Enhanced Sedimentation Stability of Carbonyl Iron Powders with Hydrophilic Siloxane Polymer Coatings in Ethanol. Issue 1 (31st December 2023)

• Record Type: Journal Article
• Authors: Ha, Heebo; Thompson, Russ; Hwang, Byungil
• Is Part Of: Journal of natural fibers. Volume 20:Issue 1(2023)
• Publication Date: 2023-12-31
• Subjects: Magnetorheological suspension -- carbonyl iron powder -- sedimentation -- surface modification -- siloxane -- turbiscan; 磁流变悬液 -- 羰基铁粉 -- 沉降 -- 表面改性 -- 硅氧烷 -- 涡轮机扫描; Textile research -- Periodicals; Textile research; Periodicals; 677.005
• DOI: 10.1080/15440478.2023.2166648
• Languages: English
• ISSNs: 1544-0478

Abstract

ABSTRACT: Achieving resistance to sedimentation of carbonyl iron powders (CIPs) in ethanol is important to fabricate reliable magnetorheological suspensions. The traditional method to improve the sedimentation stability is to add dispersants, but this approach can suffer from high costs and toxicity of added surfactants. In this study, the surface of CIPs was modified with 3-aminopropyl triethoxysilane (APTES) or tetraethyl orthosilicate (TEOS) to enhance the sedimentation stability of CIP suspensions without using toxic dispersants. After coating APTES or TEOS on the CIP surface, the surface energy of the CIP powders increased, which was attributed to the increased amino or hydroxyl groups on the CIP surface due to APTES or TEOS, respectively. The Gibbs free wetting enthalpy (ΔG) was calculated to evaluate the wettability of the modified CIPs, and APTES@CIPs or TEOS@CIPs had a low ΔG, indicating that both had a high thermodynamic spontaneity of wetting in ethanol. The enhanced wettability due to APTES or TEOS coating resulted in low CIP agglomeration, which resulted in APTES@CIPs or TEOS@CIPs dispersions having smaller average particle sizes than pure CIP dispersions. Therefore, APTES@CIPs or TEOS@CIPs showed more than 2 times slower sedimentation velocity than pure CIPs, resulting in enhanced sedimentation stability.