Luigi Nicolais

Bio: Luigi Nicolais is an academic researcher from University of Naples Federico II. The author has contributed to research in topics: Glass transition & Epoxy. The author has an hindex of 61, co-authored 455 publications receiving 13902 citations. Previous affiliations of Luigi Nicolais include University of Connecticut & National Research Council.

Stress-strain behavior of styrene-acrylonitrile/glass bead composites in the glassy region

Abstract: The effects of temperature, strain rate and filler content on tensile properties of SAN/glass bead composites are studied. A point of discontinuity on the stress-strain curves for unannealed composites is investigated, annealing results in smooth curves with no discontinuities. A simple model for the filler effect on yield stress is suggested and shown to be in a good agreement with experimental data. A double shifting procedure to account for the temperature and filler effects on yield stress as a function of strain rate is proposed. A single master curve that can be represented by the equation: relates composite yield stress to strain rate, temperature and filler volume fraction.

Novel superabsorbent cellulose-based hydrogels crosslinked with citric acid

Abstract: This work is focused on the preparation of new environmentally friendly hydrogels derived from cellulose and hence originating from renewable resources and characterized by biodegradable properties. Two cellulose derivatives, sodium carboxymethylcellulose (CMCNa) and hydroxyethylcellulose (HEC), were used for superabsorbent hydrogel preparation. Citric acid (CA), a crosslinking agent able to overcome toxicity and costs associated with other crosslinking reagents, was selected in a heat activated reaction. Differential scanning calorimeter (DSC), fourier transform infrared spectroscopy (FTIR), and swelling measurements were performed during the reaction progress to investigate the CA reactivity with each of the polymers. Also, CMCNa/HEC polymer mixtures (3/1 w/w) crosslinked with CA were investigated and compared with previous results. Finally, a possible reaction mechanism was proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Metal-Polymer Nanocomposites

Abstract: Preface.Contributors. 1. Physical and chemical properties of nanosized metal particles (C.N.R. Rao, et al.). 2. Metal containing polymers: cryochemical synthesis, structure and physico-chemical properties (L.I. Trakhtenberg and G.N. Gerasimov).3. Controlled pyrolysis of metal-containing precursors as a way for synthesis of metallopolymer nanocomposites (A.D. Pomogailo, et al.). 4. Nanostructured polymeric nanoreactors for metal nanoparticle formation (L.M. Bronstein).5. Metal-polymer nanocomposite synthesis: Novel Ex Situ and In Situ approaches (G. Carotenuto, et al.).6. Plamon absorption of embedded nanoparticles (A. Heilmann).7. Magnetooptic of granular materials and new optical methods of magnetic nanoparticles and nanostructures imaging (V. Belotelov, et al.). 8. Optical extinction of metal nanoparticles synthesized in polymer by ion implantation (A.L. Stepanov).9. Optically anisotropic metal-polymer nanocomposites (W. Caseri).Index.

Poly(lactic acid)/organoclay nanocomposites: Thermal, rheological properties and foam processing

Abstract: In this study, polymer nanocomposites based on poly(lactic acid) (PLA) and organically modified layered silicates (organoclay) were prepared by melt mixing in an internal mixer. The exfoliation of organoclay could be attributed to the interaction between the organoclay and PLA molecules and shearing force during mixing. The exfoliated organoclay layers acted as nucleating agents at low content and as the organoclay content increased they became physical hindrance to the chain mobility of PLA. The thermal dynamic mechanical moduli of nanocomposites were also improved by the exfoliation of organoclay; however, the improvement was reduced at high organoclay content. The dynamic rheological studies show that the nanocomposites have higher viscosity and more pronounced elastic properties than pure PLA. Both storage and loss moduli increased with silicate loading at all frequencies and showed nonterminal behavior at low frequencies. The nanocomposites and PLA were then foamed by using the mixture of CO2 and N2 as blowing agent in a batch foaming process. Compared with PLA foam, the nanocomposite foams exhibited reduced cell size and increased cell density at very low organoclay content. With the increase of organoclay content, the cell size was decreased and both cell density and foam density were increased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 689–698, 2005

Isothermal crystallization and chain mobility of poly(L-lactide)

Abstract: Isothermal melt crystallization of poly(L-lactide) (PLLA) has been studied in the temperature range of 90 to 135°C. A maximum in crystallization kinetic was observed around 105°C. A transition from regime II to regime III is present around 115°C. The crystal morphology is a function of the degree of undercooling. At crystallization temperatures (Tc) below 105°C, further crystallization occurs upon heating; this behavior is not detected for Tc above 110°C. The analysis of the heat capacity increment at glass transition temperature (Tg) and of dielectric properties of PLLA indicates the presence of a fraction of the amorphous phase which does not relax at the Tg, and the amount of this so-called rigid amorphous phase is a function of Tc. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 911–919, 1997

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

A review of chitin and chitosan applications

Abstract: Chitin is the most abundant natural amino polysaccharide and is estimated to be produced annually almost as much as cellulose. It has become of great interest not only as an underutilized resource, but also as a new functional material of high potential in various fields, and recent progress in chitin chemistry is quite noteworthy. The purpose of this review is to take a closer look at chitin and chitosan applications. Based on current research and existing products, some new and futuristic approaches in this fascinating area are thoroughly discussed.

Gold nanoparticles in chemical and biological sensing.

Abstract: Detection of chemical and biological agents plays a fundamental role in biomedical, forensic and environmental sciences1–4 as well as in anti bioterrorism applications.5–7 The development of highly sensitive, cost effective, miniature sensors is therefore in high demand which requires advanced technology coupled with fundamental knowledge in chemistry, biology and material sciences.8–13 In general, sensors feature two functional components: a recognition element to provide selective/specific binding with the target analytes and a transducer component for signaling the binding event. An efficient sensor relies heavily on these two essential components for the recognition process in terms of response time, signal to noise (S/N) ratio, selectivity and limits of detection (LOD).14,15 Therefore, designing sensors with higher efficacy depends on the development of novel materials to improve both the recognition and transduction processes. Nanomaterials feature unique physicochemical properties that can be of great utility in creating new recognition and transduction processes for chemical and biological sensors15–27 as well as improving the S/N ratio by miniaturization of the sensor elements.28 Gold nanoparticles (AuNPs) possess distinct physical and chemical attributes that make them excellent scaffolds for the fabrication of novel chemical and biological sensors (Figure 1).29–36 First, AuNPs can be synthesized in a straightforward manner and can be made highly stable. Second, they possess unique optoelectronic properties. Third, they provide high surface-to-volume ratio with excellent biocompatibility using appropriate ligands.30 Fourth, these properties of AuNPs can be readily tuned varying their size, shape and the surrounding chemical environment. For example, the binding event between recognition element and the analyte can alter physicochemical properties of transducer AuNPs, such as plasmon resonance absorption, conductivity, redox behavior, etc. that in turn can generate a detectable response signal. Finally, AuNPs offer a suitable platform for multi-functionalization with a wide range of organic or biological ligands for the selective binding and detection of small molecules and biological targets.30–32,36 Each of these attributes of AuNPs has allowed researchers to develop novel sensing strategies with improved sensitivity, stability and selectivity. In the last decade of research, the advent of AuNP as a sensory element provided us a broad spectrum of innovative approaches for the detection of metal ions, small molecules, proteins, nucleic acids, malignant cells, etc. in a rapid and efficient manner.37 Figure 1 Physical properties of AuNPs and schematic illustration of an AuNP-based detection system. In this current review, we have highlighted the several synthetic routes and properties of AuNPs that make them excellent probes for different sensing strategies. Furthermore, we will discuss various sensing strategies and major advances in the last two decades of research utilizing AuNPs in the detection of variety of target analytes including metal ions, organic molecules, proteins, nucleic acids, and microorganisms.