non-linear friction effects
slip-stick https://en.wikipedia.org/wiki/Stick–slip_phenomenon
sticktion https://en.wikipedia.org/wiki/Stiction#:~:text=Stiction (a portmanteau of the,of stationary objects in contact.
slip-stick https://en.wikipedia.org/wiki/Stick–slip_phenomenon
sticktion https://en.wikipedia.org/wiki/Stiction#:~:text=Stiction (a portmanteau of the,of stationary objects in contact.
Hello Hans,I know the term slap-stick but have no idea what stick-slip is
Hans
As you know, "slap-stick" actually involves a stick. whereas "stick-slip" means the transition from static friction to sliding friction and back to static friction, repeatedly.
Ralf
Either of those effects would manifest as very strong audio noise signals, whereas we only observe windband surface noise so they can be ruled out on observational data. These are the kinds of effects on a violin string coated in rosin, not vinyl containing plasticisers. Rosin has unusual friction properties, if you added it to a vinyl disc you might have trouble!!
This is a fascinating discussion.
I may have missed if clarity was ever provided around a few topics / definitions.
Glass transition temperature of the polymer. It's been accurately described, but I don't think I've read the term used. Perhaps someone has found this temperature in literature for not only the "raw polymer", but in the actual physical form used in the manufacture of LPs.
Amorphous vs. crystalline structure. It's not an either or. The vast majority of polymers have both amorphous and crystalline regions. This is largely affected by the chemistry of the polymer itself, the degree of polymerization (in general this is an indication of how long the polymer chains are), and the physical / heating and cooling processes used both in manufacturing and in its intended use. As an example, the same (roughly) PET has vastly different amorphous and crystalline structures when it's processed as a textile fiber or a bottle.
Additives also affect physical properties immensely in terms of friction. The additives used on the surface ("spin finish") and within a PET fiber intended for textile manufacturing are vastly different than the additives used for PET pellets intended for blow molding bottles. These additives are only a few ppm in some cases, but they very meaningfully affect performance both in manufacturing and for the end product.
In addition, polymers from various manufacturers would (in general) have meaningfully different physical and chemical properties. At one time there were even two distinct polymerization processes within the industry to make "the same" PET material. Materials made from those two processes were not interchangeable in many situations.
I am not directly familiar with the polymers / copolymers used in the manufacture of LPs nor the actual manufacturing process of LPs. However, I'd think some of the properties / definitions between the polymers I'm most familiar with (aramids, nylons, and polyesters) may translate into your research.
Some questions that may lead toward answers -
Are there different manufacturers of the raw materials used to make LPs?
Is the handling of the raw materials from receipt to pressing the same for all LP manufacturers?
This could possibly answer a few questions re: the variability in observations between engineers running roughly the same experiments if the starting material were different in any meaningful way.
Overall, what does seem somewhat likely is that the vinyl material is reaching the glass transition temperature during play if only for fractions of a second and while under pressure. This would almost certainly cause temporary deformation on a (relatively speaking) macro scale, and it's highly likely that the internal structure of the polymer might be altered.
What hasn't been discussed (that I've seen) is whether the total mass remains constant. Is material being abraded away and/or is it simply being deformed?
The heat history and degree of polymerization along with the "percent crystallinity" of the material can be (in general) assessed by a polymer chemist. Reaching out to the raw material manufacturer(s) could be beneficial if they are known. I know something like that would be 'relatively' trivial for PET from most manufacturers. It needs to be stated that the degree of polymerization and % crystallinity should not be viewed as absolutes in my opinion. They should only be looked at relative to other "identical" materials tested using the same methodology in the same lab. i.e. you would not (typically) compare the degree of polymerization of a PET to a "vinyl", and you would not (generally) compare results of different PETs between laboratories. The results would have little actionable meaning.
Again... fascinating discussion. I'll ponder if there is anything actionable I could do to help assist in moving toward more fact-gathering re: the raw material properties / variants if they are unknown.
Cheers,
Patrick
I may have missed if clarity was ever provided around a few topics / definitions.
Glass transition temperature of the polymer. It's been accurately described, but I don't think I've read the term used. Perhaps someone has found this temperature in literature for not only the "raw polymer", but in the actual physical form used in the manufacture of LPs.
Amorphous vs. crystalline structure. It's not an either or. The vast majority of polymers have both amorphous and crystalline regions. This is largely affected by the chemistry of the polymer itself, the degree of polymerization (in general this is an indication of how long the polymer chains are), and the physical / heating and cooling processes used both in manufacturing and in its intended use. As an example, the same (roughly) PET has vastly different amorphous and crystalline structures when it's processed as a textile fiber or a bottle.
Additives also affect physical properties immensely in terms of friction. The additives used on the surface ("spin finish") and within a PET fiber intended for textile manufacturing are vastly different than the additives used for PET pellets intended for blow molding bottles. These additives are only a few ppm in some cases, but they very meaningfully affect performance both in manufacturing and for the end product.
In addition, polymers from various manufacturers would (in general) have meaningfully different physical and chemical properties. At one time there were even two distinct polymerization processes within the industry to make "the same" PET material. Materials made from those two processes were not interchangeable in many situations.
I am not directly familiar with the polymers / copolymers used in the manufacture of LPs nor the actual manufacturing process of LPs. However, I'd think some of the properties / definitions between the polymers I'm most familiar with (aramids, nylons, and polyesters) may translate into your research.
Some questions that may lead toward answers -
Are there different manufacturers of the raw materials used to make LPs?
Is the handling of the raw materials from receipt to pressing the same for all LP manufacturers?
This could possibly answer a few questions re: the variability in observations between engineers running roughly the same experiments if the starting material were different in any meaningful way.
Overall, what does seem somewhat likely is that the vinyl material is reaching the glass transition temperature during play if only for fractions of a second and while under pressure. This would almost certainly cause temporary deformation on a (relatively speaking) macro scale, and it's highly likely that the internal structure of the polymer might be altered.
What hasn't been discussed (that I've seen) is whether the total mass remains constant. Is material being abraded away and/or is it simply being deformed?
The heat history and degree of polymerization along with the "percent crystallinity" of the material can be (in general) assessed by a polymer chemist. Reaching out to the raw material manufacturer(s) could be beneficial if they are known. I know something like that would be 'relatively' trivial for PET from most manufacturers. It needs to be stated that the degree of polymerization and % crystallinity should not be viewed as absolutes in my opinion. They should only be looked at relative to other "identical" materials tested using the same methodology in the same lab. i.e. you would not (typically) compare the degree of polymerization of a PET to a "vinyl", and you would not (generally) compare results of different PETs between laboratories. The results would have little actionable meaning.
Again... fascinating discussion. I'll ponder if there is anything actionable I could do to help assist in moving toward more fact-gathering re: the raw material properties / variants if they are unknown.
Cheers,
Patrick
I'm late to the game, the discussion is very interesting here, and I don't want to sidetrack things... but I have to comment on Chris's reference to the flight of the bumblebee. I first heard about bumblebees' violation of known aerodynamics from my grad-school officemate in the late 1990s. That same year, Michael Dickinson gave a very memorable colloquium talk in which he explained how flies fly (and by extension, bumblebees and hummingbirds). He later published the work in Science. Unfortunately, the paper is behind a paywall, but there are standard techniques for acquiring such papers. Besides, the abstract tells you the punchline.
I think if you do the maths the heating is minimal (certainly with a diamond stylus which conducts the heat phenominally well). Here's a page about glass transition: https://omnexus.specialchem.com/polymer-property/glass-transition-temperature
The new Dune movies seem to get the butterfly wings right ("ornithopters"). The fault is not in our stars, Duncan Idaho, but in our models.
Not entirely sure that temperature, a macro-sized, composite, summed and averaged, Steam Era term even applies at the stylus / PVC groove wall interface. Certainly observed performance is inconsistent with 400F "temperatures". We understand bigger things very well, and we understand very small (atomic sized) things very well, but understand each differently. Different models, different terms, different rules.
The transition from one model to the next is conventionally hand-waved off as "emergent properties", but this is for convenience rather than rigor. Gotta suspect that what we're interested in happens somewhere in the size zone between our well defined models.
All good fortune,
Chris
Not entirely sure that temperature, a macro-sized, composite, summed and averaged, Steam Era term even applies at the stylus / PVC groove wall interface. Certainly observed performance is inconsistent with 400F "temperatures". We understand bigger things very well, and we understand very small (atomic sized) things very well, but understand each differently. Different models, different terms, different rules.
The transition from one model to the next is conventionally hand-waved off as "emergent properties", but this is for convenience rather than rigor. Gotta suspect that what we're interested in happens somewhere in the size zone between our well defined models.
All good fortune,
Chris
I'm quite familiar with the term. I had simply not seen it directly used in this thread previous to my post. I had seen it loosely described. So, I thought I would mention it by name.
Regardless of the math... people have speculated upon, and some claim to have measured certain temperatures. Those temperatures may well be near or above the glass transition temperature of the material.
It depends on whose models are being discussed, but IMO, you are spot on.
If we call micro the molecular structure of an individual polymer chain, and macro the "vinyl" material used to form an LP; there is a well-known middle ground.
The phenomena / changes in behavior of multiple polymer chains interacting with one another is studied and well known. I think it's most applicable to this situation, but I truly don't 'know'. I don't know if models exist for this particular material in this application, but they certainly exist for aramids, nylons, and polyesters for multitudes of applications. We relied on those models for everything from polymerization and extrusion, through to post processing. From a commercial standpoint, the mechanical attributes of various resins and how they behaved in our customers' manufacturing through to the final consumer were critical. Those mechanical attributes were LARGELY dependent on the heat history and the mechanical processes applied to multiple polymer chains formed into a "structure" of intended properties with both amorphous and crystalline regions.