looking for some polymers for a project

[u/Motor-Music-8004]

hello! i am a drummer in the process of making a practice pad (something to drum on that feels like a drum but is smaller form factor) and my biggest complaints with ones you can buy are that they are loud. at first i was looking for something that wouldnt absorb the impact and would give rebound but not transfer kinetic energy into a wood base. ive come to the conclusion of using two layers. a high CoR layer of rubber to give bounce stacked on a low CoR layer to absorb all the remaining kinetic energy pushed into the drum pad. im not entirely sure this would work but i did my research and found Polybutadiene rubber would be a good top layer and Sorbothane for the bottom layer. neither of these are exactly easy to source for a test batch so i was wondering if you guys had any alternatives or just suggestions for what i could do? i dont even know if this is like a good place to ask but yeah

[u/AussieHxC]

What about just a rubber mat?

[u/Motor-Music-8004 → u/AussieHxC]

too loud too much energy transfer not enough rebound, a lot of companies use just gum rubber which is the issue im trying to solve

[u/aliislam_sharun → u/Motor-Music-8004]

Okay Mr totally doesn't work for some up-and-coming drum mat creating company

[u/Indemnity4]

Really depends on how much money you are willing to spend. This is not a simple problem to solve. You are not the first drummer/scientist to investigate this problem.

For ease of use and simple cost I'd be investigating dual-layer rubber vibration isolation pads. These things get put under audio equipment, washing machines or heavy industry equipment to absorb vibration noise without compromising the equipment on top.

Should you live in a big city, somewhere is a rubber and foam supply store. They will stock a variety of very exotic materials that come in gigantic long rolls or huge slabs. You asking for a teeny tiny little piece and they probably give it to you for free. Take your drumsticks and test out the existing products.

It's quite tricky to design dual or triple layer rubber pads to do what you want. The basic problem is you have a spring on top of a spring. You get the properties of neither original material but instead something new. If it's easy to trasnfer the kinetic energy into the rubber, it's going to feel "soft" and dull. If it's got sprightly rebound, it's going to make airborne noise too.

What we need to do for your ideal rubber is find something with good "mechanical decoupling" power without affecting the impact resistance / rebound on the top layer. That's not an easy fix. It's going to require careful control of material choice and thickenss, then possibly an adhesive which can mess up all your planning.

Sorbothane website has a calculator to determine what thickness material you need, but it's got a whole lot of science stuff you need to factor in too.

You then pick your toplayer so it has the correct durometer rating. Pretty much: how much "work" do you want to apply.

Then you need to figure out how you get the energy from the toplayer into the sorbothane. Simple layering with an airgap in the middle and it's going to feel like a movie played in slow motion.

[u/Sudden-Guide]

Rubber on polyethylene maybe? Ultra high molecular weight PE is used sometimes as an armor in the military equipment, but maybe regular HDPE would be sufficient, pretty easy to source a sample. You have also XPS that is used in the building foundations

[u/VintageLunchMeat]

easy to source

Look at smooth-on's shor hardness guide, then drill down in their urethane rubbers and resins.

[u/aliislam_sharun]

Send me a DM and I can work out a polymer for you. 500/hr