The present work deals with polymer blends produced from poly(3-hydroxybutyrate), P3HB and polyurethane. Linear polyurethane (PU) was here synthesized by reacting polypropylene glycol with 4,4'-diphenylmethane diisocyanate, and was used in amounts of 5, 10 and 15 wt. %. The polymers were melt-mixed using a twin-screw extruder after prior premixing. The obtained blends were tested by differential scanning calorimetry analysis (DSC), Fourier transformation infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). Their thermal and mechanical properties, including impact resistance, hardness, tensile and flexural properties, were also determined, and the surface topography and roughness were analyzed. FTIR analysis of the prepared blends confirmed the interactions of PU with the P3HB matrix via hydrogen bonding. Analysis of the surface topography of the samples showed that the higher the PU content, the greater the regularity and homogeneity of the surface structure. The roughness of the P3HB blend containing 5 wt. % PU was the greatest. SEM images of the fracture surfaces of the blend samples explain the mechanism of the improvement of their mechanical properties. The obtained polymer blends were characterized by significantly lower hardness, and better impact strength and relative elongation at break compared to native P3HB. The DSC results confirm a decrease in the glass transition, melting and crystallization temperatures with increasing amounts of PU in the blends. The lower melting temperature and the higher degradation temperature of the resulted blends than native P3HB make the processing conditions easier, and prevent the degradation of the material. The best mechanical and thermal properties were shown by blends containing 10 wt. % of PU.

• Keywords
• mechanical properties, polyhydroxyalkanoates, polymer blends, polyurethanes, structure, structure-properties relationship, thermal stability,
• Publication type
• Journal Article MeSH

In the present work, hybrid nanobiocomposites based on poly(3-hydroxybutyrate), P3HB, with the use of aromatic linear polyurethane as modifier and organic nanoclay, Cloisite 30B, as a nanofiller were produced. The aromatic linear polyurethane (PU) was synthesized in a reaction of diphenylmethane 4,4'-diisocyanate and polyethylene glycol with a molecular mass of 1000 g/mole. The obtained nanobiocomposites were characterized by the small-angle X-ray scattering technique, scanning electron microscopy, Fourier infrared spectroscopy, thermogravimetry, and differential scanning calorimetry, and moreover, their selected mechanical properties, biodegradability, and cytotoxicity were tested. The effect of the organomodified montmorillonite presence in the biocomposites on their properties was investigated and compared to those of the native P3HB and the P3HB-PU composition. The obtained hybrid nanobiocomposites have an exfoliated structure. The presence and content of Cloisite 30B influence the P3HB-PU composition's properties, and 2 wt.% Cloisite 30B leads to the best improvement in the aforementioned properties. The obtained results indicate that the thermal stability and mechanical properties of P3HB were improved, particularly in terms of increasing the degradation temperature, reducing hardness, and increasing impact strength, which were also confirmed by the morphological analysis of these bionanocomposites. However, the presence of organomodified montmorillonite in the obtained polymer biocomposites decreased their biodegradability slightly. The produced hybrid polymer nanobiocomposites have tailored mechanical and thermal properties and processing conditions for their expected application in the production of biodegradable, short-lived products for agriculture. Moreover, in vitro studies on human skin fibroblasts and keratinocytes showed their satisfactory biocompatibility and low cytotoxicity, which make them safe when in contact with the human body, for instance, in biomedical applications.

• Keywords
• biodegradability, cytotoxicity, mechanical properties, polyester, polyurethane, structure–properties relationship, thermal stability,
• Publication type
• Journal Article MeSH