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Your search keyword '"Li, Yinwen"' showing total 6 results
Start Over Author "Li, Yinwen" Topic dispersion (chemistry)
6 results on '"Li, Yinwen"'

1. Novel poly(amino acid)-type superplasticizers with enhanced dispersing performance for Portland cement doped with clay impurities

Author

Xu Shoufang, Xingjian Li, Ma Mingzhu, Enjuan Feng, Li Yinwen, Faqiang Li, Wei Zhang, and Chen Huizhu

Subjects
Aqueous solution, technology, industry, and agriculture, Superplasticizer, biochemical phenomena, metabolism, and nutrition, law.invention, Portland cement, chemistry.chemical_compound, Colloid and Surface Chemistry, Adsorption, Montmorillonite, Chemical engineering, chemistry, law, Side chain, Dispersion (chemistry), Ethylene glycol
Abstract

Poly(amino acid)-type macromolecules (PAAs), poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAAs), and poly(ethylene glycol)-b-poly(glutamic acid) (PEG-PGAs) were synthesized, and their states in aqueous solutions were studied. PEG-PAAs and PEG-PGAs were first used as novel polycarboxylate superplasticizers, and their dispersion and adsorption behaviors were investigated in cement slurries in the absence and presence of montmorillonite (MMT) clay. The results demonstrated that both PEG-PAAs and PEG-PGAs not only showed excellent water reducing and fluidity retention capabilities but also exhibited remarkable MMT clay tolerance. In contrast to the stretched molecular conformation of traditional polycarboxylate superplasticizers (PCEs), the hydrophobic main chain and the side methylene and ethylene linkers connected to the carboxylic groups of PAA and PGA segments resulted in self-assembly of the PEG-PAAs and PEG-PGAs in aqueous solutions, and the self-assembled nanosized aggregates exhibited relatively uniform spherical morphologies with average sizes of 30–100 nm. Carboxylic groups located on the periphery of the nanoaggregates acted as anchors and adsorbed on the surfaces of the cement particles. The nanoaggregates and the stretched hydrophilic PEG side chains, which jointly produced and enhanced the steric hindrance to prevent cement particle aggregation and hydration, resulted in notable dispersion capabilities. Total organic carbon (TOC), X-ray diffraction (XRD), and thermogravimetry–differential scanning calorimetry (TG-DSC) analyses revealed that the adsorption between the MMT clay and PAA nanoaggregates was surface adsorption (rather than interlayer adsorption), and this significant finding could be ascribed to the enlarged steric hindrance of the PAA nanoaggregates, which prevented the interlamination adsorption consumption of MMT clay to PAAs and revealed the outstanding clay insensitivity. This study provides a new perspective and strategy to design novel poly(amino acid)-type superplasticizers (PAAs) with excellent dispersion performances and improved clay tolerance.

Published
2022

2. Synthesis of amphiphilic polycarboxylate copolymer and its notable dispersion and adsorption characteristics onto cement and clay.

Author

Li, Yinwen, Zheng, Xiuwen, Wu, Kun, and Lu, Mangeng

Subjects
*COPOLYMERIZATION, *AMPHIPHILES, *DISPERSION (Chemistry), *ADSORPTION (Chemistry), *CEMENT, *CLAY
Abstract

Zwitterionic (ZI) polymers have great potential for dispersion and adsorption effects because of their dual functional groups (acidic and basic) grafted on polymer matrices. The ZI monomer 3-(2-(methacryloyloxy) ethyl) dimethylammonio-propane-1-sulfonate (DMAPS) and novel amphiphilic polycarboxylate copolymers (APCs) were prepared and characterised. The dispersion and adsorption behaviours of APCs as superplasticisers in a cement system in the absence and presence of clay were investigated. The results indicated that APCs had excellent dispersing ability, and a notable feature was that APCs could effectively inhibit the preferential adsorption of APCs into clay. A mechanistic study including dispersion, adsorption, zeta potential and x-ray diffraction revealed that, compared with traditional polycarboxylate superplasticisers, APCs with ZI groups were more easily adsorbed on the surface of clay but were not incorporated into the layer structure of the clay. This work not only fabricated a new superplasticiser with potential for development, but also provided a concept for preparing new superplasticisers to solve problems involved in their application. [ABSTRACT FROM AUTHOR]

Published
2016
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3. Preparation and Application of New Polycarboxylate Superplasticizers with Mild Retarding Performance Based on Monovinyl β-Cyclodextrin Monomer.

Author

Li, Yinwen, Zheng, Jian, Guo, Huilong, and Lu, Mangeng

Subjects
*CARBOXYLATES, *CYCLODEXTRINS, *MONOMERS, *RANDOM copolymers, *FOURIER transform infrared spectroscopy, *DISPERSION (Chemistry), *SUBSTITUENTS (Chemistry)
Abstract

Based on monovinyl β-CD monomer (GCD), random copolymers (PTCDs) were first synthesized by AA, TPEG, and GCD, and characterized by FTIR and GPC. The application performances of PTCDs as superplasticizers in cement and concrete were investigated considering dispersion, adsorption, setting times, and compressive strength. The results indicated that PTCDs had more excellent applied performance compared with AA-co-GCD copolymers, and the outstanding feature is that PTCDs had a mild tunable retarding effect. When with certain amount of CD pendants and PEO side chains, PTCD2had the best dispersion and mild retarding performances, which were mainly attributed to the joint steric hindrance effect provided by CD pendants and PEO side chains. This study offers a new type of superplasticizer from CD and its derivatives with excellent dispersion and retarding performances to concrete engineering. [ABSTRACT FROM AUTHOR]

Published
2015
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4. Study on dispersion, adsorption and flow retaining behaviors of cement mortars with TPEG-type polyether kind polycarboxylate superplasticizers.

Author

Li, Yinwen, Yang, Chaolong, Zhang, Yunfei, Zheng, Jian, Guo, Huilong, and Lu, Mangeng

Subjects
*DISPERSION (Chemistry), *MORTAR, *POLYETHERS, *CARBOXYLATES, *PLASTICIZERS, *ADSORPTION (Chemistry)
Abstract

Highlights: [•] MA and SMAS were introduced into the TPEG-type PCEs to improve the dispersion and flow retention abilities. [•] This paper discussed the dispersion and adsorption effects of TPEG-type PCEs compared with conventional MPEG-type PCEs. [•] PCE2 has excellent water-reducing and flow-retaining abilities, which is attributed to the synergistic effects of steric hindrance and electrostatic repulsive force. [•] Application results showed that PCE2 can be used as high-range water reducer in practical applications. [Copyright &y& Elsevier]

Published
2014
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5. Synthesis of copolymers with cyclodextrin as pendants and its end group effect as superplasticizer.

Author

Li, Yinwen, Guo, Huilong, Zhang, Yunfei., Zheng, Jian, Li, Zhaoxia, Yang, Chenghua, and Lu, Mangeng

Subjects
*COPOLYMERIZATION, *CYCLODEXTRINS, *PLASTICIZERS, *MONOMERS, *VINYL polymers, *DISPERSION (Chemistry)
Abstract

Highlights: [•] The synthetic processes of β-cyclodextrin (CD) based functional monomers were improved and characterized in detail. [•] Based on the monovinyl CD based monomer, a new copolymer (PCDs) bearing CD pendants was synthesized and used as superplasticizer. [•] PCDs behaved excellent dispersion ability and strong retarding effect. [ABSTRACT FROM AUTHOR]

Published
2014
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6. Dispersion and rheological properties of concentrated kaolin suspensions with polycarboxylate copolymers bearing comb-like side chains.

Author

Li, Yinwen, Zhang, Yunfei, Zheng, Jian, Guo, Huilong, Yang, Chenghua, Li, Zhaoxia, and Lu, Mangeng

Subjects
*POLYCARBOXYLIC acids, *DISPERSION (Chemistry), *RHEOLOGY, *KAOLIN, *SUSPENSIONS (Chemistry), *COPOLYMERS, *ADSORPTION (Chemistry), *ACRYLATES
Abstract

Abstract: Comb-like polycarboxylate copolymers (PCs) were synthesized and first used as the dispersants for kaolin suspensions. The apparent viscosity, adsorption behavior, zeta potential, rheological behavior, and TEM images of concentrated kaolin slurries deflocculated with these copolymers were systematically investigated. Sodium acrylate homopolymer (SA) was selected as a reference in order to contribute to the knowledge of how the electrostatic interaction and molecular structure of these copolymers influenced the dispersion, adsorption, and rheological properties of colloidal kaolin suspensions. The results showed that the dispersion of kaolin slurries mainly depended on the synergistic effects of electrostatic interaction and steric hindrance for APEG type comb-like copolymers. PC2 bearing proper carboxylic groups and side chains produced stable dispersion and fluidity in concentrated kaolin slurries. Based on the electrostatic and steric effect of comb-like copolymers, the kaolin slurries displayed a shear thickening behavior, and the Herschel–Bulkley model well described their rheological behaviors. [Copyright &y& Elsevier]

Published
2014
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