Highly dispersed nanosilica–epoxy resins with enhanced mechanical properties

• Published in: Polymer (Guilford) 2008-08, Vol.49 (17), p.3805-3815
• Main Authors: Chen, Chenggang, Justice, Ryan S., Schaefer, Dale W., Baur, Jeffery W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; FRACTURE PROPERTIES; GLASS; MATERIALS SCIENCE; MECHANICAL PROPERTIES; MORPHOLOGY; Nanocomposites; Polymer industry, paints, wood; RESINS; SCATTERING; SILICA; Small-angle scattering; Technology of polymers; TRANSITION TEMPERATURE; TRANSMISSION ELECTRON MICROSCOPY
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2008.06.023

Epoxy–nanocomposite resins filled with 12-nm spherical silica particles were investigated for their thermal and mechanical properties as a function of silica loading. The nanoparticles were easily dispersed with minimal aggregation for loadings up to 25wt% as determined using transmission electron microscopy (TEM) and ultra-small-angle X-ray scattering (USAXS). A proportional decrease in cure temperatures and glass transition temperature (for loadings of 10wt% and above) was observed with increased silica loading. The morphology determined by USAXS is consistent with a zone around the silica particles from which neighboring particles are excluded. The “exclusion zone” extends to 10× the particle diameter. For samples with loadings less than 10wt%, increases of 25% in tensile modulus and 30% in fracture toughness were obtained. More highly loaded samples continued to increase in modulus, but decreased in strength and fracture toughness. Overall, the addition of nanosilica is shown as a promising method for property enhancement of aerospace epoxy composite resins. [Display omitted]