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Nanomaterials-Based Self-Healing Cementitious Materials
Published in Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban, Self-Healing Cementitious Materials, 2022
Ghasan Fahim Huseien, Iman Faridmehr, Mohammad Hajmohammadian Baghban
In the past, polycarboxylates (PCE) nanomaterials have been utilized in concrete [52]. PCE is a polymer-based compound that is obtained from methoxy-polyethylene glycol co-polymer. It functions in the secondary or side reactions which are reinforced to methacrylic acid co-polymer as the major element. Usually, the carboxylate group is comprised of a water molecule, rendering a negative charge alongside the backbone of PCE. The polyethylene oxide group provides a non-uniform electron cloud distribution and chemical polarities to the secondary or side reactions. The number and the length of secondary or side groups are can easily be changed. In case the secondary or side reactions possess numerous electrons, it lowers the large molar mass and alters the polymer density, resulting in reduced performance of cement suspension [11, 53]. For both chains to combine and pair simultaneously, longer side groups and strong charge density from one to another reaction end must form. Usually, polycarboxylate is used in concrete as high range water reducer (HRWR). Inclusion of PCE allows in controlling the concrete workability better at lower water-to-cement ratios.
Admixtures
Published in Peter Domone, John Illston, Construction Materials, 2018
These basic chemicals can be used alone or blended with each other or lignosulphonates to give products with a wide range of properties and effects. A particular feature is that polycarboxylates in particular can be chemically modified or tailored to meet specific requirements, and much development work has been carried out to this end by admixture suppliers in recent years. This has undoubtedly led to improvements in construction practice, but a consequence is that the websites of the major suppliers contain a confusing plethora of available products, often with semi-scientific sounding names.
Admixtures
Published in Marios Soutsos, Peter Domone, Construction Materials, 2017
These basic chemicals can be used alone or blended with each other or lignosulphonates to give products with a wide range of properties and effects. A particular feature is that polycarboxylates in particular can be chemically modified or tailored to meet specific requirements, and much development work has been carried out to this end by admixture suppliers in recent years. This has undoubtedly led to improvements in construction practice, but a consequence is that the websites of the major suppliers contain a confusing plethora of available products, often with semi-scientific sounding names.
Synthesis and hard water resistance mechanism of polycarboxylate dispersant for pesticide water dispersible granules
Published in Journal of Dispersion Science and Technology, 2020
Qingmei Tian, Yanyan Zhang, Zhiyu Jia, Qiang Zhang
Polycarboxylate dispersants are usually synthesized by monomers containing carboxyl groups (acrylic acid, methacrylic acid, etc.) with other monomers. A novel comb-like amphoteric polycarboxylate had been synthesized by polyethylene glycol-acrylate monoester, sodium p-styrene sulfonate and methacrylatoethyl trimethyl ammonium chloride in aqueous solution as a dispersant for coal-water slurry.[9] And a series of poly (acrylic acid)-g-poly (ethylene oxide) comb-like copolymer dispersants for cement suspensions were synthesized by free radical copolymerization, and the influence of side chain length of comb-like copolymer dispersants on dispersion and rheological properties of concentrated cement suspension was investigated.[10] In our previous study,[11] a new type of dispersant for pesticide WDG, sodium salt of styrene-methacrylic acid copolymer/montmorillonite nanocomposite was synthesized via in-situ intercalation polymerization method, it exhibits excellent advantages, for example, high performance and low cost, etc.
Synthesis and properties of a novel structure of phosphated superplasticizer
Published in Journal of Dispersion Science and Technology, 2020
Bing Wang, Shuai Qi, Shimin Fan, Tao Wang, Jianfeng Ma, Zheng Han, Qianping Ran
Polycarboxylates are comb-like copolymers with a succession of methacrylic acid units in the main chain, and a substitution of part of these methacrylic acid units by poly (ethylene glycol) methyl ether methacrylate, forming side chains from the main chain.[9,10] It is known from various studies on the mechanism of action of superplasticizers that the effectiveness of the molecules used is based on two different effects.[11] First, the negatively charged acid groups of the plasticizers are adsorbed on the positively charged cement particle surface resulting from calcium ions.[10] The electrostatic double layer formed in this way (zeta potential) leads to electrostatic repulsion between the particles, but this is relatively weak. In the case of the above-mentioned comb polymers, this electrostatic repulsion is reinforced additionally by the bulkiness of the water-soluble, non-adsorbing poly(alkylene oxide)s. this steric repulsion is much stronger than the electrostatic repulsion, so that it is easy to explain why the plasticizing action of the polycarboxylates is very much stronger than that of naphthalenesulphonates or melaminesulphonates,[12] i.e. in order to achieve comparable plasticization, the polycarboxylate can be added in a significantly smaller amount.[13]
Research progress on scaling mechanism and anti-scaling technology of geothermal well system
Published in Journal of Dispersion Science and Technology, 2023
Huijun Zhao, Yahong Huang, Song Deng, Lei Wang, Haoping Peng, Xin Shen, Dingkun Ling, Lu Liu, Yuan Liu
In the production of high temperature geothermal fluid, the scale inhibition effect of some of the above scale inhibitors will be greatly reduced. Antiscalants including polyphosphates and phosphate esters are generally only used at temperatures below 66 °C due to their low thermal stability. Phosphonate scale inhibitors have excellent scale inhibition efficiency, however, these products typically become unstable at temperatures around 149 °C. Currently, low molecular weight polycarboxylates and their derivatives are widely used for high temperature calcium scale control due to their thermal threshold up to 260 °C.[78] To select an appropriate scale inhibitor for deepwater high temperature applications, Wang et al.[78] evaluated the thermal stability and scale inhibition performance of five polymeric scale inhibitors. The results show that the thermal stability of polyacrylate and polyacrylate terpolymer is better. Wylde et al.[79] introduced an example of the application of an ultra-high temperature antiscalant in fire tube heaters. They used differential scanning calorimetry to study the thermal stability of several polymeric scale inhibitors and their existing products. The results show that the best thermally stable antiscalants are polymaleic acid copolymers and polymeric acrylic acids of low to medium molecular weight. Cenegy et al.[80] treated geothermal wells with an effective amount of a scale inhibitor formulation containing sodium acrylate/acrylamide copolymer to inhibit CaCO3 scaling in them, and proposed an optimal formulation.