Regrind Versus Vrgin Fluoropolymer

There are some potential problems with reground material.

Thermal degradation and contamination are the two biggest.

Each time the material is processed (heated, then extruded either into a mold or around wire) the material ages, or degrades slightly. Virgin material has never been processed before, so when molded or extruded, it's as close to the original chemical and physical properties of the material as possible. You will need to determine if once molded, reground material still meets your quality standards.

I would not accept material that cannot be certified as "once used". It is conceivable that these materials can be used over and over, with some loss of properties with each mold/extrusion/regrind cycle.

Contamination potential is obvious.

Finally, I'd use a mixture of regrind and virgin material, and not 100% regrind.

You may see some loss of insulation resistance and flexibility using regrind, but depending on the blend these may not degrade at all. I'd do whatever testing you do now.

You'll probably be OK.

Good luck.

Reground material from wire stripping may have metal particle inclusions.

brgds

Snel

At least I expect that the regrind offered is consisting of material collected at a well defined spot in a production process which due other reasons can't handle it anymore itself. (medical parts production)

I'm by no means an expert on this (and those who are feel free to correct me), but it's my understanding the virgin material hasn't actually polymerized yet, but will do so on initial processing. Regrind, the polymer chains have already set so any reprocessing can only reduce the polymer chain size (ie degrade it as Lyn pointed out above).

Let me correct you.

Polymerization has already taken place. That's why we can call them polymers, and not pre-polymers.

So, you are correct in assuming that additional shearing (as in extruding) would shorten the chains and there's the rub. Without testing the physical properties after each processing cycle it's difficult to predict the point at which the properties become unacceptable for the intended use.

One processing cycle will not normally degrade thermoplastics all that much, but it depends on the requirements.

Thanks for the correction. My knowledge base only extends to TFE (the pre-polymerized form of teflon). I guess I should have been able to figure it out from the OP where it say fluoroPOLYMER. LOL... anyhow... thanks for the schooling.

Regrind may have similar mechanical properties but I have often found metal particles in some mechanical grade plastics (regrind for lower cost). Watch carefully that you have 100% breakdown voltage testing. You will need to do a corona inception test 100% as well. That will determine what type of foreign particles may be present that create corona point sources and the location of eventual insulation failure. You never need the corona inception test with virgin material as there is no foreign material present.

My two cents worth Dave K.

We use 100 % regrind in one of our processes exclusively and have for the last couple of years. Although it is polypropylene not a Fluoropolymer as you are suggesting in your process. I have not seen any affects in the process with these materials to date (except the materials are not as clear). We have had several different suppliers over the years and the consistency in materials has not changed. The only thing I have done different is to add magnets to the bottom of hoppers to insure metals are not ingested into extruder.

Hope this helps.

Some one trying to fool you.

Regrind is old polymer and two major issues are

1. Degradation of polymer with time

2. Contamination picked up by polymer during use and during regrinding process.

I have not seen in my 30+ years of experience both are same. I have worked on tons of copper and silver inks and can not add more than 50% of then old ink after sieving and magnetic septation along with other cleaning method. This guy is trying to tell you virgin polymer and reground is same.

World is not that fool to believe this nor do you

Masyood,

1. No one ever said that virgin material and re-grind are the same thing.

2. There is absolutely no connection between ink processing and thermoplastic resin processing.

3. Had you bothered to read the prior posts, you would have seen that both of your topics had already been pointed out to the OP, twice.

Good to see that you did earlier. It is just same thaught process high up in the organization had that metal is metal and organic is organic and paste color is same so we can use it and they fall flat on face and I have walk them through the cleaning steps and even after all that max we can use was 50% to have acceptable quality. That was the reason I was forced to write without going down as if it is going to bite someone else and good idea to share my run down to this

Thanks. I got the impression that the OP was going to use once processed medical grade regrind. That is probably the best choice for cleanliness.

You are always going to get some degree of polymer degredation (ie: breaking of polymer chains) with each heat/shear history of processing. Different polymer families vary greatly as to the ammount. Are they proposing regrind with only 1 heat history or more than 1. Will any regrind from your product be put back into the process. Often material with 3 or 5 process cycles is used for testing, but this depends upon your process.

You also need to look at degredation/changes in the fillers and other additives. These might include UV or thermal stabilizers, pigments, flame retardants, anti-static additives, processing aids, etc. The raw material manufacturer will likely be able to give you some information/guidance. Granted they are in the business to sell virgin polymers, but they may have some data available on regrind.

Once you know how these properties might change, you need to determine how they might affect your product. Are you currently making this product with virgin material or is this a new product? What validation testing was done on the original product? Is your product subject to any regulations (UL, industry, etc.) You will need to conduct testing on your end product to determine if it is still of acceptable quality.

Some products/materials will do fine with 100% regrind, some can tolerate a little to none. Some industries also dictate this for certain products (medical, information technology, etc.) Beyond that you need to look at the business case. How much are you going to have to spend to validate a regrind versus looking elsewhere for the availability of virgin material.

The most important feature is Insulation value? Thermal Resistance, Radiation Resistance?

So please check for the following and compare both:

1. Dielectric resistance (Volts per mil thickness)

2. Thermal Conductivity

3. Density to four places after decimal

4. Porosity and Voids

PFA is 76% Fluorine containing polymer and may be you can do some analytical and/ or spectrographical testing to see if chemical structure is identical or not.

My previous comment was deleted by accident