This work is aimed at investigating how molecule structure of polyurethanes (PUs) as sizing agents influence the interface properties of carbon fiber (CF) reinforced polycarbonate (PC) composites. Effects of four PUs as sizing agents for CF on the interlaminar shear strength (ILSS) of CF reinforced PC composites are investigated. It is found that the three PUs except PC-PU as sizing agents on oxidized CF (OCF) made the ILSS of their reinforced PC composites increase up to 62.9 MPa by more than 24.8%. The chemical interaction between PU sizing agents and CF are attributed to high reactivity of isocyanate, but carbonate groups on PC-PU may have a chain unzipping reaction due to active groups on the surface of OCF. The chemical interaction between PU sizing agents and PC are attributed to transesterification. As a result, PUs containing isocyanate or polyester groups are ideal sizing agents for CF reinforced PC composites.

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