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Zhao F.-N.,East China University of Science and Technology | Deng Z.-L.,Shanghai Sunrise Polymer Material Co. | Zheng B.-C.,East China University of Science and Technology | Feng Z.-J.,Shanghai Sunrise Polymer Material Co.
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2013

The effect caused by gypsum and polycarboxylates on the hydration reaction of tricalcium aluminate (C3A) was studied. C3A was prepared by solid-solid reaction. The results show that C3AH6 is the main hydration product in pure water. Total hydration heat evolved for C3A is approximately 879.99 J/g, and it has reached maximum in two hours. In the gypsum system, the addition of gypsum prolongs the time of hydration heat evolved for C3A. At the same time, gypsum changes the constitution of C3A hydration products. When the gypsum of small addition, AFm as the main hydration product. When the gypsum was excessive, AFt as the main hydration product. The polycarboxylate superplasticizer defered the hydration reaction of C3A as well. And in the same C3A hydration reaction period the degree of hydration decreased by the increase of addition of polycarboxylates. The conductivity tests reflected that the existence of polycarboxylates dcereased the concentration of calcium ion, thus delaying the hydration reaction of C3A. Source

Xu J.,Shanghai Sunrise Polymer Material Co. | Feng Z.-J.,Shanghai Sunrise Polymer Material Co. | Fu L.-F.,Shanghai Sunrise Polymer Material Co. | Zheng B.-C.,Shanghai Sunrise Polymer Material Co.
Advanced Materials Research | Year: 2013

Acrylate polymer emulsion was synthesized by semi-continuous seeded emulsion polymerization with methacrylic acid (MAA) as the hydrophilic shell monomer. The redispersible polymer powder was prepared by spray drying method. The effects of the amount of MAA, styrene (St) stoichiometry equivalents to methyl methacrylate, and two kinds of spray drying methods on size distribution of the redispersible polymer powder were further systematically investigated. The Malvern laser particle size analyzer, transition electron microscopy (TEM), scanning electron microscopy (SEM) and differential scanning calorimeter were employed to characterize the redispersible polymer powder. Results showed that the redispersible polymer powder obtained by pneumatic spray drying with excellent re-dispersibility could be synthesized at 10% of MAA, 50% of St stoichiometry equivalents. The final copolymer emulsion with "perfect" core-shell morphology was approved by TEM, and the comparable film forming ability of the redispersible polymer powder with the original emulsion was observed by SEM, which could form a dense and smooth membrane. © (2013) Trans Tech Publications, Switzerland. Source

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