Studies of Formation Mechanism, Structure, and Properties of Network Copolymers Obtained by Cocuring of Rolivsan Thermosetting Resins with Aromatic Diamines

Rolivsan thermosetting resins (ROLs) demonstrate high glass-transition temperatures and excellent processability. In our work, high-temperature properties of ROLs were significantly improved using a novel technique for structural and chemical modification of microheterogeneous network polymers. This technique involves, among other procedures, cocuring of rolivsan resins with aromatic diamines (ADA). The most noticeable increase in storage moduli and glass transition temperatures (Tg) of these copolymers was achieved when ROLs were modified with 10-15 wt.% of ADA and the resulting blends were subjected to thermal treatment in air in the temperature range 180 to 320°C for several hours. FTIR, 13С NMR spectroscopy, and dynamic mechanical and thermal analyses were used for studying the structure and properties of the obtained products. It was demonstrated that the mechanism of formation of ROL-ADA copolymers includes the following high-temperature reactions: (i) three-dimensional radical copolymerization of unsaturated ROL components and (ii) cleavage of heat-sensitive methacrylate crosslinking units inside the polymer network. The second process is accompanied by formation of pending units of methacrylic acid and methacrylic anhydride, which participate in condensation reactions with ADA.