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# 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 ...
1 vote
172 views

### 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 ...
153 views

### 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 ...
1 vote
40 views

### 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 ...
104 views

### Pressurizing with nitrogen vs vacuum? [closed]

pressurizing with vacuum causes volatilization of liquid.
578 views

### 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 ...
1 vote
223 views

### 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): $$F_{\eta}=\eta \space \frac{du}{dt}.$$
281 views

### Stress relaxation time scale [closed]

What is the definition and physical meaning of "stress relaxation time scale" in (non-Newtonian) fluids?
1 vote
29 views

### 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 ...
4k views

### 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 ...
1 vote
89 views

### 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 ...
3k views

### 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 ...
106 views

### 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 ...
1k views

### 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 ...
3k views

### 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 ...
1 vote
2k views

### 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 ...
1 vote
92 views

### 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 ...
1k views

### 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 ...
1 vote
95 views

903 views

### 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 ...
426 views

### 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}...
384 views

### 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 ...
1 vote
529 views

### 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 ...
103 views

### 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.
753 views

### 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 ...
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-... 