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.
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Williams-Landel-Ferry (WLF) and Vogel-Fulcher-Tammann (VFT) equations
I'm doing some research on polymers (vitrimers to be precise) and I have recently come across the Williams-Landel-Ferry (WLF) and Vogel-Fulcher-Tammann (VFT) equations. I am struggling to find the ...
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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\...
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How to obtain Non-Equilibrium (NE) Statistical Associating Fluid Theory (SAFT) expressions starting from equilibrium SAFT expressions?
I'm interested in applying Non-equilibrium Thermodynamics for Glassy Polymer (NET-GP) [1] framework to Statistical Associating Fluid Theory (SAFT) variations (e.g PC-SAFT [2]).
In short, the main NE→...
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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 ...
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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 ...
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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
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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
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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 ...
- 145
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Is toughness or elasticity more responsible for Kevlar's bullet resistance?
TL;DR: is Kevlar made bullet-resistant by its toughness or by its elastic modulus?
My understanding of why Kevlar is bullet-resistant is written out below, and is relevant to understanding this ...
- 11
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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 ...
- 6,387
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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 ...
- 627
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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 ...
- 1,023
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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
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1
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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:
\...
- 627
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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 ...
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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
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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 ...
- 2,235
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1
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106
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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
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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 ...
- 7,905
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49
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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
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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 ...
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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 ...
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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 ...
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1
answer
67
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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 ...
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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....
- 54.9k
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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 ...
- 49
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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
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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 ...
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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
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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 ...
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2
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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 ...
- 342
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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
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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 ...
- 1,102
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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 ...
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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?
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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 ...
- 111
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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 ...
- 111
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2
answers
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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
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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 ...
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1
answer
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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 ...
- 465
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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
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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 ...
- 421
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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 ...
- 157
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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
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1
answer
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Linking elastic moduli to shape fluctuations
I am simulating a polymer network shaped as a sphere. I would like to compute its elastic moduli (bulk and Young's, for example) not by their shear-strain definition but by looking at the fluctuations ...
- 1,162
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1
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Why do rubber bands at higher temperatures stretch more?
I did an experiment where i placed a rubber band in water at different temperatures (-15°C till 90 °C) , and then a put a constant mass on the rubber band, to see how far it would stretch.
What i ...
- 11
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2
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Elasticity of rubber bands at varying temperatures
So what i read online was that when rubber bands can stretch (become more elastic) more when their at colder temperatures. How i understood is that entropy allows for the molecules to align up more ...
- 11
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Unexpected behaviour in numerical simulation of polymer
I noticed some strange behaviour when simulating the behaviour of a polymer subjected to an external pulling force at both ends, and would like to better understand its origin.
I used LAMMPS to ...
- 311
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1
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710
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Understanding roles of energy and entropy in different polymer models
Polymers can be modeled as ideal chains and bead-springs (among other various models). However, in an ideal chain, the interactions are entirely entropic, whereas in the bead-spring model, there are ...
- 217
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Relationship between Kuhn length and persistence length
What is the persistence length of poly(N-isopropyl acrylamide)? Is there a definite relation between kuhn length and persistence length? I know that the persistence length is considered to be one ...
- 529