Polyethylene/Sepiolite Nanocomposites: Structure/Properties/Processing Relationship

Abstract

Polyethylene (PE) - sepiolite nanocomposites are very interesting materials because they combine their properties in a synergetic manner. Chemically, sepiolite is a hydrated magnesium silicate with the ideal formula Si12Mg8O30(OH)4(OH2)4.8H2O. It is not a layered phyllosilicate, its structure can be considered a quincunx of talc type sheets. The particular arrangement of atoms produces a needle-like structure, instead of typical plate-like one. The high surface area and porosity account for the remarkable adsorptive and absorptive properties of this clay. In addition sepiolite has good mechanical strength and thermal stability. These properties make sepiolite ideal for reinforcement of polymer materials, which has been recently used for the reinforcement of elastomers [1, 2], thermoplastic polymers [3], and biopolymers [4]. On the other hand, Polyethylene (PE) is considered one of the most used thermoplastic commodity for both industrial and consumer products. It has good mechanical properties, chemical resistance and processability. Then, PE - sepiolite nanocomposites are very interesting materials because they can combine their properties to obtain new materials with enhanced properties.In this chapter, is shown PE-sepiolite nanocomposites used in different processing operations: injection molding, film and fiber formation. The behavior of the nanocomposite in each process is analyzed and discussed. Also, the final properties obtained are related with the resulting structure of the material. Several changes in PE crystallization, dispersion and distribution of sepiolite nanofibers, alignments, etc. are included into the discussion. Then, a complete characterization of each product is obtained, described and discussed even related with process operations.