Effect of "core-shell” polymeric nanofiller on the structure and properties of polylactide
and thermoplastic corn starch blend
Polimery 2012, No 5, 354
The influence of "core-shell” polymeric nanofiller (DASI) and compatibilizer (maleated polylactide —MPLA) on the structure, mechanical and barrier properties of polylactide and thermoplastic starch blend was investigated. All materials were compounded in a co-rotating twin-screw extruder and then injection molded. The composites were characterized with SEM (Figs. 1—3), DSC (Fig. 4) and DMTA (Fig. 5) methods. Tensile and flexural mechanical and barrier properties were also determined. The addition of DASI in the presence of maleated PLA improves adhesion between the PLA and TPS. It was found out, that contents of DASI particles have great impact on nanocomposites properties. Melting temperature and crystallinity were found to decrease by adding TPS as well as DASI (Table 1). PLA/MPLA/TPS/DASI nanocomoposites showed significantly lower stiffness due to lower storage modulus than pure PLA. However, G' slightly increases as a function of nanofiller (Table 2). Moreover, dynamic mechanical thermal analysis demonstrated that relaxation temperatures (Ta, Tb, Tg) of PLA/MPLA/TPS/DASI nanocomposites decreased (Tables 3, 4). The gradual enhancement in impact, tensile and flexural strengths of PLA/TPS blend containing MPLA was observed (Table 5). The addition of DASI nanoparticles to the PLA/MPLA/TPS blend increased impact strength and elongation at break and decreased tensile and flexural modulus simultaneously (Table 6). The improved barrier properties of nanocomposites containing TPS can also be mentioned as a positive effect (Table 7).