Exploiting colloidal interfaces to increase dispersion, performance, and pot-life in cellulose nanocrystal/waterborne epoxy composites. (26th June 2015)

• Record Type: Journal Article
• Authors: Girouard, Natalie; Schueneman, Gregory T.; Shofner, Meisha L.; Meredith, J. Carson
• Is Part Of: Polymer. Volume 68(2015)
• Page Start: 111
• Page End: 121
• Publication Date: 2015-06-26
• Subjects: Interfaces -- Colloidal stability -- Polymer nanocomposite -- Cellulose; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2015.05.009
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: In this study, cellulose nanocrystals (CNCs) are incorporated into a waterborne epoxy resin following two processing protocols that vary by order of addition. The processing protocols produce different levels of CNC dispersion in the resulting composites. The more homogeneously dispersed composite has a higher storage modulus and work of fracture at temperatures less than the glass transition temperature. Some properties related to the component interactions, such as thermal degradation and moisture content, are similar for both composite systems. The mechanism of dispersion is probed with electrophoretic measurements and electron microscopy, and based on these results, it is hypothesized that CNC preaddition facilitates the formation of a CNC-coated epoxy droplet, promoting CNC dispersion and giving the epoxide droplets added electrostatic stability. The implication of these structural changes in polymer network formation results in an extension of the epoxy and crosslinker mixture's pot life by three orders of magnitude. Graphical abstract: Highlights: Cellulose nanocrystal (CNC) dispersion in a waterborne epoxy matrix was improved. Improved dispersion was due to a physical CNC-epoxy interaction. CNCs imparted stability to the epoxy droplets via electrostatic repulsion. The CNC-stabilized epoxy droplets extended the pot life by 3 orders of magnitude. CNC content and processing method impacted thermomechanical performance.