Gel in oil extended rubber
Gel in oil extended rubber
(OP)
Hi there,
Could you tell me about the effects of the gel on cured-rubber's physical properties when the rubber is an oil extended one and have many gels in it?
I guess it will make inconsistancy especially in the physical properties? Am I wright?
Could you tell me about the effects of the gel on cured-rubber's physical properties when the rubber is an oil extended one and have many gels in it?
I guess it will make inconsistancy especially in the physical properties? Am I wright?





RE: Gel in oil extended rubber
Depending on the amount of gel and the geometry of the finished parts, the effect can be very or minimally significant. If the cured part is relatively thick, the presence of the gel particles may not be a big factor in the bulk strength of the part.
Hope this helps.
Tom Jablonowski, TSE Industries, Inc.
www.tse-industries.com
RE: Gel in oil extended rubber
RE: Gel in oil extended rubber
You can also press some of the polymer in a heated press, putting the polymer between Mylar sheets. The non-gel polymer will smooth out nicely, while any gel particles will usually not flow out, and may look like a smooth or rough lump. We typically use press temperatures of about 150C, with max pressure (on our 12"x12" lab press).
Lastly, you may be able to extrude the polymer in a small extruder and extrude a thin strip which will show gel particles as lumps in the (hopefully) smooth extrudate. The raw polymers I work with don't extrude very smoothly without compounding with fillers and plasticizers, so this may or may not work with the polymers you're working with.
Hope this helps!
Tom Jablonowski, TSE Industries, Inc.
www.tse-industries.com
RE: Gel in oil extended rubber
RE: Gel in oil extended rubber
As I know, most of SBR adopted the cold polymerization method to prevent it from having gel. But in case of oil extended SBR, there is possibly a lot of gels in it, because its molecular weight is very high compared to non-extended SBRs.
But there is no problem in tire-application.
The only case gel will effect on the physical properties would be one the end product is thin relatively.
Am I right?
RE: Gel in oil extended rubber
Regarding gel in oil extended polymers, I used to work for a company that produced EPDM rubber, and light (UV) can cause gel in oil-extended EPDM, moreso when the oils had significant aromatic content. I'd assume the same effect happens in SBR, so protecting these rubbers from light (even flourescent light) may be highly desirable to prevent gel formation on the surface. FWIW.
Tom Jablonowski, TSE Industries, Inc.
www.tse-industries.com
RE: Gel in oil extended rubber
Thanks for your quick and valuable reply.
RE: Gel in oil extended rubber
polymer (SBR) compositional variability in:
molecular weight
molecular weight distribution
styrene/butadiene ratio
other compositional variations (emulsifier?)
oil
oil amount
oil type/composition
gel
If you mix test batches in your lab, maybe with just curative added to the OESBR, you should be able to get some information as to what the variability might be (for example, Mooney viscosity would probably give an indication of molecular weight/distribution; specific gravity would give an indication of oil content.
What does your OESBR supplier say about the variability you're seeing? If you have an alternate supplier, you may want to evaluate their material for consistency.
Tom Jablonowski, TSE Industries, Inc.
www.tse-industries.com