Tri-iso distributes a wide range of prepolymers that allow formulators to produce high quality polyurethane and polyurea elastomers. Prepolymers are reactive intermediates between monomeric Isocyanates and fully reacted polyurethane polymers. Prepolymers contain reactive NCO groups which react with hydroxyl or amine groups to chain extend and crosslink the prepolymers. There are several key characteristics which define what performance properties a given prepolymer will impart in a given polyurethane or polyurea system. These characteristics include: the type of prepolymer selected (aliphatic or aromatic), the NCO equivalent weight, the %NCO, and the functionality of the prepolymer.
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Aromatic prepolymers are prepolymers where the NCO functional group is directly attached to an aromatic ring, and aliphatic prepolymers are prepolymers where the NCO functional group is not directly attached to an aromatic ring. Aromatic prepolymers are typically less expensive than aliphatic prepolymers. Aliphatic prepolymers are colorless, UV stable, and transparent.
NCO equivalent weight is the number of grams of a given product that contains one equivalent of isocyanate groups (NCO). One equivalent of NCO groups is 42.02 grams/mol
%NCO = 4202/NCO equivalent weight.
Prepolymer functionality refers to the number of NCO groups per molecule. Increasing the number of NCO groups results in greater crosslinking. Greater crosslinking yields stiffer, harder products with enhanced chemical and thermal resistance.