Any chance this is for a brake friction material? Barite is added to phenolic resins for high-temperature friction stability. Here is a report on the subject:
BaSO4 is a spherical filler that has poor adhesion to the polymer, thus strength is decreased by adding it as it would be for any other similar filler such as CaCO3, Dolomite or silica. The loss will be in proportion to the volume % of the filler added and not a very big loss either. As BaSO4 is rather dense, adding 40 weight % would only equate to around 10 volume % filler so you would only get perhaps 5% loss in strength.
If we knew what you were trying to achieve with the filler, we could give better advice. Fillers and filled plastics is my top area of expertise. See my website for book recommendations to learn more about the topic.
Lol. I'd welcome the work mate. It's not that easy building a consultancy business from scratch although I must admit it's going far better than I'd expected. I'm still hoping you and I can work out a project to do together just because it would be fun and I'd have an excuse to have some pints with you. Our daughter was born last week so I have plenty of extra work and sleepless nights to deal with! Pretty rewarding being a dad though.
Apologies for being vague in the initial post. Was still trying to gather more information at that stage.
Basically, the (allegedly) phenolic component is a return manifold in a water cooler (heat exchanger). If you can envisage a rectangular plate with two rows of recessed holes, with this plate being the lid of a container made from similar material. Water enters one row of holes and leaves via the other row.
Operates at about 60C. The OEM component is supposed to have a life in excess of 150,000 hrs, but reverse engineered spares are not lasting more than 60,000 hrs before cracking around the holes (recess fillet radii) occured. Still trying to determine the cause - fatigue via vibration, ESC, shrinkage cracks (question - are delayed shrinkage cracks possible?).
Managed to get samples of OEM and RE components under the SEM - major filler component was silica, although the OEM appeared to have BaSO4 as well (still need to confirm this). Hence my query.
I've sent the samples for FTIR to see if they match, probably looking at performing some GCMS to better ID the materials.
Polymers aren't my field of expertise, but I figured I'll collect as much info as I can and see what I can do for myself without the hired help. I've left enough samples that if I do screw it up, there will be enough for a consultant to work on.
Anyway, would appreciate any tips - I'll post more results when I get them.
What colour is the component. When exposed to a flame does it melt and burn or just burn. Does the smoke smell like overheated brakes or clutch or something else
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
The component is red in colour. When exposed to flame, it burns but does not melt. Gives off black sooty smoke. Not sure about the smell - still have a bit of a cold!
Thanks for the images. From what I can see you have fracture initiated at a flow line. The filler particles are huge and that's a problem. Large particles (or agglomerates of small ones) make for brittle materials. As a rule of thumb, fillers for plastics should be around 2 microns in size with no particles larger than 10-20 microns. The ones in your SEMS are way larger than that. See if you can find a supplier of a more appropriate grade of BaSO4.
We've gone back and done some more SEM work. Turns out that the BaSO4 was a red herring - and likely contamination in sample prepration.
What we are seeing are a lot of silicon in the EDS scans, and what you previously commented was BaSO4 is likely silica.
However, we also found traces of iron (<1% by weight), most likely in the form iron oxide. More interesting is the particle morphology of these iron particulates.
A few questions:
The iron oxide looks intentional, and imbedded in the polymer. What role would it play, even in those small amounts? Colouring? (the plastic was red)
Would the difference in the particle morphologies for the two above samples affect mechanical properties? I'm guessing that the larger particle would lead to a more brittle plastic as suggested by your previous thread - crack propagation could just follow the particle boundaries.
The filler giving the red is probably micaceous iron oxide, a platy filler with a density around 5 gcm-3. It is black when it's present as large particles and only becomes red below about 20 microns in platelet thickness.
It's used in thermosets to provide a barrier to protect against corrosion.
The new pictures look like you have absolutely huge chunks of metal in your polymer, probably a contaminant from the filler. I would change supplier of iron oxide if it were my material.
