Extrusion of poly(ether imide) foams using pressurized C: effects of imposition of supercritical conditions and nanosilica modifiers

• Published in: Polymer engineering and science Vol. 54; no. 9; pp. 2064 - 2074
• Main Authors: Aktas, Seda, Gevgilili, Halil, Kucuk, Ilknur, Sunol, Aydin, Kalyon, Dilhan M
• Format: Journal Article
• Language: English
• Published: Society of Plastics Engineers, Inc 01-09-2014
• Subjects: Carbon dioxide; Extrusion; Foamed materials; Glycol ethers; Plastics; Production processes; Properties; Silica
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.23753

Foams of an engineering plastic, poly(ether imide), were extruded using a single screw extruder employing pressurized C[O.sub.2] as the blowing agent. The porosity, pore size distributions, and the density of the foams were especially affected by the pressure drop, the pressure loss rate, and temperature at the die. Significant increases in porosity and pore size and corresponding decreases in density were observed when the pressure imposed on C[O.sub.2] became greater than the critical pressure values of C[O.sub.2] (i.e., the temperature was always greater than the critical temperature of the C[O.sub.2] in the extruder and the die). The viscoelastic material functions of the extruded foams depended especially on the density of the foam, with the elastic modulus increasing with density. The incorporation of nanosilica particles in the 0.08-0.6% by weight range increased only the density of the foam and did not provide any benefits in controlling of the nucleation rate and the pore size distribution, presumably due to their poor dispersibility and agglomerated state in the single screw extruder. POLYM. ENG. SCI., 54:2064-2074, 2014.