Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [polymers]

For questions about synthetic or natural polymers, their chemical or physical properties, and their synthesis, etc.

1
vote
1answer
33 views

What is the refractive index of poly(methacrylamide)?

I've been looking for the index of refraction for poly(methacrylamide). I searched several vendors and in https://polymerdatabase.com/ with no success. Is there any database where I can find this ...
-1
votes
0answers
14 views

Understanding Polymer Derived Ceramics [on hold]

Polysiloxanes are pre ceramic polymers. What happens (in details) at the atomistic level as the polymer is heated until it reaches its ceramic end product $(\ce{Si_xC_yO_z})$ ?
0
votes
0answers
15 views

How to get polyethylene isophthalate pellets from pellet form into a cast film?

For some research I'm doing, I need to form a cast film from pellets of polyethylene isophthalate. I'm unable to find a listed melt temperature of PEI, although as this is an isomer of PET, I can ...
2
votes
2answers
61 views

Question during radius of gyration calculation from XYZ trajectoris of atoms

I have molecular dynamic simulation result of 100 polymer molecules (liquid), and I'm trying to calculate the radius of gyration using atomistic mass, molecular mass, and xyz coordinate of atoms. I'm ...
2
votes
2answers
39 views

How long does a linear hydrocarbon chain have to be before we call it polyethylene?

Might be a really silly question here but here goes. Polyethylene is a polymer with a repeating unit of just 2 carbon atoms attacked to 2 hydrogens each which connect to other repeat units. This ...
4
votes
1answer
38 views

Why is Buna-S called so?

Styrene Butadiene synthetic rubber is also called Buna-S. It is the abbreviation of Butadiene (Bu) Sodium (Na) Styrene (S). Why is Sodium included?
1
vote
0answers
13 views

How to align povidone-iodine molecules in order to look for optical polarization?

In this answer I mention how early polarizing filters (e.g. sunglasses) were made by doping a polymer with iodine atoms and then stretching the film to orient the polymer molecules. Electrons donated ...
1
vote
1answer
44 views

Role of substituents in radical initialized polymerization

Here, the answer given is (iv), and I don't see the reason why methoxyethene is not forming an addition polymer with radical initiators. Clearly, the first option will form polystyrene and the second, ...
0
votes
1answer
57 views

How to remove MEHQ from Methacrylic acid monomer without reduced pressure distillation?

I am aware that the standard way to remove MEHQ from Methacrylic Acid is to perform reduced pressure distillation. The papers I see suggest using ~ 10 Torr pressure to perform distillation. Sandler's ...
1
vote
2answers
44 views

Are the bonds in the monomers at the end of a polymer filled or unfilled?

In polymers the bonds between monomers are changed, usually from double to single1, to form a long-chain polymer with the now single bond joining another monomer. But in the monomers at the very ends ...
0
votes
1answer
66 views

What is a “tri-salt polymer” as described by this product that eliminates and prevents mold?

This answer mentions an anti-mold product called Concrobium Mold Control. The FAQ linked on their website says: Q: I see Sodium Carbonate listed on the label. Is Concrobium Mold Control just Sodium ...
2
votes
1answer
157 views

Can superglue (cyanoacrylite) be thinned with acetone and still harden?

I'm looking for something with an extremely low viscosity to use as a binder for cold casting iron oxide with very fine detail (it's to make a slotted winding core for an electric motor with $\pu{1mm}$...
5
votes
2answers
1k views

Why does lavender oil dissolve plastic?

A few weeks ago I decided to harvest the lavender in my garden and put it through a still to extract the essential oils. The still in question is essentially just an air cooled condenser. I collected ...
9
votes
1answer
112 views

How can the solid state structure of cyclopentadienyllithium be explained?

In the solid state, LiCp adopts a polymeric multidecker structure where Li atoms are sandwiched between two Cp rings (shown in this diagram from Organometallics 1997, 16 (17), 3855–3858): If we ...
0
votes
0answers
23 views

Is there a non-destructive way to remove acrylic paint from polystyrene?

I've got some plastic miniatures made from polystyrene which are painted with acrylic paint (above a layer of acrylic paint primer). I would like to repaint the miniatures, which requires me to strip ...
4
votes
1answer
120 views

Are there chiral carbons in PVC polymers?

PVC polymers are formed from the monomer CH2=CHCl. Below picture is a section of PVC molecule. Is there any chiral carbon centre in this polymer molecule. If yes, then how? I have a source of CAIE ...
0
votes
1answer
28 views

Are polyhydroquinones considered to be polyphenols?

Looking at the Wikipedia article for polyphenol, I was struck by how the monomer units shown are all substituted meta or ortho for the hydroxyl groups. https://en.wikipedia.org/wiki/Polyphenol#...
3
votes
2answers
168 views

Why is FEP transparent and PTFE not?

fluorinated ethylene propylene (FEP) is close relative of poly(tetra-fluoroethylene) (PTFE), both only contain fluorine and carbon atoms,both have very similiar properties yet FEP is relatively ...
1
vote
1answer
57 views

What's the difference between FFKM and PTFE?

These two fluorocarbon polymers seem to me very similar, the only difference I see is that FFKM is elastomer while PTFE aka Teflon is more of hard type of plastic. Isn't FFKM just PTFE with lower ...
5
votes
1answer
45 views

Do conjugated polymers absorb very low energy photons?

I was reading that in conjugated compounds, the extent of conjugation decides what wavelength photon it can absorb. Longer the conjugation "chain", lesser the photon energy required. So, molecules ...
4
votes
1answer
47 views

Why are some chemicals packaged in incompatable containers?

I've noticed that some organic chemicals are sold in HDPE containers despite compatibility charts indicating that such containers are not appropriate acetone. For example, this acetone listing from ...
4
votes
1answer
57 views

Will PAEK polymers hydrolyze in concentrated sulfuric acid?

One of my duties at the company where I work is to perform intrinsic viscosity (IV) experiments on PAEK (poly(arly ether ketone)) polymers. These polymers don't dissolve well in most solvents, so the ...
1
vote
1answer
19 views

Polycarbonate resistance to acids

If polycarbonate plastic is a polar material with ester bond linkages which usually hydrolyze in acids, why is it resistant to both weak and strong acids (as polar substances)?
0
votes
0answers
58 views

Determining Number-Average Molecular Weight from 29Si NMR Data

I have some $^{29}$Si NMR data for a particular poly(siloxane) polymer that we have isolated from a very dilute solution. I can clearly identify tri-substituted (T) and di-substituted (D) species in ...
7
votes
1answer
108 views

Non-conventional polymers

IUPAC defines a monomer as, A molecule which can undergo polymerisation thereby contributing constitutional units to the essential structure of a macromolecule. Bearing this in mind, I thought ...
0
votes
1answer
69 views

What is the softening temperature of styrofoam?

Does anybody know the softening temperature of styrofoam (expanded polystyrene)? By styrofoam I mean the solid made of expanded polystyrene balls used in packaging.
0
votes
3answers
236 views

What's the monomer in a polycarbonate?

I know what the repeating unit is, but what's the monomer in a polycarbonate?
2
votes
1answer
25 views

Thermoplastic & Thermoset adhesives:

I have a question that is bothering me since few weeks. I'm not a chemist, nor I have any experience with polymers theory, but: Epoxy - is defined on Wikipedia as a thermoset polymer as a process of ...
0
votes
1answer
29 views

Oligomer Terminology

As we know, dimers, trimers etc. can be produced from a certain amount monomers. In the case of a dimer being produced, two monomers dimerise. Let's take an example of a dimer (glycine anhydride): ...
0
votes
0answers
27 views

What decrease the whiteness index of virgin PTFE powder?

I have a friend doing PTFE recycling where scrap PTFE were grind into powder form in a grinding machine where tab water is used for machine cooling. I had been told that high TDS (total dissolved ...
11
votes
2answers
1k views

Why is polyethylene not called polymethylene?

I understand that the monomer that polymerises to give polyethylene is an ethylene, but after polymerisation, the smallest repeating monomer in polyethylene seems to be a methyl and not an ethyl. So ...
1
vote
0answers
21 views

How to predict and measure excess values of reactivity ratios for copolymerization with three monomers?

I ask this question because I haven't found interesting literature on the subject and I would like to know if my way to think is good or pure bullshit. Also the question is quite long because I have ...
0
votes
1answer
77 views

What happens to the chlorine in epichlorohydrin when a two-part epoxy is air-cured?

Where does the chlorine go? Does it evaporate as a by-product or does it remain in the epoxy? I'm using a two-part resin and hardener and curing them at room temp. The resin is bisphenol-A-...
-1
votes
1answer
44 views

Polyamides Reaction mechanism

I already know that polyamides are made through condensation polymerisation with a carboxylic acid and an amine. But how exactly does the mechanism work? If the reaction takes place in acid for ...
5
votes
1answer
263 views

Repeating unit of poly lactic acid (PLA)

Which repeating unit for poly lactic acid (PLA) is correct, picture 1 or picture 2? and I read somewhere that in polymerization, acids give $\ce{OH}$ and alcohol gives $\ce{H}$, creating water. ...
0
votes
1answer
28 views

Lyophilization Advantage

I've been reading about freeze drying and how it increases the shelf life of certain foods and is overall a good preserving technique. My question is with regard to the actual process. I understand ...
2
votes
1answer
48 views

Relating properties and structures of polymers

Why would it be more favorable for a polymer designer to design copolymers with irregular chain structures, rather than design homopolymers? Hint: Discuss intermolecular bonds I understand that ...
1
vote
1answer
25 views

What's the difference between demixing temperature and cloud point?

I am learning something about polymer solution which has LCST phenomenon. But I met researchers used demixing temperature and cloud point to describe the transformation of this kind of solution from ...
1
vote
1answer
37 views

What does it mean for a higher glass transition temperature in terms of crystallinity?

The glass transition temperature is associated with amorphous regions in a polymer. If I have observed in a lab experiment that polymers with a higher glass transition temperature tend to have less ...
1
vote
0answers
35 views

About how long do polymer chains have to be for their physical properties to resemble the polymer more than the monomer? (Or are at least comparable)

For example: According to wikipedia, Styrene is a liquid at room temperature, whereas isotactic Polystyrene does not melt until the 200s celcius. This is a simple property but quite a large change. I ...
0
votes
1answer
85 views

What are the intermolecular forces between polychloroethylene?

Does polychloroethylene have only van der Waals/London forces between its molecules? Surely, if all the chlorine atoms are on one side, due to the fact that chlorine is more electronegative than ...
1
vote
0answers
54 views

Formulation of a suspension of Magnesium Hydroxide

For a school project of mine, I have to formulate a suspension of Magnesium Hydroxide which contains at least 50% of solid matter. This suspension is prepared from Magnesium Oxide 98% with a ...
0
votes
0answers
8 views

where to find data on thermal decomposition of polysaccharide in aqeuous solution

This is a follow up of my previous question: "effect of over-pressure on lowering viscosity of polysaccharide solution" I would like to know where to find data on thermal decomposition of ...
1
vote
1answer
53 views

effect of overpressure on lowering viscosity of polysaccharide solution

it has been reported that agarose dissolved at 110C under slight over-pressure has a viscosity at least 10X smaller than dissolved at atmospheric pressure at 90C (ref:https://doi.org/10.1016/j....
1
vote
1answer
387 views

Calculating the enthalpy of polymerisation of ethylene given the bond strengths

Given the average bond dissociation enthalpies of a $\ce{C-C}$ bond (say $x$) and a $\ce{C=C}$ bond (say $y$), find the enthalpy of the following polymerisation reaction (per mole of ethylene): $$...
0
votes
0answers
28 views

Predict the most stable homocomplex formed in solution on heating a polymeric compound

A solution of the compound shown below is heated to 50 degrees celcius for 30 minutes and then allowed to cool to ambient temperature. The solvent used was chloroform. Predict the most stable ...
0
votes
0answers
224 views

Calculating the conversion in polymerization

From Course outcome(CO) - Published by Anne Hampton (slide 39): Different between step and chain polymerisation % conversion Molecular weighht Molecular weight - In chain polymerisation, ...
0
votes
0answers
66 views

Why is kapton/polyimide not food safe?

This engineering plastic is known to be extremely resistant to heat - it is used for applications like flexible circuit boards that can withstand direct contact with a soldering tip - and would seem ...
3
votes
1answer
257 views

Is teflon a poison if ingested?

Nowadays, a lot of frying pans are made with a non-stick coating. That's usually teflon, or chemically speaking polytetrafluorethylene - $\ce{(C2F4)}_n$. Can you be poisoned if some of that teflon ...
1
vote
2answers
89 views

Good Alternative for Plasticized PVC [closed]

In my current job we use gloveboxes, but unlike most we use disposable PVC bags on the entry ports instead of fixed gloves. The bags have an O ring which is stretched onto a spigot proud of the ...