Preparation and flammability properties of polyethylene-clay nanocomposites

Polyethylene (PE)–clay nanocomposites have been prepared using melt blending in a Brabrender mixer. X-ray diffraction and transmission electron microscopy were used to characterize the nano-structure of these composites while the thermal stability was evaluated from thermogravimetric analysis and the flammability parameters using cone calorimetry. It is found that the PE–clay nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when maleic anhydride is combined with the polymer and clay to be melt blended. The reduction in peak heat release rate is 30–40%

A Carbocation Substituted Clay and its Styrene nanocomposite

A substituted tropylium ion can be ion-exchanged onto montmorillonite to give a novel organically-modified clay. One can prepare a polystyrene nanocomposite of this clay by emulsion, but not bulk, polymerization. This is the first example of a clay that contains a carbocation and its use to prepare a polymer-clay nanocomposite. Both the clay and its nanocomposites exhibit outstanding thermal stability. Characterization by X-ray diffraction, transmission electron microscopy, cone calorimetry, thermogravimetric analysis and the evaluation of mechanical properties shows that a mixed intercalated-exfoliated nanocomposite is obtained

Polyethylene and Polypropylene Nanocomposites Based on Polymerically - Modified Clay Containing Alkylstyrene Units

Sodium montmorillonite was modified with a new polymeric surfactant. The high molecular weight of the surfactant appears to have led to incomplete cation exchange of the clays, but did promote nanocomposite formation with polyethylene and polypropylene. X-ray diffraction combined with transmission electron microscopy revealed a mixed nanocomposite morphology. The thermal stability of the nanocomposites was evaluated by thermogravimetric analysis, while flammability of the nanocomposites was evaluated by cone calorimetry. A significant 40% reduction in peak heat release rate was observed at 10% organo-clay (3% inorganic clay) loading with an even higher 50% reduction at a loading level of 16% modified clay (5% inorganic clay). Despite possible plasticization effects by the polymers used as an organic modification for the clays, the mechanical properties such as Young\u27s modulus and elongation were not severely impacted by the nanocomposite formation

Polymerically Modified Layered Silicates: An Effective Route to Nanocomposites

Polymer/clay nanocomposites have been under an extensive investigation for about 15 years. Traditional methods to modify the clay are usually limited to small organic cations, preferably containing long alkyl chain(s), which are exchanged with the inorganic cations in the clay gallery. This article provides a comprehensive review on the strategies for clay modification using polymeric surfactants or polycations: from the synthesis of such surfactants, through the preparation of the polymerically modified clays, and to the fabrication of the respective polymer nanocomposites and their properties

Polyethylene and Polypropylene Nanocomposites based upon an Oligomerically-Modified Clay

Montmorillonite clay was modified with an oligomeric surfactant, which was then melt blended with polyethylene and polypropylene in a Brabender mixer. The morphology was characterized by X-ray diffraction and transmission electron microscopy, while thermal stability was evaluated from thermogravimetric analysis and the fire properties by cone calorimetry. The nanocomposites are best described as mixed immiscible/intercalated/delaminated systems and the reduction in peak heat release rate is about 40% at 5% inorganic clay loading

Thermal and Flame Properties of Polyethylene and Polypropylene Nanocomposites Based on an Oligomerically–Modified Clay

An oligomerically-modified clay was made using a surfactant which is the ammonium salt of an oligomer. The newly modified clay contains 37.5% inorganic clay and 62.5% oligomer. Polyethylene and polypropylene nanocomposites were made by melt blending the polymer with the oligomerically-modified clay in a Brabender mixer at various clay loadings. The structure of the nanocomposites was characterized by X-ray diffraction and transmission electron microscopy. Mechanical testing showed that the polyethylene nanocomposites had an enhanced Young\u27s modulus and slightly decreased elongation, while the changes for polypropylene nanocomposites are small compared with the virgin polymers. The thermal stability and flame properties were evaluated using thermogravimetric analysis and cone calorimetry, respectively. The plasticising effect of the oligomer was suppressed because of the increased inorganic content. The maximum reduction in peak heat release rate is about 40%