Simultaneously stiffening and toughening epoxy by urea treated hydroxylated halloysite nanotubes

Epoxy and its composites have been extensively applied in widespread applications, such as encapsulation of electronics, automobile parts, aircraft components, and so on. The stiffening and toughening of epoxy via the incorporation of nanofillers, such as halloysite nanotubes (HNTs), a naturally occ...

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Bibliographic Details
Published in:Polymer (Guilford) 2022-09, Vol.256, p.125194, Article 125194
Main Authors: Zeng, Songshan, Hou, Zaili, So, Chinting, Wai, Heilong, Jang, Dongwook, Lai, Wingki, Sun, Luyi, Gao, Zhaoli
Format: Article
Language:English
Subjects:
Epoxy
Halloysite nanotubes
Interfacial adhesion
Nanocomposite
Urea
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Summary:Epoxy and its composites have been extensively applied in widespread applications, such as encapsulation of electronics, automobile parts, aircraft components, and so on. The stiffening and toughening of epoxy via the incorporation of nanofillers, such as halloysite nanotubes (HNTs), a naturally occurring and low-cost aluminosilicate, have attracted increasing research attention. Herein, we introduce an effective and facile method that substantially enhances the interface of hydroxylated HNTs (h-HNTs) and epoxy matrix by the introduction of urea molecules. As confirmed by the characterization results, urea formed hydrogen bonds with the external surface of the h-HNTs and covalent bonds with the epoxy matrix. The resultant epoxy/h-HNT-urea nanocomposites exhibited significant enhancements simultaneously in tensile strength, Young's modulus, and fracture toughness by 23.4%, 31.4%, and 61.4%, respectively, as compared with the neat epoxy. Through systematic investigation, it was determined that micro-cracking, nanotube bridging, and crack pinning were responsible for the toughening of the epoxy/h-HNT-urea nanocomposites. [Display omitted] •Improving mechanical properties of epoxy nanocomposite via incorporating hydroxylated halloysite nanotubes/urea hybrids.•Achieving strong interfacial adhesion between epoxy and hydroxylated halloysite nanotubes/urea hybrids.•Simultaneously enhancing tensile strength, Young's modulus, and fracture toughness of epoxy nanocomposite.•Micro-cracking, nanotube bridging, and crack pinning collectively acting as toughening mechanism for epoxy nanocomposite.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2022.125194