Min Qiao,Jian Chen,Nanxiao Gao,Guangcheng Shan,Jingzhi Wu,Bosong Zhu,Qianping Ran
To explore the potential application of high-performance viscosity-modifying admixtures (VMAs) is of great importance. In this work, the effects of the adsorption group and molecular weight of VMAs on the properties of fresh cement paste were studied. A series of copolymers having similar molecular weights but different adsorption groups (carboxyl, sulfonic, and quaternary ammonium groups) were compared for the first time. A series of copolymers having the same chemical structure but different molecular weights were also compared. The adsorption, fluidity, bleeding, and rheological properties of the fresh cement paste mixed with different copolymers were tested. The results show that the copolymer, having stronger adsorption group (carboxyl group) and higher molecular weight, could decrease the bleeding and fluidity while enhancing the stability of the fresh cement paste more effectively. The study may help explore ideal materials for the design and preparation of synthetic polymer VMAs.
The liquid burning rate suppressants (BRSs) at room temperature were first prepared by combining urea with adsorption group from AP-bonding agents. The novel urea BRSs were applied in triethylene glycol dinitrate (TEDGN) plasticized hydroxyl-terminated polyether (HTPE) propellants. The results show that only 0.5% of them can reduce the burning rate and pressure index of the propellants at the same time. Owing to the adsorption group from AP bonding agents, the novel urea BRSs can adsorb onto the surface of AP during mixing by themselves, which are more suitable for industrial application than nano-sized or encapsulated BRSs. In addition, the desirable mechanical performance can be obtained and the BRSs have little influence on the hazardous properties of propellants.
Ma Jianfeng,Zhao Hongxia,Shang Yazhuo,Peng Changjun,Liu Honglai,Zheng Shuzhen,Wang Tao,Qi Shuai,Ran Qianping
Abstract The presence of a highly alkaline environment or large amounts of Ca 2+ in concrete exerts a great influence on the dispersion of graphene oxide (GO) particles. Therefore, the development of a highly efficient GO dispersant to adapt to complex concrete environments is important. In this work, novel phosphate-modified small molecular polydentate polymers were synthesized and used as efficient dispersants for cement and high-concentration GO solutions. The chemical structure of the polymers was confirmed by 1 H NMR and IR spectroscopy, and the effect of adsorption groups on the adsorption ability of polymers was studied by using adsorption experiments and theoretical calculations. Results showed that the dispersant inositol hexaphosphate–methoxy polyether (IHP-MP) features a high adsorption equilibrium constant and strong adsorption ability. IHP-MP exhibited not only good water-reducing and slump-retaining properties but also remarkable cement hydration-retarding effects due to its numerous phosphate groups. IHP-MP could be used as an auxiliary GO dispersant with the comb polymer PCE to effectively reduce the viscosity and improve the stability of GO solutions. SEM, TGA and IR characterization indicated that IHP-MP strongly interacts with the surface groups of GO particles. Graphic Abstract
危险品化学品经营许可证（带存储）