Atactic polypropyle. From industrial by-product to high added value material for advanced applications through chemical modification processes

En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 3 pages.This work is related to the conversion of an industrial by product (or waste) coming from polymerization reactors, as the atactic polypropylene is considered, into materials to be used as interfacial modifiers in heterogeneous materials based on polymers. In fact, this work concerns with the obtain of interfacial modifiers by chemical modification of the polymer by grafting of polar monomers either by one step processes to graft succinic anhydride (SA) or p-phenylen-bis-maleamic acid (pPBM) onto the polymer backbone, or by a two step process to yield succinil-fluoresceine grafted atactic polymers from the modified with SA. The comparison of these chemical processes both in solution and in the melt has allow to us to establish a reaction mechanism, and as a consequence, to obtain interfacial agents with very different functionalities and molecular architectures providing the researcher the ability to design taylor-made advanced materials such as micro- and nano-structured blends, alloys and composites, becoming the interfacial modifiers as the key for their advanced ultimate properties.Peer reviewe

Morphological variations and improve properties on PP/PA6 blends with modified interphases by grafted atactic polypropylenes coming from industrial by-product

En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.-- 4 pages, 6 figures.In the present communication the fifty/fifty isotactic-polypropylene (PP) and polyamide (PA6) has been chosen as representative of the thermodynamical incompability and then the heterogeneous morphology of an organic polymer blend. It is the most general case when facing a problem of management any fraction of organic plastic wastes coming from big solid waste streams like urban, agricultural or post-consumer out of use organic plastic big parts. The thermodynamical incompatibility between the organic polymers from different structural families, together inefficient processing and/or compounding technologies, it results in deficient set of properties and bad performance. The true possibility to change those morphologies by the presence of different amounts and different kinds of interfacial agents based on atactic polypropylenes grafted with polar groups: Succinic Anhydride (SA) or Succinil-Fluoresceine (SF) moieties is ascertained by the changes in the mechanical and thermal properties of the blends with modified interphase and the morphological changes supported by the optical and emission field scanning electron microscopies (OM and FE SEM).Peer reviewe

The effect of a succinic anhydride/succinil-fluoresceine grafted atactic polypropylene on polypropylene/polyamide 6 blends at the polypropylene glass transition as revealed by dynamic mechanical analysis

This work deals with a dynamic mechanical analysis study on the effect of a novel interfacial agent containing grafts rather than maleated ones, in all the compositional spectra of the iPP/PA6 system. The interfacial agent used is an atactic polymer (from polymer wastes) with succinic bridges and both backbone and terminal grafted succinil fluoresceine groups (aPP-SF/SA) containing 6.2 % of total grafted groups (2.5% SA and 3.7% SF), equivalent to 6.2 ·10-4¿g.mol¿1, obtained at the authors¿ labs. The effects of both PA6 and aPP-SFSA cause changes in the glass transition temperature (Tg) of iPP in the blend. One of the novelties of the work is introducing an interfacial agent with other groups rather than only maleic anhydride, capable to modify the behavior of the system in a positive, and very different manner, than raditional maleated agents. This has let a better understanding of the interphase between components. In this work we have used dynamic mechanical parameters to evidence the interfacial modifications caused by the presence of aPP-SF/SA in the iPP/PA6 system at the iPP Tg. Besides, by considering each component of the blend as interacting each other, we have used a Box-Wilson model by resembling the so called ¿agent based models¿ to obtain algorithms capable to make forecasts of the dynamic mechanical parameters (storage, E¿, and loss moduli, E¿¿, at the glass transition of iPP, in all the composition range of whatever iPP/PA6/aPP-SFSA modified blend.Peer Reviewe

A dynamic mechanical analysis of the interfacial changes induced from both the reinforcement and the matrix sides in polypropylene/surface modified talc composites

The interfacial changes associated with a series of polypropylene based composite materials with modified interphases from the reinforcement side, from the matrix side and both were studied by following their dynamic mechanical behavior. Composites consisted in an isotactic polypropylene (iPP) matrix, a series of talc with different surface functionalities (hydroxyl, chloride, n-butyl amine, and silanes) and a commercial interfacial agent form the matrix side (iPP-SA with 5% of grafts). A comprehensive interpretation of the link existing between the dynamic mechanical responses of the series of 75/25 iPP/talc composites and the molecular relaxation spectrum occurring in the polymer phase of the composites is made with emphasis on the role played by the interfacial modifications performed from each and both sides of the interphase. Dynamic mechanical analysis has been used here to study how the intended interfacial modifications affected the behavior of the composites. The efficiency of the interfacial phenomena is discussed from a phenomenological point of view as well as by considering classical criteria such as the glass transition temperature and the glass to rubbery transition. Finally, a correlation between mechanical parameters from the microscopic scale and others from the macroscopic scale appears to emerge.Peer Reviewe

Virus sincicial respiratorio en niños nacidos prematuros: 19 años de vigilancia epidemiológica activa en un hospital pediátrico

Introduction. Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection (ALRTI) in pediatrics. Preterm infants are at a higher risk for complications. We aimed to describe and compare the clinical and epidemiological characteristics associated with ALRTI due to RSV in preterm and term infants and to establish the predictors of fatality among preterm infants. Methods. Prospective, cross-sectional study of patients admitted due to ALRTI in the 2000-2018 period. Viral diagnosis was done by indirect immunofluorescence or reverse transcription polymerase chain reaction in nasopharyngeal aspirates. Clinical and epidemiological characteristics were recorded. A multiple logistic regression model established the predictors of fatality among preterm infants. Results. A total of 16 018 ALRTI cases were included; 13 545 (84.6 %) were tested; 6047 (45 %) were positive; RSV was prevalent in 81.1 % (4907), with a seasonal epidemic pattern; 14 % (686) were preterm infants. Comorbidities, perinatal respiratory history, congenital heart disease, malnutrition, chronic respiratory disease, bronchopulmonary dysplasia, prior hospitalization due to ALRTI, and chronic neurological disease (p < 0.001) were more common among preterm infants; they required more intensive care and a longer length of stay, and had a higher fatality rate (p < 0.01). Congenital heart disease was an independent predictor of fatality due to RSV among preterm infants (OR: 3.67 [1.25-10.8], p = 0.01). Conclusion. RSV showed an epidemic pattern and affected more preterm infants with certain comorbidities, with a higher morbidity and mortality, compared to term infants. RSV fatality among preterm infants was associated with congenital heart disease.Fil: Gentile, Angela. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Lucion, Maria Florencia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: del Valle Juárez, María. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Castellano, Vanesa. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Bakir, Julia. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Pacchiotti, Anabella. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Areso, María S.. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Viegas, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; ArgentinaFil: Goya, Stephanie. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez". Laboratorio de Virología; ArgentinaFil: Mistchenko, Alicia Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentin

Surface Expression and Subunit Specific Control of Steady Protein Levels by the Kv7.2 Helix A-B Linker

12 p.Kv7.2 and Kv7.3 are the main components of the neuronal voltage-dependent M-current, which is a subthreshold potassium conductance that exerts an important control on neuronal excitability. Despite their predominantly intracellular distribution, these channels must reach the plasma membrane in order to control neuronal activity. Thus, we analyzed the amino acid sequence of Kv7.2 to identify intrinsic signals that may control its surface expression. Removal of the interlinker connecting helix A and helix B of the intracellular C-terminus produces a large increase in the number of functional channels at the plasma membrane. Moreover, elimination of this linker increased the steady-state amount of protein, which was not associated with a decrease of protein degradation. The magnitude of this increase was inversely correlated with the number of helix A - helix B linkers present in the tetrameric channel assemblies. In contrast to the remarkable effect on the amount of Kv7.2 protein, removal of the Kv7.2 linker had no detectable impact on the steady-state levels of Kv7.3 protein.This work was supported by grants from the VII European framework program managed by the Fondo de Investigaciones Sanitarias (PI071316), from the Spanish Ministry of Education (BFU2009-07581 and SAF2006-1450), the Spanish Ion Channel Initiative Consolider project (CSD2008-00005), and the Basque Government (SAIOTEK SA-2006/00023). A. Alaimo was partially funded by Fundacion Biofisica Bizkaia. PA and JFO held a FPI fellowship from the Spanish Ministry of Science and Innovation (BES-2008-002314). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip