Table Tennis Rubbers
Table Tennis Rubbers
(OP)
What would make a table tennis rubber more springy? I understand that rubber has long chains of polymers that can be compressed or stretched. I also know that there is some molecular resistance that must absorb some of the energy. How does one reduce the molecular resistance so the rubber transfers more energy to the ball instead of internal heat? Also, does anybody have examples of existing rubbers that have a low internal resistance?
I am an electrical engineer a little bit about out side my field of expertise but it seems to me that a table tennis ball hitting a paddle can be modeled as a sphere ( mass ) hitting a bunch of coiled springs. Hooke's law would apply but one must also take into account the mass of the springs and the internal damping.
Thanks
I am an electrical engineer a little bit about out side my field of expertise but it seems to me that a table tennis ball hitting a paddle can be modeled as a sphere ( mass ) hitting a bunch of coiled springs. Hooke's law would apply but one must also take into account the mass of the springs and the internal damping.
Thanks
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
I think that you'll find that there are:
> A LOT of material choices https://www.megaspin.net/store/Default.asp?cid=rub...
> all of them have some compromise somewhere to achieve the totality of performance required
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RE: Table Tennis Rubbers
If you look at the ratings for table tennis equipment, you will be absolutely baffled at how many parameters there are. Most of them subjective, no idea how they claim to test them.
If you really want to get confused, look up "speed glue." Ignoring the context and just answering the initial question, speed glue makes table tennis rubber more springy. It has been banned for competition.
RE: Table Tennis Rubbers
[quote=CoryPad]
Elastic moduli and damping vary with crosslink density in thermosetting elastomers (e.g. rubber). Crosslink density is varied by adjusting material (resin type, hardener/initiator concentration, etc.) and process conditions (e.g. temperature).
[/quote]
Would I be correct in assuming that those polymers with fewer crosslinks would have a lower internal resistance?
If I drop a ball on a rubber the ball will only bounce up a fraction of the original height because of the coefficient of restitution. Clearly the rubber absorbs some of the impact energy. This must be due to some form of internal resistance in the rubber. Are these crosslinks responsible for the internal resistance?
Thanks
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Table Tennis Rubbers
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
Have a look at the article Guide to Choosing Table Tennis Rubber on mega.spin.net
RE: Table Tennis Rubbers
RE: Table Tennis Rubbers
basically damping is a frictional force proportional to the velocity x'. The higher the damping the more the rubber or sponge will absorb energy and not return it to the ball. Assume the reference is the paddle. On impact the ball will compress the rubber converting all the kinetic energy into potential energy and heat. When the rubber accelerates the ball in the opposite direction some of the potential is lost again due to damping but also the some of the energy must move the sponge as well as the ball.
[quote=CoryPad]
Increasing crosslinking means the chains are covalently bonded to each other in more locations, which decreases damping. If you increase crosslinking enough, the part moves from a flexible elastomer to a stiff, brittle thermoset.
[/quote]
Doesn't increasing the number of cross links make it more difficult for the polymers to slide by each other. This would increase internal friction or damping.
To get maximum speed after impact one would want to reduced the damping d to as low as possible and also reduce the mass of the spring ( rubber ) so less energy is used to accelerate the rubber and more can accelerate the ball.
Reducing the d term, damping, is part of making rubbers more efficient ( faster ). My question is how does one reduce the d term at the polymer level. It seems that more cross links is not the answer. Few cross links may let the polymer chains slide by each other more easily and therefore have a lower internal resistance.
Longer cross links may also allow the polymers to move relative to each other more freely.
I said above, I am a mid level club player and an engineer.
I am aware of megaspin.net. Most of the information there is marketing hype and opinion.
I have bought many rubbers but playing with them doesn't tell me anything about how a manufacture makes one rubber "faster", springier or more efficient than another rubber.
I am looking into what rubbers would be the most efficient and how are they cross linked that makes them so special.
Thanks again for any useful information
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: Table Tennis Rubbers
My company looked at compound development many years ago, but if my memory serves me there was nothing worth pursuing. Which isn’t really a surprise given the influence of pimples, surface tack, thickness, tensioning, glue etc. Hence the wide selection of rubber covers now available, including the anti-spin harder sheets and the use of synthetic elastomers such as neoprene. Sometimes I think it comes down to personal preference and a question of faith rather than science, and naturally we can’t forget the skill factor. However, good luck with your investigation
RE: Table Tennis Rubbers
If this is true then it's nothing to do with cross-linking or the rubber material. You could test the theory by first stretching a rubber then gluing it in place. That would get you around the rules against speed glue as well.
https://en.wikipedia.org/wiki/Speed_glue
Chris DeArmitt PhD
President - Phantom Plastics LLC
Trusted adviser to leading companies around the world
www.phantomplastics.com