Questions tagged [plastics]

For questions relating to the structures, properties, production methods and potential hazards of polymer materials commonly known as plastics

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28
votes
2answers
3k views

Ripping apart plastic: is this a chemical or physical change?

I was holding a piece of plastic earlier, and I ripped it in half. This caused me to start to think about what was happening at the atomic level. If the plastic is being ripped, clearly bonds are ...
24
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1answer
17k views

What makes ABS plastic turn yellow?

If you owned old kitchen appliances or old computer you might notice that they the once cream white plastic become increasingly yellow, old and disgusting. I have read that UV lighting can damage ...
17
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2answers
6k views

Why do many transparent plastics turn opaque when deformed?

Many transparent plastic materials, rigid or not, turn opaque (white) when subjected to stress, deformations or when folded (if not rigid) . The effect seems to be irreversible. What is the cause? ...
13
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2answers
8k views

Does latex protect against acids?

I heard somewhere that some plastics are pretty good at resisting decently strong acids. To what degree is this true? Does latex protect against corrosives? Are plastics good at "resisting" bases or ...
13
votes
1answer
1k views

What causes plastic to become brittle and can it be softened again?

I have some old computer case parts made of ABS plastic. Two decades of storage has embrittled the plastic to the point where they easily crack or shatter with the slightest bend. What is going on ...
13
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3answers
32k views

Why does alcohol crack acrylic (plexiglass)?

I have seen videos and discussions about alcohol cracking acrylic, and waterblock manufacturers reminding users to not use alcohol in cooling systems with plexiglass acrylic, but why is this so? The ...
12
votes
1answer
37k views

What's that tangy smell on cheap plastic?

Most cheap items (from China mostly) have a strong tangy odor to the plastics (or some resin, but I can mostly smell it on plastics). The smell is always consistent over a broad range or products and ...
12
votes
1answer
148 views

Polymers that aren't brittle at the cryogenic temperatures found on Titan?

For entertainment purposes, I'm imagining a colony on a non-terraformed Titan, and wondering what is achievable. Hydrocarbons are incredibly plentiful there, while metals and even silicon would be ...
11
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2answers
3k 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 ...
10
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1answer
6k views

How do cloves break down plastic?

When my family buys powdered cloves in bulk, we put them in plastic until we get home - which takes at very most an hour. As soon as we get home, we transfer them into glass because we have had issues ...
9
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2answers
10k views

Is bamboo based plastic less likely to leak chemicals?

Some plastics have been known to leak plasticizers (bisphenol and phthalates) into the food they contain, especially when heated. Because such compounds are suspected of being endocrine disruptors it ...
8
votes
3answers
125k views

Are all PP(Polypropylene), i.e. resin code 5 plastics, safe for microwave and steaming?

If a plastic is marked PP as in Polypropylene (i.e. resin code 5), is it automatically safe for steaming and microwaving, such that it wouldn't leach chemicals into the food(besides not melting)?
8
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2answers
22k views

Which kind of plastic material would be suitable for a clutch cover on a motorcycle transition?

I'm going to have an online machine shop build a part for me using a CAD drawing that I specify. Typically, these parts are made of aluminium, but this manufacturer also mills parts out of these ...
8
votes
7answers
31k views

How to dissolve PLA (polylactic acid)?

I'm a maker and I've been interested in 3d printing for years. I have found a technique for dissolve the PLA supports in a model printed in 3D in HIPS I have printed the model in HIPS and the ...
7
votes
4answers
1k views

Can flexible plastics have reflective coating (vacuum metalized)?

Is it possible to achieve an optical mirror coating to a flexible plastic part? If vacuum metalization is possible, would the reflective coating layer be durable enough to withstand the bending of a ...
7
votes
2answers
256 views

Is there a heatformed vinyl-like plastic that is hard as shellac when cold?

I recently started collecting shellac records, and got the idea of releasing my own music on 78rpm shellacs. But the exact formulas and techniques for making shellac records seems pretty much lost to ...
7
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2answers
4k views

Is polylactic acid (PLA) soluble in ethylacetate?

I'm searching for polylactic acid (that used in 3D printing) solvent, that is less toxic. It's used to postprocessing to polish object. Dichloroethane is toxic, acetone and dichloromethane less, but ...
7
votes
1answer
2k views

Why does sunlight cause plastics to become a faded blue color?

Due to the UV absorption, I knew that the plastics can be easily affected, especially PP. But is it normal that the change is always into faded blue from white color? and Why? Because I made an ...
6
votes
2answers
713 views

How do I heat my borosilicate reflux column?

I am gonna use a ceramic tape heater, but cannot wrap it around evenly. Is the glass column gonna be okay? I am running some tests on plastic pyrolysis. I am using the reflux condenser to make the ...
6
votes
3answers
3k views

Can plastic leak into water from a HDPE "2" plastic container at room temperature?

Here in USA supermarkets often sell water in plastic 1 gallon jugs. These jugs seem to all be stamped with the text "HDPE" (meaning that the material is High-density polyethylene) and a resin number ...
6
votes
1answer
14k views

Pipetting strong acid with plastic material

Can I pipette concentrated sulfuric acid using a plastic pipette tip? Will either the plastic or the acid be affected?
6
votes
1answer
11k views

Does melting HDPE plastic produce toxic fumes? (melting, not burning)

● The question isn't about burning HDPE but melting it at the proper temperature. (At 120 to 180°C depending on it's density, it becomes gooey. According to the source below the "extrusion" ...
6
votes
2answers
7k views

UV-Transparent Plastic?

I am looking for a type of plastic, preferably in the form of a sheet or film, that is weatherproof, durable, flexible, and both transparent and UV-transparent. Most films I've seen so far are treated ...
6
votes
1answer
9k views

A thermoset or a thermoplastic?

How do you know if a polymer is a thermoset or a thermoplastic? For example: hydroxybutanoic acid 2-amino-3- hydroxybutanoic acid (I am not sure if these are correct in English) I know what ...
5
votes
1answer
4k views

Chemically Speaking, What's Bad About Inhaling Plastics?

I hear about things like dioxin, but I really don't see what's dangerous about plastics-shouldn't you be ble to just breathe it out, or pass it out of your system? How would it cause cancer?
5
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2answers
18k views

What is the plastic material of the CD cases?

What is the material of which the transparent part of CD cases are made of? It is nicely rigid and really lightweight.
5
votes
2answers
143 views

higher viscosity base oil instead of better lubrication results in worse

UPDATE: The problematic "symptom" that I try to fix, is the static friction of two sliding plastic parts. This is about a keyboard key switch that was made during the 80s. The problem/issue ...
5
votes
3answers
3k views

Why plastic sheets contract when heated?

Why do thin plastic sheets contract when heated, contradictory to the behavior of most other materials ? What are the things going on at the molecular level ?
5
votes
1answer
540 views

Why are plastics lipophilic?

My wife prepares lunch for me every morning. After eating it on my desk, I typically wash the lunchbox and utensils in the company's kitchen. I have noticed that it is very difficult to remove the ...
5
votes
1answer
551 views

How is silica bead bonded into polystyrene?

What kind of bonds silica bead forms with polystyrene? Silica is now as ~100 $\mu$m spherical particles in bulk polystyrene that is made by melting. How can I bond the silica particles more tightly ...
5
votes
0answers
70 views

What determines 3D printing material compatibility?

3D printing, specifically the type common for consumers FDM or FFF, involves laying down thin (typically 0.1 to 0.2mm) layers of molten plastic. Modern consumer printers can use various filaments: PLA,...
4
votes
1answer
207 views

At what temperature do complex hydrocarbons become ashes?

When heating a metal tube with polypropelene in it, i found that i still had brittle black foam and flakes in it even though it had been in a blue flame at around 500'C What happens to complex ...
4
votes
1answer
2k views

Etching ITO on PET without damage

I am planning to use some of this to construct a transparent touch panel for a prototype of mine. It is PET plastic coated in Indium Tin Oxide. My plan is as follows: Use some of this UV-cure dry ...
4
votes
1answer
1k views

The walls of a plastic vial with Mercury inside are darkening. What is causing this?

I have a sample of Mercury in a plastic vial, The vial is a BD Vacutainer (genuine), made of polyethylene terephthalate. It is used for blood samples, and the one I used was new. When the vial was ...
4
votes
1answer
1k views

What is a food-safe level of exposure of plastic containers to heat?

There are many articles about how heat can trigger the release of potentially harmful carcinogens from plastic containers into the food or liquid they contain. Specifics they fail to mention, though, ...
4
votes
2answers
3k views

Plastic membrane that lets water in from the outside only?

I'm looking for a type of plastic membrane that would let water through it from the outside, but wouldn't allow water to escape once it's inside the membrane. Ideally available in a roll. Does such ...
4
votes
1answer
7k views

How does the catalyst in a polyester resin or epoxy work?

I would like to understand how the polyester resin or epoxy catalyst works and to what degree it must be mixed with the base material in order to be effective. Typical product instructions advise to ...
4
votes
1answer
64 views

Are there softeners in synthetic materials?

Are there softeners used in polyester or polypropylene to make these materials more flexible? Or is this not needed for this kind of synthesis?
4
votes
2answers
774 views

Biopolymers as alternative for PVC and PU?

I'm working on a project making a product line more sustainable, environmentally friendly and ready for recycling. Now I'm searching for good and suitable biopolymers for a part of the product that ...
4
votes
1answer
666 views

What chemical could dissolve low-density polyethylene?

What chemical could dissolve plastic aside from acetone? Preferably, low-cost and environmentally friendly. Any suggestions would be helpful. I'm targeting for thin plastic (low-density polyethylene)....
4
votes
1answer
1k views

Why does plastic tear easier when you pull it quickly?

If you've ever taken the plastic from a plastic bag and pulled on it, you might know what I mean. If you pull quickly, the plastic tears relatively easily, but if you pull it slowly, it gets stretched ...
4
votes
1answer
252 views

Plastics for food packaging

There are many types of plastics that can be used for food packaging, for example: Polyethylene terephthalate (PET) Polyethylene (PE) Polyvinyl chloride (PVC) Polypropylene (PP) What are the ...
4
votes
1answer
124 views

What barriers prevent plastic from becoming a fiber optic, data transmission medium?

This is a question that has bothered me for a while. In the past many years, no company has been able to develop a material that can transmit light nearly as well as fiber optic glass, or at least ...
4
votes
1answer
460 views

How is solid PVA filament (for 3D printing) synthesized?

Polyvinyl alcohol (PVA; also referred to as: PVOH, PVAl) filament--the sacrificial support polymer filament used in 3D printing, how is that made? All the reactions I've seen that make PVA create a ...
4
votes
2answers
1k views

Tallow and polymer pellets

Bank of England has issued a new £5 note which contains Animal Tallow. I was wondering if you can explain to me as to how the animal tallow is used in this process. Also would you be able to speculate ...
4
votes
0answers
51 views

"Nivea Sun protect & refresh" melted my tub

I stupidly applied spray sunscreen on my children inside our white, acrylic bathtub and the floor ended up with a white, very sticky residue that rubs off on things, but will not wash away with ...
3
votes
2answers
811 views

Is HDPE affected by long term exposure to methanol?

For at least several years I'be been storing various chloride solutions with methanol as a solute in Nalgene containers, which I believe are made from high density polyethylene (HDP). But recently ...
3
votes
2answers
901 views

What is the name of the crinkly plastic used in clear parts of envelopes?

I've always wondered what it is, as it makes a lot of noise on being deformed. No other common plastic that I've come across has quite the same properties.
3
votes
1answer
5k views

Decomposition products of PET

On Wikipedia, it says that polyethylene terephthalate (PET) decomposes at temperatures above 350°C. What are these decomposition products? I read further that acetaldehyde is produced, but is that ...
3
votes
2answers
546 views

How metal-plating on plastics is performed?

Metal coated plastics are commercially abundant now-a-days. I want to know how they're plated. Before posting, I did a quick search and found a nice link. It refers to this process as metallization, ...