Development of Quebracho (Schinopsis balansae) Tannin-Based Thermoset Resins

One of the major challenges currently in the field of material science is finding natural alternatives to the high-performing plastics developed in the last century. Consumers trust synthetic products for their excellent properties, but they are becoming aware of their impact on the planet. One of the most attractive precursors for natural polymers is tannin extracts and in particular condensed tannins. Quebracho (Schinopsis balansae) extract is one of the few industrially available flavonoids and can be exploited as a building block for thermoset resins due to its phenol-like reactivity. The aim of this study was to systematically investigate different hardeners and evaluate the water resistance, thermal behavior, and chemical structure of the quebracho tannin-based polymers in order to understand their suitability as adhesives. It was observed that around 80% of the extract is resistant to leaching when 5% of formaldehyde or hexamine or 10% of glyoxal or furfural are added. Additionally, furfuryl alcohol guarantees high leaching resistance, but only at higher proportions (20%). The quebracho-based formulations showed specific thermal behavior during hardening and higher degradation resistance than the extract. Finally, these polymers undergo similar chemistry to those of mimosa, with exclusive reactivity of the A-ring of the flavonoid

Interpretation of Evidence: The Key to Conveying Information to Court

Abstract The advent of new technologies such as DNA typing, the weight of scientific evidence in criminal trials of widespread publicity, and the proliferation of fictional and non-fictional works in popular media have contributed to making forensic science well known, although perhaps not as well understood, by the general public. One of the consequences of this popularisation of forensic science was a sharp change in the attitude of investigators, who increasingly tend to delegate to scientists the collection of information necessary to identify the perpetrator of the crime. However, the prominent focus on the search of biological traces or fingerprints, due to their high potential for the personal identification of the individuals present at the crime scene, somewhat fade the interest towards other kinds of evidence, such as trace evidence. This kind of evidence is in fact perceived by judges and lawyers as less informative, because they think that “all plastic items are the same”, i.e. that it is impossible to discriminate among mass produced items. The purpose of this paper is to stress that, with sound methods for interpreting evidence, it is possible to improve the communication between the scientist and the Court, and to show the real significance of the analytical results, in the context of the case. The analysis of the traces found on a knife used in a murder case were performed by optical microscopy, IR spectroscopy, and UV-visible spectroscopy. The interpretation of evidence was carried out according to a Bayesian approach. A description of the interpretation of evidence in a case in which fibres were the key evidence. It is shown that the key aspects for having a high value of the evidence are the circumstances of the case and the reconstruction of the events given by the prosecutor and by the defence, in addition of course to a sound analytical procedure. In other words, it is shown that in some cases the evidential value of fibres or other trace evidence can be very high, sometimes comparable to that of fingerprints or DNA: when properly interpreted, trace evidence can give key information for solving cases

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

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Surface tailored PS/TiO2 composite nanofiber membrane for copper removal from water

none8siPolystyrene (PS)/TiO2 composite nanofiber membranes have been fabricated by electrospinning process for Cu2+ ions removal from water. The surface properties of the polystyrene nanofibers were modulated by introducing TiO2 nanoparticles. The contact angle of the PS nanofiber membrane was found to be decreased with increasing concentration of TiO2, depicted enhanced hydrophilicity. These membranes were highly effective in adsorbing Cu2+ ions from water. The adsorption capacity of these membranes was found to be 522 mg/g, which is significantly higher than the results reported by other researchers.This was attributed to enhanced hydrophilicity of the PS/TiO2 composite nanofiber membranes and effective adsorption property of TiO2 nanoparticles.noneWanjale, Santosh; Birajdar, Mallinath; Jog, Jyoti; Neppalli, Ramesh; Causin, Valerio; Karger-Kocsis, József; Lee, Jonghwi; Panzade, PrasadWanjale, Santosh; Birajdar, Mallinath; Jog, Jyoti; Neppalli, Ramesh; Causin, Valerio; Karger Kocsis, József; Lee, Jonghwi; Panzade, Prasa

Nylon fiber-reinforced polymer composites

Questo capitolo passa in rassegna lo stato dell'arte e le prospettive future dei materiali polimerici caricati con fibre di nylon

CHAPTER 21. Scattering Studies on Natural Rubber Based Blends and IPNs

To optimize the design of rubber-based materials, a thorough and detailed knowledge of their structure and morphology is paramount. Under this point of view, scattering and diffraction techniques are extremely useful and informative. Scattering techniques are especially suited for characterizing heterophasic blends because they are sensitive to fluctuations of the composition, therefore yielding useful information on the mutual dispersion of the polymers composing the material. This chapter offers brief introductions on wide-angle X-ray diffraction, small-angle X-ray scattering, small-angle neutron scattering, and light scattering, and it presents a number of examples where these techniques were determinant for the investigation. It should not thus be intended as a \u2018textbook\u2019 on these techniques but as a collection of stimulating approaches, among which the reader could find the most suitable solution for his or her particular characterization problem

Wide-Angle X-ray Diffraction and Small-Angle X-ray Scattering Studies of Rubber Nanocomposites

With their predominantly amorphous nature, elastomers would not seem very prone to X-ray diffraction or scattering studies. As will be shown in the following pages, this is not so true. It must be borne in mind that many elastomers, when stretched, can indeed crystallize. Moreover the preparation of rubber-based nanocomposites consists in the introduction in an elastomeric matrix of fillers, which are crystalline or at least produce a material with fluctuations in electron density within its bulk. The nanocomposite approach has its roots in the vivid academic and industrial research activity spurred by the increasing demand for high performance materials. Rather than designing and synthesizing novel polymeric materials employing innovative monomers, it is more convenient under an applicative and industrial point of view to prepare composite materials. The double objective of filler addition is enhancing properties while keeping the cost of the material at an affordable level. Carbon black is nowadays by far the most important filler employed in the rubber industry. It is produced by pyrolysing oil or natural gas under controlled conditions, and is thus associated to pollution. Moreover, it confers a black color to the materials limiting their application in medical, sports and domestic product segments. The quest for other fillers to substitute carbon black in rubber compounds included testing of fillers such as sepiolite, kaolin and silica, but their performance was not adequate and remained below that obtained with carbon black. Due to their inorganic nature, these fillers are not compatible with the polymer matrix and it is therefore very difficult to homogeneously disperse them. More recently, a novel approach has been introduced for the preparation of effective compounds. Clay-based nanocomposites were firstly discovered by the Toyota group [1,2]. The dispersion of the reinforcement agents on a nanometer scale and the high aspect ratio of fillers confer to nanocomposites innovative physical and chemical properties with respect to their bulk counterparts [3-5]. A wide variety of nanofillers has thus been tested for reinforcing rubbers, generating the need of techniques that can accurately describe their degree of dispersion in the matrix and the morphology of the obtained composite. This is the aspect that X-ray scattering studies can contribute to shed light on. A quantitative approach to wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS), although somewhat labor intensive, allows to obtain a very thorough description of the structure and morphology of nanocomposites. An especially interesting advantage of X-ray diffraction methods is that, differently from microscopy techniques, they sample the whole bulk of the specimen, thus giving a more generalized picture of its morphology. Being able to exploit this peculiarity at its full extent offers an invaluable tool for a complete characterization of polymer-based nanocomposite materials. This chapter, after a brief introduction on WAXD and SAXS, will present a number of examples of literature works where these techniques were determinant for the investigation. It should not thus be intended as a \u201ctextbook\u201d on these techniques (many excellent books of this kind already exist [6-13]) but as a collection of stimulating approaches, among which the reader could find the most suitable solution for his or her particular characterization problem