Plastic Identifier or recognition sensor

hello dears is there any sensor can identify or recognize a plastic materials? regards...

zardasht: hello dears is there any sensor can identify or recognize a plastic materials? regards...

In fact, the industry standard is to use the human sense of smell. You burn a small sample of the plastic and from the smell, and experienced person can tell the general type of plastic.

Paul

That is similar to asking how many stars are in the sky. Do you want to determine what type of plastic it is? Is the plastic in a certain position? How thick is the plastic? etc. You need to make the question more complex like a lot more details, possibly the application etc. Good Luck & Have Fun! Gil

I mean just recognizing plastic with non-contact sensing, I know there is a method called NIR reflection spectroscopy , but it too expensive and complex method, I said if there is a sensor or simple method which just tells us this material is plastic or not?!

zardasht: I mean just recognizing plastic with non-contact sensing, I know there is a method called NIR reflection spectroscopy , but it too expensive and complex method, I said if there is a sensor or simple method which just tells us this material is plastic or not?!

If you can tell us what you THINK plastic is perhaps you can find a sensor to match. Some "plastic" is made from petroleum, some from natural gas, some from wood products and other organic material.

Paul

I assume you mean you want to tell different plastics apart, rather than tell "plastic" vs "something else - wood, metal, glass, ...".

There exist IR methods for telling plastics apart, but those are very limited in function (can distinguish only a few plastics, and require good conditions: no dirt or so) and expensive.

Paul_KD7HB: In fact, the industry standard is to use the human sense of smell. You burn a small sample of the plastic and from the smell, and experienced person can tell the general type of plastic.]/quote]

Works great indeed, and not much experience needed really, unless you want to be able to tell the difference between HDPE and LDPE for example (just looking at the product is usually much easier in that case). Styrenics are also not that easy to tell apart, especially GPPS and HIPS smell very similar.

It is, by the way, not just the smell. A burn test can tell you a lot more. To tell apart cast PMMA from regular PMMA you listen to the flame: the cast PMMA one crackles. Flame retardants obviously stop the material from burning. PC foams big time. Being able to pull a thread from the molten plastic tells you about the quality, better material can make longer threads. The viscosity of the melt gives you a feel for the grade: injection or extrusion/film. Glass filled materials will have the glass fibres stick out from the melt when you pull it apart as it's solidifying. Excessive ash tells you there is a mineral filler in it.

And no, it's not a healthy thing to do, and they don't teach you this in college or university :-)

zardasht: I mean just recognizing plastic with non-contact sensing, I know there is a method called NIR reflection spectroscopy , but it too expensive and complex method, I said if there is a sensor or simple method which just tells us this material is plastic or not?!

No, you need spectroscopy or similar (the human sense of smell is by far the easiest simple way!)

With multiple sensors you could correlate various properties and give a reasonable guess (density, hardness, dielectric constant/losses, conductance, magnetic permeability, and thermal conductivity together will give a good idea).

In general sensors detect properties, not materials. Many materials share some properties with plastics.