聚合物胶粉对PC和SAC水泥砂浆的改性研究

通过对比性试验,研究了聚合物胶粉对改性硅酸盐水泥砂浆和改性硫铝酸盐水泥砂浆的力学性能和柔韧性的影响,并采用扫描电子显微镜观测了二种水泥基聚合物改性砂浆的形态结构.试验结果表明:试验所用的聚合物胶粉对硫铝酸盐水泥砂浆的性能改善较普通水泥砂浆的性能改善更明显,尤其是抗折强度的影响更为突出:聚合物胶粉能显著降低二种水泥砂浆的压折比,改善砂浆柔韧性,其中改善硫铝酸盐水泥砂浆柔韧性的效果较明显.     

聚合物改性水泥基复合材料研究进展

总结了不同聚合物改性水泥基材料的性能及改性机理。从力学性能、耐久性和黏结强度等方面阑述了聚合物改性水泥基材料的性能,从聚合物在水泥基材料内部成膜、聚合物影响水泥砂浆的水化过程和聚合物作为混凝土内养剂三方面分别讨论了聚合物改性砂浆和混凝土的改性机理。     

苯丙乳液改性水泥修补砂浆的制备与性能研究

采用复配技术制备苯丙乳液改性水泥修补砂浆,并进行性能研究.探讨了聚合物乳液、偏高岭土、煅烧膨润土等外加剂对该砂浆物理性能的影响.结果表明:苯丙乳液的掺入虽然在一定程度上降低了砂浆的抗压强度,但显著改善了水泥砂浆的和易性和需水量.通过掺加偏高岭土或煅烧膨润土等火山灰活性掺合料可弥补砂浆力学性能的不足.     

聚合物胶粉改性硫铝酸盐水泥砂浆

通过与硅酸盐水泥对比,研究聚合物改性硫铝酸盐水泥砂浆的力学性能、柔韧性和干缩性能,并采用扫描电子显微镜观测水泥基聚合物改性材料的形态结构。结果表明：聚合物胶粉硫铝酸盐水泥砂浆的性能较普通水泥砂浆有明显的改善,尤其抗折强度更为突出。聚合物胶粉均能显著降低水泥砂浆的压折比,改善砂浆柔韧性,尤其是改善硫铝酸盐水泥砂浆的效果较明显。由于硫铝酸盐水泥的微膨胀性能,使其砂浆的干缩性能优于硅酸盐水泥砂浆。     

苯丙乳液改性高强水泥基材料性能及机理

苯丙乳液作为聚合物改性材料已经在水泥基材料中得到应用,而对其改性机理尚不清楚.本文测试了苯丙乳液改性高强水泥基材料的工作性、凝结时间及力学性能,利用微量热仪法与X射线衍射(XRD)分析了苯丙乳液对水泥基材料水化的影响,通过扫描电镜(SEM)及能谱分析(EDS)研究了其微观结构.研究结果表明,苯丙乳液延缓了水泥基材料的水化与二次水化反应,苯丙乳液能有效改善高强水泥基材料界面结构与水泥石结构.苯丙乳液与水泥或其水化产物间存在化学反应的可能性.     

丙烯酸乳液改性水泥加固砂浆的性能研究

基于参编的《聚合物水泥加固砂浆》指标要求,采用丙烯酸乳液对加固砂浆进行了改性,并且研究了丙烯酸乳液的加入对加固砂浆凝结时间、力学性能、黏接性能及干缩性能的影响.结果表明:随着乳液掺量的增加,加固砂浆的初凝和终凝时间延长,抗折和抗压强度下降,黏接强度变大,干缩率降低.当乳液掺量为16.2％时,其综合性能较好,初凝和终凝时间分别缩短为120 min和160 min;28 d龄期下的抗压强度达到55.3 MPa,抗折强度达到14.2 MPa,黏接强度达到3.01 MPa,干缩率达到0.08％,均满足正在参编的《聚合物水泥加固砂浆》标准指标.进一步对比观察不同乳液掺量下加固砂浆的扫描电镜图像,从微观的角度印证了上述结论.     

无固化剂环氧树脂乳液对油井水泥早期水化的影响EI北大核心CSCD

将不同聚合度环氧树脂乳液以不同掺量掺加到固井水泥浆中,制备环氧树脂乳液改性水泥浆。在无固化剂、不同温度条件下,通过水化热测量,扫描电子显微镜,X射线衍射等方法研究了环氧树脂乳液对油井水泥早期水化特性的影响。结果表明:相对于纯油井水泥浆体,环氧树脂水泥浆的水化进程被延缓,但是水化产物没有明显变化,环氧树脂在硬化水泥浆体中主要以聚合物膜的形式存在,可填充水泥石内部的毛细孔隙,使环氧树脂水泥石的抗压强度随着环氧树脂掺量的提高而略有增加。     

环境温度对新拌水泥基材料流变性能的影响研究进展

新拌水泥基材料的流变性能表面上影响其施工性能,实质上决定了其结构的力学性能和耐久性能.水泥基材料的流变性能是时间和温度的非线性函数,获得不同温度下水泥基材料流变性能时变规律,是确保水泥基材料施工质量的关键.基于净浆、砂浆、混凝土三个层次详细介绍了温度对新拌水泥基材料流变性能影响,从水泥水化反应速率、有效水含量和减水剂分散效果三个方面分析了温度影响新拌水泥基材料流变性能的机理,以期为不同温度下水泥基材料施工提供指导.     

新型湿拌砂浆外加剂及其应用

针对传统湿拌砂浆外加剂易分层、开放时间短、力学性能差的问题,采用和易型聚羧酸系高性能减水剂(PCE)、改性纤维素醚和超缓释型PCE制备了新型湿拌砂浆外加剂.通过对比传统与新型湿拌砂浆外加剂各组分对砂浆稠度及经时变化、容重、保水率和抗压强度的差异,揭示了新型湿拌砂浆外加剂作用机理,其通过化学释水与物理释水相结合的原理实现了湿拌砂浆长时保塑,提高了水泥的水化程度,同时不影响砂浆力学性能的发展.     

无固化剂环氧树脂乳液对油井水泥早期水化的影响

将不同聚合度环氧树脂乳液以不同掺量掺加到固井水泥浆中,制备环氧树脂乳液改性水泥浆。在无固化剂、不同温度条件下,通过水化热测量,扫描电子显微镜,X射线衍射等方法研究了环氧树脂乳液对油井水泥早期水化特性的影响。结果表明:相对于纯油井水泥浆体,环氧树脂水泥浆的水化进程被延缓,但是水化产物没有明显变化,环氧树脂在硬化水泥浆体中主要以聚合物膜的形式存在,可填充水泥石内部的毛细孔隙,使环氧树脂水泥石的抗压强度随着环氧树脂掺量的提高而略有增加。     

Mechanical and adhesion properties of polymer-modified cement mortars in relation with their microstructure

In this study, cement mortars were modified with a commercial polymer admixture. The aim of this study is to investigate the influence of the polymer content on the mechanical and adhesion properties of the mortars and to relate these properties with mortars’ microstructure. A series of mortars were produced with various polymer/cement/water/aggregate ratios. The adhesion properties of the mortars to clay bricks were tested with a simplified tensile testing measurement. The microstructure of mortars, as well as interfaces, were evaluated by Scanning Electron Microscopy (SEM). It was found that with high polymer content, large size hardened particles are formed, reducing the compressive strength of the mortars. Polymer addition enhances the adhesion between the mortar and brick. The mortar microstructure at the interface affects the adhesion properties and the mode of failure.     

Effect of the monomer ratio on the properties of poly(methyl methacrylate butyl acrylate) latex‐modified mortars

This article deals with the effect of the monomer ratio on the typical properties of polymer‐modified mortars with poly(methyl methacrylate butyl acrylate) latices. Polymer‐modified mortars, with methyl methacrylate/butyl acrylate copolymer latices of various methyl methacrylate/butyl acrylate ratios, were prepared with different polymer/cement ratios and were tested for their workability, air content, compressive strength, flexural strength, and water absorption. On the basis of the test results, the effects of the monomer ratio and polymer/cement ratio on the typical properties were examined. The properties of the latex‐modified mortars were affected to a great extent by both the monomer ratio and polymer/cement ratio. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2403–2409, 2004     

AN／BA复合乳液聚合方法的研究

用三种不同的加料方法和两种不同的加料顺序制备了ＡＮ／ＢＡ复合聚合物乳液。测定了聚合物乳液的流变性，电解质稳定性，乳胶粒子的大小及分布，胶膜的耐水、耐溶剂性。探讨了不同聚合方法乳胶粒子的增长机理及影响乳胶性能的微观因素。     

Sustainable polymer latexes based on linoleic acid for coatings applications

The synthesis of new waterborne polymer latexes based on renewable linoleic acid (LA) was investigated. Methacrylic functionality was incorporated into the LA and the resulting monomer was successfully polymerized via miniemulsion polymerization. The effect of the initiator amount and type on microstructure was analyzed. Almost totally converted latexes with different microstructures were achieved. Furthermore, the effect of the presence of labile allylic hydrogens on the LA backbone was discussed in terms of microstructural properties, as well as final film properties. The results suggested that LA based latexes have great potential to replace petroleum based waterborne coating materials.     

Influence of Low Fractions of Styrene/Butyl Acrylate Polymer Latexes on Some Properties of Ordinary Portland Cement Mortars

The influence of the chemical structure of styrene/butyl acrylate latexes on some properties of ordinary Portland cement mortars has been investigated for low fractions of polymer with respect to the amount of cement. The structural parameters that were varied included the presence of carboxylic surface charges, the nature of the surfactant system, the molecular weight of the non‐ionic emulsifier, and the particle surface coverage. The first part of the study showed that sterically stabilised latexes remain colloidally and chemically stable for several hours in the cement interstitial medium. Moreover, no interaction could be shown between cement and latex components. Then, for a fraction of about 5wt.‐% of polymer, no significant influence of the presence of the latex was observed on the end‐use properties of the mortars. However, it clearly appears that the use of a fraction of anionic stabiliser is highly detrimental to the paste workability, whereas this latter property is improved by the presence of non‐ionic surfactant due to steric repulsion forces. Finally, the microstructure analysis confirms that the particles are homogenously dispersed in the mineral matrix and that they remain smooth and spherical.

     

Physical and mechanical properties of styrene-butadiene rubber emulsion modified cement mortars

Polymer-modified cement mortars were prepared by varying polymer/cement mass ratio (P/C) with a constant water/cement mass ratio of 0.4. The effect of styrene-butadiene rubber (SBR) emulsion on the physical and mechanical properties of cement mortars is studied. With P/C below 10%, the toughness of the modified mortars enhances with the increase of P/C. A relationship between the physical and mechanical properties of the modified cement mortars at P/C below 10% is found; that is, the compressive strength and flexural strength of the modified mortars are directly proportional to the apparent bulk density. But when P/C is above 10%, the mechanical properties are not highly dependent on the apparent bulk density, and the flexural and compressive strength of the mortars are not improved further with more polymer. Two curing methods [wet cure: 2, 6 or 27 days immersed in 20 °C water; mixed cure: 6 days immersed in 20 °C water followed by 21 days at 20 °C and 70% relative humidity (RH)] were also evaluated in this paper. The results have shown that the mixed cure is more beneficial to the improvement of the mortar properties. A possible mechanism for polymer modification and the relationship between the physical and mechanical properties is proposed based on SEM and IR analyses. The interpenetrating structure between the polymeric phase and cement hydrates forms at a P/C of 8%, and fully develops at a P/C of 10%. The properties of the polymer-modified mortars are influenced by the polymer film, cement hydrates and the combined structure between the organic and inorganic phases.     

高吸水性树脂对水泥砂浆体积收缩及力学性能的影响

将自行研制的高吸水性树脂加入砂浆配方,研究了高吸水树脂对不同水灰比下新拌砂浆的流动度、砂浆存下燥养护过程中的体积收缩以及力学性能的影响.研究发现:高吸水性树脂的加入一定稃度上降低了砂浆的流动度:砂浆在干燥养护时,在水灰比(质量比)为0.5~0.7范围内,砂浆的总体积收缩与水灰比关系不大,高效减水剂多聚羧酸酯的加入能增大砂浆的体积收缩;在水灰比为0.5～0.6的砂浆下燥养护时,将高吸水性树脂加入到砂浆中町以明显减小其体积收缩;而对水灰比为0.7的高水灰比砂浆的体积收缩改善作用不明显;对于水灰比为0.7的高水灰比砂浆,高吸水性树脂的加入导致其二次浸水时的吸水率增大.此外高吸水性树脂的加入能提高十燥情况下养护后砂浆的力学性能,尤其在较低水灰比的砂浆中作用更为明显.     

细乳液聚合胶乳性能的研究

本文用细乳液聚合方法制备了一系列苯乙烯/丙烯酸丁酯,甲基丙烯酸甲酯/丙烯酸丁酯胶乳,从多方面考察了其胶乳和胶膜的性能,并与传统乳液聚合方法制得的胶乳进行了比较,结果表明,采用细乳液聚合方法制备得到的胶乳具有更优良的性能.     

Towards anti-corrosion coatings from surfactant-free latexes based on maleic anhydride containing polymers

We report on the film formation of surfactant-free, artificial latexes based on copolymers containing maleic anhydride. Different metallic substrates, such as aluminum, steel and magnesium alloys, were coated with three different latexes. A commercial polyester based coating was used as a comparative sample. Two of the latexes were based on polymer with a high T_g (resp. 100 and 130 °C), and one on a polymer with a T_g of −70 °C. The wetting of the substrates could be optimized by etching the metal substrate, acidic or alkaline, leading to homogenous film formation and improved adhesion. For aluminum substrates an alkaline pretreatment improved the adhesion with the polymer films, whereas for magnesium the acidic pretreatment improved the adhesion. Furthermore, acid pretreatment increased the corrosion resistance of the coated magnesium substrate, when compared to an alkaline pretreatment. The films formed from latex displayed comparable or better anti-corrosive properties when compared to the commercial polyester.     

纤维素醚和乳胶粉在商品砂浆中的作用

简述了商品砂浆在国内外的发展历史,讨论了纤维素醚和乳胶粉2种聚合物干粉在干混商品砂浆的作用,包括对砂浆的保水性、毛细孔吸水性、抗折强度、抗压强度、弹性模量、不同环境温度养护的粘结抗拉强度的影响.