The widespread application of poly(3-hydroxybutyrate) (PHB) in the food packaging and biomedical fields has been hindered by its high brittleness, slow crystallization, poor thermal stability, and narrow processing window. To overcome these limitations, a mixture of biodegradable and biocompatible plasticizers was used to modify PHB. Epoxidized soybean oil (ESO), acetyl tributyl citrate, poly(ethylene glycol) 4000 (PEG4000), and poly(ethylene glycol) 6000 (PEG6000) were tested to improve PHB melt processing and to achieve balanced thermal and mechanical properties. These plasticizers increased the flexibility and decreased the melt viscosity, improving the processability. The tensile strength was maintained within the limit of experimental error for ESO and decreased slightly (6-7%) for the other plasticizers. PEG6000 and ESO delayed the decomposition process of PHB. The plasticizers did not hinder the crystallization, and poly(ethylene glycol)s increased the crystallinity. The change in the interplanar distance and crystallite size, correlated with lamellar stack dimensions, gave more information on the plasticizers' effects in PHB. The blend with 5 wt % ESO was considered suitable for the fabrication of marketable PHB films. This study showed that it is possible to tailor the rheological, thermal, and mechanical behavior of a commercial PHB through the addition of a second plasticizer.

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Polymer composites with cellulose microfibrils are materials with unique properties compared to existing materials: high strength, formability, and geometrical complexity at very small scale, low density, and abrasivity, biomedical compatibility, and possibility of recycling. Polymer composites from polypropylene and two types of cellulose microfibrils were prepared and characterized. To enhance the compatibility of cellulose microfibrils with polypropylene matrix, a silane‐coupling agent and a modified polypropylene were used. Depending on the applied method, composite materials with enhanced mechanical properties were obtained. Morphostructural properties of cellulose microfibrils and polymer composites with treated and untreated microfibrils were investigated using scanning electronic microscopy (SEM), FTIR spectroscopy, and differential scanning calorimetry (DSC). POLYM. ENG. SCI., 47:1228–1234, 2007. © 2007 Society of Plastics Engineers

Polymers filled with inorganic nanoparticles have become interesting materials as dielectrics because of their improved mechanical and electrical properties compared with the unfilled polymers and with polymer microcomposites. These improvements are mainly due to the large surface area of nanoparticles and new polymer-nanofiller interface characteristics. In the present work, polyethylene nanocomposites with SiO 2 and Al 2 O 3 nanoparticles were prepared by melt mixing. Mechanical and electrical properties of these composites were determined and morphological aspects were revealed by scanning electron microscopy, wide-angle X-ray diffraction, and atomic force microscopy. The effect of nanostructure and the importance of nanofiller dispersion were analyzed in connection with mechanical and electrical properties.

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