Questions tagged [polymers]
Polymers is concerned with the physical properties of individual macromolecules. For questions regarding bulk behavior of ensembles of polymers, the [condensed-matter] tag may be more appropriate.
89 questions
0
votes
0
answers
15
views
What is the relationship between persistence length and timescale?
I have calculated the bending persistence length of a polymer using MD simulations in the nanosecond timescale. The persistence length is long (410 nm) compared to the contour length (40-45 nm). But ...
- 1
0
votes
0
answers
23
views
Drying polymers (e.g. FDM 3D printing filaments)
As far as I understand, a polymer absorb some moisture and amount of (maximum) moisture that can be absorbed depends on its type (PLA ~1%, ABS? ~10%). Both simple commercial filament dryers and drying ...
- 101
1
vote
0
answers
40
views
Partition function 1D polymer chain attached to a spring
Statement of the problem:
Consider a polymer chain consisting of $N$ linked monomer units with $N\gg 1$. Every monomer can be in state $\alpha$ or $\beta$ with energies $E_\alpha$ and $E_\beta$. In ...
0
votes
1
answer
28
views
Polymer scattering isotropic assumption
I am reading the Polymer Scattering wikipedia page (https://en.wikipedia.org/wiki/Polymer_scattering). I don't understand how using an isotropic assumption they have gone from the first equation to ...
0
votes
0
answers
39
views
What will be the effect of density on relaxation time?
I am doing a Monte Carlo simulation of protein chains of various lengths.
I change the densities of the simulation box.
In my experiment, I found that density has no effect on relaxation time.
Do you ...
- 137
0
votes
0
answers
16
views
How can I assess the validity of a time-temperature superposition (TTS) master curve obtained from stress relaxation experiments?
I'm working on analyzing the viscoelastic behavior of a elastomer using time-temperature superposition (TTS) techniques based on stress relaxation experiments. I've come across various conditions for ...
- 1
0
votes
0
answers
50
views
Flory-Huggins Chemical Potential of Mixing
Within FH theory, for a binary polymer blend the following is commonly found:
$$
\mu - \mu_0 = \left(\frac{\partial A_{mix}}{\partial n_A}\right)_{V, T, n_b} =\frac{\partial}{\partial n_a}\left(\chi \...
user345007
0
votes
0
answers
20
views
Small-Angle X-Ray Scattering of Bulk Polymers
Does anyone have any recommendations on how to get useful information from SAXS of polymers when the system is not dilute?
This is the type of data we're working with:
My understanding is that since ...
0
votes
0
answers
36
views
Energy of pulling a polymer
When we have a polymer of $N$ monomers with position vectors $\vec{r}_1, \vec{r}_2, \ldots, \vec{r}_N$, pulled by a force $\vec{f}$, why is the potential energy then given by:
$U = \left( \vec{r}_N - \...
0
votes
0
answers
53
views
Divergence of the Oseen tensor for the Zimm model?
While studying the Zimm model on the Doi & Edwards book "The Theory of Polymer Dynamics", I faced equation 4.41 which states that:
$$
\frac{\partial}{\partial\boldsymbol{R}_j}\cdot\...
1
vote
0
answers
64
views
Material that is one-sided translucent [closed]
Is there a polymer material that is translucent from one side but not from the other side?
I want to build some custom push buttons that should appear completely black. Only when they are led by an ...
- 111
1
vote
0
answers
34
views
Calculating the angle distribution of a worm like chain
I'm trying to calculate a probability distribution of orientation in 3D space for a worm like chain from one segment to another. In particular, I am trying to calculate the probability distribution of ...
1
vote
0
answers
25
views
Why are tears in some plastics hard to start but easy to grow? [duplicate]
Take a generic bag of crisps, or a pack of ice cream: it takes some effort to tear open, you may want to use scissors, but then once you've opened it it's torn so effortlessly that you have to be ...
- 111
1
vote
0
answers
184
views
Partition function for a 1 dimensional polymer
A one-dimensional polymer (a chain), made of (N + 1) monomers, is diffusing on top of a one-dimensional lattice having a lattice constant a = 1. The i-th monomer (i = 0, 1, 2,..., N) is located at a ...
- 129
2
votes
0
answers
69
views
Is a worm-like-chain purely entropic?
I consider a worm-like chain with the Hamiltonian given by:
\begin{equation}
H(L)=\frac{\kappa}{2}\int_{0}^{L}ds\left(\frac{\partial\vec{t}}{\partial s}\right)^2
\end{equation}
where $\kappa$ is the ...
- 175
1
vote
0
answers
25
views
Flory Theory of the real Polymer: Why is the Gain per Monomer contribution proportional to $kT$?
In Flory Theory of the real Monomer (see for example Rubinstein / Colby Polymer Physics, p.102), we want to estimate the free enrgy of a real polymer, that doesn't admit overlaps in the monomers. To ...
- 6,970
0
votes
1
answer
116
views
Expanding ensemble averages
I am reading Statistical Physics of Particles by Kardar. I am struggling with problem 12d, in chapter 2, about semi-flexible polymers in two dimensions. The problem is as follows:
Configurations of a ...
- 707
1
vote
0
answers
206
views
Little's model for superconducting oxidized atactic polypropylene?
Little’s organic superconductor is illustrated by this picture , which is taken from this site, and by his words: “Consider an electron moving along the spine of such a molecule. As the electron ...
- 1,113
1
vote
0
answers
117
views
Derivation of second-order derivative of harmonic potential well
For a harmonic potential well:
\begin{equation}
U(r)=\frac{1}{2}(r-R) \cdot K(r) \cdot(r-R)
\end{equation}
where $R$ is a $3N$ dimensional vector describing the stable conformation of $N$ atoms, and $...
- 121
1
vote
1
answer
42
views
Derivation of probability density of isolated polymers
I am reading Introduction to Polymer Physics by Doi, and in his proof for the probability distribution for ideal polymers of length $N$ and end-to-end vector $\mathbf{R}$, he does the following:
\...
- 707
0
votes
0
answers
179
views
Canonical partition function, simple model of 2D polymer
I am trying to simulate using monte-carlo method the behavior of a simple of polymer.
The model -
The polymer is made of N bars with length a , each bar can be placed in +a or -a relative to
the end ...
0
votes
0
answers
46
views
Discriminate closed-chain from open-chain
I have two classes of chains: closed-chains where a random path ends near where it starts (ie. loop), and open-chains without this restriction (ie. random walk). These chains are a directed graph ...
- 121
0
votes
2
answers
304
views
Having trouble understand why excluded volume effect occurs
In the book of Edwards The Theory of Polymer Dynamics, at page 24 it is given that
2.5 Excluded volume effect
In the models of polymers considered in the previous sections, the interaction among the ...
- 2,313
1
vote
1
answer
154
views
Worm-like chain model integral formula derivation (Kratky-Porod model)
I am having trouble understanding the derivation of the integral formula, most papers just assume the resistance to bending is:
$$\frac{A}{2}\left|\frac{dt(s)}{ds}\right|^2.$$
I have found some ...
- 111
0
votes
1
answer
123
views
Why does burning polythene bags cause shrinkage while cutting them makes no change?
I don't know why polythen bags shrink on burning. But one of my friend informed me that it shrinks because at the time of its processing, the polymer is stretched and when burnt the internal stress ...
- 8,456
0
votes
1
answer
85
views
Converting order parameter to director (nematics)
If I have a differential equation for the order parameter of a uniaxial nematic, like
$\frac{\partial S_{\alpha \beta}}{\partial t} = f(S_{\alpha \beta})$,
for
$S_{\alpha \beta} = S(n_{\alpha}n_{\beta}...
- 35
0
votes
0
answers
150
views
Are the breakdown voltages of silicon dioxide and silicone dioxide the same?
Silicon dioxide has a breakdown voltage of $> 10$ MV/cm [1]. However, I am unable to find any information about the breakdown voltage of silicone dioxide. Since silicone contains oxygen (and ...
- 3
1
vote
1
answer
167
views
Using Persistence length to establish straightness of position data
In the following picture I am showing 3D position data for 4 different tracks just to illustrate how the tracks looks like.
As we can see that we have all kind of behaviors occurring from helical ...
0
votes
0
answers
30
views
Does sputtering Au on top of PEDOT:PSS thin film alter its properties?
I have grown thin films (~100-500 nm) of PEDOT:PSS by electrodeposition on top of thin films of Au (~1 nm) and now I want to measure the impedance of the PEDOT:PSS thin film.
To accomplish this I am ...
0
votes
1
answer
78
views
How does contraction of polyethylene strip depend upon the heat it receives?
Strip is made of polyethylene and is cold drawn so that all polymer chains are oriented in one direction. Now, if heat is supplied to it via external source then how much will this strip contract. Is ...
3
votes
1
answer
77
views
Exploring potential landscape with Monte Carlo
I am using a Monte Carlo approach for studying folding of a polymer chain. The polymer may fold in many configurations, corresponding to local potential minima, studying which is what interests me (i....
- 65k
1
vote
1
answer
2k
views
Temperature dependence of rubber elastic modulus
Why does the elastic modulus of rubber increase with temperature? I read the article on rubber elasticity and it showed that the modulus increases with the temperature (rubber shrinks as heated). But ...
- 59
1
vote
0
answers
57
views
Entropy due to linearization of Freely-Jointed Chain
Say I model a polymer as a freely jointed chain in 3D with N bonds of length L each one. If I stretch the chain (initially coiled) along a 2D surface until it becomes linear (basically a 1D line of ...
- 31
0
votes
1
answer
121
views
Can the UV degradation of polymers be calculated?
Is it possible to calculate the mass lost due to the UV degradation of polymers (like PET or LDPE)?
I have found no information regarding equations or formulas which would provide an answer.
Any ...
- 1
2
votes
1
answer
50
views
Why do stress whitening occur on certain polymers?
In polymers under strain, white lines start to appear first before fracture..what are they? And why they occur?
- 27
1
vote
1
answer
88
views
Text Recommendation: Random Walks (for physicists)
I am an incoming graduate student in Theoretical Physics in the Netherlands, and I would like to know if any of you could recommend texts on random walks with applications to physics. My university ...
1
vote
2
answers
301
views
Solids are crystalline or amorphous. Where do polymers fit in?
Traditionally, solids are classified as being either crystalline (well-ordered, periodic lattice structure at large spatial scales) or amorphous (disordered structure).
A well-ordered polymer is a ...
- 392
0
votes
1
answer
649
views
What is the link between the meaning of excluded volume and its mathematical derivation?
When we examine real polymer chains we have to consider the interactions between single monomers. Therefore we consider a Lennard-Jones-like potential for bringing two monomers together and calculate ...
- 167
0
votes
1
answer
1k
views
One-dimensional polymer (Gibbs canonical ensemble)
Let's consider a polymer that is formed by an horizontal linear chain of $N$ disc-shaped monomers. Each monomer can either adopt either a vertical alignment (with length $l_1$ and energy $E_1$) or an ...
- 1,202
0
votes
1
answer
48
views
Can any body suggest me a set up that I can build it up to study the surface roughness of transparent polymeric fibres? [closed]
I need to study the surface of nylon-6 blank fibres with a thickness of nearly 40 micrometre. I work in optics lab with many optical components such as beam splitters, lenses, mirrors, etc; can I ...
0
votes
0
answers
39
views
Can I build up a profilometry set up, to study the surface roughness of polymer fibres?
I need to study the surface roughness of some fibres, I was told that the best way is the profilometer, but can I design and build up a set up of a profilometer?
4
votes
0
answers
87
views
What does triviality and non-triviality mean in field theory?
I am studying polymer physics and their basic field theoretical models which has connections to $\Phi ^{4}$ field theory. I frequently come in touch with statements about triviality and non-triviality ...
- 131
1
vote
0
answers
22
views
Is there any connection between instantons and surface-interacting polymers?
Excluded volume polymers interacting with a penetrable hypersurface of variable dimension is a very interesting system to study critical behavior via perturbative renormalization. Since a penetrable ...
- 131
2
votes
2
answers
2k
views
Reason for very low speed of sound in rubber
I just came by a table in the Class 11 Physics NCERT textbook, listing speeds of sound in different media.
Vulcanised rubber has an unusually low speed of sound $54\ \mathrm{m}/\mathrm{s}$ as compared ...
- 131
5
votes
1
answer
277
views
Reference Request - Modern Polymer Dynamics
I'm an applied math graduate student studying the cytoskeleton. I wanted to know of any reference(s) providing the most general mathematical theory of polymer dynamics, think an updated version of Doi ...
1
vote
1
answer
1k
views
Derivation of the upper convected time derivative
I read on wikipedia theat the upper convected time derivatvie is the rate of change of some tensor property of a small parcelof fluid that is written in the coordinate system rotating and stretching ...
- 482
1
vote
0
answers
57
views
How to calculate path integral of polymer system?
We have the functional integral $(1)$ of viriable $\delta p_j$. In our case this intergral follows from RPA (random phase approximation) method assuming $\ p_j(r)=p_j^*+\delta p_j(r)$. The task is to ...
- 11
0
votes
0
answers
30
views
Does crosslinking a polymer film increase the stress within the film?
If I crosslink a polymer film, does that increase the internal stress of the film? Intuitively I think it should for entropy reasons; chains with greater links are more restricted and have a smaller ...
- 393
1
vote
1
answer
4k
views
How do UV light curable adhesives work?
How do UV light curable adhesives (such as Loctite's and Permabond's UV glues) work? What gives them the ability to join two non-porous surfaces such as glass-to-glass, glass-to-metal?
Also, do ...
- 167
0
votes
0
answers
52
views
How to theoretically determine thermal emissivity of thin polymeric films?
Maybe someone could help with determining gray-body emissivity of thin films such as polyethylene. There is a lot of conflicting data online with some sources stating polyethylene's epsilon value as 0....
- 383