Papers by Keyword: Gel Time

Abstract: Loss of durability of concrete materials in sewage and chemical treatment facilities exposed to acidic environments is a key issue that affects the life cycle performance. Applications of organic coating such as epoxy and acrylic usually covers the concrete surface by physical addition normally failed to act as an effective coating due to debonding when the organic coating absorbs water. In this work, geopolymer was used as alternative material for concrete coating. Preparation of geopolymer involved fly ash, a materials containing high aluminosilicate and calcium mixed with various concentrations (6, 8 and 12M) of sodium hydroxide (NaOH). Subsequently, all samples were tested and analysed through compressive strength test and gel time. Geopolymers synthesised from 12M NaOH concentration exhibited high compressive strength and low gel time, hence was chosen as a coating for the concretes for the erosion evaluation. Results show that, concretes coated with geopolymers yielded low percentage of mass loss compared to the uncoated concretes. This suggest that geopolymers has high potential to be used as erosion mitigation coating to prevent the concretes from degrading due to the acidic environment.

Abstract: This paper made a study of preparation of the electrorheological materials applied to ER clutch. Several experiments were made to research the influence of the solvent, deionized water, dropping rate, and the inhibitor on the gel time,and different gel time under different experimental conditions were obtained. The experimental results provided a reference of experimental conditions for preparing electrorheological materials applied to ER clutch. The conclusions can be good used to analyze the effect of the gel time on electrorheological fluid nature for ER clutch, and then improve the ER clutch performance.

Abstract: Polyureas series were synthesized via two-step solution process by reaction of sophorone diisocyanate (IPDI), amine terminated polyether (Jeffamine D-2000) with different chain extenders including dimethyl-thiotoluene diamine (E300), 1,6-hexamethylene diamine (HDA) and 4,4-diamino cyclohexylmethane (H₁₂MDA). The structure of polyureas was characterized and thermal properties were measured by TGA and DSC. The influence of diamine chain extenders on gel time of polyurea was investigated. The gel time was prolonged to 753s using the E-300 as the chain extenders.

Abstract: SiO₂ optical fiber preform, the parent material in manufacturing optical fiber, plays an important role in the properties of optical fiber. In this paper, SiO₂ dry gel was prepared by Sol-Gel method. According to this method, the gel was formed by hydrolyzing tetraethyl orthosilicate(TEOS) with hydrochloric acid and ammonia water, and the SiO₂ dry gel was obtained by heat treatment of the gel at different temperature. The structure of the dry gel as prepared was characterized by X-ray Diffraction(XRD), Fourier Transform Infrared Spectroscopy(FT-IR) and Scanning electron microscope(SEM). As a result, amorphous structure is proved. Meanwhile, microscopic cracks are found to be decreased by adding formamide and increased when the heat-treatment temperature is above 75°C.

Abstract: Anti-corrosion coating in desulphurization flue of one wet flue gas desulfurization equipment (FGD) (model 1 and model 2) was designed and studied according to environmental and technical parameters of a coal-fired power plant. And relevant design requirements were confirmed. Application results showed that polyureas has wear and high temperature physical properties, so that it can be used in flue desulfurization equipment for anticorrosion. When the construction of a thickness of 2.0 mm, the high-temperature polyureas protective coating appearance smooth, EDM(electric discharge machining) 100% pass rate, adhesion 10.8 MPa, at 160 °C environment still had outstanding performance, that make sure it could reach its design life of the flue based on estimating the corrosion margin.

Abstract: Recently glass fibre reinforced polymer (GFRP) tubular piles have been developed for civil engineering applications instead of conventional concrete piles. Considering their suitable applications, the new polymer based filling materials are being developed at the University of Southern Queensland as a part of work done for timber pile rehabilitation. This ongoing project aims to replace portion of the deteriorated timber pile by using GFRP piles. Due to good compressive strength, pumpability and workability, the new polymer base materials are to be filled in between GFRP pile and existing timber pile base. An ongoing research program has been initiated to improve fundamental understanding of these materials and to provide the knowledge required for their broad utilization. In this development, sample trial mixes were considered based on several weight percentages of polymer resin, fly ash and sand. Material parameters such as compressive strength, stiffness, shrinkage and gel time were achieved from the experimental investigation. It has been found that most polymer based trial mixed fillers have high compressive strength and considerable plastic region with more than 10% strain. These results imply that the polymer based filling materials are suitable for both compression and tensile loading situations. However, the behaviour of fillers with GFRP pile connector under different loading conditions is yet to be fully understood.