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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Why melting temperature of polymers depends on the prior crystallization temperature?
This graph should show that the melting temperature of a polymer rises when the crystallization temperature of a polymer was higher (the melting temperature of a 100% crystalline polymer should be ...
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Simple model of a polymer
Let's describe a polymer as a linear chain of $N$ links which all have a bendable part. The energies of one link are $\epsilon_-$ (unbended) and $\epsilon_\wedge$ (bended). Additionally, the lengthsof ...
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Can anyone explain this condensation pattern?
What is the hair-like "polymer" that condenses on the caps of the plastic cell vial? Inside vial are cells in a mixture of FBS and DMSO. The vials were frozen slowly in a special isopropanol-filled ...
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How can the presence of a solvent be included in a polymer bead-spring model?
I have a bead-spring model of a polymer melt and I would like to simulate what happens when a solvent is added to the system.
The most direct way to do this would be to add solvent particles into the ...
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Pressurizing with nitrogen vs vacuum? [closed]
pressurizing with vacuum causes volatilization of liquid.
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Molecular Dynamics Software for Coarse Grained Polymers
I am looking around for MD software that I can use to simulating polymers and I can't decide which software I should use.
I would like to simulate the swelling of crosslinked polymers, and I would ...
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Standard linear solid model - dashpot "short out" at $t=0$
My professor said that at $t=0$ the dashpot in standard linear solid is "short out". Why?
I know that the force of dashpot is ($u$ is the dislplacement):
$$F_{\eta}=\eta \space \frac{du}{dt}.$$
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Stress relaxation time scale [closed]
What is the definition and physical meaning of "stress relaxation time scale" in (non-Newtonian) fluids?
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Electret analog of Curie temperature
If you heat a permanent magnet above its Curie temperature then individual dipoles re-align to cancel each other out and it loses its strength.
An electret is the electrical analog of a permanent ...
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What do people mean with "per unit volume" in polymer solutions theory?
I am reading Modern Theory of Polymer Solutions by Hiromi Yamakawa and in the context of the virial expansion the following puzzles me a bit:
"...expanded in terms of solute concentration $c$ (in ...
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Scaling argument for friction force on a chain in shear flow
In her paper entitled "Deformations of One Tethered Chain in Strong Flows", the author makes the argument that given a shear flow velocity $v_x(y)=sy$ in a solution of viscosity $\eta$, and a tethered ...
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Partition function for polymer chain
Supposing that I have linear chain with polymer of $N$ identical particles (interacting harmonically with adjacent particle) with position of first and last particle fixed, how do I find the partition ...
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Is a folded protein's conformation subject to thermal fluctuations?
In biology class we learn that proteins are folded, and that the shape the protein takes affects its bioactivity. Typically we don't go much further into protein shape from that, at least not at the ...
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Hindered rotation model for flexible polymers: deriving the Flory characteristic ratio
In the hindered rotation model we assumes constant bond angles $\theta$ and lengths $\ell$, with torsion angles between adjacent monomers being hindered by a potential $U(\phi_i)$. In Rubinstein's ...
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Difference in viscosity-concentration and reduced viscosity-concentration graphs
I prepared 3 different polymer solutions with varying concentration of 100, 50 and 25 ppm in order to measure their viscosity . When I plot concentration vs viscosity graph in the excel, I have a ...
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Why polymeric solids are said to be intermediate between crystalline solids and amorphous solids?
Crystalline solids have ordered arrangement and amorphous solids do not. Polymeric solids are simply formed by the joining of some monomeric units. It has nothing to do with ordered or not ordered ...
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Effective length factor of a polymer in solution
If one wants to calculate the force needed to buckle a polymer in solution with Euler buckling, what would the effective length factor be? The polymer is free to move and rotate in solution as it sees ...
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Calculating relaxation time
When exploring the viscoelastic properties of glassy polymer like PMMA, there are usually two relaxation mechanism: alpha and beta.
Usually beta relaxation time varies with temperature following ...
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Probability of sequence for given rate constants
Consider a copolymer, $C_{r,s}^A$ containing $r$ number of $A$ monomers and $s$ number of $B$ monomers with $A$ at the reactive end of the polymer. The equilibrium constant for $A$-$A$, $A$-$B$, $B$-$...
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Where I can find information about how helium gas diffuses through different polymer materials
I need more experimental information about helium gas diffusion in solid materials such as different plastics, metals, ceramics etc.
For example I am scientifically curious about what is the polymer ...
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Flory-Huggins ternary phase diagram with a neutral component
I am searching the literature for the Flory-Huggins phase diagram with the following components : polymer, solvent, and a third component that does not interact with the other components (just entropy ...
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Thermodynamics, chaperones: How to model polymer fragmentation?
Living polymers are well described by equilibrium statistical physics. Now I would like to consider a case were living polymers undergo fragmentation due to chaperones. I can think of a kinetic ...
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Entropic force in polymers
According to my textbook, the elastic force in a rubber is caused to the tendency of the polymers to return to their initial disordered state of higher entropy.
But isn't this looking at entropy on ...
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liquid polymers of high molecular weight
We often see a limit of melting point as a function of polymer chain length. Polyethlyene tops at about 190C, and polyethlyene glycol saturates at only 67C no matter how long the chain is:
http://www....
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Deriving equations of motion of polymer chain with Hamilton's equations
This is related to a question about a simple model of a polymer chain that I have asked yesterday. I have a Hamiltonian that is given as:
$H = \sum\limits_{i=1}^N \frac{p_{\alpha_i}^2}{2m} + \frac{1}{...
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Hamiltonian of polymer chain
I'm reading up on classical mechanics. In my book there is an example of a simple classical polymer model, which consists of N point particles that are connected by nearest neighbor harmonic ...
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Semiflexible discrete polymer chain
Suppose we have a 2D polymer model described by a set of 2D vectors {$\mathbf{t}_i$} ($i=1,2,\dots N$) of length $a$.
The energy of the polymer is given by:
$$
\mathcal{H}~=~-k\sum^N_{i=1}\mathbf{t}...
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Computing microstate probabilities based on Boltzmann distribution for chemical systems - Is it rigorous?
One approach to predicting the folded structure of a polymer (DNA, RNA, protein) is to compute the probability that any particular part of the polymer $x_i$ is "paired" with another part of the ...
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helmholtz free energy of a polymer
You have a polymer chain of $N$ units, which is represented by $N$ independent springs in series. The springs are Hookean, with spring constant $L$, and the end to end vector is $\mathbf r$. So the ...
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Good references for specific heats
Does anyone know of a good reference for specific heats? It seems that it is no longer popular to publish values. I am especially interested in the specific heats of polymers.
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The entropic cost of tying knots in polymers
Imagine I take a polymer like polyethylene, of length $L$ with some number of Kuhn lengths $N$, and I tie into into a trefoil knot. What is the difference in entropy between this knotted polymer and ...
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Force curve associated with squeezing a worm-like chain (WLC) between two parallel plates
Let's say I have a polymer, of contour length $L_p$ and persistence length $P$, positioned between two parallel plates separated by a distance $z$. I slowly squeeze the plates together until only two-...
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Entropy of a polymer contained in a sphere with infinitely thin chords
Imagine that I have a polymer (approximated as a freely diffusing, freely jointed chain with some number of subunits 'N'), and I place this polymer into a sphere of some volume 'V'. Next, I proceed to ...
MorningCoffee1998