engleski

PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE POLYLACTID ACID AND POLY(ETHYLENE OXIDE) BLENDS

The aim of this work was to prepare blends of biodegradable polylactid acid (PLA) with poly(ethylene oxide) (PEO) and to investigate possible interactions within prepared polymer blends. Investigated blends were prepared by hot melt extrusion (HME) process in a laboratory extruder. The thermal characteristics of neat polymers and their blends were investigated by means of differential scanning calorimetry (DSC) in a nitrogen atmosphere. The glass transition temperature of PLA in the PLA/PEO blends could not be determined because it was overlapped with an endothermic peak of PEO melting. Therefore, the melting point of investigated samples as a miscibility criterion were used. The depression of melting temperatures at higher PLA or PEO content (80%) indicated that PLA and PEO are only partially miscible in the melt. Likewise, Fourier transform infrared spectroscopy (FT-IR) was used to investigate possible interactions. The observed shifting of peak maxima in FT-IR spectra of blends with higher PLA or PEO content (80%) are significant enough to confirm the interactions between the investigated polymers in blends, as well as the results of DSC analysis. Thermal stability of PLA/PEO blends has been investigated by thermogravimetric analysis (TG) in nonisothermal heating regime in a nitrogen atmosphere. Neat polymers exhibit single stage degradation, while a two-stage degradation pattern is seen in the case of all PLA/PEO blends. From characteristic of TG curves, it could be concluded that the degradation of PLA/PEO blends starts at lower temperatures and occurs more slowly by addition of PEO.

polylactid acid, poly(ethylene oxide), differential scanning calorimetry, Fourier transform infrared spectroscopy, thermogravimetric analysis

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