Silica carbon black, comparison

This assumption is based on the fact that PTFE agglomerates are soft and deformable particles in comparison to conventional (hard) fillers such as carbon black and silica for which (2) was originally derived. Morphological analysis (shown in Fig. 5) reveals that PTFE agglomerates can be considered as soft deformable particles. 

Figure 15.10 Comparison of tear strength of the NR/EPDM blends containing carbon black (3%), silica (30%), and carbon black/siUca (3 30). (From Reference 70 with the permission from John Wiley Sons.)...

On silica gel and alumina, the PAHs show a wide range of photolytic activity suggesting a relationship between structure and activity. On the fly ash, similar half-lives were observed that would indicate, in this instance, that the process is independent of the PAH structure and dependent on the physical and chemical properties of the substrate. The PAHs are more stable on the carbon black and there is little variation among the different compounds. For comparison, the vapor-phase half-lives have been calculated and in most instances are shorter than those observed on the particles. Pyrene is a noted exception showing more rapid degradation on silca gel and alumina than by the hydroxyl radical process in the vapor phase. 

The most commonly used technique to qualify filler dispersibility is to study light reflectivity of clean-cut mixes. Some apparatuses have been developed to evaluate filler dispersion using a calibrated set of reference mixes (Dispergrader). However, such characterization mainly detects dispersion defects of a few tens of microns, and direct comparison of carbon black and silica mixes has to be done cautiously. In any case, it is necessary to make a mix, which means choosing a formula, a mixer, and mixing conditions thus the result cannot be considered as an intrinsic dispersibility measurement of the filler, but just reflects the dispersibility of the filler in one mix with a set of mixing conditions. 

Non-linear mechanical properties were observed for rubber eomposites and referred to as the Payne effect. The Payne effeet was interpreted as due to filler agglomeration where the filler clusters formed eontained adsorbed rubber. The occluded rubber molecules within filler elusters eould not eontribute to overall elastic properties. The composites behaved similarly to rubber composites with higher filler loading. Uniform and stable filler dispersion is required for rubber composites to exhibit linear viscoelastic behaviour. Payne performed dielectric measurements on SBR vulcanizates containing silica or carbon black. The dielectric data were used to construct time-temperature superposition master curves. The reference temperature increased with crosslinking but not significantly with filler. Comparison of dynamic mechanical and dielectric results for the SBR blended with NR was made and interpreted. ... 

White reinforcement This is obtained through the use of silica. Grades are defined by size surface area and method of mannfacture, although there is no universally accepted grading system such as exists for carbon black. A comparison of the effects of silica and carbon black as reinforcing fillers is given in Table 2. In general, unless one needs a non-black rubber, less trouble is experienced with black reinforcement. 

F. 4.11 Comparison of RDG scattering with GMM via ratio of the corresponding extinction cross sections Cext for DLCA and RLCA aggregates variation of the pimaty particle size and of the aggregation number N silica (left) and carbon black (right) in walta-... 

Oxides.—The adsorbent properties of silica gel are known to be highly dependent on the degree of hydroxylation of the surface, and this dependency has been widely investigated in relation to gas adsorption.Khopina and Eltekov have continued earlier work of Kiselev and his collaborators on the influence of the surface chemistry of silica on adsorption from solution. In the present paper a comparison is made of the adsorption of a series of aromatic hydrocarbons (benzene, naphthalene, biphenyl, phenanthrene, o- and m-terphenyl) from n-heptane solution by hydroxylated silica, dehydroxylated silica, and graphitized carbon black, using data obtained in the present work together with earlier published data. The results are analysed in terms of the separation factor(partition coefficient)... 

Murakami K, lio S, Tanahashi T, Kohjiya S, Kajiwara K and Ikeda Y (2001) Reinforcement of NR by silica generated in situ comparison with carbon black stock, Kautschuk Gummi Kunststoffe 54 668-672. 

Radjy and SeUevold [54] developed a phenomenological theoretical theory for the f-method of pore structure analysis for slit-shaped and cylindrical pores. A comparison [55] of adsoiption and desoiption methods for pore size distribution, with transmission electron microscopy using closely graded cylindrical pores in alumina, closed at one end, confirmed the superiority of the Broeckhoff-de Boer equations over the Kelvin equation. Lamond [56] found Lippen s t silica values unsuitable for carbon black and proposed a new set based on adsorption data for fluffy carbon blacks. 

Figures 4.18 and 4.19 show the TGA spectra for the FEP resins, DSCs of which have been shown in the Figs 4.20 and 4.21. A comparison of these figures indicates deterioration in the thermal stability of FEP after incorporation of pigment. Figure 4.22 represents the TGA thermogram for a PTFE (31% wt.) compounded with carbon black (18% wt.) and silica (50.5% wt.). The 0.5% difference is due to the evolved volatile gases, which have not been shown in Fig. 4.22.

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