In this work, new polyoxymethylene (POM)/hydroxyapatite (HAp) nanocomposites for long‐term bone implants have been obtained via extrusion and injection molding processes and characterized by differential scanning calorimetry (DSC), temperature‐modulated DSC (TMDSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), wide‐angle X‐ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and tensile mechanical and in vitro stability tests. Based on the DSC results, it was found that the degree of crystallinity increases for POM/0.5% HAp sample and decreases for POM/1.0% HAp and POM/2.5% HAp. SEM and TEM observations for POM/HAp nanocomposites indicated that the dispersion of HAp in the polymer matrix was uniform and the diameter of the HAp particles was less than 100 nm for most of them. Young's modulus increases with increasing HAp concentration, whereby elongation at break decreases. On the contrary, HAp concentration does not have a significant influence on the tensile strength. TG results show that for POM/0.5% HAp, POM/1.0% HAp, and POM/2.5% HAp, thermal stability slightly increases in comparison to pure POM, whereas for POM/5.0 HAp and POM/10.0% HAp, lower thermal stability was observed. In vitro data reveal that with an increase of HAp content, bioactivity of nanocomposites increases; a good in vitro chemical stability of POM and POM nanocomposites was confirmed. Copyright © 2011 John Wiley & Sons, Ltd.

The effect of plasticizer (polydimethylsiloxanol) and neat (SiO2) or modified (having amine functional groups) silica (A-SiO2) on morphology, thermal, mechanical, and rheological properties of PLA/TPS blends compatibilized by maleated PLA (MPLA) was investigated. Toughened PLA/MPLA/TPS (60/10/30) blend containing 3 wt.% of plasticizer and various contents (1, 3, or 5 wt.%) of silica were prepared in a corotating twin-screw extruder. From SEM, it is clear that plasticized PLA/MPLA/TPS blend continuous porous structure is highly related to the silica content and its functionality. The results indicate that polydimethylsiloxanol enhances ductility and the initial thermal stability of the plasticized blend. DSC and DMTA analyses show that nucleation ability and reinforcing effect of A-SiO2on plasticized blend crystallization are much better than those of SiO2. Silica practically had no effect on the thermo-oxidative degradation. However, the composites with A-SiO2had better thermal stability than those with SiO2. Moreover, silica significantly improved the elongation at break.

Biodegradowalne nanokompozyty polimerowe CZ. I. METODY OTRZYMYWANIA Streszczenie-Dokonano przegl¹du literatury dotycz¹cej metod otrzymywania biodegradowalnych nanokompozytów polimerowych na podstawie nanonape³niaczy nieorganicznych oraz skrobi, celulozy, ¿elatyny, chitozanu, poli(kwasu mlekowego) (PLA), poli(kwasu hydroksymas³owego) (PHB), poli(bursztynianu butylenu) (PBS), poli(kaprolaktonu) (PCL) lub poliestrów alifatycznych. Na przyk³adzie montmorylonitu przedstawiono mechanizm wspó³oddzia³ywania polimerów z warstwowymi nanonape³niaczami. Omówiono metody mieszania tych sk³adników nanokompozytów w stanie stopionym b¹dŸ w roztworze, procesy wspó³str¹cania, polimeryzacjê in situ, technikê zol-¿el oraz sposoby niekonwencjonalne, przede wszystkim wysokoenergetyczne rozdrabnianie (HEBM). S³owa kluczowe: polimery biodegradowalne, nieorganiczne nanonape³niacze, montmorylonit, nanokompozyty, metody otrzymywania. BIODEGRADABLE POLYMER NANOCOMPOSITES. PART I. METHODS OF PREPARATION Summary-A literature review (83 references) concerning the methods of synthesis of the biodegradable polymer nanocomposites, based on inorganic nanofillers or cellulose, gelatin, chitosan, poly(lactic acid) (PLA), poly(hydroxybutyric acid) (PHB), poly(butylene succinate) (PBS), poly(ε-caprolactone) (PCL) or aliphatic polyesters, was done. The mechanism of polymer interaction with layered nanofillers was presented using montmorillonite as an example (Fig. 1-3, Table 1). The methods of blending in melt or solution, co-precipitation processes, in-situ polymerizaton, sol-gel technique as well as unconventional methods, mainly High-Energy Ball Milling (HEBM), were described.

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Potato thermoplastic starch (TPS) containing 1 wt.% of pure halloysite (HNT), glycerol-modified halloysite (G-HNT) or polyester plasticizer-modified halloysite (PP-HNT) was prepared by melt-extrusion. Halloysites were characterized by FTIR, SEM, TGA, and DSC. Interactions between TPS and halloysites were studied by FTIR, SEM, and DMTA. The Vicat softening temperature, tensile, and flexural properties were also determined. FTIR proved the interactions between halloysite and the organic compound as well as between starch, plasticizers and halloysites. Pure HNT had the best thermal stability, but PP-HNT showed better thermal stability than G-HNT. The addition of HNT and G-HNT improved the TPS’s thermal stability, as evidenced by significantly higher T5%. Modified TPS showed higher a Vicat softening point, suggesting better hot water resistance. Halloysite improved TPS stiffness due to higher storage modulus. However, TPS/PP-HNT had the lowest stiffness, and TPS/HNT the highest. Halloysite increased Tα and lowered Tβ due to its simultaneous reinforcing and plasticizing effect. TPS/HNT showed an additional β-relaxation peak, suggesting the formation of a new crystalline phase. The mechanical properties of TPS were also improved in the presence of both pure and modified halloysites.

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