Advanced search
Start date
Betweenand

Assembly and testing of a system of co-axial electro spinning for production of polymeric nanocomposites nanofibres

Grant number: 12/17580-7
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): October 01, 2012
Effective date (End): September 30, 2013
Field of knowledge:Engineering - Materials and Metallurgical Engineering
Principal Investigator:Rosario Elida Suman Bretas
Grantee:Vinicius da Silva Chimello
Home Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The electrospinning process allows to produce polymeric fibers with diameters on the nanometers scale. The small diameter of these nanofibers provides a high ratio between area and volume and high aspect ratio. These polymeric nanofibers can be utilized as filtration membranes, in protective clothing, covering of wounds, drug delivery systems, artificial blood vessels, mirrors for use in the aerospace industry, application of pesticides, structural elements in artificial organs and reinforced composites (nanocomposites), among others. To improve some property (mechanical, conductivity, etc. ) of the polymer, electrospinning is made of polymeric systems (blends, composites and polymeric nanocomposites). In a nanocomposite, in theory, it is necessary to form a percolating network to obtain better mechanical properties. The percolation threshold of the nanoparticle mainly depends on the aspect ratio of the particle (in addition to the polymer-particle interactions, etc. ). Thus to obtain better mechanical properties in these materials it is necessary that the nanoparticle, regardless of their morphology, is well dispersed and homogeneously distributed in the polymeric matrix. Both the blends and the polymeric nanocomposites has in common the fact that both are composed of two or more components that need to be dissolved and dispersed in maybe different solvents, so they can be electrospun. For example, in the case of binary blends, where both polymers are similar (polar, for example) and easily dissolved in the same solvent, one can obtain a homogeneous solution. However, if both polymers are very dissimilar (one polar and one nonpolar, for example), the dissolution of each polymer will be in different solvents, and the electrospinning solution will then consist of a mixture of different solutions that might evaporate at different rates during electrospinning, also affecting the miscibility and morphology of the resulting blend. In the case of polymeric nanocomposite, the polymer should be dissolved in a given solvent, whereas the nanoparticles must be dispersed in another type of solvent. However, in the case of lamellar clays that need to be exfoliated to form a percolating network, sometimes the solvent in which they are dispersed don't produce this exfoliation. It may then also occur formation of clusters of nanoparticles, yielding nanofibers in which the nanoparticle is agglomerated and heterogeneously distributed in the polymer matrix. One of the ways to produce nanofibers of nanocomposites and blends, in which the particles or the other polymeric component, respectively, are well distributed along the nanofiber, would be to use a system of co-axial electrospinning. This system allows to produce nanofibers with biphasic morphology: a central (core) and an outer (shell). (AU)