温度对不同相对分子质量缓释型聚羧酸保坍剂性能的影响
|
摘要
将丙烯酸羟丙酯引入保坍剂(PCE)中,合成了4种不同相对分子质量(M_w)的缓释型聚羧酸保坍剂,系统研究了温度对不同M_w保坍剂的分散和分散保持、水解速率及吸附进程的影响。随温度升高,PCE水解速率增大,吸附量增加,但初始流动度减小。低温(20℃)时,随着M_w减小,吸附速率(K)变小,吸附变慢,浆体溶液中残留的保坍剂分子多,可进一步发挥分散作用,低M_w样品的保坍能力优异。高温(30℃和40℃)时,随着M_w减小,K变大,吸附加快,浆体中残留的分子较少,且高温使水泥水化速度加快,分子更易被水化产物包埋,分散保持性能变差,合适M_w的样品初始分散性能优异,后期保坍能力也优异,温度对水化的影响超过对PCE水解速率增加的分散作用。
Four polycarboxylate copolymers(PCEs) with different molecular weight(M_w) were synthesized by introduction of hydroxypropyl acrylate(HPA) into water-based free radicals. The effects of temperature on the dispersion, dispersion retension, hydrolysis rate and adsorption process of slump agent with different M_w were studied systematically.With the increase of temperature, the hydrolysis rate and adsorption capacity of PCE increase, but the initial fluidity decreases. At low temperature(20 ℃), as M_w decreases, the adsorption rate K becomes smaller and the adsorption becomes slower. Therefore more residual molecules in slurry solution can play the role of dispersion. Thus low M_w samples have excellent slump retentions. At high temperature(30 ℃ and 40 ℃), with M_w decreasing, K and the rate of adsorption increase, resulting to less residual molecules in the slurry. High temperatures make the cement hydration faster, so molecules are more easily buried by hydration products resulting to a poor dispersion retention. Samples with the appropriate M_w show the excellent initial dispersibility and excellent post slump retention. The effect of temperature on hydration exceed the effect of increased dispersion of PCE hydrolysis.
Four polycarboxylate copolymers(PCEs) with different molecular weight(M_w) were synthesized by introduction of hydroxypropyl acrylate(HPA) into water-based free radicals. The effects of temperature on the dispersion, dispersion retension, hydrolysis rate and adsorption process of slump agent with different M_w were studied systematically.With the increase of temperature, the hydrolysis rate and adsorption capacity of PCE increase, but the initial fluidity decreases. At low temperature(20 ℃), as M_w decreases, the adsorption rate K becomes smaller and the adsorption becomes slower. Therefore more residual molecules in slurry solution can play the role of dispersion. Thus low M_w samples have excellent slump retentions. At high temperature(30 ℃ and 40 ℃), with M_w decreasing, K and the rate of adsorption increase, resulting to less residual molecules in the slurry. High temperatures make the cement hydration faster, so molecules are more easily buried by hydration products resulting to a poor dispersion retention. Samples with the appropriate M_w show the excellent initial dispersibility and excellent post slump retention. The effect of temperature on hydration exceed the effect of increased dispersion of PCE hydrolysis.
引文
[1] Zhang L R, Kong X M, Xing F, et al. Working mechanism of post-acting polycarboxylate superplasticizers containing acrylate segments[J]. J. Appl. Polym. Sci., 2018, 135: DOI: 10.1002/app.45753.
[2] 刘金芝, 周栋梁, 江姜, 等.具有缓释作用的聚羧酸分散剂的制备及机理研究[J].功能材料, 2013, 44(S2): 277-279.Liu J Z, Zhou D L, Jiang J, et al. Preparation and mechanism research of polycarboxylate dispersant with slow released effect[J]. Journal of Functional Materials, 2013, 44(S2): 277-279.
[3] Shu X, Ran Q P, Liu J P, et al. Tailoring the solution conformation of polycarboxylate superplasticizer toward the improvement of dispersing performance in cement paste[J]. Constr. Build. Mater., 2016, 116: 289-298.
[4] Ran Q P, Jiang J, Liu J P, et al. Influence of temperature on properties of ester-type acrylate polycarboxylate superplasticizer[J]. J. Build. Mater., 2011, 14: 757-760.
[5] Yoshioka K, Tazawa E, Kawai K, et al. Adsorption characteristics of superplasticizers on cement component minerals[J]. Cem. Concr. Res., 2002, 32: 1507-1513.
[6] Ran Q P, Liu J Z, Yang Y, et al. Effect of molecular weight of polycarboxylate superplasticizer on its dispersion, adsorption, and hydration of a cementitious system[J]. J. Mater. Civ. Eng., 2016, 28: 04015184.
[7] Lange A, Hirate T, Plank J. The role of non-adsorption PCE molecules in cement dispersion: experimental evidence for a new dispersion mechanism[C]. Prague: Tenth International Conference on Superplasticizers and Other Chemical Admixtures, 2012: 435-449.
[8] Zhang Q, Ran Q P, Zhao H X, et al. Effect of counter-ions on comb-like polycarboxylate conformation in aqueous solutions[J]. J. Dispersion Sci. Technol., 2017, 38: 721-728.
[9] Dalas F, Nona A, Pourchet S, et al. Tailoring the anionic function and the side chains of comb-like superplasticizers to improve their adsorption[J]. Cem. Concr. Res., 2015, 67: 21-30.
[10] Liu J Z, Yang Y, Zhang Q, et al. Effect of molecular weight of slow-release polycarboxylate superplasticizer on the properties of cementitious system[J]. Adv. Cem. Res., 2017, 30(7): 285-292.
[11] Wang W S, Zheng B C, Feng Z J, et al. Adsorption of polycarboxylate-based superplasticizer onto natural bentonite[J]. J. Adv. Concr. Technol., 2012, 10: 323-331.
[2] 刘金芝, 周栋梁, 江姜, 等.具有缓释作用的聚羧酸分散剂的制备及机理研究[J].功能材料, 2013, 44(S2): 277-279.Liu J Z, Zhou D L, Jiang J, et al. Preparation and mechanism research of polycarboxylate dispersant with slow released effect[J]. Journal of Functional Materials, 2013, 44(S2): 277-279.
[3] Shu X, Ran Q P, Liu J P, et al. Tailoring the solution conformation of polycarboxylate superplasticizer toward the improvement of dispersing performance in cement paste[J]. Constr. Build. Mater., 2016, 116: 289-298.
[4] Ran Q P, Jiang J, Liu J P, et al. Influence of temperature on properties of ester-type acrylate polycarboxylate superplasticizer[J]. J. Build. Mater., 2011, 14: 757-760.
[5] Yoshioka K, Tazawa E, Kawai K, et al. Adsorption characteristics of superplasticizers on cement component minerals[J]. Cem. Concr. Res., 2002, 32: 1507-1513.
[6] Ran Q P, Liu J Z, Yang Y, et al. Effect of molecular weight of polycarboxylate superplasticizer on its dispersion, adsorption, and hydration of a cementitious system[J]. J. Mater. Civ. Eng., 2016, 28: 04015184.
[7] Lange A, Hirate T, Plank J. The role of non-adsorption PCE molecules in cement dispersion: experimental evidence for a new dispersion mechanism[C]. Prague: Tenth International Conference on Superplasticizers and Other Chemical Admixtures, 2012: 435-449.
[8] Zhang Q, Ran Q P, Zhao H X, et al. Effect of counter-ions on comb-like polycarboxylate conformation in aqueous solutions[J]. J. Dispersion Sci. Technol., 2017, 38: 721-728.
[9] Dalas F, Nona A, Pourchet S, et al. Tailoring the anionic function and the side chains of comb-like superplasticizers to improve their adsorption[J]. Cem. Concr. Res., 2015, 67: 21-30.
[10] Liu J Z, Yang Y, Zhang Q, et al. Effect of molecular weight of slow-release polycarboxylate superplasticizer on the properties of cementitious system[J]. Adv. Cem. Res., 2017, 30(7): 285-292.
[11] Wang W S, Zheng B C, Feng Z J, et al. Adsorption of polycarboxylate-based superplasticizer onto natural bentonite[J]. J. Adv. Concr. Technol., 2012, 10: 323-331.