数: 190 | 21 When engine is running, the film thickness between the contact surfaces is
mainly determined by the speed, the viscosity.If the film thickness is too
thin, then there will be wear problem in that contact area(in bearings,
pistons etc) So the viscosity is the main effector in the Elastohydrodynamic
Lubrication. |
|
k*******n
发帖数: 190 | 22 When engine is running, the film thickness between the contact surfaces is
mainly determined by the speed, the viscosity.If the film thickness is too
thin, then there will be wear problem in that contact area(in bearings,
pistons etc) So the viscosity is the main effector in the Elastohydrodynamic
Lubrication. |
|
|
s*********d
发帖数: 912 | 24 viscose是粘胶纤维， rayon是人造棉。人造棉指短纤维的粘胶纤维。粘胶纤维还可以
做成像丝绸的质感，我倒是没见过像麻的。 应该可以机洗， 容易起皱，但是皱了喷上
水挂一会儿就好了。 |
|
p****u
发帖数: 1940 | 25 老板想要下面这些东西溶液的viscosity，不知道我应该在什么地方查找？
Norleucine
Phenylalanine
1-octanol
Na+ Octanoate
Glycerol
Xylose
DHA
Glucose
Sucrose
Sorbital
Trimethylamine
Betaine
Proline
Sarcosine
那个大虾能给点方向阿？ 跪谢！！！ |
|
p****u
发帖数: 1940 | 26 crc hand book?
看了一下，不过里面fluid properties
viscosity 那里没有说明白浓度是多少，看得我想杀人。。。
还是我太愚蠢了 |
|
s**********8
发帖数: 25265 | 27 inherenet viscosity 和温度关系是啥？ sample flow time 和 T0 都随温度变， 是
不是就彼此抵消了， 影响不大？
谢谢。 |
|
l*****g
发帖数: 556 | 28 RI yes.
Viscosity depends.
and |
|
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D********g
发帖数: 533 | 30 因为根据经验和Stribeck Curve，很多时候粘度大的时候在金属表面形成的保护膜也比
较厚。不过润滑油的viscosity grade主要并不是标定它的lubricity的。只是表示它的
粘度性能的。
lubricant
't |
|
x******a
发帖数: 6336 | 31 Øksendal, Bernt(N-OSLO); Reikvam, Kristin(N-OSLO)
Viscosity solutions of optimal stopping problems. (English summary)
Stochastics Stochastics Rep. 62 (1998), no. 3-4, 285–301.
my email: l******[email protected]
多谢。 |
|
c*******n
发帖数: 1648 | 32 Suppose I have a shear thinning liquid flowing in a complex geometry
as a pressure flow。Is the viscosity the same everywhere regardless diff。
shear rate everywhere？How to justify this from math？
Furthermore，if I have two components in the flow，
one is more viscous than the other， how to justify the less viscous one
always goes to high shear rate region？THANK YOU！ |
|
s*i
发帖数: 5025 | 33 If it is Newtonian material, its viscosity is constant. |
|
s*i
发帖数: 5025 | 34 I think it is easy to understand that low viscosity component will flow faster,
because that requires less energy to do so. |
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c*******n
发帖数: 1648 | 35 Thank you! Almost all polymer flow are laminar. I knew the viscosity should be
the same, because it's like a boundry conditions sometimes for solving the
problem. However, because I am a polymer chemisty major, I felt difficult to
understand why this happen. I always feel difficult when I want to ask why on
lots of things in Non newtonian fluid mechanics. |
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t*****o
发帖数: 74 | 36 if temeperature is changing, viscosity changes too
it's true in most polymer chemisty
be
on |
|
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k*******n
发帖数: 190 | 38 同一种机油,在不同的发动机,不同的往复和旋转的部件中,磨损或是润滑的效果是不同
的.
对于机油来说,viscosity(不同温度下的)是最好的分类方法. |
|
d*****i
发帖数: 213 | 39 从这一点上来说，我同意把粘度作为标号，因为如果粘度用错了，润滑油本身的润滑性
能都是白扯。
但是在同一粘度里面，难道机油的润滑性能就没有差别了吗？
比如Mobil和Shell各自生产的5W-30的润滑油，在viscosity方面类似，但是他们在润滑
性能方面应该有区别吧？ |
|
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k*******n
发帖数: 190 | 41 同一种机油,在不同的发动机,不同的往复和旋转的部件中,磨损或是润滑的效果是不同
的.
对于机油来说,viscosity(不同温度下的)是最好的分类方法. |
|
d*****i
发帖数: 213 | 42 从这一点上来说，我同意把粘度作为标号，因为如果粘度用错了，润滑油本身的润滑性
能都是白扯。
但是在同一粘度里面，难道机油的润滑性能就没有差别了吗？
比如Mobil和Shell各自生产的5W-30的润滑油，在viscosity方面类似，但是他们在润滑
性能方面应该有区别吧？ |
|
|
O***e
发帖数: 89 | 44 Thanks very much for up floorers and your discussions, here is my thoughts:
definition of viscosity as shear stress/velocity gradient is clear in liquid
and glass, but the internal friction is not that cleat to me. In soilds
like glass, some papers mention it as the ratio of acoustic phonon full
width of half maximum(FWHM) and acoustic phonon frequency(f, f is at GHz
level) IF=FWHM/f; in liquid, it should be the same definition and from the
unit, I think FWHM(inverse of the phonon lifetime) is ... 阅读全帖 |
|
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a********s
发帖数: 575 | 46 Should we change oil every 3000 miles like Dad did?
It depends on conditions, so I have included an article from Consumer
Reports to help you decide.
Our 4-1/2-million-mile test with a fleet of New York City taxicabs turned
some conventional wisdom on its head.
Mobil commercial claims its oil "has been in more Indy 500 winners than any
other oil." Quaker State shows an engine with a terminally corroded inside
what they imply could happen when you use another oil. Exxon's commercial
for its Super... 阅读全帖 |
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p*********e
发帖数: 32207 | 47 ☆─────────────────────────────────────☆
yeemartin (猪头) 于 (Mon Aug 17 05:10:38 2009, 美东) 提到:
看了一篇的文章
有解释为啥Shell Rotella T、Mobil Delvac这些heavy duty diesel oil的Used oil
analysis结果都很突出的原因，普通engine oil是S certification，例如SJ、SM。商
用truck engine oil是C certification， 目前是CI、CJ。C的additive package比S的
牛x很多，但有可能会不兼容乘用车上的catalytic converter。
我的G35目前就在用Shell Rotella T，摩托车下次换油也准备用这个。mobil的
synthetic motorcycle oil 1 quart 12刀，受不了。
Commercial (Diesel) Oil
The additive packages for C (commercial) certification... 阅读全帖 |
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c*********d
发帖数: 9770 | 48 http://baike.baidu.com/item/viscose/1883570
viscose 编辑
Viscose：译为粘胶，Viscose面料是由粘胶纤维纺织而成的。兰精集团生产第一代纤维
素纤维– 粘胶（Lenzing Viscose®)，已经有70多年的历史。其生产粘胶纤维的
专业技术充分体验在兰精粘胶的优质质量中。现在，兰精粘胶的质量更被业界设定为工
业标准。
粘胶纤维是最早投入工业化生产的化学纤维之一。由于吸湿性好，穿着舒适，可纺性优
良，常与棉、毛或各种合成纤维混纺、交织、用于各类服装及装饰用纺织品。粘胶纤维
是一种应用较广泛的化学纤维。
ダウン日
【ダウン】【daunn】①
1. 【英】down ;落下，降落，下降。（下がること。落ちること。）
コスト・ダウン。/成本降低； 落价。
2. 倒下，击倒。（ボクシングで、倒れること。）
ノック・ダウン。/击倒。
3. 羽绒服。（「鳥の胸毛、羽毛」の意で、それを詰めてジャケットにしたものを言
う。
4. 極寒地の軍服や作業服に用いられたものだが、現在では冬のカジュアルウェアと
して... 阅读全帖 |
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b***z
发帖数: 2723 | 49 The Society of Automotive Engineers (SAE) has established a numerical code
system for grading motor oils according to their viscosity characteristics.
SAE viscosity gradings include the following, from low to high viscosity: 0,
5, 10, 15, 20, 25, 30, 40, 50 or 60. The numbers 0, 5, 10, 15 and 25 are
suffixed with the letter W, designating their "winter" (not "weight") or
cold-start viscosity, at lower temperature. The number 20 comes with or
without a W, depending on whether it is being used to ... 阅读全帖 |
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s**********a
发帖数: 18 | 50 The viscosity is controled by two factors: entanglement and Van der waals
force.
entanglement is decided by molecular weight and chain flexbility. HMWPE has
very high viscosity. Usually PE has higher viscosity than PP because the
entanglement.
Van der waals force is also important. at the same temperature and molecular
weight level, high van der waals force gives high viscosity. PC has higher
viscosity than PE. |
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