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

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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 ...
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0answers
15 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 ...
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4 views

Are organic and metal based PVC stabilisers compatible?

I have a PVC compound containing a metal based stabiliser and another constituting organic based stabilisers. Can I run the two PVC formulations in the same factory? Moreover I'm currently using ...
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0answers
13 views

What makes paint mildew resistant at a molecular level?

What makes (water soluble) paint mildew resistant at a molecular level? Is it because the binder polymer can kill or suppress mildew somehow? Or is it more related to the way the paint surface forms?
2
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1answer
54 views

Chirality on Carbon of PVC molecule

PVC polymer is formed by a monomer CH2=CHCl. Below picture is a section of PVC molecule. My question is: Is there any chiral carbon centre in this polymer molecule.If yes, then how? I have a source ...
0
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1answer
25 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#...
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2answers
51 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
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1answer
36 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
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1answer
39 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
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1answer
37 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
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1answer
52 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
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1answer
18 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)?
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33 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
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96 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
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1answer
22 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.
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3answers
57 views

What's the monomer in a polycarbonate?

I know what the repeating unit is, but what's the monomer in a polycarbonate?
2
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1answer
23 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 ...
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0answers
22 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): ...
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0answers
24 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 ...
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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 ...
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0answers
12 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 ...
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1answer
31 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
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1answer
80 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
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1answer
23 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
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1answer
44 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 ...
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0answers
17 views

Is there any one who knows what kind of material it is in this video or similar materials which can achieve the same effect?

Here is the video: https://www.youtube.com/watch?v=1BaYViGWazI Here is an reference related to the similar topic: What are some materials that expand a lot proportionally to heat? Here is the material ...
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0answers
15 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 ...
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1answer
20 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 ...
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0answers
27 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
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1answer
72 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 ...
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0answers
44 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 ...
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0answers
5 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
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1answer
52 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....
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1answer
92 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): $$...
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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 ...
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108 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, ...
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0answers
53 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
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1answer
87 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 ...
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2answers
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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 ...
0
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1answer
104 views

Hydroxyl group to free amine in polyethylene glycol using CDI?

For converting $\ce{OH}$ of methylated polyethylene glycol. The first step is converting hydroxyl group to imidazole carbamate as an active intermediate. But what about the next step? If I will add ...
2
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1answer
55 views

Is it possible to melt HDPE to a point where it has similar viscosity to engine oil?

I have a few pieces of HDPE that I want to melt and cast into a cube of around $\pu{5 cm}$ each side, similar to what one would do with cast resin. I tried putting it into an oven and heating it to $...
0
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1answer
33 views

First and last unit of polyethene

Is a hydrogen atom bonded to the first and the last unit of polyethene? If yes, where does the hydrogen come from?
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23 views

Mechanism behind colloidal suspension

There are two most common ways to stabilize colloids -- electrostatic stabilization and steric (or polymer mediated) stabilization. To my understanding, most of the electrically stabilized ...
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0answers
42 views

Long-term durability of linen vs polyamide vs polyester?

What is the comparative long-term durability of linen vs polyamide vs polyester when exposed to oxygen, but not sunlight? I assume that linen, polyamides (Nylon) and polyesters will all oxidize and ...
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0answers
28 views

Need help with an IR spectrum (polymer identification)

I have been given an unknow polymer and I have to identify it. DSC measurements showed no glass transition (which means it's below room temperature) and a melting temperature at around 100-120°C. So,...
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1answer
54 views

What causes the anti-siccative effect of soot (amorphous carbon) as a pigment in oil paints?

Oil paint containing carbon black (soot, charcoal) pigment is known to polymerize ("dry") a lot slower than if it has other pigments. I understand this is not just due to the absence of pigments which ...
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30 views

Correct monomer for polycondensation?

I'd like to formulate the synthesis reaction of this polymer: I assume this is a normal polycondensation reaction, and the monomer would then be: Is this correct?
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0answers
39 views

Hardest transparent polymer

The hardest I know is polycarbonate, it's used as a layer in bulletproof glass. Is there any solid optically transparent polymer that's harder than polycarbonate? Please note, I really mean hardness, ...
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Study long term properties of two polymers

This is a material-science question, and I didn't know where else to put it. I (and two others) are mechanical engineering students and are starting a bachelor's thesis which involves some material ...
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How to change the Glass transition Temperature ( Tg ) of a Compund? [closed]

we wanna Increase our compound damping (loss) , we know that Damping properties of a polymer is dominated by glass transition... So how can we change Tg In our PP/EPDM Compounds?