Thermomechanical properties of cross-linked oligoester methacrylates

Thermomechanical properties of some cross-linked oligoester methacrylates were studied by means of a static method. The model compounds were obtained by radical polymerization of 20% methyl methacrylate and 80% oligomers of the following structure: where n = 1, 3, 5, and 9: R = ─ CH 3 , ─ C 2 H 5 , ─ C6H5, and ─ CH 3 C 6 H 4 . The results are used in discussing the influence of chemical structure and molecular weight of the oligoester methacrylatres on Tg(transition from the glasslike state into the rubberlike state), modulus of viscoelasticity, and temperature of discernible thermo-mechanical destruction of the cross-linked polymers under study. It was found that T g depends on the chemical structure and increases with decreasing n. The transition from the glass state region into the region of high elasticity was measurably influenced in appearance and slope by the molecular weight and nature of the oligomer. The initial temperature of thermomechanical destruction depends on n and on the side-chain substituants in the oligomer; they increase with decreasing n. The experimental cross-link density, v e , depended linearly on the total possible cross-link density v c with v e > v c . This may be attributed not only to the entanglement of molecules but to the supermolecular structure as well.