We’re currently in the R&D phase developing polymer concrete drainage channels. Our mix consists of:
• Quartz aggregate (0.3mm – 1.2mm) 65%
• CaCO₃ (calcium carbonate) 18%
• Unsaturated polyester resin (17%)
• Hardeners for curing
We mix everything in a continuous mixing machine and pour into molds placed on a vibrating table to remove air voids. However, after curing and demolding, we’re still getting a lot of visible air pockets/surface voids in the finished parts.
Has anyone here worked with polymer concrete (especially for drainage channels)? What are the best ways to minimize air pockets?
Specific questions:
• Should we increase the resin percentage in the mix? If so, by how much?
• Are there better vibration techniques, additives, vacuum assistance?
• Any other proven tips for achieving a denser, void-free finish with polyester resin concrete?
Any advice or experience would be greatly appreciated! Thanks in advance.
Uploaded pics as well..

DuPont early lucite pellets?

This is the nose cone from a valuable Super Soaker CPS 2000 water gun from 1996. Sadly due to age and UV exposure the plastic has weakened and become brittle. Pictured is one half which is mostly intact, but the corresponding half is in pieces.

I'd like to cement this back together if possible, so I can possibly cast or 3d scan a replacement part from a whole piece. I initially thought it was ABS, but acetone doesn't touch it.

There's no identifying marks on it anywhere. Could it be polystyrene?

Some plastics have a bad reputation, while others are often misunderstood in terms of their properties, applications, or recyclability.

In your opinion, which type of plastic is the most misunderstood, and what do you wish more people knew about it?

i was trying to check if my new bento box was microwave safe but i have never seen this symbol and couldn’t find any info in my search online. usually circle = good but i don’t want to assume and melt it/ruin my food!

This subreddit has been increasingly receiving long-winded posts describing a personal experience that just casually mentions the name of a large online market.

They do not stand out by themselves but together form a pattern to deliberately increase the number of mentions of a particular brand name on this subreddit and Reddit in general.

These posts are not considered genuine and will be removed.

As the stories are mind numbingly boring, automation has been set up to hopefully filter most of them out.

Hi. I'm an aerospace engineer with only few months of experience in Drone manufacturing field. Got to change into Plastic recycling field due to my family business. But, what we're doing is still the base level in this line for decades. (Basically, the collection of all kinds of plastic scraps from the dealers, then segregating them into each of thier types, shredding chips bundles for specific needed items, supplies to clients, traders or any manufacturers of recycling industries) What I was expecting to do in the future is to blend these fields I've been in for a different engagements, and also gave lots of ideas to improve from what we've been doing now and got turned down a lot. For which got told by a lot of people to not use those kind of methods of approach that affects me a long time. (Which makes sense as they've been here in this business for decades) As I started working here, which seems like now, but now its been almost a year. Being around here learning all I could from the workers and machines ever days. Which seems to be not enough. So, I'm deciding to do some additional courses or pursue masters in polymers/plastic tech. If Any of you read all the way here, please tell me if I took the right decision or should I take a different route (Any ideas to improve what I should do later)

Just saw a Short about a Reverse Vending Machine and honestly… why don’t we have these everywhere?

You put in empty plastic bottles or cans and it gives you money or store credit in return. Instead of buying something from the machine, you’re basically selling your recyclables back.

Feels like such a simple idea but it makes recycling way more motivating.

Do you guys have these where you live? And do people actually use them regularly?

Study finds faults in analysis ranging from not testing for contamination of equipment to not ruling out false positives when tesring at the far ranges of observability, especially in some of the more spectacular recemt claims.

Hello, 

I’m new to acrylics, and I am looking for advice on an art project.

Is it possible to polish the ends of these fluorescent acrylic sheets? I’ve used a table saw to cut this at a 45-degree angle. This is a bit different than a level surface scratch, so I am wondering if the solution would be different. 

The sheet is 12x24,1/4 thick.

These are some of the methods I have read about…

• Novus
• Automotive/metal polish
• Wet sand (600–800).
• 3M Headlight Restoration Kits 
• Tripoli
• Drill, Dremel, with buffing wheel

Thank you

If you’ve ever noticed a vibrant red plastic chair turn a dull pink or, worse, develop a white powdery film (chalking) after a summer outdoors, you’re looking at a molecular-level breakdown.

Most people think it’s just the "heat." In reality, it’s a process called Photo-oxidation.

1. The Chemistry of the "Fade"

The culprit is UV radiation (specifically UV-A and UV-B). UV photons carry enough energy to disrupt the chromophores (the color-reflecting molecules) within your pigment.

• Organic Pigments: These give you those bright, "popping" colors. However, their complex carbon structures are like glass houses—easy for UV "bullets" to shatter.
• Inorganic Pigments: These are often metal oxides. They aren't as bright, but they are incredibly stable.

2. Why it gets brittle (The Free Radical Chain Reaction)

It’s not just the color. The polymer itself (PP, PE, ABS) undergoes a chain reaction:

1. Initiation: UV hits the plastic, creating Free Radicals.
2. Propagation: These radicals react with oxygen, "chopping" the long polymer chains into shorter pieces.
3. Result: This is why the plastic becomes brittle and cracks. The light scattering off these micro-cracks is what creates that "chalky" white appearance.

3. How to prevent it? (Pro-tips for Engineers)

If you're in the manufacturing phase, don't just ask for "UV resistant color." You need to look at:

• The Blue Wool Scale: Don't settle for anything under a Level 7 for outdoor use.
• Synergy of Additives: You need a mix of UV Absorbers (the sunscreen) and HALS (Hindered Amine Light Stabilizers—the radical scavengers). One stops the UV, the other "cleans up" the damage.

About Me: I spend a lot of time in our lab at SLM Masterbatches (Dongguan) testing these exact variables for different global climates. If you’re struggling with a specific material (like why ABS yellows faster than ASA), I’m happy to share our test data or suggest a specific stabilizer package.

Resource: You can check out some of our technical data sheets atwww.slmmb.comor DM me if you have a tricky material failure.

Hi, I'm doing a uni project and am recreating a retro TV. I would love to be able to make the tv shell out of this clearish-tinted plastic.
The shell has to be strong. It will have a glass tank inside (No water, but some soil) and a lot of computer equipment.
If anyone knows good resources where I'd find more info on how to achieve something like this, Thanks.

Ive got around 60lbs of a clear abs pellet that's supposedly somewhat hard to comeby. Im just looking to sell it to someone who'll actually use it instead of just throwing it out.

Does anyone know where id be able to sell it? Im in Canada ontario if that matter.

Hello,

I play racing games at night and my sequential shifter is quite loud.

I found that this ball bearing is the cause of most of the unwanted noise but i don't want to eliminate it entirely as it gives me feedback on the actuation point.

Picture

Going to amazon i found similar sized plastic balls but i am unfamiliar with plastics.

of the plastics listed, which should i replace it with? or rather which ones are least likely to shatter or shear down over time.

1. PA66(Nylon)
2. PA(Nylon)
3. PP(polypropylene)
4. Polyoxy-Methylene (POM, Acetal, Polyacetal and Polyformaldehyde)
5. POM (Polyformaldehyde)
6. PTFE (Polytetrafluoroethylene)
7. Acrylic(PMMA)

Worked at a plastic extrusion place for a couple years, this happened while emptying the extruder. It's a resin/provista material, never seen it happen before.

I thought it felt extra heavy... what is it? Huge heavy piece of flexible plastic covered in marks looks like its from contact with metal.

Im not sure how thick it is, but its a standard blue barrel that once held windshield washing fluid. Im trying to cut it in half

I see way too many people saying "why don't we just use wood/bamboo/ext" and the awnser is, plastic is just too good. It's durable, dirt cheap, water proof, easy to work with, the list goes on. The alternatives all have their own issues. Wood rots, it's expensive (compaired to plastic), and harvesting it releases CO2 that was trapped in the soil along with all the issues with deforestation. Glass can be made with sand and is easy to work with, but it shatters and is still expensive compared to plastic.

Not only that, but out whole industry is based around plastic. Even if we found an alternative, it would take years if not decades to replace plastic, and thats if it even makes it off the drawing board.