The structure of an aminosilane coupling agent in aqueous solutions and partially cured solids

Abstract

The molecular structures of partially cured polyaminopropylsilsesquioxane and aminopropyltriethoxysilane in water have been studied using Fourier‐transform infrared, laser Raman, and quasielastic laser light‐scattering spectroscopy. A multiply hydrogen‐bonded structure is proposed for the intramolecularly interacting amine and silanol groups on the basis of isotope exchange experiment and conformational energy calculations. Conformational restrictions are rather low for the proposed structure, which is thus suitable for the partially cured solid where there are slight perturbations by the surrounding amine and silanol groups. The O.…N distance was experimentally determined to be in the range 2.70–2.67 Å and estimated theoretically as 2.49–2.45 Å. The aminosilane in very dilute solution is found to be mostly monomeric. The isolated monomer‐oligomer transition lies around 0.15% by weight and this transition influences the amount of silane uptake by glass fibers. It is also proposed that this phenomenon may be general for surface treatments by silane coupling agents. Hydrolyzed aminosilane oligomers exist in part as submicron aggregates which can be broken up by the addition of an alcohol. The neutralized aminosilane hydrolyzes very slowly although it dissolves in water instantaneously. Micelle formation is also proposed.

Study on interfacial adhesion strength of single glass fibre/polypropylene model composites by altering the nature of the surface of sized glass fibres

“…2b), the absorbance bands at 2923 and 2852 cm -1 are assigned to asymmetric and symmetric stretching vibration of >CH 2 , the strong and broad peak at 1029 cm -1 is the typical stretching absorbance band of Si-O-Si. The absorbance bands between 1650~1130 cm -1 are attributed to the stretching vibration of carbonyl group and bicarbonate salts due to the interaction between the amino group of γ-APS based components and environmental CO 2 and water Page 8 of 22 [34,35]. From the similarity between Fig.…”

Structure and adsorption characteristics of silane coupling agents on silica and E-glass fiber; dependence on pH

“…The high adsorption of VS on silica may be explained by the size effects. The VS molecule is smaller The estimated area occupied by a VS and a y-MPS molecule are 40 12/ 02 molecule [13] and 50 A /molecule, respectively [21].…”

Affecting glass fibre surfaces and composite properties by two stage sizing application

“…Thus, great attentions have been paid on the sizing structure or radial chemical composition to deepen the understanding of the correlation between the mechanical properties of composites and both the sizing and sizing technology. Post treatments and analyses [3,[26][27][28][29][30][31][32] on model reinforcements, especially 3-aminopropyltriethoxysilane (γ-APS) sized GF or silica, revealed that the surface of γ-APS sized model reinforcements consists of three layers, which are physically adsorbed, chemisorbed, and chemically covalent bonded polysiloxanes from air/sizing interface to sizing/GF interface [29][30][31]. It was found that the physically adsorbed polysiloxanes based on γ-APS have a detrimental effect on the GF-matrix adhesion strength [33].…”