A modified blister mixing element for generating extensional flow in a twin‐screw extruder: Process characterization and dispersion state of carbon nanotubes in cyclo‐olefin polymer. Issue 4 (3rd February 2022)

• Record Type: Journal Article
• Authors: Matsumoto, Koki; Tanaka, Tatsuya
• Is Part Of: Polymer engineering & science. Volume 62:Issue 4(2022)
• Page Start: 1223
• Page End: 1238
• Publication Date: 2022-02-03
• Subjects: dispersive mixing -- extensional flow -- nanocomposite -- single‐walled carbon nanotube -- twin‐screw extrusion; Polymer engineering -- Periodicals; Polymers -- Periodicals; 668.9
• DOI: 10.1002/pen.25921
• Languages: English
• ISSNs: 0032-3888

Abstract

Abstract: This study aimed to improve the dispersion state of single‐walled carbon nanotubes (SWCNTs) in a cyclo‐olefin polymer (COP) matrix by introducing extensional flow during the compounding through a twin‐screw extruder (TSE). A modified mixing element with multiple holes, called a fixed blister disc (XBD), was developed. To describe the mixing performance of XBD, the flow state was characterized via numerical simulation and acquisition of process data such as pressure drop ( ∆ P ) at XBD and specific mechanical energy (SME), while the operational conditions of TSE were varied. The dispersion state of SWCNTs was evaluated from the viewpoint of the melt viscoelastic property, surface resistivity of extruded samples and mechanical properties of injection molded samples. Furthermore, the dispersion morphology was observed via optical microscopy and scanning electron microscopy. As a result, the mixing performance of XBD was improved by increasing the ratio of throughputs Q to screw speed N s (Q/ N s ) since ∆ P, which is related to extensional stress, was increased. However, the trade‐off relationship between ∆ P and SME was confirmed versus Q/ N s . Although the dispersion state at the submicron level was markedly improved with higher SME inputs, higher ∆ P reduced the largest agglomerate size and improved dispersion uniformity. Consequently, the mechanical properties were improved significantly. Abstract : A process characteristic and mixing performance of a modified blister mixing element for generation of extensional flow in a co‐rotating twin‐screw extruder.