Thermal degradation of methyl methacrylate polymers functionalized by phosphorus-containing molecules I. TGA/FT–IR experiments on polymers with the monomeric formula CH 2C(CH 3)C(O)OCHRP(O)(OC 2H 5) 2 (RH, (CH 2) 4CH 3, C 6H 5Br, C 10H 7)

Abstract

The thermal behaviour of methyl methacrylate polymers (PMMA) prepared from phosphorus-containing monomers: CH 2C(CH 3)C(O)OCHRP(O)(OC 2H 5) 2 (RH, (CH 2) 4CH 3, C 6H 5Br, C 10H 7) was investigated by thermal gravimetric analysis (TGA) coupled with on-line FT–IR analysis of evolved gases. Four homopolymers and two MMA/functionalized-MMA copolymers were studied. They exhibited a thermal behaviour largely different from that encountered for PMMA. Particularly, the results revealed a major and common degradation stage near 300°C leading to diethyl phosphite HPO(OC 2H 5) 2 or diethyl phosphonate RPO(OC 2H 5) 2, aldehyde RCHO, CO, CO 2 and ethylene C 2H 4. Functionalization introduces high temperature degradation stages (above 750°C) and weak points in the polymeric chain leading to a complete cracking of the polymer as no monomer molecules were found during the degradation, in contrast to PMMA. A first evaluation of the fire retardation properties of the polymers was performed by determining the limiting oxygen index (LOI).