Aluminum hydroxide silane

Quantitative FT-IR diffuse reflectance analysis of vinyl silanes on an aluminum hydroxide substrate... 

Abstract—This study extends previous work on silanized kaolin clays to other substrates, such as aluminum hydroxide. It will also show that high precision quantitative Fourier Transform Infrared Spectroscopy (FT-IR) diffuse reflectance measurements can be performed on this vinyl silanized substrate and predict that other silanized finely divided powders can be analyzed using these techniques. 

More recently, the need to analyze vinyl silane on an aluminum hydroxide (alumina trihydrate) substrate has arisen. The silanized aluminum hydroxide substrate system was investigated to determine whether quantitative diffuse reflectance measurements were practical for routine control of the vinyl silaniz-ation process. In this paper, we discuss a method to quantify the amount of silane adsorbed on the aluminum hydroxide substrate. 

Figure 4 shows diffuse reflectance spectra of a 1.5% vinyl silanized aluminum hydroxide powder (with average particle size of 2 /iin), both KM-corrected [8, 9] as well as uncorrected, using KBr powder as a reference. The KM correction compensates for the ordinate reflectance non-linearity induced by the diffuse reflection process and is expressed quantitatively by the expression Rkm = (1 - Rob)2/2Rob where Rob is the measured uncorrected reflectance and Rk, is the corresponding KM-corrected reflectance. The ordinates of both spectra were normalized to 100% reflectance at 4000 cm 1. 

Figure 4. Diffuse reflectance spectral comparison of vinyl silanized (1.5%) aluminum hydroxide powder.

Figure 5 shows the comparison of the KM-corrected diffuse reflectance spectra for the 0.0% and the 1.5% vinyl silanized aluminum hydroxide concentrations. Note again that on this scale and particularly for KM-corrected spectra, the hydrocarbon absorptions between 3200 cm 1 and 2600 cm-1 are not discernible. However, upon closer inspection of the C-H stretch region and particularly the vicinity of the 3060 cm 1, the absorptions are indeed found. 

This is more clearly seen in Fig. 6 with superimposed KM-corrected spectra of the various concentrations of vinyl silanized aluminum hydroxide powder between 0.0% and 1.5% vinyl silane in the range between 3080 cm-1 and 3030 cm-1. 

Figure 5. Diffuse reflectance spectral (KM-corrected) comparison of aluminum hydroxide powder silanized at two concentrations.

Figure 6. Spectra of various concentrations of vinyl silanized aluminum hydroxide powders used as analytical standards (Kubelka-Munk corrected).

This LSF plot is shown in Fig. 7 with the axes of A divisions (mm) vs. concentration of vinyl silane on aluminum hydroxide at 3060 cm-1. Each division, in millimeters, is equal to 0.006 log (1/R) or equivalent absorbance units. The correlation coeficient calculated from these data is 0.9868, which is reasonably good. In fact, the results are excellent considering that the data were obtained from the first set of samples specifically prepared of the vinyl silanized aluminum hydroxide for quantitative FT-IR analysis. 

From a composite report of the QUANT-3 analysis of the 1.0% vinyl silanized aluminum hydroxide sample using the other concentrations as standards, the calculated concentration (1.0%) is within experimental error, while the peak-to-peak (p/p) error of 0.00028 refers to the remaining residuals of the unknown... 

Figure 7. LSF calibration curve of vinyl silanized aluminum hydroxide powder standards shown in Fig. 6.

We have shown that the determination of vinyl silane on aluminum hydroxide powders is comparable to similar analyses on kaolin clays as reported earlier [2] and suggest with confidence that this technique can be extended to other powder substrate systems with sufficiently small particle sizes, i.e. comparable or less than the wavelength of the analytical frequency radiation as well as to the various other silanes that have been deposited on other substrates. 

The authors are greatly indebted to Mr. Robert E. Schultz, from the J. M. Huber, Solem Division, Fairmount, GA, who supplied the eight vinyl silanized aluminum hydroxide powder samples used in this study, and details of their preparation. 

The reaction of different quantities of aluminum hydroxide with a constant amount of dimethylsilanediol formed by the hydrolysis of its ethyl-ester (4) or with solutions of diethylsilanediol 5) developed 1 mole H per mole of A1 (OH) a up to the point at which the atomic ratio of silicon to aluminum was 5. Increased aluminum hydroxide beyond this point did not develop acidity. Although a reaction may have occurred, no acidity developed upon the addition of aluminum hydroxide to trimethylsilanol formed by the hydrolysis of its ethyl ester. Acidity developed when methyltriethoxy-silane hydrolysis products were used, giving 1 mole H+ per mole Al(OH)a to a silicon-aluminum atomic ratio of 3. Increased aluminum hydroxide beyond this ratio did not result in increased acidity. These data have been interpreted to signify compound formation between aluminum hydroxide and the indicated silanols, and the failure to develop acidity beyond a specific concentration of aluminum hydroxide suggests that the ratio of silicon to aluminum in the compound may be represented by the atomic ratios of silicon to aluminum at this concentration of aluminum. 

A. G. Davies University College, London) Professor Danforth has described the products of the reaction of dihydroxy-, trihydroxy-, and tetrahydroxy-silanes with aluminum hydroxide. I should like to ask him if he has attempted to prepare the analogous compounds from monohydroxy-silanes, perhaps by treating the sodium salt with aluminum chloride ... 

Some of the basic effeds obtained with aluminum hydroxide-filled EVA in the absence of peroxide and additional stabilizer are illustrated in Table 6.2, which contains a comparison between various unsaturated adds and three common organofimctional silane coupling agents. The silanes are all seen to significantly... 

Liauw CM, Lees GC, Hurst SJ, Rothon RN, Ali S. Effect of silane-based filler surface treatment formulation on the interfacial properties of impact modified polypropylene/magne-sium hydroxide composites. Compos Part A Appl Sci Manuf, 1998 29(9-10) pp. 1313-1318. Liauw CM, Lees GC, Hurst S), Rothon RN, Dobson DC. The effect of filler surface modification on the mechanical properties of aluminum hydroxide filled polypropylene. Plast Rub Compos Process Appl, 1995 24(5) pp. 249-260. 

Vamac D Elvax 265 Elvax 40LO3 Stearic acid Armeen 18D Vanfre VAM Pigment Vinyl silane Aluminum hydroxide Magnesium hydroxide Varox DBPH50 TAC... 

A typical embodiment for the porous layer technology is described in several patents and patent applications, e.g., a US patent application in 2006. This patent application describes a method for the preparation of silicon dioxide dispersions wherein the surface of the silicon dioxide is modified by treatment with the reaction products of a compound of trivalent aluminum with amino-organo-silane. The invention relates to recording sheets for inkjet printing having such a dispersion incorporated in the porous inkreceiving layer. Another US patent describes the preparation of nanoporous alumina oxide or hydroxide which contains at least one element of the rare earth metal series with atomic numbers 57 to 71. 

Acacia Acetylated lard glyceride Acrylic acid/acrylamide copolymer Adipic acid Allyltrimethoxysilane Allyltrimethyl silane Aluminum orthophosphate N-(2-Aminoethyl)-3-aminopropyl methyidimethoxy silane 3-Aminopropylmethyldiethoxysilane Aminopropyltrimethoxysilane Ammonium hydroxide Ammonium molybdate (VI) Ammonium ricinoleate Amyltrichlorosilane Arachidyl alcohol Barium petroleum sulfonate Bis (dimethylamino) dimethylsilane 3-[Bis (2-hydroxyethyl) amino] propyltriethoxysilane Bis-(N-methylbenzamide) ethoxymethyl silane Bismuth... 

On some metals, such as aluminum, the condensation of the silanol groups may oceur with the metal substrate, which results in metallo-siloxane (-Me-O-Si-) on the interface. These metallo-siloxane bonds are, however, hydrolytically unstable, which means that the metallo-siloxane groups are in a reversible equilibrium with silanols and metal-hydroxide groups. Hence, to maintain the adhesion of the silane film to the metal and for adequate corrosion protection, the silane film should be made hydrophobic enough to prevent water permeation into the metallo-siloxane layer [59]. 

Protective Coatings. Corrosion protection of metals in most cases requires specially tailored interfaces. In the case of aluminum surface, the use of reactive silanes should lead to an interface characterized by the formation of chemical bonds. In the presence of wet atmosphere, Al-hydroxides are formed on the surface and SiOH and SiOR containing coating solutions should form a stable bond to the AlOH covered surfaces following equation 7... 

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