anyone good at maths ?
Discussion
trying to make a math model of a polymer molecule to describe the changes in width as it gets stretched out. There is a side group which should rotate as the main chain gets lengthened (bit like a dog's leg), in turn pushing against neighbouring chains (its a liquid crystal polymer).
I've the experimetnal data for the real thing (which does nothing of the sort) but it should make a good comparison versus the model predictions of what we want to happen.
You did ask...
How long before Ted shuts this thread for being boring... ?
I've the experimetnal data for the real thing (which does nothing of the sort) but it should make a good comparison versus the model predictions of what we want to happen.
You did ask...
How long before Ted shuts this thread for being boring... ?
It's not a boring post! Why are you trying to model what the experiment doesn't show? I mean, are you trying to make a polymer that has this behavior (that it spirals as it stretches), and the data you have show that the material doesn't do that? You can have different bulk configurations of the same polymer. Are you a chemical engineer?
You mean... I'm not alone ..?
Actually in materials. Yes we want this behaviour and we've been working with some polymer chemists and trying to get them to make this stuff. They've made some but its not happening (we measure the Poisson's ratio).
That is it's not happening at room temp but it does seem to happen in the smectic state (about 150-200 C). Nice XRD patterns of increasing d space upon stretching.
We think its something to do with the mobility of the side groups. At room temp either the energy hump to get over to push out the side groups is too big , or the angle to the main chain the side groups lie at in the resting state is too big and its started to contract again.
We want to show that we can model the behaviour, even if its not doing what we want by adjusting the angle parameter in the model to fit the data. If we can't then its a fair bet the side groups aren't doing what we think they should (probably the case).
back to the drawing board.
Actually in materials. Yes we want this behaviour and we've been working with some polymer chemists and trying to get them to make this stuff. They've made some but its not happening (we measure the Poisson's ratio).
That is it's not happening at room temp but it does seem to happen in the smectic state (about 150-200 C). Nice XRD patterns of increasing d space upon stretching.
We think its something to do with the mobility of the side groups. At room temp either the energy hump to get over to push out the side groups is too big , or the angle to the main chain the side groups lie at in the resting state is too big and its started to contract again.
We want to show that we can model the behaviour, even if its not doing what we want by adjusting the angle parameter in the model to fit the data. If we can't then its a fair bet the side groups aren't doing what we think they should (probably the case).
back to the drawing board.
I'm a mechanical engineer, so I've only studied a little in materials. I suspect atg is an engineer too. I know the poisson's ratio is the ratio of the elastic deformation in one axis to the elastic deformation in a perpendicular axis (in the face normal to the load) if you're measuring the elastic modulus. This is not my subject, and you probably already know this, but what does it do in shear (torsion) if part of the polymer twists when it's in tension? Probably doesn't give you any more information, since modulus of rigidity (torsion)
G=E/(2(2(1+v)) Well, I have to quit now, since I basically don't know what I'm talking about.
Good luck.
G=E/(2(2(1+v)) Well, I have to quit now, since I basically don't know what I'm talking about.
Good luck.
??? Studied physice many moons ago and now do quant stuff in finance.Gassing Station | General Gassing [Archive] | Top of Page | What's New | My Stuff