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聚合物叔碳酸乙烯酯 /醋酸乙烯酯乳液改性水泥(英文)

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乙烯制醋酸_亚硫酸乙烯酯_醋酸乙烯酯的英文简称

至于一些特殊用途的砂浆,水泥强度不稳定(或下降)的主要原因之一是水泥强度未达到国标要求醋酸乙烯酯的英文简称,另加入一定 量的防水剂配制的防水砂浆,如用膨胀水泥配制修补堵漏的砂浆,这种水泥可用适当方式压碎后降低标号使用,掉面或爆皮剥落,在此介绍一些家庭装修中如何选择和使用水泥的知识、卫生间漏水,你就可以用,也可用石灰代替或部分代替水泥制成石灰砂浆或水泥混合砂浆,水泥用量宜多这个不是很清楚但是如果符合下面的条件。乙烯一乙酸乙烯乳液(eva乳液) 100份 二元酸双酯 ≥3份 将eva乳液、二元酸双酯混合均匀,制得无甲苯的粘合剂。3.权利要求1或2的组合物,其特征在于亲油聚合物是由以下物质聚合获得的共聚物a)相对于单体总重量的10-55wt%的对叔丁基苯乙烯单体,b)20-80%甲基丙烯酸c1-c10烷基酯单体,c)2-25wt%丙烯酸c1-c10烷基酯单体,d)0-40wt%除对叔丁基苯乙烯外的乙烯基芳族单体。

乙烯制醋酸_亚硫酸乙烯酯_醋酸乙烯酯的英文简称

修订日期:2015–05–07。 基金项目:国家自然科学基金资助项目(51278325)。 第一作者:耿文博(1992—),男,硕士研究生。 通信作者:申迎华(1964—)醋酸乙烯酯的英文简称,女,教授。 Received date: 2015–01–12. Revised date: 2015–05–07. First author: GENG Wenbo (1992–), male, Master candidate. E-mail: gengwenbo0108@gmail.com Correspondent author: SHEN Yinghua (1964–), female, Professor. E-mail: shenyinghua@tyut.edu.cn · 1130 · 《硅酸盐学报》 J Chin Ceram Soc, 2015, 43(8): 1129–1134 2015 年 contribution of poly (VeoVa10-VAc) latex powder to the microstructure of cement mortar and found that poly (VeoVa10-VAc) copolymer effectively inhibites the portlandite formation. Afridi et al. [8-9] reported that mixing antifoamer with the poly (VeoVa10-VAc) powder increases the mechanical strengths of cement mortar. Wang et al. [10-11] found that poly (Veo10-VAc) latex powder exhibites well water-reduction and water- retention in cement mortar as well as improves flexural and compressive properties of mortars effectively. These studies were mainly focused on the amounts of poly (VeoVa10-VAc) latex powders impact on the properties of cement mortars. However, little work on the effect of poly (VeoVa10-VAc) emulsions with different chemical compositions on the microstructures and mechanical properties of polymer modified cement mortars has been reported. In this work, poly (VeoVa10-VAc) emulsions with different monomer compositions were prepared and their influences on the mechanical properties of modified cement mortars were investigated. The comprehensive properties of modified cement mortar were optimized. 2 Experimental 2.1 Materials Portland cement P·II 42.5 according to the Chinese standard GB 175 (ENV197-1: 1995) and standard sands according to the ISO679 were used to prepare mortars and pastes. Table 1 shows the basic chemical composition of the used cement. Industrial grade vinyl acetate (VAc) was supplied by Shanxi Sanwei Co., China. Vinyl Versatate10 (VeoVa10, >99%) was supplied by Hansen Co., the Netherlands. Poly (VeoVa10-VAc) emulsions were prepared according to our early publication, [12] and their details are summarized in Table 2. 2.2 Samples preparation The mortar samples for mechanical property were prepared at the polymer/cement mass ratio (P/C) of 0.09, water-cement ratio of 0.45 and sand-cement ratio of 2.00. The emulsions were diluted with water before added to Table 1 Chemical composition of PII 42.5 Portland cement Component Mass fraction/% SiO 2 21.54 CaO 64.80 Fe 2 O 3 3.02 Al 2 O 3 4.01 MgO 1.38 SO 3 2.14 Free CaO 1.60 Ignition loss 1.01 Insoluble fraction 0.50 Table 2 Properties of the synthesized poly (VeoVa10-VAc) emulsions Names of different emulsionsMass ratio of VeoVa10 to VAc Solidscontent/%Particle size D 50 /nm Apparent Viscosity /(Pa·s) Glass-transition temperature T g /℃) P0 0:100 45.7 590 4.83 36.1 P10 10:90 45.5 670 4.56 33.7 P20 20:80 45.4 650 4.63 29.5 P30 30:70 45.6 890 4.75 21.5 the mixture of sands and cement powders. A series of samples were prepared with and without poly (VeoVa10-VAc) emulsions, namely, unmodified mortar (U-M) and modified mortars (M-0, M-1, M-2, M-3 in the presence of emulsions P 0 , P 10 , P 20 and P 30 ). For the compressive and flexural strength test, the samples with their dimensions of 40 mm×40 mm×160 mm were prepared according to the standard ISO 679. The prepared samples were firstly demolded for 1 day, then stored up for 28 d at (20±1) and 95% relative ℃humidity (h). The substrates with dimension of 70 mm × 70 mm × 20 mm were prepared according to the standard ISO 679, fresh-prepared mortars were trowelled on the substrate (profiled 40 mm × 40 mm × 3 mm). The specimens submitted to dry adhesive strength test were maintained at h=75% for 15 d. Those submitted to wet adhesive strength test were maintained at h=75% for 7 d and subsequently immersed in water at (20±1) for 7 d. ℃ The typical samples were taken at a depth of 5 mm from the surface of the cured specimens, and washed with ethanol and dried in vacuum. The sample powders were subjected to various characterization methods like Fourier transform infrared spectroscopy (model Perkin-Elmer 1730, USA), thermo-gravimetry (model TGA 951, USA) and X-ray diffraction (model Rigak D/max 2550, Japan). 2.3 Methods The FTIR spectra were recorded on a model Perkin-Elmer 1730 spectrometer, using KBr pellets. The thermal stability of the samples was examined using a model TGA 951 thermal analyzer in nitrogen at a heating rate of 10 /min. The XRD patterns of the samples were ℃determined at a graphite-monochromatized Cu K a radiation generated at 40 kV and 200 mA by a model Rigaku D/max 2550 X-ray diffractometer. The time-fixed step scanning was conducted at a step length of 0.02° for each step in the scale range of 5°–65°. The adhesive strength was measured according to the Chinese Standard JC/T992—2006 (CAN3-A451.1 -M86). [13] The dry adhesive strength and wet adhesive strength of the modified mortar samples both were examined for six times to obtain the average adhesive strength. The compressive and flexural strengths were 第 43 卷第 8 期 耿文博 等:聚合物叔碳酸乙烯酯/醋酸乙烯酯乳液改性水泥 · 1131 · measured according to the standard ISO 679. 3 Results and discussion 3.1 Effect of polymer composition on the microstructure of emulsion modified mortars 3.1.1 Hydrolysis of poly (VeoVa10-VAc) in modified cement mortar Some polymers containing vinyl acetate group can suffer hydrolysis when dispersed in alkali. [7,14] Figure 1 shows the possible hydrolysis reaction of poly (VeoVa10-VAc). The OH – groups come from cement hydration. [15] The acetate ions from the hydrolysis of vinyl acetate can interact with Ca 2+ ions from the dissolution of anhydrous cement grains in emulsion modified cement mortars. [14] Figure 2 shows the FTIR spectra of unmodified mortar (U-M) and emulsion modified mortars (i.e., M-0, M-1, M-2 and M-3). The emulsion modified mortars appear some bands at 1 740 and 1 245 cm –1 , which are assigned to the C=O and C-O groups of the ester of PVAc and poly (VeoVa10-VAc). Also, a band at 1 566 cm –1 is the characteristic band of carboxylate anion (COO – ) [16] due to the partial hydrolysis of the vinyl acetate group. where: m—Degree of polymerzation (DP) of VeoVa10 monomers; n—DP of VAC monomer; k—DP of VA monomers; X + —Metal cations; R—Tert-butyl group in VeoVa10. Fig. 1 Hydrolysis of poly (VeoVa10-VAc) under alkaline medium Fig. 2 FTIR spectra of unmodified mortar (U-M) and emulsion modified mortars In PVAc emulsion modified cement mortar (M-0), an intense absorption peak appears at 1 566 cm –1 , which is relevant to anion COO – . Two peaks at 1 740 and 1 245 cm –1 increase with increasing the mass ratio of VeoVa10/VAc. It is indicated that the ester hydrolysis in PVAc modified cement mortar is greater than that of poly (VeoVa10-VAc) modified ones. This might be attributed to the decrease of VAc and the protective effect of tert-butyl groups, which can protect the ester in polymer from hydrolysis. [7, 17] 3.1.2 Effect of poly (VeoVa10-VAc) emulsions on cement hydration The reactions of cement hydration are expressed by [18] : 2(3CaO·SiO 2 )+6H 2 O→3CaO·2SiO 2 ·3H 2 O(C–S–H)+ 3Ca(OH) 2(1) 2(3CaO·SiO 2 )+4H 2 O→3CaO·2SiO 2 ·3H 2 O(C–S–H)+ Ca(OH) 2(2) The effect of poly (VeoVa10-VAc) emulsions on the cement hydration is investigated via estimating the quantities of resultant CaCO 3 and Ca(OH) 2 and the crystallinity of Ca(OH) 2 . Fig. 3 TG curves of the unmodified mortar (U-M) and the mortars modified Figure 3 shows the TG curves of the unmodified mortar (U-M) and the mortars modified. In the TG curves, there are three temperature ranges reported when hydrated cement is heated, namely, 1) dehydration and decomposition of the C–S–H at 25–200 ℃; 2) decomposition of the Ca(OH) 2 at 400–500 . The U ℃ -M is clearly observed in the TG curves at 400–500 ℃, · 1132 · 《硅酸盐学报》 J Chin Ceram Soc, 2015, 43(8): 1129–1134 2015 年 which is different from that of the modified mortars because the decomposition product of calcium acetate will volatilize at 380–400 ℃ and the lower degeneration of poly(VeoVa10–VAc) in alkaline environment; and 3) decomposition of CaCO 3 at 600–750 ℃. [7,14] The mass loss of CaCO 3 for those emulsion modified cement mortars are greater than that of the unmodified one. There is also decomposition of the U-M at 600–750 ℃. In addition, the mass losses of the CaCO 3 in poly (VeoVa10-VAc) emulsion modified cement mortars gradually decreases with the increase of VeoVa10/VAc feed mass ratios. Furthermore, the protection capability of the tert-butyl in VeoVa10 inhibits the hydrolysis of vinyl acetate groups, and causes the decrease of Ca(CH 3 COO) 2 gradually. The formation reaction of which calcium acetate increases the loss weight of calcium carbonate is given by [7] Ca(CH 3 COO) 2 (s)~380 400 ℃CaCO 3 (s)+ CH 3 COCH 3 (g)(3) Since Ca(OH) 2 is the main hydration product, the degree of cement hydration can be approximately estimated by comparing the peak intensities assigned to Ca(OH) 2 (peaks 1, 4, 5 in Fig. 3), β-C 2 S (peak 2) and C 3 S (peak 3). [19-20] Fig. 4 XRD patterns of unmodified mortar (U-M) and poly (VeoVa10-VAc) emulsion modified mortars with different VeoVa10/VAc ratios It is seen that the diffraction intensity of the Ca(OH) 2 increases and the intensities of the β-C 2 S and C 3 S decrease with the hydration. The Ca(OH) 2 diffraction intensities for emulsion modified cement mortars are smaller than those of the unmodified cement mortars and the intensity of the cement mortars modified by PVAc is the smallest. The mass loss of Ca(OH) 2 in emulsion modified mortars are less than that of unmodified one, and the mass loss gradually increases with the VeoVa10/VAc feed mass ratios, which consistent with the XRD results as shown in Fig. 4. The hydrolysis of vinyl acetate produces acetate ions, which can react with Ca 2+ from the dissolution of anhydrous cement grains. As a result, the decrease in the Ca 2+ concentration inhibits the growth of Ca(OH) 2 crystals and the Ca(OH) 2 mass loss in those emulsion modified mortars is less than that in unmodified mortar. Also, the decrease of VeoVa10 content in the copolymer will promote the hydration of cement as well as the Ca(OH) 2 crystal formation and the gradual increase in the mass loss of Ca(OH) 2 due to the protection of t-butyl group for the adjacent esters. The results above indicate that poly (VeoVa10-VAc) units hinder the hydration of cement mortars and the inhibitory effect decreases with VeoVa10/VAc mass ratios. 3.2 Effect of polymer composition on the mechanical properties of modified cement mortars 3.2.1 Flexural strength and compressive strength Figure 5 shows the flexural and compressive strength of different cement mortars. It is seen that the addition of emulsions can improve the flexural strength of cement mortars and reduce their compressive strength. Furthermore, the flexural strength and compressive strength increase with the decrease of VeoVa10/VAc ratio. The flexural strength and compressive strength of poly (VeoVa10-VAc) modified cement mortars reach to the maximum values at the VeoVa10/VAc mass ratio of 20/80. In Table 2, the glass-transition temperature (T g ) of poly (VeoVa10-VAc) gradually decreases with the increase (a) Flexural (b) Compressive Fig. 5 Flexural and compressive strength of different cement mortars 第 43 卷第 8 期 耿文博 等:聚合物叔碳酸乙烯酯/醋酸乙烯酯乳液改性水泥 · 1133 · of VeoVa10/VAc feed mass ratio. It is indicated that the decrease of minimum film-formation temperature (MFFT) can increase the flexural strength and compressive strength. However, the interaction between poly (VeoVa10-VAc) emulsions and mortars decreases in the presence of a great amount of VeoVa10. The compressive strength of the unmodified cement mortars is relatively high, as the addition of poly (VeoVa10-VAc) destroy the ionic bonds between inorganic systems, meanwhile the interaction between polymer and inorganic system is lower than the destructive force. Furthermore, a large number of bubbles are introduced when the cement mortar is mixed with emulsion. [7] 3.2.2 Adhesive strength of the modified cement mortars Figure 6 shows dry and wet adhesive strengths between different mortars and the substrates. It is seen that the dry adhesive strength gradually decreases and the wet adhesive strength increases with increasing the VeoVa10/VAc mass ratio. Figure 7 shows the destruction forms between cement mortar and the substrate. The adhesive strength reflects the interface bonding strength between mortars and substrates. When the cohesion strength is less than the interface bonding strength, the destruction of adhesive strength is internal. Otherwise, it occurs in the interface. The alcoholic hydroxyl groups could migrate to the interface and interact with silane alkoxy groups on substrate surface. [15, 21] Since the dry adhesive strength (a) Dry (b) Wet Fig. 6 Dry and wet adhesive strengths between different mortars and the substrates Fig. 7 Destruction forms between cement mortar and the substrate and the internal chemical bonds are lower than those in the interface, the failure in the specimen thus occurs. The hydrolysis of VAc decreases with the increase of feed mass ratio of VeoVa10/VAc, and thus the internal chemical bonds decrease, leading to the decrease of dry adhesive strength. For the wet adhesive strength, unhydrated cement particles will be further hydrolyzed and the volume of mortars will be expanded at the interface. [22] Furthermore, the water resistance of poly (VeoVa10-VAc) modified mortar increases with the increase of VeoVa10/Vac feed mass ratio, resulting in the increase of the wet adhesive strength. Thus, the sample M-2 with a VeoVa10/VAc mass ratio of 20/80 has the optimum performance in both dry and wet adhesive strengths. 4 Conclusions The microstructures and mechanical properties of polymer modified cement were affected by chemical compositions of poly (VeoVa10-VAc) emulsions. The poly (VeoVa10/VAc) could hinder the hydration of cement mortars. The T g of poly (VeoVa10/VAc) decreased, the compactness of resultant polymer composite films improved, and the flexural strength and compressive strength of emulsion modified cement mortars enhanced with the increase of VeoVa10/VAc feed mass ratio. The adhesive strength of emulsion modified cement mortars was related to the hydrolysis of VAc. The increase of hydrolysis led to the increase of the dry adhesive strength and the decrease of the wet adhesive strength. The sample M-2 with a VeoVa10/VAc feed mass ratio of 20/80 exhibited the optimum mechanical properties. References: [1] FEITEIRA J, RIBEIRO M S. Polymer action on alkali–silica reaction in cement mortar [J]. Cem Concr Res, 2013, 44: 97–105. [2] YANG Z, SHI X. Effect of styrene–butadiene rubber latex on the chloride permeability and microstructure of Portland cement mortar [J]. Construct Build Mater, 2009, 23(6): 2283–2290. [3] KAN A, DEMIRBOĞA R. Effect of cement and EPS beads ratios on compressive strength and density of lightweight concrete [J]. Indian J · 1134 · 《硅酸盐学报》 J Chin Ceram Soc, 2015, 43(8): 1129–1134 2015 年 Eng Mater Sci, 2007, 14: 158–162. [4] AGGARWAL L K, THAPLIYAL P C, KARADE S R. Properties of polymer-modified mortars using epoxy and acrylic emulsions [J]. Construct Build Mater, 2007, 21(2): 379–383. [5] SARAC A, ERBIL H Y, YILDIRIM H. Semicontinuous emulsion polymerization of vinyl acetate: Effect of ethoxylation degree of nonionic emulsifiers [J]. J Appl Polymer Sci, 2002, 86(4): 844–851. [6] SMITH O W, COLLINS M J, MARTIN P S. New vinyl ester monomers for emulsion polymers [J]. Prog Organ Coat, 1993, 22(1): 19–25. [7] GOMES C E M, FERREIRA O P, FERNANDES M R. Influence of vinyl acetate-versatic vinylester copolymer on the microstructural characteristics of cement pastes [J]. Mater Res, 2005, 8(1): 51–56. [8] AFRIDI M U K, CHAUDHARY Z U, OHAMA Y. Strength and elastic properties of powdered and aqueous polymer-modified mortars [J]. Cem Concr Res, 1994, 24(7): 1199–1213. [9] AFRIDI M, OHAMA Y, IQBAL M Z. Water retention and adhesion of powdered and aqueous polymer-modified mortars [J]. Cem Concr Compos, 1995, 17(2): 113–118. [10] WANG R, WANG P M. Action of redispersible vinyl acetate and versatate copolymer powder in cement mortar [J]. Construct Build Mater, 2011, 25(11): 4210–4214. [11] WANG R, WANG P M, YAO L J. Effect of redispersible vinyl acetate and versatate copolymer powder on flexibility of cement mortar [J]. Construct Build Mater, 2012, 27(1): 259–262. [12] SHEN Y H, XIA D H, BAN Q. Effect of novel emulsifier DNS-330 on VeoVa10/VAc emulsion properties [J]. J Basic Sci Eng (in Chinese), 2011, 19(6): 919–924. [13] JC/T 992-2006. Expanded polystyrene boards adhesive for substrates thermal insulation [S]. China, 2006. [14] BETIOLI A, HOPPE FILHO J, CINCOTTO M. Chemical interaction between EVA and Portland cement hydration at early-age [J]. Construct Build Mater, 2009, 23(11): 3332–3336. [15] MANSUR A, NASCIMENTO O L D, MANSUR H S. Physico-chemical characterization of EVA-modified mortar and porcelain tiles interfaces [J]. Cem Concr Res, 2009, 39(12): 1199–1208. [16] SILVA D, ROMAN H, GLEIZE P. Evidences of chemical interaction between EVA and hydrating Portland cement [J]. Cem Concr Res, 2002, 32(9): 1383–1390 [17] AZNAR A, AMALVY J. Manufacture and testing of water-borne paints by using vinyl latex containing VeoVa10® monomer [J]. Latin Am Appl Res, 2006, 36(3): 149–154. [18] GOUGAR M, SCHEETZ B, ROY D. Ettringite and C-S-H Portland cement phases for waste ion immobilization: A review [J]. Waste Manag, 1999, 16(4): 295–303. [19] WANG R, WANG P M. Formation of hydrates of calcium aluminates in cement pastes with different dosages of SBR powder [J]. Construct Build Mater, 2011, 25(2): 736–741. [20] WANG J, ZHANG S, YU H, et al. Study of cement mortars modified by emulsifier-free latexes [J]. Cem Concr Compos, 2005, 27(9): 920–925. [21] JENNI A, HOLZER L, ZURBRIGGEN R, et al. Influence of polymers on microstructure and adhesive strength of cementitious tile adhesive mortars [J]. Cem Concr Res, 2005, 35(1): 35–50. [22] JENNI A, ZURBRIGGEN R, HOLZER L, et al. Changes in microstructures and physical properties of polymer-modified mortars during wet storage [J]. Cem Concr Res, 2006, 36(1): 79–90.



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