Microfoamed Strands by 3D Foam Printing

Abstract

We report the design, production, and characterization of microfoamed strands by means of a green and sustainable technology that makes use of CO2 to create ad-hoc innovative bubble morphologies. 3D foam-printing technology has been recently developed; thus, the foaming mechanism in the printer nozzle is not yet fully understood and controlled. We study the effects of the operating parameters of the 3D foam-printing process to control and optimize CO2 utilization through a maximization of the foaming efficiency. The strands’ mechanical properties were measured as a function of the foam density and explained by means of an innovative model that takes into consideration the polymer’s crystallinity content. The innovative microfoamed morphologies were produced using a bio-based and compostable polymer as well as polylactic acid and were then blown with CO2. The results of the extensive experimental campaigns show insightful maps of the bubble size, density, and crystallinity as a function of the process parameters, i.e., the CO2 concentration and temperature. A CO2 content of 15 wt% enables the acquirement of an incredibly low foam density of 40 kg/m3 and porosities from the macro-scale (100–900 μm) to the micro-scale (1–10 μm), depending on the temperature. The foam crystallinity content varied from 5% (using a low concentration of CO2) to 45% (using a high concentration of CO2). Indeed, we determined that the crystallinity content changes linearly with the CO2 concentration. In turn, the foamed strand’s elastic modulus is strongly affected by the crystallinity content. Hence, a corrected Egli’s equation was proposed to fit the strand mechanical properties as a function of foam density.

Design, Manufacturing and Acoustic Assessment of Polymer Mouthpieces for Trombones

“…Further studies are still to be conducted, so the effect of coatings to reduce the roughness and minimize the accumulation of particles in the mouthpieces, the use of antibacterial PLA to minimize possible infections with pathogens, or the use of foamed polymers for the 3D printed designs [ 26 , 27 ] to manufacture even lighter mouthpieces can be evaluated.…”

A Review of the Preparation of Porous Fibers and Porous Parts by a Novel Micro-Extrusion Foaming Technique

“…Table 2. Material systems that have been used for micro-extrusion foam stacking, including PLA [106,[151][152][153], PEI [102,126,144,148], ABS [154], and TPU [155][156][157].…”

Highly Electroconductive Metal-Polymer Hybrid Foams Based on Silver Nanowires: Manufacturing and Characterization

“…In ref. [22], a method of direct printing of porous foams through the generation of CO 2 microbubbles in situ, right during the printing process, was presented, achieving a very low polymer density of just 40 kg/m 3 . It is predictable that if this polymer mass contained AgNWs, which are quasi-one-dimensional formations, during the bubbles' expansion in the molten mass, a controlled flow of the liquid polymer mass would occur that would generate an ordering of the AgNWs, which could become parallel to the cell walls.…”