Browsing by Author "Tsvetanov K."

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    PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE POLYMERIC NANOCOMPOSITES BASED ON POLYLACTIDE AND GRAPHENE OXIDE
    (2020-01-01) Velev P.; Samichkov V.; Atanasov V.; Tsvetanov K.
    A homogeneous dispersion had been prepared with a concentration of 1 % nanosized graphene oxide in ammonium hydroxide. In a simple mixer, the polylactide granulate was homogenized with varying amounts of nanosized dispersion and then dried to a constant mass. From the so-treated granulate test specimens were prepared using injection molding. The resulting nanoparticles containing graphene oxide in concentrations of 0.01, 0.05 and 0.1 % were characterized by tensile strength and elongation at break, infrared spectroscopy, dynamic mechanical thermal analyzer, X-ray diffraction, scanning electron microscopy (SEM). The results show that nanocomposites are homogeneous enough, having in mind their preparation method. Their physicomechanical characteristics are some lower than those for pure polylactide. These types of composites could find an application as a nutrient medium for definite bacterial strain.
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    Preparation and Characterization of Polylactide and Natural Rubber Based Composites with Improved Impact Resistance
    (2021-01-01) Tsvetanov K.; Velev P.; Samichkov V.
    The properties of poly(lactic acid) (PLA) based composite materials with natural rubber (NR) or epoxidized natural rubber (ENR) have been investigated in order to improve the impact strength of the polylactide. The influence of glycidopropyl- 3-methoxysilane as a compatibilizer between the polylactide and the epoxidized rubber to improve adhesion on the phase/medium boundary was investigated. The physico-mechanical properties of the resulting molecular composites have been determined, dynamic mechanical analysis and IR spectroscopy have been performed. It is established that filling PLA with low concentrations of NR or ENR significantly improves the impact strength of the resulting composite material.