Sossio Cimmino

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.

Morphology of a melt crystallized iPP/HDPE/hydrogenated hydrocarbon resin blend

Abstract The structure, phase structure, morphology, crystallization and melting behavior of isotactic polypropylene (iPP) blended with a master batch (MB), formed by high density polyethylene and hydrogenated hydrocarbon resin (iPP/MB), have been in details investigated by using X-ray diffraction, optical microscopy and differential scanning calorimetry. It was found that the structure and morphology depend on crystallization conditions. A new family of α spherulites of iPP (type I spherulites) can be activated using appropriate crystallization conditions. Nucleation of these spherulites has been explained by using the approach of nucleus migration in polymer blends. Type I spherulites present specific morphological, kinetic and thermal behaviors. In particular it was found that the growth rate of type I spherulites, at a given T c , is higher than the growth rate of spherulites grown from plain iPP.

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.

Study of electroless copper plating onto PVDF modified by radio frequency plasma treatment

Surface properties of polyvinylidene fluoride (PVDF) films have been modified by treatment in a radio frequency (RF) nitrogen plasma, at different treatment powers (25, 50 and 75 W). The surface properties of the PVDF films before and after RF plasma treatment, as well as the quality of the deposited copper layer, were investigated by various investigation methods (Scanning electron microscopy, atomic force microscopy, ATR-FTIR and contact angle measurements). RF plasma treatment significantly improved the adherence and the quality of the deposited metal layer. The results obtained for PVDF RF plasma treated were compared with those corresponding to a microwave plasma treatment.

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.

Effect of TiO2 and ZnO on PLA degradation in various media

This work shows the effect of 2 and 5 wt% TiO2 nanoparticles (modified by fluorocarbons and not) and of 1, 3 and 5 wt% ZnO particles on PLA degradation evaluated under UV irradiation, hydrolytical 1N NaOH solution, enzymatical proteinase K solution, and isothermal condition. The presence of TiO2 nanoparticles and ZnO particles decreases the degradation processes of PLA under UV light exposure and increases the PLA hydrolytic degradation. The enzymatic degradation is faster with TiO2 nanoparticles than with ZnO particles, respect neat PLA; whereas the opposite effect is identified in the PLA enzymatic degradation. Correspondence to: CAntonella Marra, Istituto per i Polimeri Compositi e Biomateriali (IPCB), Consiglio Nazionale delle Ricerche (CNR), Via Campi Flegrei 34, Comprensorio Olivetti, 80078 Pozzuoli (NA), Italy, E-mail: marranto.nella@libero.it

Effect of PLA/ZnO Packaging and Gamma Radiation on the Content of Listeria innocua, Escherichia coli and Salmonella enterica on Ham during Storage at 4 °C

The effect of ZnO and low γ-radiation on PLA based-films was investigated to be used for food packaging application. Ham slices were inoculated with E. coli, L. innocua and S. enterica and then covered with PLA and PLA/5% ZnO films. The samples were irradiated with a γ-radiation dose of 0.3 kGy at dose rate of 13.5 kGy/h. Microbiological analysis was performed at 0, 1 and 5 days on samples stored at 4 °C. Results showed that no onsistent reduction of bacteria was obtained, even at the fifth day of storage, when the ham was covered with PLA/5% ZnO film and no γ-radiation was performed. The use of γ-radiation results necessary to reduce the bacteria growth. In fact E. coli and S. enterica were not detected after 5 days of storage; whereas in the case of test with L. innocua a reduction of 1.3 log CFU/g was observed after 5 days of storage. The antibacterial results indicate that the presence of ZnOin PLA film is effective only for E. coli. The differences of the results obtained here with those reported in literature (where ZnO particles are reported to be very effective as antimicrobial material) are accounted for the different methodologies used. In conclusion considering the positive results, even if small, obtained here at least only for the E. Coli and considering that PLA/5% ZnO film shows, compared to plain PLA film, good tensile properties (especially Young’s modulus and stress at yielding) and good permeability (to O2 and CO2) induce to consider the PLA/5% ZnO composite film usable for food packaging when long shelf life and food safety are required, considering also that it is biodegradable and compostable.