Compounding accelerator adsorption

The reinforcing properties measured as M300/M100 are similar for the two vulcanized samples. However, the cured A1 compounds show lower ultimate elongation at break, higher curing rate (T90), and shorter breakdown time (T2), which are the signs of lower adsorption of accelerators on the A1 particles surface. 

Highly dealuminated Y zeolite, commercially labeled as DAY (dealuminated Y), with an FAU framework type is an excellent adsorbent for the removal of organic compounds in wastewaters, as a consequence of the hydrophobic surface properties of this zeolite, owing to the low concentration of A1 (see Section 2.5.1). As an example of adsorption in a zeolite, in Figure 6.9, the N2 adsorption isotherm at 77 K of the DAY zeolite, DAY-20 F (Si/Al = 20), provided by Degussa AG, Dusseldorf, Germany, is shown. The N2 adsorption isotherms were measured with an Accelerated Surface Area and Porosimetry System (Autosorb-1) from Quantachrome, Boynton Beach, FL, USA [21] which is a volumetric automatic equipment similar to that reported in Figure 6.8. 

For solutions sufficiently concentrated for ionic micelles to be present in considerable quantity (this occurs with the twelve-carbon compounds at about N/100 and with the sixteen-carbon at about N/1,000)4 the surface tension reaches the final value in a few seconds and this value is usually the same as that attained slowly in the very dilute solutions. Additions of salt to the very dilute solutions accelerate the attainment of the final tension. Doss (see Appendix) ascribes the slow adsorption to an electrical effect. 

It has been reported in the literature that water accelerates the desorption of IBA and MAA (ref. 11,12). This is demonstrated in Fig, 4 When water is added into the feed (filled symbols) no decrease due to adsorption phenomena can be observed. In fact, during the first few hours of time on stream even a slight increase to a constant level in the formation of MAA is observed. It has been reported in the literature (ref. 13) that the presence of water stabilizes the Keggin unit and even the formation of new heteropoly compounds out of oxides is possible. Therefore, it can be assumed that the observed initial increase is related to these effects. After 2Et hours tirrre on strearn the addition of water... 

In the experiments on accelerators the required short-lived products of nuclear reactions are converted into volatile compounds and separated by gas-solid chromatography techniques in a continuous regime. Open columns of a meter in length and a few millimeters in diameter are used. The linear velocity of the carrier gas has varied from centimeters to meters per second. To optimize the separation process, it is important to understand how the experimental conditions, the properties of the separated species and other factors affect the shape and position of the resulting adsorption zone. 

Diatomite (Kieselguhr). Diatomaceous earth (as it is also called) is chemically ineit, but it has high adsorptive power. This can account for adsorption of curing ingredients that interfere with accelerated-sulfur vulcanization. However, diatomite is used as a filler in silicone rubber. Because of its high adsorptive capacity, it is used as a process aid in high-oU rubber compounds. 

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