Core‐shell structured ferrite‐silsesquioxane‐epoxy nanocomposites: Composite homogeneity and mechanical and magnetic properties

Abstract

Epoxy‐based composites of ferrite nanoparticles (50 nm) with 3‐glycidoxypropyl‐ (GPTMS), aminopropyl‐ (APTMS), or methyl‐silsesquioxane (MTMS) coatings are reported. The GPTMS coatings (30‐nm thick) allowed uniform particle dispersion in the epoxy and prevented sedimentation of the nanoparticles, whereas the APTMS‐coated particles formed agglomerates, leading to particle sedimentation. The particles with the thinnest coating (MTMS – 3 nm) agglomerated in the composites without sedimentation. The composites based on GPTMS‐coated particles showed higher fracture toughness than the composites based on MTMS‐coated particles. The uniformity and thickness of the coatings were related to alcohol composition of the coating media. Coating removal by a novel ultrasonic etching allowed precise determination of the effective ferrite content in the coated nanoparticles. A markedly lower coercivity for nanoparticles without coatings as compared with the nanoparticles with thicker coatings was observed. The saturation magnetization and the coercivity of the composites were independent of coating and casting procedures. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Influence of nanoparticle surface treatment on particle dispersion and interfacial adhesion in low-density polyethylene/aluminium oxide nanocomposites

“…The spectrum of the C1-coated nanoparticles also showed absorption at 1270 cm À1 (Fig. 1, spectrum b), which is assigned to the Si-CH 3 stretching vibration [20]. An absorption band at 1119 cm À1 assigned to the Si-O-Si stretching vibration was observed in the same spectrum, indicating the formation of a cross-linked silicon oxide structure on the nanoparticle surfaces [44].…”

“…Significant efforts have been devoted to the development of methods to modify the particle surfaces by either physical or chemical methods and to increase the compatibility between the inorganic particles and the polymer matrix. This includes encapsulating the particles in surfactant [10,11], and grafting polymer chains [7,[12][13][14][15] and silanes [16][17][18][19][20][21] onto the particles. The use of surfactants would incorporate mobile ionic or polar species in the nanocomposite, and this is not a feasible solution for HVDC cable insulations since ionic/polar species increase the electrical conductivity of the insulation.…”

Morphology and properties of silica-based coatings with different functionalities for Fe3O4, ZnO and Al2O3 nanoparticles

“…Fig. 15 The absorption bands at 990 -1090 cm -1 were assigned to the asymmetric Si-O-Si stretching vibration, which confirmed the formation of a condensed silicon oxide network structure. The coating thickness increased from 1.4 nm after half an hour (Fig.…”

“…The uniformity of the coating thickness was the major advantage of this method, 11 whereas the separation processes required to remove the excess surfactant, the limited yield of material per reaction volume, and the use of a non-aqueous reaction medium are draw-backs. 14,15,16 To prevent the aggregation of nanoparticles during the coating reactions, the use of different surfactants (acting as a template for silica growth) has been reported as a prior coating step. Goyal and Huang et al 12,13 used anhydrous solvents as reaction media to prevent silicone oxide condensation from occurring apart from on the surface of the nanoparticles.…”

Cellulose nanofillers for food packaging

“…110 For inorganic nanoparticle systems these phenomena have resulted in coatings of agglomerates rather than the individual nanoconstituents. 118,119 Surface acetylation or acylation of CNFs is performed by reacting the reactive hydroxyl groups on the surface of the nanofillers with either acid or anhydride groups, leading to the transformation of hydroxyl groups into acetyl groups (acetylation) or more generally into acyl groups (acylation). The gradual conversion of cellulose into cellulose triacetate (CTA) by adding a mixture of acetic anhydride and acetic acid in the presence of a small amount of catalyst was studied in order to elucidate the mechanism of the acetylation.…”