2 research outputs found

    Mechanical and fracture characterization of 50:50 HDPE/PET blends presenting different phase morphologies

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    Uncompatibilized and compatibilized blends of poly(ethytene terephthalate) (PET) and high-density polyethylene (HDPE) (50:50 PET/HDPE) have been prepared and characterized. A commercial grade of ethylene/methacrylic acid copolymer was used as compatibilizing agent and added to the blends in two different proportions, 1 % and 7%. Compounded blends were processed following three different procedures: compression molding, extrusion, and extrusion followed by annealing. In every case, there is evidence that suggests that HDPE constitutes the matrix and PET is the dispersed phase. The PET phase shape was related to the processing procedure of the blends. PET adopted a globular morphology in the compression molded samples but it took the form of microfibers (microfibrillar-like reinforced composites) in extruded samples, which were flattened during the postextrusion annealing process. According to the results obtained in tensile and fracture tests, extruded blends having 7% of ethylene/methacrylic acid copolymer appeared as the optimum combination of processing method and compatibilizer content.Fil: Fasce, Laura Alejandra. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂ­a. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales; ArgentinaFil: Seltzer, RocĂ­o. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂ­a. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales; ArgentinaFil: Frontini, Patricia Maria. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales. Universidad Nacional de Mar del Plata. Facultad de IngenierĂ­a. Instituto de Investigaciones en Ciencia y TecnologĂ­a de Materiales; ArgentinaFil: Pita, V.J. Rodriguez. Universidade Federal do Rio de Janeiro; BrasilFil: Pacheco, E.B.A.V.. Universidade Federal do Rio de Janeiro; BrasilFil: Dias, M.L.. Universidade Federal do Rio de Janeiro; Brasi

    Multi-messenger Observations of a Binary Neutron Star Merger

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    International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∌1.7 s\sim 1.7\,{\rm{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of 40−8+8{40}_{-8}^{+8} Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26  M⊙\,{M}_{\odot }. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∌40 Mpc\sim 40\,{\rm{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∌10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∌9\sim 9 and ∌16\sim 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
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