Radical polymerization of methyl methacrylate in the presence of biodegradable poly(L-lactic acid). Preparation of blends, chemical-physical characterization and morphology

Poly(L-lactic) (PLLA)-based blends containing poly(methyl methacrylate) (PMMA) as dispersed phase are reported in the present paper. The blends are prepared by reactive (R-type blends) as well as non reactive (NR-type blends) methodologies, according to the preparation of the blends either polymerizing the acrylic monomer in the presence of PLLA or melt mixing the two polymers (PLLA and PMMA) in bulk. Thermal as well as morphological studies performed on both R and NR blends have revealed an intimate dispersion of PLLA and PMMA. Unlikely previous studies carried out on different aliphatic polyesters but following similar chemical approach, mechanical tests on the PLLA-based blends gave no satisfactory response for reactive-type blends. The results are interpreted on the basis of extensive cross-linking of the system caused by the high sensitivity of PLLA to radical attack. The copolymeric phase formed during the reactive blending is isolated and characterised by NMR technique.