Cement hydration and microstructure formation in the presence of water-soluble polymers

Hardening of cement mortars modified with small amounts of water-soluble polymers implies both cement hydration and polymer film formation. In this paper, the effect of the presence of water-soluble polymers on the cement hydration reactions is investigated by means of isothermal calorimetry, thermal analysis, FT-IR spectroscopy and SEM investigation. In spite of an initial retardation of the hydration reactions, a higher degree of hydration is found after 90 days for 1% PVAA, MC and HEC modified mortars, due to a better dispersion of the cement particles in the mixing water. MC also affects the morphology of the Ca(OH)₂ crystals. Polymer bridges are detected between the layered crystals, gluing the layers together and strengthening the microstructure. Additionally, the internal cohesion of all bulk polymer modified cement pastes is improved. In the presence of the polymers, a more cohesive microstructure with a smaller amount of microcracks is created.     

Recent application developments of water-soluble synthetic polymers

In the history of man-made macromolecules, water-soluble polymers have primarily maintained passive roles; examples include the uses of water-soluble polymers for viscosity control and as binders. The importance of water on earth has increased research into the development of active roles for water-soluble polymers. These expanding roles span from medical applications, such as drug delivery to environmental applications, such as the removal of heavy metals. The development of water-soluble polymers brings significant benefits to the structural engineering and production of nanomaterials and electronic materials. The current limits of the structure–property relationship have been challenged to meet these rapidly-developing application areas.     

PVP对C14BE胶束增溶苯甲醇的影响

通过＾１Ｈ－ＮＭＲ的分光光度法探讨了含有和不含有ＰＶＰ时,苯甲醇在十四烷基甜菜碱（Ｃ１４ＢＥ）胶束溶液中的增溶行为。ＮＭＲ设没有出现Ｃ１４ＢＥ分子长链亚甲基质子的信号峰裂分现象,说明苯甲醇增溶于胶束的极性区域,没有深入到胶束内部。ＰＶＰ的存在未能改变苯甲醇的增溶位置,且使胶束的增溶量呈现减少趋势。     

The effect of hydrogen bonding on vapor diffusion in water-soluble polymers

Water-vapor transport in poly(acrylic acid) (PAA), poly(N-vinyl-2-pyrrolidone) (PVPo), and their 2 : 1 interpolymer complex was measured between 30 and 50°C. It was found that the formation of interpolymer hydrogen bonding not only caused the T_g of the complex to be higher than those of the individual components, but also affected vapor-sorption behaviors. In the high vapor pressure region (P_r > 0.5), sorption isotherms in pure PAA and PVPo follow the Flory–Huggins solution theory and the sorbed water molecules may form clusters around the COOH groups in PAA and C=O groups in PVPo. However, sorption in the complex is almost linear for the entire range of water activities. The binary polymer—polymer interaction parameter between PAA and PVPo in the complex, ξ_PAA–PVPo, is less than zero, which is indicative of favorable interaction between PAA and PVPo. At lower water activities, sorption behaviors for water in the three polymers can be approximated by Henry's law and vapor-diffusion coefficients can be ranked as PVPo > complex > PAA. The water vapor diffusion coefficients in each system decrease with increasing P_r, in the region of P_r > 0.5 because the proportion of immobilized water molecules increases with vapor concentration. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 279–291, 1997     

油田污水处理工艺中COD的去除研究进展

概述了油田污水的组成特点,并从近年来聚合物驱油和三元复合驱油产生污水带来的新问题出发,阐述了油田污水处理的难点所在。同时对当前油田污水处理工艺流程特点、实际工艺中存在的不足等作了比较,得出当前油田污水处理过程中工艺流程的选择标准和目标。重点对工艺处理中的絮凝沉降、生化处理以及膜法处理等不同的工艺流程中COD的去除进行了研究,通过比较各种方法得出在油田污水处理中利用生化法和膜处理方法的有机结合将是油田污水处理的主要发展方向。同时对当前油田污水处理中亟待需要解决的问题作了进一步表述。     

接枝型高分子絮凝剂在食品废水处理中的应用研究

研究了淀粉-丙烯酰胺接枝共聚物(SGC)、壳聚糖-丙烯酰胺(Ch—AM)接枝共聚物、壳聚糖(Ch)及聚丙烯酰胺(PAM)在食品废水处理中的絮凝性能,选出了经济高效的絮凝剂——淀粉-丙烯酰胺接枝共聚物。经其处理后的污水,清澈透明,BOD5去除率在75％左右,CODCr的去除率在60％左右．SS去除率在70％以上。它与壳聚糖-丙烯酰胺相比BOD5,去除率提高了15．14％．CODCr去除率提高了33．53％;与壳聚糖相比BOD5去除率提高了44．46％．CODCr去除率提高了50．00％;与传统的絮凝剂PAM相比BOD5、CODCr去除率相差不大。     

高氮豆制品废水的短程硝化反硝化脱氮技术及其过程控制

采用交替好氧 /缺氧运行方式和适时过程控制策略开发了一种生物脱氮新工艺 ,该工艺结合了短程硝化反硝化脱氮技术。试验过程中选择了 3种不同运行模式去实现短程硝化反硝化脱氮技术 ,即传统的序批式活性污泥法 (SBR)运行模式、固定时间控制交替好氧 /缺氧运行模式和适时过程控制交替好氧 /缺氧运行模式。结果显示 ,适时过程控制交替好氧 /缺氧运行模式效果最佳 ,它不但能提高硝化、反硝化速率和减少总反应时间 ,而且可以节省硝化过程中碱度的投加和反硝化过程碳源的投加量 ,降低了运行成本。     

Synthesis and viscoelastic behavior of water-soluble polymers modified with strong hydrophobic side chains

A new series of associating polymers were prepared by grafting highly hydrophobic side chains: poly(n-butyl acrylate), PNBA; poly(n-butyl methacrylate), PNBMA; and poly(N-(tert-butyl)acrylamide), PTBA of different sizes onto a poly(sodium acrylate), PAANa, backbone. Due to the strong hydrophobic character of the stickers, the dynamics of the associations is very slow as compared to more conventional water-soluble polymers modified with short alkyl chains and the physical associations mainly behave as chemical ones in the experimental conditions. As a consequence, all the copolymers readily self-assemble in aqueous solution forming clusters in very dilute conditions and then gels at higher concentrations. From dynamic measurements, it was shown that the copolymer solutions follow the same scaling relation η^∗ ∼ c^a, where a is a frequency dependent exponent. In these conditions, all the copolymer solutions exhibit a sol-gel transition which obeys the main rules of the percolation theory. For each copolymer, the critical gel concentration c_g depends strongly on the hydrophobic character of the stickers and a single master curve can be drawn by plotting the complex viscosity vs. the reduced concentration, c/c_g. Although the temperature dependence of the viscoelastic properties is very weak, due to the slow dynamics of the associations, it was clearly evidenced that the alkyl acrylamide derivative (PAANa-g-PTBA) exhibits a slight thermothickening behavior which contrasts with the thermothinning behavior of alkyl(meth)acrylate derivatives (PAANa-g-PNBA and PAANa-g-PNBMA). The opposite type of behavior is explained by the presence of the amide function which is known to play an important role in the LCST (lower critical solution temperature) phase diagram of N-alkyl derivatives.     

Modifying stainless steel surfaces with responsive polymers: effect of PS-PAA and PNIPAAM on cell adhesion and oil removal

The treatment of stainless steel surfaces with responsive polymers was investigated using X-ray photoelectron spectroscopy and scanning electron microscopy. Poly(N-isopropylacrylamide) (PNIPAAM) is a temperature-sensitive polymer which is soluble in water below 32°C (Lower Critical Solubility Temperature (LCST)) but collapses and aggregates above 32°C. This polymer was adsorbed at 50°C from solutions at different concentrations, followed by rinsing and different drying procedures. Thereby, a large variety of surface structures could be obtained, from smooth films to surfaces showing marked relief features due to residues of PNIPAAM aggregates. Two poly(styrene)-b-poly(acrylic acid), PS-PAA, with different block lengths, were spin-coated on stainless steel and showed preferential exposure of PS blocks at the outermost surface. PNIPAAM-conditioning was shown to strongly reduce yeast cell adhesion and to facilitate the removal of oil soil due to its high water affinity and chain mobility below the LCST. PS-PAA coatings also reduced yeast cell adhesion; this may partly be due to a reorganization of the surface, leading to exposure of PAA chains in contact with water and thus to electrostatic repulsion of the yeast cells.     

Fe(Ⅱ)(EDTA)/O3工艺处理含聚废水实验

采用Fe(Ⅱ)(EDTA)/O₃工艺处理含聚废水,研究EDTA浓度、Fe²⁺浓度、水力停留时间（HTR）、初始pH对聚丙烯酰胺（PAM）去除率和COD降解效能的影响,探讨了Fe(Ⅱ)络合催化臭氧反应动力学特征及其机理。结果表明：当EDTA浓度为0.050mmol/L、Fe²⁺浓度为0.050mmol/L和HRT为120min时,PAM去除率为75%;增加水样初始pH有利于提高PAM去除率,同时水样pH随HRT增加缓慢下降;废水COD值在HRT为30min内逐渐增至最大,随后逐渐减小并达到稳定。Fe(II)(EDTA)/O₃工艺处理含聚废水的反应符合二级动力学反应,初始PAM质量浓度在50~100mg/L范围内,二级反应速率常数为2.35×10^-4~3.35×10^-4L/(mg·min)。     

Optimization of photooxidative removal of p-nitrophenol in a spinning disc photoreactor using response surface methodology

In this article, response surface methodology (RSM) was used to obtain optimum conditions for removal of p-nitrophenol (PNP) by UV/H₂O₂ process using spinning disk photoreactor (SDP). For this purpose, the effect of five independent variables, the initial concentration of PNP, the initial concentration of H₂O₂, pH, solution volume, and irradiation time on the PNP removal percent, was investigated. Central composite design, one of the response surface techniques used for process optimization. The results showed a good agreement between the RSM predicted and experimental data with “R²” and “Adjusted R²” of 0.9692 and 0.9480, respectively. In addition, “Predicted R²” of 0.8909 is in reasonable agreement with “Adjusted R²” of 0.9488. At optimal conditions, that is, PNP concentration of 20.78?mg L^?1, H₂O₂ concentration of 1355.83?mg L^?1, solution volume of 566.08?mL, irradiation time of 12.30?min, and pH of 4.59 the removal percent predicted by RSM is 100% which has good correspondence with its experimental value (98.67%).     

Investigation on crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends by solution casting

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by solution casting. The crystallization behavior and hydrophilicity of ternary blends were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and contact angle test. According to morphological analysis, the surface was full of typical spherulitic structure of PVDF and the average diameter was in the order of 3 μm. The samples presented predominantly β phase of PVDF by solution casting. It indicated that the size of surface spherulites and crystalline phase had little change with the PMMA or PVP addition. Moreover, FTIR demonstrated special interactions among the ternary polymers, which led to the shift of the carbonyl stretching absorption band of PVP. On the other hand, the melting, crystallization temperature, and crystallinity of the blends had a little change compared with the neat PVDF in the first heating process. Except for the content of PVP containing 30 wt %, the crystallinity of PVDF decreased remarkably from 64% to 33% and the value of t_1/2 was not obtained. Besides, the hydrophilicity of PVDF was remarkably improved by blending with PMMA/PVP, especially when the content of PVP reached 30 wt %, the water contact angle displayed the lowest value which decreased from 98.8° to 51.0°. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Morphology,Microstructure and Properties of PEG-plasticized PVC

Poly(vinyl chloride) (PVC) could be plasticized with poly(ethylene glycol) (PEG) introduced via solution mixing. Infrared and gel permeation chromatography (GPC) analysis indicated the combination of PEG with PVC. The plasticization effect of PEG was obvious for PVC film with less than 40 wt.% PEG. Thermogravimetric analysis (TGA) showed PEG reduced the thermal stability of PVC. Atomic force microscope (AFM) and optical microscope (OM) results indicated micropores formed on plasticized PVC films due to the enrichment of PEG from PVC matirx. The PEG also increased the hydrophilicity of PVC by reducing the water contact angles.     

Phototransformation of water-soluble polymers. Part II: photooxidation of poly(ethylene oxide) in aqueous solution

Poly(ethylene oxide) (PEO) was irradiated in aqueous solution under long wavelengths (λ>300 nm, 20 °C) and in presence of oxygen. The photooxidation of PEO was studied by IR spectrophotometry, viscometry and size exclusion chromatography. The formation of the oxidation photoproducts was studied by infrared analysis of films obtained by evaporation of aliquots of irradiated aqueous solutions. The photoproducts were identified by chemical derivatization treatments coupled with infrared measurements. Viscosimetry and SEC analysis showed that photooxidation was leading to a dramatic decrease of the molecular weights. The influence of the pH of the aqueous solutions was also examined. Unexpected results were obtained for the pH 12 solutions, indicating a strong inhibition of the oxidation.

Comparison with the results obtained in the case of PEO irradiated in the solid state showed that no direct transposition of the knowledge concerning the behavior of the solid polymer could be made.     

Electrochemical remediation of metal-bearing wastewaters Part II: Corrosion-based inhibition of copper removal by iron (iii)

A hitherto undocumented inhibition to electrodeposition of Cu(ii) from dilute (<200 mg L–1) wastewaters was traced to the presence of Fe(iii) at concentrations comparable to those of copper ion. This inhibition was found to differ from heterogeneous side-reduction of Fe(iii) that is well known to decrease faradaic efficiency for copper removal. Based on bench-scale electrolysis as well as cyclic voltammetry studies, an inhibition mechanism was qualitatively identified that involved copper corrosion by Fe(iii). This corrosion process was found to be strongly favoured by sluggish heterogeneous reduction of Fe(iii) at carbon electrode materials. One procedure shown to substantially improve copper removal from solutions demonstrating corrosion inhibition was alkali precipitation of iron. Real mine drainage wastewater that was pretreated in this manner was consistently depleted of copper by flow-through electrolysis to levels below 50 g L–1.     

改性高速酪蛋白贴标胶粘剂的研制

介绍了以干酪素为主要原料经聚丙烯酰胺(PAM)、聚乙烯醇缩甲醛(PVF)等改性的酪蛋白标签胶的制备工艺,分析了产品的各项性能,并讨论了各种因素对胶粘剂性能的影响。结果显示:该胶具有初粘性强,良好的低温储存稳定性及成本低廉等优点。     

Changes in microstructures and physical properties of polymer-modified mortars during wet storage

The decrease in strength of tile adhesive mortars during wet storage was investigated. In a first approach, the water resistance of the polymer phases was tested on structures isolated from the mortar and in situ. It was observed that cellulose ether and polyvinyl alcohol structures are water-soluble. Subsequent investigations on polymer mobility within the mortar showed that the migrating pore water transports cellulose ether and polyvinyl alcohol during periods of water intrusion and drying. This leads to enrichments at the mortar-substrate interface. In contrast, latices interacting with the cement are water-resistant, and therefore, immobile in the mortar. Further experiments revealed that the mortar underwent considerable volume changes depending on the storage condition. Cracking occurred mainly close to the mortar-tile interface, cement hydrates grew within these shrinkage or expansion cracks. Test results revealed that the strength decrease of wet stored tile adhesives is caused by different mechanisms related to cement hydration, volume changes of the mortar, and reversible swelling of latex films.     

Crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by melt mixing. The miscibility, crystallization behavior, mechanical properties and hydrophilicity of the ternary blends have been investigated. The high compatibility of PVDF/PMMA/PVP ternary blends is induced by strong interactions between the carbonyl groups of the PMMA/PVP blend and the CF₂ or CH₂ group of PVDF. According to the Fourier transform infrared and wide‐angle X‐ray difffraction analyses, the introduction of PMMA does not change the crystalline state (i.e. α phase) of PVDF. By contrast, the addition of PVP in the blends favors the transformation of the crystalline state of PVDF from non‐polar α to polar β phase. Moreover, the crystallinity of the PVDF/PMMA/PVP ternary blends also decreases compared with neat PVDF. Through mechanical analysis, the elongation at break of the blends significantly increases to more than six times that of neat PVDF. This confirms that the addition of the PMMA/PVP blend enhances the toughness of PVDF. Besides, the hydrophilicity of PVDF is remarkably improved by blending with PMMA/PVP; in particular when the content of PVP reaches 30 wt%, the water contact angle displays its lowest value which decreased from 91.4° to 51.0°. Copyright © 2011 Society of Chemical Industry     

Preparation of poly(vinyl chloride) (PVC) ultrafiltration membranes from PVC/additive/solvent and application of UF membranes as substrate for fabrication of reverse osmosis membranes

Ultrafiltration (UF) membranes were prepared from poly(vinyl chloride) (PVC) as main polymer, poly(vinyl pyrrolidone) (PVP) as additive, and 1‐methyl‐2‐pyrrolidone (NMP) as solvent using Design Expert software for designing the experiments. The membranes were characterized by SEM, contact angle measurement, and atomic force microscopy. The performance of UF membranes was evaluated by pure water flux (PWF) and blue indigo dye particle rejection. In addition, the molecular weight cutoff of UF membranes was determined by poly(ethylene glycol) (PEG) rejection. The UF membranes were used as substrates for fabrication of polyamide thin film composite (TFC) reverse osmosis (RO) membranes. The results showed that the model had high reliability for prediction of PWF of UF membranes. Also, increment in PVC concentration caused reduction of PWF. Moreover, at constant PVC concentration and if the concentrations of PVC was lower than 10 wt %, the PWF reduced by increasing the concentration of PVP. However, at PVC concentration higher than 11 wt %, increment in PVP concentration showed increment and reduction of PWF. The PEG rejection results showed that the prepared membranes had UF membranes properties. Finally, the NaCl rejection tests of RO membranes by PVC as substrates indicated that the performance of RO membranes were lower than commercial membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46267.     

Microwave dielectric relaxation and molecular dynamics in binary mixtures of poly(propylene glycol) 2000 and poly(ethylene glycol)s of varying molecular weight in dilute solution

Molecular dynamics of binary mixtures of poly(propylene glycol) (PPG) and poly(ethylene glycol)s (PEGs) of varying molecular weight due to molecular interactions, chain coiling and elongation in dilute solution under various conditions, ie varying number of monomer units of PEG, method of mixing of polymers and solvent environment, has been explored using microwave dielectric relaxation times. The average relaxation time τ_o, relaxation time corresponding to segmental motion τ₁ and group rotations τ₂, of a series of binary mixtures of poly(propylene glycol) 2000 and poly(ethylene glycol) of varying molecular weight (ie PPG 2000 + PEG 200, PPG 2000 + PEG 300, PPG 2000 + PEG 400, and PPG 2000 + PEG 600 mixed by equal volume in the pure liquid states, and PPG 2000 + PEG 1500, PPG 2000 + PEG 4000 and PPG 2000 + PEG 6000 mixed equal weights in solvent) have been determined in dilute solution in benzene and carbon tetrachloride at 10.10 GHz and 35 °C. A comparison of the results of these binary systems of highly associating molecules shows that the molecular dynamics corresponding to rotation of a molecule as a whole and segmental motion in dilute solutions are governed by the solvent density when the solutes are mixed in their pure liquid state. Furthermore, the molecular motion is independent of solvent environment when the polymers are added separately in the solvent for the preparation of binary mixtures. It has also been observed that there is a systematic elongation of the dynamic network of the species formed during mixing of pure liquid polymers in lighter environment of solvent with increasing PEG monomer units, while the elongation behaviour of the same species in the heavier environment of carbon tetrachloride solvent is in contrast to the elongation behaviour of the polymeric species formed in pure PEG. The role of rotating methyl side‐groups in the PPG molecular chain has been discussed in term of the breaking and reforming of hydrogen bonds in complex polymeric species for the segmental motion. In all these mixtures, the relaxation time corresponding to group rotations is independent of the solvent environment and constituents of the binary mixtures. The effect of chain flexibility and coiling in these binary mixtures is discussed by comparing the relaxation times of the mixtures with their individual relaxation times in dilute solutions measured earlier in this laboratory. © 2001 Society of Chemical Industry