Biodegradable films from grafting of modified PLA onto starch nanocrystals

GARCIA NANCY; LAMANNA, MELISA; DACCORSO, NORMA; DUFRESNE, ALAIN; ARANGUREN, MIRTA; GOYANES SILVIA

Strasburgo

Congreso; 3rd International Conference on Biodegradable and Biobased Polymers, BIOPOL; 2011

The lack and the high costs of fossil resources, have generated numerous initiatives aimed at replacing these sources with renewable ones. As polylactic acid (PLA) is a biodegradable, thermoplastic polymer, it is an ideal candidate to replace oil derivatives. On the other hand, starch is a cheap, abundant, renewable and biodegradable biopolymer, and then it is also a viable alternative1.  In previous works, the production and characterization of starch nanoparticles was reported; to be an interesting reinforcing agent2. Starch-PLA composites seem to be the most promising combination for starch-based packaging, but PLA and starch are thermodynamically immiscible3. In this work we inform a strategic synthetic pathway to modify PLA to allow an appropriate grafting of PLA onto the surface of starch nanocrystals. PLA pellets, (90% L-LA, 10% D-LA; Mn= 49860 determined by SEC) was subjected to a two-step reaction. The first one was carried out to protect the PLA hydroxyl groups with benzoyl chloride and a new material was obtained (PLABz). The second one was performed to activate the terminal carboxylic acid by treatment with thionyl chloride (PLAM). Then, PLAM was grafted onto the starch nanocrystal. The evolution of the reactions was studied by infrared spectroscopy, which confirmed the success of each step. The grafting efficiency was investigated by TGA, FTIR and DSC.