Glass fiber-reinforced polymer bars are currently used to reinforce concrete in an attempt to overcome the corrosion issue encountered with ordinary steel. Different types of surface treatment were applied to the smooth rods in order to enhance bonding with concrete. Experimental results show that using bars coated with coarse sand notably improve the bond strength. The influence of granulometry sand, rebar diameter, length embedded, and concrete strength are analyzed. Rebars coated with finer sand lead to a stronger chemical adhesion with concrete. However, the effect of friction and interlocking forces produced by coarse sand prevails over the chemical adhesion in the pull-out test.Fil: Morales Arias, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Construcciones y Estructuras. Laboratorio de Materiales y Estructuras; ArgentinaFil: Vázquez, Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Construcciones y Estructuras. Laboratorio de Materiales y Estructuras; ArgentinaFil: Escobar, Mariano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Construcciones y Estructuras. Laboratorio de Materiales y Estructuras; Argentin

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Styrene–butadiene rubber compounds reinforced with commercial multiwall carbon nanotubes (MWCNT) in amounts between 0.5 and 10 parts per hundred of rubber (phr) were mixed in a two‐roll mill. A compound with 40 phr of carbon black (CB) was prepared as reference. From rheometric curves at five different temperatures (between 140°C and 180°C), a similar maximum torque and vulcanization time values in the samples reinforced with 10 phr of MWCNT and 40 phr of CB were obtained. The Kamal–Sourour model was used to analyze the influence of the MWCNT content and the vulcanization temperature on the cure rate and induction time. Then, through an Arrhenius plot, it became evident the effect of the reinforcement content on the activation energy of the vulcanization process. Mechanical properties of normalized sheets vulcanized at 160°C indicate that content between 5 and 10 phr of MWCNT are enough to reach a similar performance to that sample with 40 phr of CB. SEM analysis exhibits a good dispersion of MWCNT. Swelling experiments point out a similar absorption degree of toluene in the compounds with 5 phr of MWCNT and 40 phr of CB. POLYM. ENG. SCI., 59:E327–E336, 2019. © 2019 Society of Plastics Engineers

Ablation resistance and mechanical properties of polyurethane‐based composites containing different amounts (up to 5 wt%) of organoclay were correlated with the morphological characterization. The crosslinking density of the polyurethane increased with the amount of organoclay. At low concentration (up to 1 wt%), the organoclay was well exfoliated, while at higher concentration, both exfoliated and intercalated platelets were found. A linear correlation was observed between the tensile test and the concentration of organoclay. Erosion velocity decreased 40% with the incorporation of 5% of organoclay. POLYM. ENG. SCI., 60:630–635, 2020. © 2020 Society of Plastics Engineers