The molecular weight of PLA was determined at temperature 25°C by gel permeation chromatography (GPC) using Agilent 1100 Series system with refractive index, RID 1200, and diode array 1200 detectors.
The column ZORBAX PSM 300 was used. The rate flow of the eluent tetrahydrofuran was 1 cm 3min–1.
The average molar masses (Mn, Mw) and polydispersity index (Q) were determined using software Agilent ChemStation.
Poly (styrene) standards were used for the calibration curve.
Parameters of the neat PLA from (GPC) are: Mn=60520; weight-average molecular weight Mw=160780 and polydispersity of Q=2.6.
The nanosilica Sidistar T120 with specific surface 20 m2/g and average particle size 150 nm and type N999 with specific surface 45-60 m2/g and average particle size 40 nm were supplied by Elkem (Oslo, Norway); they were used as received.