Thermal degradation of methyl methacrylate polymers functionalized by phosphorus-containing molecules I. TGA/FT-IR experiments on polymers with the monomeric formula CH 2 C(CH 3 )C(O)OCHRP(O)(OC 2 H 5 ) 2 (R H, (CH 2 ) 4 CH 3 , C 6 H 5 Br, C 1 0 H 7 )