scholarly journals Evaluation of polyurethane resin injection for concrete leak repair

2019 ◽  
Vol 11 ◽  
pp. e00307 ◽  
Author(s):  
Mohamed A. Safan ◽  
Zeinab A. Etman ◽  
Alaa Konswa
2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).


2011 ◽  
Vol 14 (1) ◽  
pp. 17-31 ◽  
Author(s):  
R. Mitlapalli ◽  
Jeffrey A. Roux ◽  
Anil L. Jeswani

2021 ◽  
Author(s):  
Felix Behnisch ◽  
Carl‐Christoph Höhne ◽  
Lukas Manas ◽  
Philipp Rosenberg ◽  
Frank Henning

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1112
Author(s):  
Raghvendra Singh Yadav ◽  
Anju ◽  
Thaiskang Jamatia ◽  
Ivo Kuřitka ◽  
Jarmila Vilčáková ◽  
...  

Superparamagnetic ZnFe2O4 spinel ferrite nanoparticles were prepared by the sonochemical synthesis method at different ultra-sonication times of 25 min (ZS25), 50 min (ZS50), and 100 min (ZS100). The structural properties of ZnFe2O4 spinel ferrite nanoparticles were controlled via sonochemical synthesis time. The average crystallite size increases from 3.0 nm to 4.0 nm with a rise of sonication time from 25 min to 100 min. The change of physical properties of ZnFe2O4 nanoparticles with the increase of sonication time was observed. The prepared ZnFe2O4 nanoparticles show superparamagnetic behavior. The prepared ZnFe2O4 nanoparticles (ZS25, ZS50, and ZS100) and reduced graphene oxide (RGO) were embedded in a polyurethane resin (PUR) matrix as a shield against electromagnetic pollution. The ultra-sonication method has been used for the preparation of nanocomposites. The total shielding effectiveness (SET) value for the prepared nanocomposites was studied at a thickness of 1 mm in the range of 8.2–12.4 GHz. The high attenuation constant (α) value of the prepared ZS100-RGO-PUR nanocomposite as compared with other samples recommended high absorption of electromagnetic waves. The existence of electric-magnetic nanofillers in the resin matrix delivered the inclusive acts of magnetic loss, dielectric loss, appropriate attenuation constant, and effective impedance matching. The synergistic effect of ZnFe2O4 and RGO in the PUR matrix led to high interfacial polarization and, consequently, significant absorption of the electromagnetic waves. The outcomes and methods also assure an inventive and competent approach to develop lightweight and flexible polyurethane resin matrix-based nanocomposites, consisting of superparamagnetic zinc ferrite nanoparticles and reduced graphene oxide as a shield against electromagnetic pollution.


2016 ◽  
Vol 699 ◽  
pp. 97-103 ◽  
Author(s):  
Laurenţiu Slătineanu ◽  
Oana Dodun ◽  
Margareta Coteaţă ◽  
Gheorghe Nagîţ ◽  
Irina Beşliu

Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.


2016 ◽  
Vol 46 (12) ◽  
pp. 1237-1243 ◽  
Author(s):  
Karun K. Rao ◽  
Molly Ferguson ◽  
Kyle Murphy ◽  
Jean Zhao ◽  
Daniel Lacks ◽  
...  

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