Electron beam curing of functionalized N-(4-hydroxy phenyl)maleimide monomers

Abstract

Electron beam (E-beam) curing by different total radiation doses (100, 200, 300 and 400 kGy at 10 kGy per pass) of functionalized maleimides (20%) [ N-(4-acryloyloxy phenyl)maleimide, N-(4-methacryloyloxy phenyl)maleimide and N-(4-cyanato phenyl)maleimide] is carried out using N-vinyl-2-pyrrolidone as the reactive diluent (80%). The swelling studies indicate the presence of highly cross-linked structure in the polymer derived from cyanate-functionalized maleimide cured using 400 kGy electron beam (E-beam) irradiation. The thermal stabilities of all the polymers are studied using thermogravimetric analyzer. The materials cured using the highest radiation dose (400 kGy) are found to have better thermal stability compared to other materials cured using lower doses (100, 200 and 300 kGy at 10 kGy per pass). The degradation kinetic studies using the Vyazovkin method showed that the activation energies for the thermal degradation of polymeric materials got by E-beam irradiation of the monomers at 400 kGy are higher. Of all the materials investigated, liquid composition having N-(4-cyanato phenyl)maleimide (20%) and N-vinyl-2-pyrrolidone (80%) cured by E-beam radiation (400 kGy) showed better thermal stability.

Studies on structurally different benzoxazines

“…Phenolic resins 4,5 are the most commonly used thermosetting materials, but these phenolic resins suffer from several problems, namely, poor shelf life, brittleness, high processing temperature, low solubility in organic solvents, and presence of residual acid or base catalysts. To overcome these problems, Holly and Cope 6 synthesized benzoxazine using phenol, amine, and formaldehyde, which can undergo ring-opening polymerization without the aid of any catalysts to new phenolic network compound without the release of any volatiles leading to void-free material.…”