You need to define those properties better. Rubber compounds vary from being very insulative (10 to the 14th ohm-cm) to "semi-conductive" (10-1000 ohm-cm)to actually conductive (actually a collection of conductive particles held together by just a bit of rubber matrix). On the conductive...
I am surprised you have anything made in recent years with an ebonite tube in it. That material was common up through maybe 1960, but is now produced in very limited amounts for special applications. Are you sure it was ebonite, not just a very old rubber tube that had hardened with age? In...
The bad news is that no matter what you do (short of freezing in liquid nitrogen) the tire compound will age over time just through molecular rearrangements. However, this is minor compared to oxidation/ozonolysis/heat aging, so the sealed and double wrapped bag in a relatively cool and dark...
If you really need long-term heat resistance to 300 deg F, you will find only a limited number of elastomers will serve. If the rubber only sees the heat and pressure (from air or inert gas) and you don't need oil resistance, EPDM might do the job OK. If the bladder is going to inflate/deflate...
Filling a Hypalon-lined tank with water seems a bit strange, Hypalon is not usually compounded with lots of plasticizer and ages very well. (Much better than nitrile.)The comments others made about some hydrocarbon fluids extracting plasticizer (and sometimes other ingredients) from rubber are...
A rubber compounder could make you a dozen different 50 durometer compounds that would vary greatly in dynamic stiffness (easily +/- 30%) and damping (even more of a contrast) so unless you generate data on YOUR compound or one very closely related to it, you won't get very far with the FEA...
I realize you wrote your question long ago, but will offer what I can in any case.
If the rubber parts are small enough, you will probably reach equilibrium swell in 8 hrs (overnight) and that is a reasonably valid and precise measure of crosslink density. You can also dry out the specimens...
I had sent a reply about which elastomers are readily vulcanized by sulfur, apparently it got lost in the ether. The answer is that NBR, HNBR (some grades), SBR, EPDM, BR, & IR are all sulfur curable.
R J Del Vecchio
Technical Consulting Services
(consultant in Applied Rubber Technology)
Actually, I think the properly designed rubber part will do this job better than steel springs, weigh less, and of course not be subject to corrosion. That's why they build rubber dock bumpers for freighters, etc, that keep the big ships from pounding the docks. Check Gent's book, if that...
Just in case it's ever of any interest, I will mention (hoping to not break any hard rules) that part of my work in the past few years has been as an Expert Witness in applied Rubber Technology. If anybody ever tries to fix the Customs definitions (how likely is that?) I would be glad to help...
The Rubber Division of the American Chemical Society offers courses, some excellent literature, and a librarian to do specific searches on rubber-related topics. Their website is http://rubber.org/
Recommended books are:
Engineering with Rubber, edited by Alan Gent
(hardbound book which is...
Aha, you don't really care about how much energy is absorbed directly, you just want the dock float to work and prevent damage. And wave action is not "seismic" in the sense that adjective is normally applied in the industry; earthquakes have short duration and put building foundations into...
Energy absorption is a function of the actual dynamic property profile of the elastomer, and that changes with the strain and frequency of the actual deformation. Most seismic bearings are made of fairly resilient compounds (Natural Rubber or Neoprene) and their function is to isolate (absorb...
OK, now I understand better and knowing you got the hysteresis loop in actual data is reassuring about your test method & equipment. The lack of the FEA answer to match reality is simply a reflection of its inadequacy to properly model the complex responses of rubber. It takes very specialized...
I have seen some work on those lines, but the studies were proprietary to clients so I cannot say much more about them. The polymer manufacturer might have such data, although in these days of minimal tech support they seem to be doing the least possible in way of property exploration.
