Interaction clay-polymer

Nanolayers of clay interacting with polymers to form nanocomposites with improved material properties relative to the untreated polymer are discussed in Chapter 17. 

A. Audibert, J. Lecourtier, L. Bailey, P. L. Hall, and M. Keall. The role of clay/polymer interactions in clay stabilization during drilling. In Proceedings Volume, pages 203-209. 6th Inst Francais Du Petrole Explor Prod Res Conf (Saint-Raphael, France, 9/4-9/6), 1992. 

Theng, B.K.G. "Clay-Polymer Interactions Summary and Perspectives", Clays and Clay Minerals, 1982, 30(1), 1-10. 

When the DMAEMA content of NVP - DMAEMA copolymers was reduced from 20% to 8%, the silica fines stabilization effectiveness appeared to improve slightly. When the 80/20 NVP - DMAEMA copolymer was converted to a terpolymer containing 8% DMAEMA (CH SO, silica fines stabilization was substantially unaffected. However, stabilization of silica/kaolinite fines was greatly improved. This suggested that the interaction of polymer quaternary nitrogen atoms with anionic sites on mineral surfaces was important for the stabilization of migrating clays but a different interaction was important for the stabilization of silica fines. Calcite fines stabilization improved while hematite fines stabilization effectiveness decreased. This also indicated the nature of the adsorbed polymer - fine particle complex varied for different minerals. 

Special considerations according to inverse gas chromatography, PMMA is considered acidic, it therefore interacts better with fillers which have basic character PMMA was found to form thick layers adsorbed on the surface of glass, titanium dioxide, silica and mica (1400, 51-70, 17, and 110 nm thick, respectively) very strong interaction between polymer and titanium dioxide caused formation of brittle coatings which failed prematurely formation of clay/K2S2O complex is a reason for catalytic effect on polymerization, the composites formed have better thermal stability, hardness, and compression strength ""... 

Clays are the most abundant inexpensive natural materials with high mechanical strength and high chemical resistance. They possess a layered structure, which can be exfoliated to yield an appreciable surface area which can be used for the adsorption of molecules [1,2]. Clay polymer materials have received considerable research attention, since interactions between them influence the properties of both the clay and the polymer [3,4]. 

B.K.G. Theng, Clay-polymer interactions Summary and perspectives. Clays and Clay Minerals 30 1 (1982). K. R. Tate and B.K.G. Theng, Organic matter and its interactions with inorganic soil constituents, in B.K.G. Theng,... 

Utracki and Lyngaae-Jprgensen [2002] observed several common aspects of exfoliated CPNCs and liquid-crystal polymers (LCPs). Similar six-phase structures are predicted for CPNCs and observed in LCPs isotropic, nematic, smectic-A, columnar, house of cards, and crystal [Porter and Johnson, 1967 Balazs et al., 1999 Ginzburg et al., 2000]. These phases in CPNCs originate in a balance between the thermodynamic interactions, clay concentration, and platelets orientation, while in LCPs they depend mainly on temperature. Since it is more difficult on the one hand to prepare disk-shaped than rigid-rod molecules, and on the other to develop flow theory for LCPs with disk moieties, the number of publications on the latter systems is small [Ciferri, 1991]. 

Sepehr et al. [2008] are investigating the viscoelastic Giesekus model [Giesekus, 1982, 1983 Bird et al., 1987] coupled with Eq. (16.41), with Dr described by Doi [1981]. The interactions between polymer and particles were incorporated following suggestions by Fan [1992] and Azaiez [1996]. These authors used Eq. (16.42) with the contribution to stress tensor caused by clay platelets [Eq. (16.43)] and viscoelastic Giesekus matrix expressed as [Fan, 1992]... 

Mixtures of clay platelets and polymer chains compose a colloidal system. Thus in the melt state, the propensity for the clay to be stably dispersed at the level of individual disks (an exfoliated clay dispersion) is dictated by clay, polymer, stabilizer, and compatibilizer potential interactions and the entropic effects of orientational disorder and confinement. An isometric dimension of clay platelets also has implications for stability because liquid crystalline phases may form. In addition, the very high melt viscosity of polypropylene and the colloidal size of clay imply slow particulate dynamics, thus equilibrium structures may be attained only very gradually. Agglomerated and networked clay structures may also lead to nonequilibrium behavior such as trapped states, aging, and glassy dynamics. 

The dispersion levels of the clay platelets helps in retaining the viscosity both at lower and higher temperatures. The anisotropy and small size prevent free rotation of the clay platelets and increases the viscosity. In addition to this, in in-situ clay-polymer hybrid, chemical bonding between the s-caprolactum and oigano-ions of clay platelets is the reason for the higher viscosity than the melt-blended system, where only physical interaction occurs. 

Balazs, A. C., Singh, C., and Zhulina E. 1998. Modeling the interactions between polymers and clay surfaces through self-consistent-field theory. Macromolecules 31 8370-8381. 

Lagalay, G. 1999. Introduction From clay mineral-polymer interaction to clay-polymer nanocomposites. Applied Clay Science 15 1-9. 

The effect of PE-g-MAH as compatibilizer of PE/OLS nanocomposites was investigated by varying its concentration. PE/PE-g-MAH/OLS samples showed an increase in both the exothermic peak temperature and activation energy compared with PE/OLS composites prepared with the same clay concentration, but without the compatibilizer. Hence, the clay was effective as nucleating agent and the composite system with PE-g-MAH was more active in nucleation process (Kim 2006). These effects were correlated with the increase of the melt viscosity in the case of PE/PE-g-MAH/OLS samples due to the confinement effect on the motion of the polymer chains and stronger interactions between polymer and clay. 

If chemical treatment of the matrix polymer blend or the filler needs to be avoided or the interaction between the components is insufficient, then a third component, such as a polymer compatibilizer [20], can be added to the composite. Compatibilizers are added especially to polyolefin/nanoclay composites prepared by melt blending because the organo modification of the clay is seldom sufficient to create a favorable interaction between polymer chains and the clay sheets [21]. The interfacial adhesion between the compatibilizer and clay galleries is influenced by the functionality and its concentration, molecnlar weight and molecular weight distribution of the compatibilizer, and the mass ratio of the compatibilizer to the clay [22]. 

VanderHart et al. (2001a-c) studied different clay nanocomposites measuring clay exfoliation by relaxation times of hydrogen that sees iron in the montmorillonite clay. They used Fe atoms in montmorillonite clay to determine clay dispersion in Nylon-6 matrix, and degraded alkyl ammoniums (from thermal processing above 200 C) were observed by NMR technique. Hou et al. (2002,2003) studied clay intercalation of poly(styrene-ethylene oxide)-b/ocfe-copolymers using multinuclear solid-state NMR. Hrobarikova et al. (2004) prepared polycaprolactone with laponite or saponite nanocomposites by in sitn polymerization and characterized by CAP NMR to understand how surfactants at clay surface interacted with polymer matrix. Hrobarikova et al. (2004) used solid-state NMR to study intercalated species in poly(e-caprolactone)/clay nanocomposites. 

Stacking of clay-polymer-clay (2.7 nm) and clay-clay (1.1 nm) aggregates], FTIR (PMEA-clay interactions) and TEM [31]. Because the TEM images of M-NCll (Fig. 36b-1, b-2) were the same regardless of the cutting direction, it was concluded that M-NCl 1 consists of clay networks that form a large number of connected clay spheres (100-300 nm in diameter), with a 20-nm-thick outer clay shell and the bulk of the flexible PMEA packed inside. 

Gain O, Espuche E, Pollet E, Alexandre M, Dubois P. Gas barrier properties of poly(e-caprolactone)/clay nanocomposites Influence of the morphology and polymer/ clay interactions. J Polym Sci, Part B Polym Phys 2004 43 205-214. 

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