共查询到20条相似文献，搜索用时 0 毫秒
1.
An inverse, free‐radical emulsion polymerization technique was designed for the preparation of copolymers of acrylamide and sodium acrylate modified with low amounts (<0.5 mol %) of a series of amphiphilic comonomers, the isooctylphenoxy–poly(oxyethylene)(n) methacrylates (1 ≤ n ≤ 12). The products of the reaction were hydrophobically modified water‐soluble polymers (HMWSPs) of high molecular weight encapsulated within water droplets dispersed in an organic medium. Kinetic studies showed that the full‐conversion samples were rather homogeneous in composition because of the specificity of the process. A mechanistic scheme is proposed that accounts for the incorporation level of the amphiphilic comonomer as a function of its hydrophile–lipophile balance and the nature of the redox initiator (hydrophilic or lipophilic). The rheological properties of the HMWSPs in aqueous solutions were investigated as a function of the comonomer content and the nature of the initiator with steady‐flow experiments. The thickening properties were directly correlated to the conditions of synthesis and were optimal when the initiator and the amphiphilic comonomer were located in two distinct phases. A maximum in viscosity was observed for a hydrophobe content of about 0.3 mol %. An examination of the viscosity as a function of the shear rate and time showed that these solutions had all the characteristics of associating polymers. The complex rheological behavior was the result of the balance between interchain and intrachain hydrophobic liaisons and the kinetics of disorganization and reorganization of the network structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1418–1430, 2002; DOI 10.1002/app.10337 相似文献
2.
A series of amphoteric polyacrylamides with different molecular weights and charges were prepared by the copolymerization of acrylamide with sodium acrylate and a subsequent Mannich reaction. The copolymerization was carried out with a redox initiation system via inverse emulsion polymerization. Reaction conditions, factors affecting emulsion stability, and applications as retention aids in papermaking were studied. Experiments showed that an ideal retention aid and a stable latex with wheat‐straw pulp of a shorter fiber length could be obtained under the following conditions: the acrylamide/formaldehyde/dimethylamine ratio was 1/1/1.2, a medium of aldehyde and amine was prepared first and then was dropped into an inverse emulsion of anionic polyacrylamide, the reaction temperature was 45°C, the reaction time was 4 h, and the pH was 5.0. When the anionic degree was 5%, the cationic degree was greater than 20%, the molecular weight was between 2 and 3 million, and the filler retention was higher. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 343–350, 2002; DOI 10.1002/app.10340 相似文献
3.
引发剂在乳液聚合反应中起着十分重要的作用,本文主要论述了引发剂对聚合反应速率,聚合物粒子形态,单体转化率的影响。 相似文献
4.
Olivier Oddes Sonia Amigoni Elisabeth Taffin de Givenchy Paul Reeve Yves Duccini Frédéric Guittard 《应用聚合物科学杂志》2011,120(5):2685-2692
Introduction of fluorocarbon segments in an associative thickener copolymer (ethyl acrylate (EA)/methacrylic acid/macromonomer) was achieved by the substitution of EA with either trifluoroethyl acrylate, 2‐perfluorobutylethyl acrylate, or 2‐perfluorooctylethyl acrylate. The thickening properties were evaluated by rheological flow experiments in aqueous medium as well as in 10 wt % of sodium dodecyl sulfate (SDS) aqueous solution. Whereas in the literature no particular attention is devoted to the impact of the ethylene moieties in hydrophobically modified alkali‐soluble emulsion (HASE) skeleton, our study reveals they contribute significantly to the performances when modified by an incompatible fluorocarbon segment. Moreover, the synthesis process has a huge influence by inducing a specific distribution of the fluorinated acrylates in the macromolecule. The amount of substitution is also important and even 20 mol % of EA substituted reveals a great impact on the rheological properties of the copolymer solutions. Whereas an SDS aqueous medium generally destroys almost all the hydrocarbon interactions from the macromonomer, the total replacement of ethyl groups by trifluoroethyl groups with a cosolvent process, leads to emulsions with an equivalent thickening effect than the reference hydrocarbon HASE used. This result is quite encouraging for research work on the synthesis of HASE with increased biocompatibility. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
5.
6.
7.
8.
A novel hydrophobically modified and cationic flocculant poly(acrylamide‐methacryloxyethyltrimethyl ammonium chloride‐methacryloxypropyltrimethoxy silane) (P(AM‐DMC‐MAPMS)) was synthesized by inverse emulsion polymerization. The molecular structure of hydrophobically cationic polyacrylamide (HCPAM) was characterized by FTIR and 1H‐NMR. The effects of DMC and MAPMS feed ratio on intrinsic viscosity and solubility were measured. The effects of hydrophobically cationic flocculants on reactive brilliant red X‐3B solution and kaolin suspension were studied. It was found that the introduction of MAPMS could increase the intrinsic viscosities of P(AM‐DMC‐MAPMS) and enhance the flocculation properties to anionic dye solution and kaolin suspension, but reduced their water‐solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
9.
Poly(acrylamide‐diallyldimethyl ammonium chloride‐vinyl trimethoxy silane) [P (AM‐DADMAC‐VTMS)] was prepared by inverse free‐radical emulsion polymerization technique. VTMS segment was hydrolyzed and condensed to form three dimensional networks. The effects of different factors, such as hydrophobic monomer feed ratio, cationic monomer feed ratio, pH value, and NaCl concentration, on decolorization efficiency were studied. Moreover, the decolorization mechanism was also explained by analyzing FTIR spectra and UV‐vis spectra. The introduction of VTMS on flocculant enhanced removal efficiency of dye molecules. With the increasing VTMS, adsorption and net roofing‐sweeping action of hydrophobically modified cationic polyacrylamide played the dominant role in the decoloring process of anion dye. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
10.
11.
Graft copolymers of poly(vinyl alcohol) and polyacrylamide (PVA‐g‐PAM) were synthesized using a ceric ion–induced solution polymerization technique at 28°C. Three grades of graft copolymers were synthesized with varying acrylamide concentrations. Three grades of hydrolyzed products of PVA‐g‐PAM were synthesized with varying concentrations of sodium hydroxide solution. Hydrolyzed and unhydrolyzed PVA‐g‐PAM were characterized by viscometry, X‐ray diffractometry, infrared spectroscopy, and thermal analysis. Rheological investigation was also carried out on the aqueous solutions of various samples. The flocculation characteristics of various materials were investigated by the use of jar and settling tests in 0.25 and 5 wt %, respectively, using kaolin and iron ore suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains showed superior performance. The flocculation characteristics of the best‐performing graft copolymer were compared with those of various commercially available flocculants in the two suspensions under investigation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2109–2122, 2006 相似文献
12.
A novel redox system, potassium diperiodatonickelate (Ni(IV))‐casein is used to initiate graft copolymerization of Styrene onto casein under different conditions in aqueous alkaline solution. Graft copolymers with both high grafting efficiency (>98%) and percentage of grafting(>300%) are obtained, which indicated that (Ni(IV))‐casein redox pair is an efficient initiator for this grafting. The effects of reaction parameters, such as monomer‐to‐casein weight ratio, initiator concentration, pH, time, and temperature, are investigated. A tentative initiation mechanism is proposed. The structures and properties of the graft copolymer are characterized by Fourier transform infrared Spectroscopy, X‐ray diffraction diagrams, and Scanning Electron Microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4247–4251, 2006 相似文献
13.
The phase separation of hydroxypropylcellulose (HPC) in a mixed solvent of glycerol and water was investigated by an elongational flow birefringence method. In the one‐phase region, the elongational flow birefringence had the characteristics of a typical coil‐stretch transition‐like pattern with a critical elongational strain rate $dot varepsilon_c.$ $dot varepsilon_c.$ increased monotonously with temperature, but in the vicinity of the phase‐separation point, $dot varepsilon_c.$ began to decrease even in the one‐phase region. In the two‐phase region, the flow‐induced birefringence pattern contained both a rigid rod‐like response and the coil‐stretch transition‐like response of a flexible polymer. The appearance of the rod‐like birefringence pattern indicates the association of HPC chains to form a precursor of the liquid‐crystalline phase formation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2984–2991, 2002 相似文献
14.
描述了碱溶性增稠剂的定义和分类和流变行为的研究。分别介绍了共聚单体、聚合物分子量、表面活性剂及交联单体对碱溶性增稠剂增稠剂性能影响的研究。同时介绍了碱溶性增稠剂疏水締合方面研究。 相似文献
15.
Low‐charge‐density amphoteric copolymers and terpolymers composed of AM, the cationic comonomer (3‐acrylamidopropyl)trimethyl ammonium chloride, and amino acid derived monomers (e.g., N‐acryloyl valine, N‐acryloyl alanine, and N‐acryloyl aspartate) have been prepared via free‐radical polymerization in aqueous media. These terpolymers with random charge distributions have been compared to terpolymers of like compositions containing the anionic comonomer sodium 3‐acrylamido‐3‐methylbutanoate. Terpolymer compositions determined by 13C‐ and 1H‐NMR spectroscopy, terpolymer molecular weights and polydispersity indices obtained via size exclusion chromatography/multi‐angle laser light scattering, and hydrodynamic dimensions determined via dynamic light scattering have allowed a direct comparison of the fundamental parameters affecting the behavioral characteristics. The solution properties of low‐charge‐density amphoteric copolymers and terpolymers have been studied as functions of the solution pH, ionic strength, and polymer concentration. The low‐charge‐density terpolymers display excellent solubility in deionized water with no phase separation. The charge‐balanced terpolymers exhibit antipolyelectrolyte behavior at pH values greater than or equal to 6.5 ± 0.2. As the solution pH decreases, these charge‐balanced terpolymers become increasingly cationic because of the protonation of the anionic repeat units. The aqueous solution behavior (i.e., globule‐ to‐coil transition at the isoelectric point in the presence of salt and globule elongation with increasing charge asymmetry) of the terpolymers in the dilute regime correlates well with that predicted by the polyampholyte solution theories. An examination of the comonomer charge density, hydrogen‐bonding ability, and spacer group (e.g., the moiety separating the ionic group from the polymer chain) indicates that conformational restrictions of the sodium 3‐acrylamido‐3‐methylbutanoate and N‐acryloyl valine segments result in increased chain stiffness and higher solution viscosities in deionized water and brine solutions. On the other hand, the terpolymers with N‐acryloyl alanine and N‐acryloyl aspartate segments are more responsive to changes in the salt concentration. An assessment of the effects of the terpolymer structure on the viscosity under specified conditions of the ionic strength and pH from these studies should allow for rational design of optimized systems for enhanced petroleum recovery. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007. 相似文献
16.
Mikhail M. Feldstein Valery G. Kulichikhin Sergey V. Kotomin Tatiana A. Borodulina Mikhail B. Novikov Alexandra Roos Costantino Creton 《应用聚合物科学杂志》2006,100(1):522-537
The rheological properties of adhesive miscible blends of high‐molecular‐weight poly(N‐vinyl pyrrolidone) (PVP) with short‐chain poly(ethylene glycol) (PEG) under oscillatory and steady‐state shear flow have been examined with dynamic mechanical and squeezing‐flow analysis. The latter allows the rheological characterization of adhesive blends under conditions modeling adhesive‐bond formation as a fixed compressive force is applied to an adhesive film. The most adhesive PVP blend with 36 wt % PEG has been established to flow like a viscoplastic (yield stress) liquid with a power‐law index of about 0.12. The study of the apparent yield stress as a function of the PVP–PEG composition, content of sorbed water, molecular weight of PVP, and temperature shows that the occurrence of a yield stress in the blends results most likely from a noncovalent crosslinking of PVP macromolecules through short PEG chains by means of hydrogen bonding of both terminal OH groups of PEG to the complementary functional groups in PVP monomer units. A molecular mechanism of PVP–PEG interaction was established earlier by direct and independent methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 522–537, 2006 相似文献
17.
18.
The liquid‐phase polymer‐based retention (LPR) technique was employed to study the retention of arsenate species by poly(vinylbenzyl trimethylammonium chloride), P(ClVBTA), and poly[2‐(acryloyloxy)ethyltrimethylammonium chloride], P(ClAETA). The effect of parameters such as polymer concentration, time exposure, competition of sulfate and phosphate anions, and the use of natural systems as drinking water on the retention of As(V) species was analyzed. The mole ratios of polymer : As(V) of (31 : 1), (20 : 1), (10 : 1), (6 : 1), and (3 : 1) by using the washing method at pH 8 and 6 were assayed. The retention capacity was a function of polymer concentration and pH. The optimum mole ratio of polymer : As(V) was (20 : 1) for all pHs studied and all polymeric structures. The polymer's activity recovery assays were performed by washing at pH 2 and 3. A 95% As(V) elimination was achieved from polymers. A study of competition in the presence of other anions was performed at the same polymer : As(V) ratio (20 : 1). At pH 8 and at the same concentration of arsenate anions, sulfate, and phosphate anions, no important competition on arsenic retention was observed. Assays for P(ClVBTA) at pH 8 and mole ratio of polymer : As(V) (20 : 1), (40 : 1), and (60 : 1) using drinking water showed that the efficiency was higher under these conditions for the three As(V) retention cases. An unbuffered system with drinking water was tested for washing and enrichment methods by determining the maximum saturation capacity of the P(ClVBTA) polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
19.
Beatriz S. Chagas Dilon L. P. Machado Roberto B. Haag Celso R. De Souza Elizabete F. Lucas 《应用聚合物科学杂志》2004,91(6):3686-3692
Acrylamide and tridecyl acrylate copolymers were synthesized by micellar copolymerization to obtain water‐soluble, hydrophobically modified polymers. Rheological properties of the obtained polymer solutions were evaluated and compared to those of solutions of a commercial polyacrylamide currently used in the petroleum industry. The behavior of the copolymer solutions was studied as a function of the variation of hydrophobic monomer content incorporated in the copolymer as well as the salt content of the aqueous medium, for diluted and semi‐diluted regimens. Comparative studies of such effects on the intrinsic viscosity and the critical concentration of those polymers were conducted. The increase in hydrophobic monomer content produced a sudden increase in the bulk and absolute viscosity of the polymeric solutions, a trend that was more intense from a certain concentration typical for each polymer. Salt addition led to lower bulk viscosity caused by a stronger interaction among hydrophobic groups, resulting from minimized exposure of such groups and water. The same effect was observed for the critical concentration. A comparison of the synthesized polymers with industrial polyacrylamide showed that the synthesized polymers were characterized by advantageously high shear strength and high salt resistance. However, in the absence of salts, higher copolymer amounts were needed to prepare solutions whose viscosity was the same as that of commercial polyacrylamide. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3686–3692, 2004 相似文献
20.
A kind of polyacrylamide (PAM) latex product dispersed in an aqueous solution was successfully prepared through the aqueous two‐phase polymerization of acrylamide in an aqueous solution of poly(ethylene glycol) (PEG). The effects of various polymerization parameters on the size and morphology of droplets rich in PAM were systematically investigated. The droplet size and morphology was significantly influenced by the polymerization rate. The high polymerization rate caused the formation of stripe‐shaped droplets because of the aggregation of more droplets rapidly separated from the continuous phase. At the same time, the monomer partition behavior mainly relied on the temperature, and the PEG concentration also dramatically affected the droplet size and morphology. The increase in PEG concentration not only changed the monomer partition behavior and restrained droplet aggregation but also shortened the critical PAM radical chain length and accelerated the droplet formation. Furthermore, the stirring speed was also recognized as the correlative factor that affected the droplet stability and monomer diffusion rate from the continuous phase into the droplets. The addition of salt and alcohol altered the droplet stability and the final droplet size and morphology. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献