Intercalation techniques

ABS/clay nanocomposites that are prepared by a direct melt intercalation technique without any conventional flame retardant, show an enhanced formation of char in the course of thermal degradation and thus exhibit an improved thermal stability (74). 

A literature survey also revealed that the above-mentioned composites were inaccessible by solution intercalation techniques. 

The synthesis of polymer nanocomposites is an integral aspect of polymer nanotechnology. By inserting the nanometric inorganic compounds, the properties of polymers improve and hence this has a lot of applications depending upon the inorganic material present in the polymers. The improvements obtained in day/PP nanocomposite structure can make this commercial thermoplastic polymer more suitable for automotive, construction and packaging applications. Different alkyl ammonium surfactants and compatibilizer was used to produce layered silicate/PP nanocomposites by the same melt intercalation technique. 

Abstract The development of polymer-clay nanocomposite materials, in which nano-meter-thick layers of day are dispersed in polymers, was first achieved about 15 years ago. Since then, the materials have gradually become more widely used in applications such as automotive production. The first practical nylon-clay nanocomposite was synthesized by a monomer intercalation technique however, the production process has been further developed and a compound technique is currently widely used. A polyolefin nanocomposite has been produced by the compound method and is now in practical use at small volume levels. In this review, which focuses on njdon- and polyolefin-nanocomposites, detailed explanations of production methods and material properties are described. This article contains mainly the authors work, but aims to provide the reader with a comprehensive review that covers the works of other laboratories too. Lastly, the challenges and directions for future studies are included. 

Poly(ether-anude)/layered silicate nanocomposites with dibenzalacetone and cinnamoyl moieties have been prepared by a solution intercalation technique from poly(ether-amide) 6 and organo-mont-moriUonite. The organoclay improves the flame retardancy of the material [53]. 

The ranges in which the clay platelets were present in the in-situ polymerized and melt-blended nanocomposite samples are given in Table 9.5. The average length of clay platelets seems to be approximately 65 nm for in-situ polymerized nanocomposites, whereas it is 100 nm for the nanocomposites prepared by melt intercalation technique. 

Starch is the main form of stored carbohydrate in plants. Starch is composed of a mixture of linear polysaccharide-amylose and highly branched polysaccharide-amylopectin. Both forms of starch are polymers of d-D-Glucose. A study of de Carvalho et al. on the preparation of TPS nanocomposites using nano-kaolin by melt intercalation technique in a... 

Cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) are thermoplastic materials produced through esterification of cellulose and are used for many packaging applications. Different raw materials such as cotton, recycled paper, wood cellulose, and sugarcane are used in the production of cellulose ester biopolymers in powder form. Such cellulose ester powders in the presence of different plasticizers and additives are extruded to produce various grades of commercial cellulose plastics. Recently, Misra et al. successfully used melt intercalation technique for the fabrication of cellulose nanocomposites and studied the effect of C30B on its performance characteristics [44]. From the study, the... 

In the melt mixing method, nanoclays are incorporated into the polymer in the molten state. This technique has considerable advantages over either the in situ intercalative polymerization or polymer solution intercalation techniques. Firstly, this method is environmentally benign due to the absence of organic solvents. Secondly, melt processing is compatible with current industrial processes, such as extrusion and injection moulding. The melt intercalation method allows the use of biopolymers that were not suitable for in situ polymerization. This has been the most widely used method in the literature for obtaining PLA/clay nanocomposites. " ... 

From an industrial point of view, the melt-intercalation technique is usually preferred to in-situ polymerization because it is simpler and uses already existing technologies. In this sense, methods that combine the efficiency of the in-situ... 

Figure 17.9 Tensile strength for neat EVA/NR and its nanocomposites prepared via solution blending and melt intercalation technique.

S. Zulfiqar, Z. Ahmad, and M. I. Sarvar, Preparation and properties of aramid/layered silicate nanocomposites by solution intercalation technique. Polymers for Advanced... 

Melt Intercalation The great advantage of the melt intercalation technique does not require a solvent. In this process, layered silicates or modified layered silicates can be mixed with the polymer matrix in the molten state using methods like extrusion and injection. In the molten state, polymer chains are intercalated between nanoplatelets and lead to exfoliated nanocomposites. A wide range of PLS nanocomposites such as poly(olefins) [56] and PVDF [57] have been generated from such route. 

De Carvalho et al. provided a first insight in the preparation and characterization of thermo plasticized starch-dtaohn composites by melt intercalation technique (2001). As films or bag, starch corrld be employed as packaging for fraits and vegetables, snacks, dry products, or as starch based adsorbent pads due to its hygroscopic nature for meat exudatiorr. 

Essentially two strategies have been considered to prepare polymerlayered silicate nanocomposites. In the so-called intercalative polymerization, the layered silicate is swollen within the liquid monomer (or a monomer solution) so as the polymer formation can occur in between the intercalated sheets. Polymerization is usually promoted either by heat or an appropriate catalyst. In another technique, the layered silicate is mixed with the polymer matrix in the molten state. Under these conditions and if the layer surfaces are enough compatible with the chosen polymer, the polymer can crawl into the interlayer space and form either an intercalated or an exfoliated nanocomposite. In this melt intercalation technique, no solvent is required. 

Even though this technique has been mostly used with water-soluble polymers, such as PEO, polyvinyl ether (PVE), polyvinylpyrrolidone (PVP), and poly(acrylic acid) (PAA) [134-141], intercalation from nonaqueous solutions has also been reported [142-145]. For example, high-density polyethylene (HDPE)-based nanocomposites have been prepared by dissolving HDPE in a mixture of xylene and benzonitrile with dispersed organomodified layered silicates (OMLSs). The nanocomposite was then recovered by precipitation from tetrahydrofuran (THE) [143], Polystyrene (PS)/OMLS-exfoliated nanocomposites have also been prepared by the solution intercalation technique, by mixing pure PS and organophilic clay with adsorbed cetyl pyrid-ium chloride [146]. Similarly, several studies have focused on the preparation of polylactide (PLA)-layered silicate nanocomposites using intercalation from solution. 

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