Effect of reaction conditions on silanisation of sepiolite nanoparticles

Abstract

The study provides insights into the silanisation process of sepiolite nanoparticles. The nanoparticles were modified applying acidic and basic silanisation methods using Methacryloxypropyltrimethoxysilane (g-MPS) as coupling agent. The silanisation reaction was performed in the following conditions: (1) acidic ethanolÀwater solution with a pH of 5 and (2) basic cyclohexane with a pH of 9. The influence of the conditions on the surface chemistry of modified particles was then investigated. To characterise the surface of sepiolite nanoparticles, analytical methods such as Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis, X-Ray diffraction (XRD), scanning electron microscopy (SEM), and zeta potential analyses were applied. In addition, the colloidal stability of the modified nanoparticles was studied using a separation analysis. According to XRD and SEM, the basal interlayer distance of pristine sepiolite is not altered by silanisation process. TGA reveals that the grafting percentage of organosilane synthesised by basic method is approximately two times of that of acidic method. The silane coverage on the surface of the sepiolite and the per cent of hydroxyl groups covalently bound to g-MPS were calculated. Separation analysis indicates decline in dispersion stability of the modified nanoparticles in ethanol due to increment of their hydrophobicity.

Sustainable Materials with Enhanced Mechanical Properties Based on Industrial Polyhydroxyalkanoates Reinforced with Organomodified Sepiolite and Montmorillonite

“…The diffraction patterns of T1 and T2 shows the expected structure for sepiolite organoclays, with the principle peak being at 2θ = 7.29, showing highest intensity. Results agree with those of Penning et al as the basal interlayer distance of pristine sepiolite seems not to be altered by the silanisation process [76], and as the authors had corroborating calculations for the basal distance for d(1,2,1) and d(1,2,0), respectively (see Table 3). In addition, T3 presents three well-differentiated peaks at 2θ = 14.03, 19.83 and 61.9, which are typical of montmorillonite organoclay.…”

Characterization and Properties of Water-Blown Rigid Polyurethane Foams Reinforced with Silane-Modified Nanosepiolites Functionalized with Graphite

“…Therefore, the loss of mass from the SFG particles should exclusively be due to the degradation of the nanosepiolites modified with silane groups. The three steps clearly displayed in the thermogram of the SFG particles are very similar to those observed in the thermograms of sepiolites [ 39 , 41 , 43 ]. The mass loss in the SFG particles and that in sepiolites are analogous, and must therefore be based mainly on the evaporation of the modifier added to the sepiolites (silane groups) as well as on the evaporation of the water contained in the sepiolites: zeolitic water, surface-adsorbed water and coordinated water.…”

“…The band at 1695 cm −1 coincides with the bending movement of the water adsorbed on the surface of the sepiolite, whereas the band at 1659 cm −1 is attributed to the flexural vibrations of zeolitic water. The 1200–400 cm −1 range is characteristic of silicates: an absorption centered at 1016 cm −1 due to the Si-O-Si vibration, other bands at 1206, 1065 (shoulder) and 964 cm −1 due to Si–O bonds, and bands at 682 and 641 cm −1 coinciding with Mg-OH bond vibrations [ 39 , 40 , 41 ].…”

Reducing off-Flavour in Commercially Available Polyhydroxyalkanoate Materials by Autooxidation through Compounding with Organoclays

“…On the other hand, for PHA1005 matrix, T1 presents some agglomerates, which in principle should be avoided due to the aminosilane modification. At times, the greater the amount of organic modifier in nanoclays, the greater the impediment to debundle [35] and this might be the behaviour observed between T1 (modified) and T2 (natural) for this matrix.…”