Bioartificial blends of poly-(epsilon-caprolactone) (PCL) with a polysaccharide (starch, S; dextran, D; or gellan, G) (PCL/S, PCL/D, PCL/G 90.9/9.1 wt ratio) were prepared by a solution-precipitation technique and widely characterized by differential scanning calorimetry analysis (DSC), Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), optical microscopy (OM), wide-angle X-ray diffraction analysis (WAXD), and thermogravimetry (TGA). DSC showed that the polysaccharide reduced the crystallinity of PCL and had a nucleation effect, which was also confirmed by OM analysis. Hoffman-Weeks analysis was performed on PCL and blend samples allowing calculation of their equilibrium melting temperatures (). WAXD showed that the crystalline unit cell type was the same for PCL and blends. FTIR-ATR did not evidence interactions between blend components. Thermal stability was affected by the type of polysaccharide. Microparticles (<125 microm) were produced from blends by cryogenical milling and characterized by scanning electron microscopy analysis (SEM). Selective laser sintering (SLS), a new rapid prototyping technology for scaffold fabrication, was applied to sinter blend microparticles according to a PC-designed two-dimensional geometry (strips and 2 x 2 mm(2) square-meshed grids). The optimal experimental conditions for sintering were established and laser beam parameters (beam speed, BS, and power, P) were found for each blend composition. Morphology of sintered objects was analyzed by SEM and found to be dependent on the morphology of the sintered powders. Sintered samples were analyzed by chemical imaging (CI), FTIR-ATR, DSC, and contact angle analysis. No evidence of the occurrence of degradation phenomena was found by FTIR-ATR for sintered samples, whereas DSC parameters of PCL and blends showed changes which could be attributed to some molecular weight decrease of PCL during sintering. CI of sintered samples showed that the polysaccharide phase was homogeneously dispersed within the PCL matrix, with the only exception being the PCL/D blend. The contact angle analysis showed that all samples were hydrophilic. Fibroblasts were then seeded on scaffolds to evaluate the rate and the extent of cell adhesion and the effect of the polysaccharides (S, D, G) on the bioactivity of the PCL-based blends.

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Composites of poly(L-lactide) (PLA) with hemp fibers (Cannabis sativa), prepared by batch mixing and plasticized with poly(ethylene glycol) (PEG; weight-average molecular weight ¼ 600 g/mol), were examined by polarized optical microscopy, scanning electron microscopy, wide-angle X-ray scattering, differential scanning calorimetry, thermogravimetric analysis, and mechanical tests. The properties of both fully amorphous and semicrystalline samples of PLA/hemp and PLA-PEG/hemp composites were analyzed as a function of the fiber amount. The cold-crystallization kinetics of PLA in amorphous composites were investigated under isothermal conditions within the range of 70-1308C. For PLA/hemp samples, the bulk crystallization rate displayed a maximum near 1108C, whereas for plasticized samples, a higher and almost constant crystallization rate was observed over the entire temperature range, independently of the hemp amount. The kinetics were then analyzed on the basis of the Avrami model. The effect of fibers on the growth morphology of PLA spherulites, as well as the influence of the plasticizer on the melting behavior of PLA crystals and their reorganization during heating, was also examined. The thermogravimetric analysis of the composites, carried out in both nitrogen and air, showed that the degradation process of fiber-filled systems started earlier than that of plain PLA, independently of the presence of the plasticizer. Mechanical tests showed that the modulus of elasticity of the composites markedly increased with the hemp content, reaching 5.2 GPa in the case of crystallized PLA reinforced with 20 wt % hemp, whereas the elongation and stress at break decreased with an increasing amount of fiber for all examined systems. Plasticization with PEG did not improve the tensile properties of the composites.

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The morphology and physical/mechanical properties of non‐compatibilized and compatibilized blends of poly(ethylene terephthalate) (PET) and polyethylene (HDPE) obtained from virgin and post‐consumer packaging materials were investigated. The blend compatibilization was carried out by melt‐mixing in the presence of various polyolefins functionalized with reactive groups (HDPE‐g‐MA, EPR‐g‐MA, E‐AA, E‐GMA, SEBS‐g‐MA). The effect of the type and concentration of compatibilizer, as well as the mixing conditions on the phase morphology, crystallization behavior, chemical interactions and melt rheology of the blends was then examined by means of electron microscopy (SEM), scanning calorimetry (DSC), FTIR and NMR spectroscopy, and capillary rheometry. The results pointed out that ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA) displayed a higher compatibilizing efficiency giving rise to a neat improvement of phase dispersion and interfacial adhesion in the blends, as compared to the other compatibilizers examined. This was accounted for by a high reactivity of epoxy groups with the chain end‐groups of PET during melt‐mixing and the effect of in situ formed graft copolymer on the interfacial properties (reduction of coalescence, interpenetration with homopolymer phases). Tensile mechanical tests showed that elongation at break of recycled PET/HDPE (75/25) blends was markedly enhanced upon addition of E‐GMA amount lower than 5 wt.‐%.

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Nanocomposites of isotactic polypropylene (PP) with polyhedral oligomeric silsesquioxanes (POSS) [RSiO1,5]8 having different alkyl substituents (R = methyl, isobutyl, isooctyl) were obtained by melt blending and analysed with electron microscopy, optical microscopy and DSC calorimetry. The influence of POSS structure on the morphological characteristics, the crystallization and melting behaviour of PP/POSS composites was investigated with varying the filler amount. The crystallization kinetics of the composites from the melt, examined both in isothermal and non‐isothermal conditions, demonstrated that the nucleation activity of the examined POSS can be related to the length of alkyl substituents which, depending on the loading amount, affect the filler dispersion in the PP matrix and the growth of polymer crystals.