the parameters you listed are important for determining if the material will extrude at high pressure, the stiffer the better, which also means it will be hard, 90 IRHD +, but at this hardness and high stiffness, the elongation may not reach 100%, so you should also look at Modulus at 50%.
The...
Hi
mould shrinkage in TPE is quite common although at a much lower rate than thermosetting elastomers. how big the problem is depends on the tolerances you are working to shrinkage can occurr as a result of various strain relaxations.see below...
Shrinkage
Due to their anisotropic nature, GLS...
Hi
Those materials are around and used by the oil and gas industry under the term of Swellable elastomers, usually used in a product called swellable packers. they are conventional rubbers like NBR or HNBR to which has been added a very hydrophillic material which absorbs water and swells...
It is a heavily loaded material so its elastic properties are compromised anyway , but I think the addition of an acid acceptor like MgO (1.5phr) should help improve the efficiency of the Peroxide
Johnnymat
I think the relevant rubber property would be rebound resilience ( stick bounce in your terminology).different rubbers have very different rebound resilience properties and the formulations(mix recipes) of these rubbers also influence the property of energy absorbtion.
However at the very...
NBR comes in a variety of polymer grades and of course mix recipes. The major factor affecting oil compatibility is the acrylonitrile content. Generally speaking NBR comes in 3 grades of Low, Medium and High acrylonitrile content (ACN).
The higher the ACN content the better the oil resistance...
96% sulphuric acid is very aggressive as you have discovered. As chemicals become more aggressive, there tends to be a thought that moving to Viton (FKM) is the answer. This is not the case, as the previuos contributor has stated there are varying grades of Viton(FKM) varying in levels of...
Hi
I think you have identified the main issues in dealing with this, Punching is impossible without getting ID curvature, drilling difficult with rubber in its natural state. Freezing is the best option and may not be so difficult depending on the rubber type. Most rubbers except silicone will...
This sounds like some form of micro peristaltic pump action. Definately need to consider some compromises.If it needs to be biocompatible probably requiring some FDA or USP compliance then this will eliminate many traditional wear resistant and easily bondable materials. PTFE is the main...
Polyurethane issues.
Everthing you have done seems to be with mouldable polyurethanes,which are optimised for ease of processing rather optimising properties. Have you tried using a castable polyuretane and machining your components from this. if it works you could get a dedicated mould made...
Adding particulate mineral to absorb water will not fgive you the the degree of swell you are looking for. You will need to add a water absorbant polymer such as crosslinked polyvinyl alcohol,this will swell considerably and swell your compound as a whole
Adjust the amount to suit.
There are...
If you have access to a DSC analytical equipment that woukld give you a definitive answer.
if it is severely undercured the material would feel ike chewing gum and not have the very elastic snap that silicone has.
porosity is a sign of undercure but you also get this if the mould was not filled...
As with most rubber technology matters.it depends..on many things, The formulation for example... many ingredients can volatolise during the process and the gas needs venting,some cure systems produce water on curing and this needs venting, complex shapes or thick mouldings will need different...
EPDM is the correct choice for a window seal and to get the balance between obtaining the correct complinace to mating faces and creating the seal without excessive bulging you should choose a hardness of 70IRHD or 70Shore A ( at this hardness there is little diffrence in the twio scales)
JohnnyMat
All organic polymers which, includes all rubbers will decompose rapidly at 800 Deg F and above, the hotter it is the faster the decomposition, no matter what filler it may be composited with the polymer matrix will come apart rapidly at these temperatures. The only way to offset this degradtion...
