• Delia, Raffaele
• Dimos, Evangelos
• Sanches, Leonardo
• Sescousse, Romain
• Cortes, Luis Quiroga
• Sauceau, Martial
• Michon, Guilhem

Abstract

Sandwich structures represent a very interesting approach for the development of new multifunctional and lightweight materials for aerospace and space applications. Nomex® or aluminum honeycomb is at this date the most widely used core materials for sandwich structures, given their extraordinary strength-to-weight-ratio. However, these materials exhibit some important drawbacks as a poor vibrational and acoustic damping, along with a limited impact energy absorption capability. Several studies are in progress in order to develop new composite materials with enhanced acoustic and vibrational damping properties. A very promising solution to overcome these issues is represented by thermoplastic foams, having several advantages as ease of processing, good impact energy absorption, recyclability and enhanced properties in terms of thermal and acoustic isolation, along with the possibility to modify their intrinsic properties through micro and nano-particles addition. A relatively new and promising technique to develop thermoplastic foams is represented by supercritical CO2 (sc-CO2) assisted foam extrusion, with sc-CO2 acting as Physical Blowing Agent (PBA). Sc-CO2 has limited environmental impact, given its low toxicity and energetic requirements to attain its supercritical conditions (31 C, 74 bars), making this process economic, sustainable and totally green. In the frame of this work, a continuous process has been used to produce PLA foams with different microstructures depending on the operating conditions. Typical densities range from 20 to 60 kg/m3, crystallinity from 10 to 30 % and cell size from 90 to 500 µm.

Topics

• impedance spectroscopy
• extrusion
• aluminium
• strength
• composite
• thermoplastic
• toxicity
• crystallinity