Ultrasound-Assisted Melt Extrusion of Polymer Nanocomposites

Abstract

A review of the latest developments in ultrasound-assisted melt extrusion of polymer nanocomposites is presented. In general, the application of ultrasound waves during melt extrusion of polymer in the presence of nanoparticles results in a more homogeneous dispersion of the nanoparticles in the polymer matrix. In spite of this, a lack of understanding in the field has hindered the development of this processing technique. Based on the analysis of literature on the field, key aspects are identified for a better understanding of the physical and chemical effects of ultrasound waves and the fabrication of polymer nanocomposites by means of melt extrusion. others [1,2]. One of the most popular methods used to prepare such materials is melt extrusion, since it is a flexible and versatile process, which does not require the use of solvents and can be scaled up at industrial level.However, even with all these advantages, the lack of homogeneous dispersion of nanoparticles in the polymer matrix is still a problem with melt extrusion. An alternative to improve the dispersion is the application of ultrasound waves during the polymer processing in the molten state, named ultrasound-assisted extrusion. The first report of the use of ultrasound coupled in extrusion was made by Isayev et al. for processing vulcanized elastomers devulcanization [3]. These authors reported that the ultrasound waves have the ability to cause an incision in the C-S and S-S bonds of the crosslinked rubber, causing the breaking of the reticulated network and thereby achieving the devulcanization of the rubber. Later, it was applied to the study of polymer mixtures in the molten state [4], and in the last decade, this technology has been used for the preparation of polymer nanocomposites. Although it has been proven that this technology improves the dispersion of nanoparticles and that it has a great potential for application, the fundamentals for applying this technology in melt extrusion process are still not well understood. For example, the effects observed by the application of ultrasound have been explained on the basis of acoustic cavitation, treating the molten polymer as a Newtonian system; however, polymer cannot be considered as Newtonian fluids. For this reason, a general overview of the basic principles of ultrasound, the development and use of this technology in the preparation of polymeric nanocomposites in the molten state, and the mechanisms that have been proposed so far for the understanding of the phenomenon that generates the dispersion of the nanoparticles in the polymer is described below. Extrusion applied in the manufacture of polymeric nanocomposites 2.1. Polymers and nanoparticlesThermoplastic polymers and nanoparticles are the main materials used to produce polymer nanocomposites by melt extrusion. Thermoplastic polymers include polyolefins, polyesters, and polyamides among other polymer families. On the other hand, the nanoparticles can be classified according to the number of dimensions in the nanometer range. Zero-dime...

Non-Woven Fabrics Based on Nanocomposite Nylon 6/ZnO Obtained by Ultrasound-Assisted Extrusion for Improved Antimicrobial and Adsorption Methylene Blue Dye Properties

“…Nylon 6/ZnO nanocomposite preparation was carried out in the following way: nylon 6 polymer with three charges of ZnO nanoparticles (0.25%, 0.5%, and 1%) were prepared by an ultrasound-assisted melt extrusion process. A laboratory-size twin-screw extruder from Thermo Scientific (model, Prism TSE-24MC) (Thermo Fisher Scientific, Waltham, MA, USA) with a screw diameter of 24 mm and L/D ratio of 40:1 was assisted by a catenoidal ultrasonic tip (Branson Ultrasonics Corp., Brookfield, CT, USA) [ 24 ]. The temperature profile was 235 °C and the rotational speed was 100 rpm.…”