Donatella Duraccio

Polylactic acid/zinc oxide biocomposite films for food packaging application

Although PLA is much more expensive than polyolefins, such as PP and PE, there is a great interest to propose PLA based material as alternative films for food packaging being PLA derivable from natural source, compostable and biodegradable. For this purpose the research has the task to investigate and propose PLA materials with enhanced properties to be effectively and efficiently alternative to polyolefin films for food packaging application. In this contribution, biocomposite films of PLA with 1, 3 and 5wt% of ZnO have been investigated to determine mechanical, barrier and antimicrobial (against Escherichia coli) properties. It is found that the biocomposite films are characterized by a good dispersion of the ZnO particles in PLA matrix, although no previous treatment was performed on ZnO particles, such as silanization, to decrease its incompatibility with the polymer. The biocomposite films have shown good mechanical properties, decrease of permeability to CO2 and O2, and only a slight increase to water vapour. Particularly important is that, for the biocomposite with 5wt% of ZnO, the % Reduction for E. Coli test reached the value of 99.99 already after 24h.

Characterisation of the Chitosan/layered silicate nanocomposites

Characterization of chitosan / layered silicate nanocomposites obtained by solution-mixing technique, having different compositions including treated and untreated montmorilonite (MMT) has been performed. The optimum amount of MMT and also the effect of nanoparticles type on nanocomposite properties by DSC, X-ray diffraction and TG measurements have been established. The chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the silicates in the nanocomposites enlarged as their amount increased. The stiffness and thermal stability enhanced.

Preparation and characterization of nanocomposites based on PLA and TiO2 nanoparticles functionalized with fluorocarbons

Poly(l-lactic acid)–TiO2 nanocomposite films were prepared by twin-screw mixer and compression molding. Compatibility between polymer matrix and nanoparticles were improved by modification of the TiO2 surface with fluorocarbons plasma treatment. 2 and 5 were the % in weight of modified functionalized TiO2 (fTi) used in this work. Not modified TiO2 nanoparticles were also used at the same % for comparison. The nanocomposites were analyzed in terms of molecular mass, structure, morphology, thermal stability, mechanical properties and UV absorbance. It was found that TiO2 nanoparticles affected slighly the PLA molecular weight during mixing and the phenomenon was more marked for functionalized nanoparticles (fTi). All the films presented a good dispersion of nanoparticles in PLA matrix. However, a better interfacial interaction was found for nanocomposites containing modified nanoparticles, and this was reflected in the improved mechanical properties. Moreover, all the nanocomposites showed extension of UV absorption area and increase of the thermal stability. Both UV adsorption and thermal stability increased by increasing TiO2 content and at a given composition for nanocomposites containing modified TiO2.

Quiescent and shear-induced non-isothermal crystallization of isotactic polypropylene-based nanocomposites

The paper reports a study of the effect of the addition of clay nanoparticles on melt rheology, phase structure, and non-isothermal crystallization process of isotactic polypropylene/hydrogenated oligocyclopentadiene (iPP/HOCP) system in quiescent conditions by DSC and under shear applied at different temperatures by SAXS. For both crystallization conditions, the addition of clay and/or HOCP shifts always the crystallization onset to lower values with respect to iPP. These results can be attributed to the diluent effect of HOCP that causes a decrease in the rate of nucleation and grow of the crystals, to the presence of segregated non-crystallizable phases/particles which hinder the transport of macromolecules chains toward the growing nuclei, and to the formation of beta iPP crystals and in the case of shear-induced crystallization to the presence of HPS which seems to reduce, mainly at low Ts, the amount of oriented polymer crystals, which are nuclei for the crystallization. At a given composition, the crystallization temperatures related at the crystallization under shear are always higher that those obtained by quiescent crystallization supporting the idea that the presence of extended chains in these samples act as nucleating agents favoring the crystallization process of iPP.

Modification of PVDF properties by dielectric barrier discharge treatment

Abstract Films of polyvinylidene fluoride (PVDF) were treated in a dielectric barrier discharge (DBD) in helium, for different exposure times. Modification of PVDF properties was followed by: contact angle measurements, ATR-FTIR spectrometry and scanning electron microscopy. The applied treatment led to the obtainment of polar surfaces, with biocompatibility characteristics. These enhancements in PVDF properties after plasma exposure, associated with the possible increase of the polymer roughness, could lead to an enhanced adhesion with other materials, condition which has to be fulfilled for a series of applications (e.g.: biosensors).

Nanocomposites Based On Montmorillonite/Acrylic Copolymer for Aqueous Coating of Soft Surfaces

Nanocomposites based on layered silicate organically modified montmorillonite (Cloisite 20A) and acrylic comonomers (butyl acrylate and methyl methacrylate) were prepared by simple “in situ” batch emulsion polymerization method. The particle size and zeta potential of the emulsions were analyzed. The structural characterizations of the nanocomposites were performed by FTIR, thermal behaviors of the films were investigated by DSC, mechanical properties of the films were tested by DMA and intercalation success was viewed by XRD. The mechanical properties of the nanocomposites were improved significantly especially at the temperatures above Tg. The ultrasonication process was found to be useful for increasing the homogeneity of the emulsions and intercalation success. The obtained nanocomposite emulsions were applied on garment leathers in a finishing formulation as aqueous binders sharing good film forming ability and elasticity.