MOCA Chain Extender for PU Sealants

MOCA (4,4'-methylenebis(2-chloroaniline)) is a slow-reacting aromatic diamine that chain-extends NCO-terminated prepolymers to build hard-segment domains. The electron-withdrawing chloro substituents reduce amine reactivity, giving longer pot life than unhindered diamines. The result is a phase-separated morphology with significantly higher tensile strength (typically 8–18 MPa), elongation at break, and improved compression set resistance compared to non-chain-extended systems.