Clay properties hybrid films

Yano, K., Usuki, A., and Okada, A. 1997. Synthesis and properties of polyimide-clay hybrid films. Journal of Polymer Science, Part A Polymer Chemistry 35 2289-2294. 

The in situ intercalative polymerization associated with the UV curing is a technique which was successfully employed in the synthesis of hybrid films, when fast polymerization of liquid monomers yielded in solid materials with designed properties. It was proved to have high eflftciency for epoxy oligomers, vinyl ethers, oxetanes in the presence of onium salts as photoinitiators [232]. The literature is not abundant in reports on the in situ UV-initiated polymerization of epoxides in the presence of layered silicates [233-237], as compared to data on thermally cured or melt compounded nanocomposites. In some studies, the clays were used either unmodified [235, 237] or organically modified [233, 236, 238] or treated with various reagents able to change their surface properties [239-243]. 

Fujimori A, Ninomiya N and MasukoT (2008), Structure and mechanical properties in drawn poly (L-lactide/clay) hybrid films , Polym Adv Technol, 19,1735-1744. 

Yano et al prepared polyimide-clay hybrid films with four different sizes of clay minerals in order to investigate the effect of the aspect ratio on the properties of the hybrids. Hectorite, saponite, montmorillonite and synthetic mica were used as clay minerals. They found that, at constant clay content (2 wt.%), the relative permeability coefficient decreases on increasing the length of the clay (Fig. 11.2). 

The structural characteristics and moisture sorption properties of two kinds of nylon-6/clay hybrids were investigated by Murase et The moisture sorption isotherms of the hybrid samples were a typical sigmoid shape similar to that of the pure nylon-6 sample, even if the extent of moisture regain of the hybrid films was comparatively low. All the isotherms obtained were explained through quantitative analysis in terms of the BET multilayer adsorption theory and complementally with the aid of the FloryHuggins solution theory. 

Material science can also benefit from oligomeric state of proteins. New retinal nano-ceramic materials with pillared hybrid micro-structures were fabricated for potential applications in optical holographic data storage. It was observed that the Schiff bases in retinal have substantial effect on optical properties of nano-ceramic films as well as diffraction efficiency for holographic storage. This study indicates feasibility of optimizing optical properties of nano-ceramic clay systems using Schiff bases for a variety of photonic applications.40... 

Sumita M, Tsukumo Y, Miyasaka K et al (1983) Tensile yield stress of polypropylene composites filled with ultrafine particles. J Mater Sci 18 1758—1764 Thellen C, Orroth C, Froio D et al (2005) Influence of montmorillonite layered silicate on plasticized poly(l-lactide) blown films. Polymer 46 1716-11727 Uyama H, Kuwabara M, Tsujimoto T et al (2003) Green nanocomposites from renewable resources plant oil-clay hybrid materials. Chem Mater 15 2492-2494 Wang SF, Shen L, Zhang WD et al (2005a) Preparation and mechanical properties of chitosan/ carhon nanotuhes composites. Biomactomolecules 6 3067—3072... 

Organophilic clays have also been blended with PLA. Ogata et al. [133] modified MMT with distearyldimethylam-monium chloride and that was solvent-cast blended with PLLA (Af = 2 x 10 ) using chloroform. Results showed that the tactoids (several stacked sificate monolayers) lay almost parallel to the film surface and were stacked with insertion of PLLA lamellae in the thickness direction of the film. Such preferred orientation of the tactoids is assumed to give excellent water barrier properties to the blends, as reported for nylon 6-clay hybrids (NCH) by Kojima et al. [134] In this nylon blend, the absence of clay delamination gave relatively poor tensile improvements compared to true nanocomposites. 

Mechanical Properties of the Latex Films. Figure 13.18 shows a noteworthy effect of the addition of Laponite on the mechanical properties of the nanocomposite film. A remarkable increase in the storage modulus at the rubbery plateau was observed with the addition of only 5 wt% Laponite. This improvement of the mechanical properties of the poly(styrene-co-butyl acry-late)-Laponite film was expected, considering the good dispersion of the clay platelets inside the polymeric matrix and the armored morphology of the hybrid particles. It is worth remembering here that similar results were reported by Ruggerone and co-workers" and Faucheu et al. for PS-Laponite films obtained from latexes prepared by emulsion and miniemulsion polymerization, respectively (see Sections 13.3.2.1 and 13.3.2.2). 

Oship, K. A., High Temperature Permeation of CO2, O2. CH4, and CH3OH in Polymide Films, M.S. thesis. State University of New York at Buffalo, Buffalo, 1991. Yano, K., A. Usuki, A. Okada, T. Kurauchi, and O. Kamigaito, Synthesis and Properties of Polyimide-Clay Hybrid, J. Polym. Sci., A Polym. Chem., 31, 2493-2498, 1993. 

---