Regarding Unsaturated Polyster Resin

Contact the manufacturer directly.

May I slip in a side question, I don't want to hijack a thread?

What is the difference between saturated and unsaturated polyester? They have different numbers in my import tariff and polyester is the only plastic that asks this question. Is there an easy way to tell them apart? (Something I can ask a non-chemist)

Again sorry for the interuption.

An unsaturated polyester is a polymer chain containing alternating dibasic acid and glycol monomers linked together by ester bonds. The unsaturation comes from the incorporation of a dibasic acid that contains a double bond, typically maleic acid formed by the ring opening of maleic anhydride. As the concentration of maleic acid in the polyester chain increases, so does the resin's reactivity. Several different glycols and/or dibasic acids can be copolymerized into the polymer chain. At the end of the reaction, the polyester resin is blended with a reactive diluent, typically styrene. The reactive diluent contains a vinyl double bond and serves to reduce the viscosity of the polyester resin so that it can be pumped and processed. Hence, the resin manufacturer can produce a wide variety of polyester resins with differing structures, reactivities, and molecular weights, which impart different properties to the resin and the final molded product.

Now,why are they classified differently? I don't know, and I can't even find the excellent site where I copied the information above. If I find it, I'll put it up here.

Back to the Original Topic.

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