PLLA-modified cellulose nanocrystals (CNC) were produced from commercial CNC by tin-catalyzed polymerization of lactide in presence of CNC. FTIR spectroscopy demonstrated that the result of the reaction produced the grafting of PLLA chains onto CNC surface (CNC-g-PLLA). Films of poly(lactic acid) (PLA) and PLA/CNC nanocomposites (with non-modified CNC and CNC-g-PLLA) containing 0.5% and 5% (w/w) of the nanofillers were prepared by casting in chloroform solution and the crystallization behavior and thermal properties investigated. All nanocomposites had similar thermal stability when analyzed by TGA analyses under an inert nitrogen atmosphere. Addition of both types of CNC influenced crystallization, the higher crystallization rate being observed for 5% (w/w) CNC. Nanocomposites with 5% (w/w) CNC-g-PLLA had the strain resistance of PLA improved in the rubbery state. PLLA-modification of CNC surface increased the crystallization of PLA in PLA/CNC nanocomposites and improved the rigidity at temperatures above the glass transition, properties which are desirable for hot drinking application.

ObstractThe biodegradable aliphatic oligoester oligo(trimethylene separate) (OTS) was synthesized by polycondensation and used to plasticize poly(lactic acid) (PLA). Casting films of PLA and PLA/OTS with concentrations of 1, 5 and 10 wt.% were prepared, and these films were characterized by thermal analyses, crystallinity, rheology and mechanical tests. DSC revealed the decrease in the T g of PLA films with addition of the oligomer and a partial immiscibility. Addition of OTS to PLA slightly decrease the thermal stability as well as increase the degree of crystallinity of these films. Dynamic-mechanical analyses of casting films showed that the PLA/OTS system presented lower storage modulus than PLA and mechanical test revealed an increased in the elongation at break for PLA films containing the oligoester. The results make possible to conclude that the oligomer synthesized from bio-based monomers acts as a plasticizer of PLA increasing the PLA ductility. Keywords: plasticization poly(lactic acid), oligoesters, trimethylene sebacate, cast films.Aiming to investigate the efficiency of oligoester as PLA biodegradable plasticizers, a oligoester based on two

The biodegradable aliphatic oligoester oligo(trimethylene malonate) (OTM) is synthesized by polycondensation and used to plasticize poly(lactic acid) (PLA). Casting films of PLA and PLA/OTM with concentrations of 1, 5,and 10 wt.% are prepared, and these films are characterized by thermal analyses, rheology, and mechanical tests. DSC revealed that the Tg of PLA films decreases with addition of the oligomer. A decrease of about 10 °C in the Tg is attained when 10 wt% of the oligomer is added to the polymer. Addition of OTM to PLA slightly decreases the thermal stability and does not change significantly the degree of crystallinity (Xc) of the films. Dynamic‐mechanical analyses of these casting films show that the PLA/OTM systems presented lower storage modulus than PLA and mechanical test shows an increased in the elongation at break for PLA films containing the oligoester up to 200%. The results make possible to conclude that the oligomer synthesized from bio‐based monomers acts as a plasticizer of PLA increasing the PLA flexibility.