Portici, Italy
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Aurilia M.,IMAST | Piscitelli F.,CNR Institute of Composite and Biomedical Materials | Piscitelli F.,University of Naples Federico II | Sorrentino L.,CNR Institute of Composite and Biomedical Materials | And 2 more authors.
European Polymer Journal | Year: 2011

Organo-modified layered silicates (OMLSs) can largely improve mechanical properties of Thermoplastic polyurethanes (TPUs) as well as affect their microdomain morphology. Nanocomposite TPU containing OMLSs were prepared by melt blending at different concentrations. The addition of OMLS has both induced variation in enthalpy of melting of hard and soft phases, and influenced the glass transition temperature of soft domains, as result of the microdomain phase segregation measured by means of fourier transform infrared spectroscopy (FT-IR). Small angle X-ray scattering (SAXS) analysis has shown that the mean distance between hard domains was mostly unaffected by the filler. However, its distribution broadened with the increasing concentration of the OMLSs, resulting in increased extent of the hard domain interface. The storage modulus of TPU nanocomposites incremented with the silicate content, while the dynamic strain scan tests showed pronounced non linear viscoelastic behavior. The analysis of morphological data obtained by SAXS and FT-IR measurements were correlated to thermal and dynamic mechanical properties of TPU samples suggesting a crucial role of the soft domains interface. The storage modulus and loss tangent of TPU nanocomposites were found to increase with the increasing of the interface area of soft domains with both hard domains and OMLS stacks. © 2010 Published by Elsevier Ltd.

Aurilia M.,IMAST | Sorrentino L.,CNR Institute of Composite and Biomedical Materials | Sanguigno L.,IMAST | Iannace S.,CNR Institute of Composite and Biomedical Materials
Advances in Polymer Technology | Year: 2010

Polyethersulfone (PES) is high performance thermoplastic polymer; however, its applications are limited by the poor resistance to several classes of solvents. Fumed silica and expanded graphite nanoparticles were used to prepare nanofilled PES by a melt-compounding technique with the view to improve the barrier properties. Solvent uptake at equilibrium and solvents resistance of nanofilled PES compounds were investigated by three different methodologies: (1) weight increase by methylene chloride absorption in a vapor-saturated atmosphere, (2) solvent uptake of acetone at equilibrium, and (3) decay of storage modulus induced by acetone diffusion. The storage modulus decay was measured by means of dynamic mechanical analysis on samples immersed in an acetone bath. The collected data were fitted to an ad hoc model to calculate the diffusion coefficient. The produced nanofilled PES showed a significant improvement in barrier properties and considerable reduction in acetone uptake at equilibrium, in comparison with the neat PES. Nanofilled PES compounds were also used to produce continuous glass fiber composites by the film-stacking manufacturing technique. The composites exhibited, by and large, improvements in flexural and shear strength. Their solvent resistance was evaluated by measuring the variation of mechanical properties after exposure to acetone for 1 and 5 days. These tests showed that the composites produced with the nanocomposite matrix did not exhibit higher solvent resistance than those prepared with neat PES, probably because of the deterioration of the fiber/nanocomposite-matrix interfacial bond in the wet state. © 2010 Wiley Periodicals, Inc.

Aurilia M.,IMAST | Sorrentino L.,CNR Institute of Composite and Biomedical Materials | Iannace S.,CNR Institute of Composite and Biomedical Materials
Polymer Composites | Year: 2010

An innovative manufacturing process for continuous fiber composites with the polymeric matrix made up of polypropylene and epoxy resin, as a model reactive low molecular weight component, was developed; variable process parameters give rise to different morphologies of matrix components surrounding the woven fabric reinforcement. Furthermore, the combination of both thermoplastic and thermosetting polymers permitted intimate fibers impregnation, typical of thermosetting matrix composites, with short process cycle time, which usually occurs in manufacturing process of thermoplastic matrix composites. Polypropylene (PP) films, glass fibers fabric, and epoxy resin film were used to produce flat composite through film-stacking technique. The preparation process focused on control of both epoxy resin cure process and polypropylene melting. The process was able to induce the two matrix components to form either a planar (sandwich-like) structure or a three-dimensional (3D) network by means of controlling the process parameters such as pressure and heating rate. The strong enhancement of the mechanical properties (Young's modulus and tensile strength of the composites with the 3D structure were almost twice as high of those of the composites with sandwich-like matrix structure) was due to the different microstructures produced by the interplanar flow of the thermoplastic polymer. © 2010 Society of Plastics Engineers.

Aurilia M.,IMAST | Sorrentino L.,CNR Institute of Composite and Biomedical Materials | Iannace S.,CNR Institute of Composite and Biomedical Materials
European Polymer Journal | Year: 2012

The effects of carbon nanotubes dispersion into thermoplastic polymers are complex and strongly dependent upon their aggregation state. A poly(ethylene terephthalate) (PET) matrix has been reinforced through addition of multiwalled carbon nanotubes (MWCNTs). Such an addition has generated an increase in flexural modulus and a decrease in flexural strength at room temperature, and an increase in both properties above the glass transition temperature (at 100°C). These different behaviours, dictated by temperature, have been investigated through two different micromechanical models that have permitted to put forward hypothesis on failure mechanisms and to shed light on the role played by crystalline phase. The results of thermal analyses have shown that the heat capacity of PET nanocomposites varies according to the MWCNTs content as the flexural modulus. Such a similarity has suggested to modify the Halpin-Tsai equations (H-T), typically used to predict elastic properties of short fibres reinforced composites, in order to determine the relationships occurring between PET specific heat and aspect ratio of dispersed MWCNT. The analyses performed by means of either classical H-T (elastic modulus) or modified H-T (heat capacity) equations, provided very similar estimation of the MWCNT aspect ratios. In addition, a simple elaboration of the modified H-T equations permitted the calculation of rigid amorphous fraction (RAF) into PET. The obtained values were slightly higher than those evaluated by means of a procedure based on the loss tangent peak variation measured through dynamic mechanical experiments. The detected strength decrease at 25°C have been attributed to crack propagation through a percolative path between crystalline coating layer of MWCNTs and PET (favoured by matrix brittleness), while at 100°C the crack propagation is hampered by rubbery behaviour of the matrix. © 2011 Elsevier Ltd. All rights reserved.

Aurilia M.,IMAST | Sorrentino L.,CNR Institute of Neuroscience | Berardini F.,University of Naples Federico II | Sawalha S.,An Najah National University | Iannace S.,CNR Institute of Neuroscience
Journal of Thermoplastic Composite Materials | Year: 2012

We have shown in an earlier work that the addition of both organomodified layered silicates and micrometric calcium carbonate (CaCO3) into a polypropylene (PP) matrix resulted in improved mechanical properties due to synergistic effect of the fillers. In this study, we analyzed the feasibility of producing continuous glass fibers composites with micro/nanoreinforced matrix. In particular, either highly filled matrices with micrometric CaCO3 (22, 40, and 50-wt %) or micro/nanoreinforced matrix were used to prepare composites in order to investigate the effect of fillers on both mechanical and thermomechanical properties. The best mechanical performances were obtained when nano- and microsized particles were combined to reinforce the thermoplastic matrices employed in the film stacking manufacturing method. In such systems, the micro/nanocomposites have improved the flexural properties of the continuous fiber laminate, producing an increase of both flexural modulus (60%) and flexural strength (130%). Moreover, storage modulus of glass fibers composite prepared with micro/nanoreinforced matrix was higher than modulus of the composites manufactured with either neat PP matrix or microreinforced matrix in -40/150°C temperature range. © The Author(s) 2011.

Borriello C.,ENEA | Masala S.,ENEA | Bizzarro V.,IMAST | Nenna G.,ENEA | And 4 more authors.
AIP Conference Proceedings | Year: 2010

Luminescent PVK:CdS and P3HT:CdS nanocomposites with enhanced electrooptical properties have been synthesized. The nucleation and growth of CdS nanoparticles have been obtained by the thermolysis of a single Cd and S precursor dispersed in the polymers. The size distribution and morphology of the nanoparticles have been studied by TEM analyses. Monodispersive and very small nanoparticles of diameter below 3 nm in PVK and 2 nm in P3HT, have been obtained. The application of such nanocomposites as emitting layers in OLED devices is discussed. © 2010 American Institute of Physics.

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