Much difference between brands of resin?

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#1

I’ve been ringing round places to get prices for a general purpose laminating epoxy resin and there is one brand that is quite a bit cheaper than all the others.

Is this because their product isn’t as good? (Or maybe the others are over charging)

How much difference is there between different brands of resin? The brands I’ve been looking at (here in the UK) are SP, West Systems and Sicomin.

Are there any other brands of resin (easily available in the UK) that I should be considering?

#2

While I can not say much about normal hobby systems for composites, epoxies are VERY different. Some are plain and boring, some are toughened, some are more flexible, some are chemically made for certain fibers. Just one company can have several very different epoxies. Each resin is created for a need. Some are custom resins that are VERY specifically designed for what composites.

#3

I’m not too sure of the differences between the resins from the companies you have mentioned but when I first started I used SP resins but soon found they were very expensive in comparison to other general purpose laminating resins. I have used resins from both http://www.ecfibreglasssupplies.co.uk/ and http://www.easycomposites.co.uk and found no difference in quality or ease of use with their resins compared with that of SP. I’m only making cosmetic parts for motorcycles so am not too worried about cured strength etc. My advice would be to go for the cheaper resins, especially if you are just starting out because no doubt you’ll be putting a few parts in the bin :slight_smile:

#4

I’ve seen that there are lots of resins (unfortunately for me when trying to decide! haha) That’s why I said about general laminating resins to try and narrow it down.

#5

That’s interesting because with the prices I’ve got, SP resins are MUCH cheaper than anyone else I’ve found.

#6

For moulds I use west system epoxy mixed with high density filler as the gel coat,for my parts I use prf composite resins, I have found them to be excellent for wet lay up or infusion,with working times from 40 minutes to 3 hours depending on complexity of part,I have found sp epoxy a bit like west system,but prf resins are far superior in matrix,I would not use for cheap parts ,prf epoxy is expensive.

#7

Take a look at the datasheets. Cheap epoxy’s usually have a lower Tg. I’ve worked with west, sicomin, SP ampreg series, ands some cheap resins. All are just fine, but I like SP ampreg the most I think. different color hardeners, good documentation, nice viscocity. Sicomin has some great resins too, actually using the 1660 to build some moulds, very high Tg, lots of documentation, and 2 dealers who can help me out ;). west, well, I guess it’s ok. But it’s thin and gets lots of air in it fast.
It’s basically what you need:, check datasheet, price, and preference (price has a lot to do with preference too, haha)

#8

Also, you need to check which type you have from a certain manufacturer. For instance Sicomin has epoxy resins with a Tg as low as 25 degrees, but also with a Tg of at least 150 degrees C…

Same goes for West, SP, or any other brand. Just naming the brand is not enough.

#9

Thanks everyone.

One of the main reasons I asked was because I’ve seen some carbon motorcycle products that I believe have used SP resins and the products seem to discolour quite quickly and just wondered if this was down to the resin being ‘cheap’ or maybe down to the chemicals contained in washing liquids that the riders use to clean their bikes (some parts don’t seem to spend much time in the sun).

#10

I doubt if the discolouration you talk about is due to the chemicals in washing products, it’s more likely to be caused by UV. Epoxy has very good chemical resistant properties especially from the type you would find in cleaning products. It could be that the parts you have seen were made with inappropriate resin or were not protected… Even using SP 207, which has UV protection, they still recommend that unpainted parts should be coated with a UV resistant varnish/clearcoat

#11

epoxy yellows. Even epoxy that is UV resistant, yellows.

SP nicely puts it like this in their datasheet:

“UV resistant epoxy (non yellowing)”
Do not expose to UV or it will yellow…

However, some curing agents make epoxy yellow quite fast. It has nothing to do with price. One of the cheaper epoxy resins I sell (Ce-Sense 301) has only a low tendency to yellow.

#12

I told the production chef a few weeks ago, about the yellowing. “but we have UV resistant epoxy” No we don’t, take a look at some older products…
Now every part gets paint :slight_smile:

#13

I’m curious. How much does yellowing effect the strength of a part?

#14

I created a thread about the degradation of carbon fiber/epoxy by ultraviolet radiation and condensation awhile ago. http://compositescentral.com/showthread.php?t=4821

“ABSTRACT: The degradation of an IM7/997 carbon fiber-reinforced epoxy exposed to ultraviolet radiation and/or condensation has been characterized. Based on observations of physical and chemical degradation it has been established that these environments operate in a synergistic manner that causes extensive erosion of the epoxy matrix, resulting in a reduction in mechanical properties. Matrix dominated properties are affected the most, with the transverse tensile strength decreasing by 29% after only 1000 h of cyclic exposure to UV radiation and condensation. While, the longitudinal fiber dominated properties are not affected for the exposure durations investigated, it has been noted that extensive matrix erosion would ultimately limit effective load transfer to the reinforcing fibers and lead to the deterioration of mechanical properties even along the fiber dominated material direction.”