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Waterborne Polyurethanes for Sealants
Published in Ram K. Gupta, Ajay Kumar Mishra, Eco-Friendly Waterborne Polyurethanes, 2022
Mehrdad Fallah, Amir Ershad Langroudi, Aida Alavi
Another characterization is based on the curing type. The parameters that influence curing are temperature, moisture, and catalyst type. According to their curing type, the sealants are divided into three general groups: two-part systems, single component sealants, and solvent or water release sealants. Also, the sealant is sometimes classified by its function and end use. The sealants are used in many conditions and places, such as automobiles, insulated glass, concrete, construction, etc., and the last characterization in this study is about the performance of sealants [3].
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Published in Joseph C. Salamone, Polymeric Materials Encyclopedia, 2020
The inorganic peroxide curing agents for liquid polysulfides are activated by water. By formulating and packaging polysulfides under anhydrous conditions, “one-part” sealants are prepared. These cure when exposed to atmospheric moisture and are used in construction sealant applications. The curing agents most commonly used have been calcium peroxide, zinc peroxide/amine, zinc peroxide/lithium peroxide, and manganese dioxide. Sodium perborate is also effective in preparing light-colored, fast-curing, one-part sealants and is growing in importance.
Uses of anti-foaming agents in paints and surface coatings
Published in David R. Karsa, Surfactants in Polymers, Coatings, Inks and Adhesives, 2020
Radiation curing materials, in contrast to, e.g. powder coatings, can be applied by almost any technique such as rolling, dipping, airless, screen printing, flexo printing, etc. The development of radiation curing was initiated by the search for economical coatings, fast production speed and high durability. UV coatings are well established in wood and paper coatings and in printing on plastic substances. Binders are mainly unsaturated (poly)ester–, (poly)urethane– and epoxy–acrylates dissolved in so-called reactive diluents which can be mono-, bis- and tris-acrylates. The high production speed requires active defoamers which in a very short time between application and UV lamp or electron beam treatment guarantee complete deaeration. Most of the UV coatings are clear coats and the defoamer has to have excellent compatibility, not influencing transparency, surface quality and gloss (Table 4.7). In addition to standard ‘solvent-free’ systems, the market provides aqueous dispersions which can be UV-crosslinked after evaporation of water. This offers the advantage of physical drying at areas which are not completely reached by the electron beam or UV light. In both systems defoamers based on modified silicone oils are often used.
Accelerated curing of G-FRP rods glued into timber by means of inductive heating using Curie-particles – large-scale experiments at room temperature
Published in The Journal of Adhesion, 2021
Acceleration of adhesive curing, and conversely reduction of process times, can be achieved using different means, as for example radiation-curing adhesives, [20] UV-curing [21,22] or using micro-waves.[23,24] However, the most common method for the acceleration of the curing process is heating. Curing at elevated temperatures not only leads to a shorter curing time, but also to increased cross-linking and thus much higher temperature and media resistance, [25] higher strength[26] and stiffness.[27] Oven curing is suitable for small components, but cannot reasonably be used for the large to very large components typical for timber engineering. Components, assemblies, and load-bearing structures can be heated resistively[28] or conductively. Zillessen et al.[29] investigated the method of conductive resistance heating for its practical applicability in wood panel construction bonded with different hot-melt adhesives. They found that after maintaining the end temperature of 150–180°C for 60 s, shear strengths could be achieved, which were comparable to typical hot pressed wooden constructions. However, external monitoring techniques for temperature control were necessary, which proved to be difficult in applicability due to the inaccessibility of the adhesive layer.
Effect of microwave-assisted curing process on strength development and curing duration of cellular lightweight geopolymer mortar
Published in Materials and Manufacturing Processes, 2021
Teewara Suwan, Boontarika Paphawasit, Mizi Fan, Peerapong Jitsangiam, Prinya Chindaprasirt
It can be explained that any heat curing process is crucial, causing the rapid development of the compressive strength of the cellular lightweight geopolymer mortar at an early age. Heat curing not only yielded enhanced densification but also promoted the dissolution of amorphous phases from FA and BA owing to the early geopolymeric gel formation.[7,9] This finding could be due to the mixture process and procedure designation of the CLWG. Heat curing can be used in quick early-strength applications, precast components, or construction blocks. Additionally, the room temperature curing process may be appropriate in applications that are not time-sensitive, including in-filled walls and grouting, which can accommodate late solidification. The calcium content in the prime raw material may have also influenced the final strength of geopolymer cement.[20,21]
Rheological characteristics of epoxy asphalt binders and engineering properties of epoxy asphalt mixtures – state-of-the-art
Published in Road Materials and Pavement Design, 2021
Ali Jamshidi, Greg White, Kiyofumi Kurumisawa
Epoxy resins and most curing agents, such as anhydrides and aliphatic and aromatic amines, are petroleum-based products. Some of these products are toxic, which limits their application due to environmental concerns (Fuhaid et al., 2018). To decrease the effects of temperature variation on the curing, different types of agents are produced. There are primarily four kinds of curing agents: low-temperature curing agent (Kim et al., 2000); room-temperature curing (Koji et al., 2015); moderate temperature curing agent (Chen et al., 2007) and high-temperature curing agent (Guo, 2014).