title: Enhanced Wear Resistance of Transparent Epoxy Composite Coatings with Vertically Aligned Halloysite Nanotubes.
abstract: The influence of nanoparticle orientation on wear resistance of transparent composite coatings has been studied. Using a nozzle spray coating method, halloysite nanotubes (HNTs) were aligned in the in-plane and out-of-plane directions and in various randomly oriented states. Nanoscratching, falling sand, and Taber Abrasion tests were used to characterize the wear resistance at different length scales. Composites consistently displayed better wear resistance than pure epoxy. Samples with out-of-plane particle orientations exhibited better wear-resistant behavior than those with in-plane particle distributions. In nanoscratching tests, the out-of-plane orientation decreases the normalized scratch volume by as much as 60% compared to pure epoxy. In the falling sand and Taber Abrasion tests, out-of-plane aligned halloysite particles resulted in surfaces with smaller roughness based on stylus profilometry and SEM observations. The decrease in roughness values after these wear tests can be as large as 67% from pure epoxy to composites. Composites with higher out-of-plane particle orientation factors exhibited better light transmittance after sand impingements and other wear tests. This study suggests a useful strategy for producing material systems with enhanced mechanical durability and more durable optical properties.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.|Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.
authors.forename: Kenan
authors.initials: K
authors.lastname: Song
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.|Department of Mechanical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.
authors.forename: Dayong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.|Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.
authors.forename: Roberta
authors.initials: R
authors.lastname: Polak
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.|Center for Materials Science and Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Rubner
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology (MIT) , 77 Mass Ave., Cambridge, Massachusetts 02139, United States.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Cohen
authors.affiliation: Department of Materials Science and Engineering, Masdar Institute of Science and Technology , P.O. Box 54224 Abu Dhabi, United Arab Emirates.
authors.forename: Khalid A
authors.identifier: http://orcid.org/0000-0003-2178-8485
authors.initials: KA
authors.lastname: Askar
keywords: HNTs; Taber Abrasion; alignment; composite; falling sand; scratching; transparent; wear