Manufacturing and properties of aramid-reinforced composites

The functional properties of the aramid-reinforced polymer composites depend primarily on the properties of the aramid reinforcing fibers, since the fraction of the fiber constituent in FRP is quite high, usually well above 30% by volume. The properties of the aramid fibers, in turn, depend on their chemical composition and manufacturing conditions: both of these determine the fibers physical structure and mechanical properties. The chapter will focus on these issues. Some specific problems related to the fiber-matrix nteraction.in aramid-containing FRP will also be addressed.Fundação para a Ciência e Tecnologia (FCT) - post-doctiral grant SFRH/BPD/45252/2008 (to Nadya Dencheva)Fundação para a Ciência e Tecnologia (FCT) - bolsa licença sabatica SFRH/BSAB/812/2008 (to Zlatan Denchev

X-ray scattering studies on multiphasic polymer systems

The scope of the present chapter had to be limited to some recent studies on the application of synchrotron WAXS and SAXS in three particular multicomponent and multiphase polymer systems. The first system comprises materials that became known as microfibrillar reinforced composites (MFC) produced from oriented blends of thermoplastic semicrystalline polymers by conventional processing techniques. These materials belong to fiber-reinforced composites that have many important engineering applications but are notoriously difficult to study. As a second material system, the structure development during processing of an immiscible polymer blend of polypropylene (PP) and polystyrene (PS) was investigated by X-ray scattering techniques. Structure formation in polymers blends has been widely investigated in the last years, mainly in terms of the development of the size, shape, and orientation of the dispersed component under flow deformation. Further, the structure evolution and damage during stretching in the solid state of polymers blends is much less researched topic. Complementing, this second study, the structure evolution of the PP/PS blend was investigated by time resolved x-ray scattering in a synchrotron source. Finally, the third case reveals investigations on the structure of polymer nanocomposites developed during processing and also during stretching. Polymer nanocomposites are a recent class of materials, and very few studies have been published on the structure development in them.This work was supported by DESY and the European Commission under HASYLAB Projects 18DESYD-II-05-101 EC, DESY-D-II-07-011 EC and the FP6 contract RII3-CT-2004-506008 (IA-SFS). This work was also supported by FCT –Portuguese Foundation for Science and Technology through projectPOCTI/CTM/46940/2002 (MICROTEST) and POCI/CTM/57358/2004 (NANOFIBCO)

Preparation, mechanical properties and structural characterization of microfibrillar composites based on polyethylene/polyamide blends

There exist only few studies on the possibility to use the in-situ microfibrillar technology in HDPE/PA blends notwithstanding the good knowledge on the structure and properties of these blends. The main objective of this chapter is to summarize these studies in the field of the preparation, mechanical and structural characterization of HDPE/PA6 and HDPE/PA12 MFC materials. Along this presentation, the relationship between the mechanical properties and the structure of the MFCs on various length scales studied by various techniques will be discussed, as well.FCT grant SFRH/BPD/45252/2008 - to Nadya DenchevaFCT sabbatical grant SFRH/BSAB/812/2008 - to Zlatan DenchevHASYLAB at DESY , Hamburg,, Germany,Grant Number II-07-011 E

A new smut fungus on a new grass: Sporisorium capillipedii-alpini (Ustilaginales) sp. nov. infecting Capillipedium alpinum (Poaceae) sp. nov., from Sichuan, China

A new smut fungus, Sporisorium capillipedii-alpini (Ustilaginales), and a new species of grass, Capillipedium alpinum (Poaceae), on which it is growing, are described and illustrated. The collections were made in western Sichuan, China. Capillipedium alpinum differs from other species of Capillipedium by its diminutive size and short, slender inflorescence. Sporisorium capillipedii-alpini is compared with the species of Sporisorium with similar symptoms (destroying all spikelets of an inflorescence) that infect Capillipedium, Botriochloa, and Dichanthium. The new smut fungus differs from these species as follows: from Sporisorium taianum by having larger spores with minutely echinulate spore walls, from S. dichanthicola by having larger spores, from S. sahayae by having lower spore wall ornamentation and thinner spore walls, from S. andropogonis-annulati by having larger spores, and smaller sterile cells with thinner walls, and from S. mysorense by possessing minutely echinulate spore walls and differently colored spores and sterile cells. The types of S. andropogonis-annulati, S. mysorense, and S. sahayae were re-examined and detailed descriptions of these species are given. A key to the smut fungi of Sporisorium, that infect Capillipedium, Botriochloa, and Dichanthium and destroy all spikelets of the inflorescence of an infected plant, is also provided.Other Research Uni

What is the Computational Value of Finite Range Tunneling?

Quantum annealing (QA) has been proposed as a quantum enhanced optimization heuristic exploiting tunneling. Here, we demonstrate how finite range tunneling can provide considerable computational advantage. For a crafted problem designed to have tall and narrow energy barriers separating local minima, the D-Wave 2X quantum annealer achieves significant runtime advantages relative to Simulated Annealing (SA). For instances with 945 variables, this results in a time-to-99%-success-probability that is $\sim 10^8$ times faster than SA running on a single processor core. We also compared physical QA with Quantum Monte Carlo (QMC), an algorithm that emulates quantum tunneling on classical processors. We observe a substantial constant overhead against physical QA: D-Wave 2X again runs up to $\sim 10^8$ times faster than an optimized implementation of QMC on a single core. We note that there exist heuristic classical algorithms that can solve most instances of Chimera structured problems in a timescale comparable to the D-Wave 2X. However, we believe that such solvers will become ineffective for the next generation of annealers currently being designed. To investigate whether finite range tunneling will also confer an advantage for problems of practical interest, we conduct numerical studies on binary optimization problems that cannot yet be represented on quantum hardware. For random instances of the number partitioning problem, we find numerically that QMC, as well as other algorithms designed to simulate QA, scale better than SA. We discuss the implications of these findings for the design of next generation quantum annealers.Comment: 17 pages, 13 figures. Edited for clarity, in part in response to comments. Added link to benchmark instance

Polyamide microcapsules and method to produce the same

National Patent application n.º 107879, data filled: 03.06.2014The invention relates to polyamide microcapsules prepared by means of activated anionic polymerization of lactams in a hydrocarbon solution containing organic or inorganic payloads in their cores and with porous polyamide shells. The capsules possess spherical or spheroid forms with average diameters in the range of 5-500 microns including payloads whose amount could vary from 0.05 to 50-60% of their weight which payload can include metals, metal oxides, carbon allotropes and/or their functionalized derivatives, clays, or any other polymeric or low molecular compounds that do not inhibit the polymerization process, being either soluble or insoluble in the reaction media. The microcapsules of the present invention can be used as obtained or can be transformed into molded parts of advanced thermoplastic composites comprising polyamide matrices reinforced by homogeneously distributed organic or inorganic reinforcements.Fundação para a Ciência e Tecnologi