Clay concentration

To obtain a high viscosity at a much lower clay concentration, certain water-soluble vinyl polymers called clay extenders can be used. In addition to increasing the yield of sodium montmorillonite, clay extenders serve as flocculants for other clay solids. The flocculated solids are much easier to separate using solids control equipment. 

The soil was loose and contained abundant spores with more genera above 0.4 m (Table 4, Fig. 6), and became denser due to the abrupt increasing in clay concentration below 0.4 m of SL profile (Chen et al. 2002a), which restrained the penetration of spores with leaching of soil water. Consequently, the quantity of spores decreased with depth (Table 4) and the genus became monotonous (Fig. 6). The loose/stiff quality of soil is then a critical factor controlling the penetration of spores. 

The flocculated suspension was then transferred to the syringe and the specific resistance was determined as described previously. Results are shown in Figure 4 for three different kaolin concentrations, flocculated with polymer A. The polymer concentration is shown as a percentage of the clay concentration. In all cases, plots of t/D vs. D were linear. 

For this purpose, 500 ml of a 140 mg/1 kaolin suspension was treated with an amount of polymer A corresponding to 0.5% of the clay concentration (i.e. the optimum dose). After 15 seconds of rapid mixing, the suspension was subjected to slow (30 r.p.m.) stirring, using a paddle stirrer. Samples were withdrawn at different intervals directly into the syringe and a filtrability determination was carried out. 

The effect of the components and conditions of preparation on the properties of a 70/30 LDPE/clay composite is shown in Table I. The 10/90 mixture of LDEE Bakelite Polyethylene Resin DYNH-1 (Union Carbide Corp.) and Hydrite 10 clay (Georgia Kaolin Co.) was compounded at 150 C in the Brabender Plasticorder in the presence of MAH and/or t-butyl perbenzoate (tBPB). The EE-coated clay was then mixed with additional DYNH-1 LDPE at 130°C to yield a 70/30 PE/clay composite. A 30 70 PE/clay concentrate was prepared in a similar manner at 150 C and converted to a 70/30 EE/ clay composite at 130 C. The 10/90 PE/clay concentrate is an easily handled, clay-like product while the 30/70 concentrate is... 

The 30/70 PE/clay concentrate yields 70/30 composites having slightly better properties at a lower MAH-tBPB concentration, based on FE, than does the 10/90 PE/clay concentrate. 

The influence of the various components of a HDPE/clay composite on the properties is shown in Table II. A 30/70 PE/clay concentrate was prepared from 15 parts HDPE Fortiflex A60-70R (Allied Chemical Corp.) and 35 parts of Hydrite 10 by mixing at 150 C in the presence of 3 parts of maleic acid (MA) and 0.75 parts of tBPB. The concentrate was then blended at 150 C with additional HDPE to yield a 50/50 HDPE/clay composite. 

The level of clay loading dramatically influences the mechanical properties of HDPE Fortiflex A60-70R/Hydrite 10 clay composites prepared from MAH-tBPB coupled 30/70 PE/clay concentrates. The 30/70 HDPE/clay mixture was prepared either in the absence of MAH and tBPB or in the presence of 20% MAH and 5%tBPB, based on PE, at 150 C and then compounded with additional HDPE to yield the final PE/clay composites shown in Table III. 

The MZC process has been used in full-scale applications and is commercially available. It can be applied ex situ or in situ. A common application of this technology is landfarming, in which contaminated soils are placed in cells, the soils are mixed and aerated, and MZC products are added. Treatment times depend on the level and type of contamination, and the ease with which the soil can be worked. Higher contamination levels require more time, as do soils with higher clay concentrations. According to the vendor, sandy soils or moderate contamination... 

Figure 7 shows the representative bright field HRTEM images of nanocomposites of NR and unmodified montmorillonite (NR/NA) prepared by different processing and curing techniques. It is apparent that the methodology followed to prepare the nanocomposites by latex blending facilitates the formation of exfoliated clay structure, even with unmodified nanoclays. It has been reported in the literature that hydration of montmorillonite clay leads to extensive delamination and breakdown of silicate layers [94, 95]. It has also been shown that NA disperses fully into the individual layers in its dilute aqueous dispersion (clay concentration <10%)... 

Bandyopadhyay et al. [138] have also studied the distribution of nanoclays such as NA and 30B in NR/ENR (containing 50 mol% epoxy) and NR/BR blends and their effect on the overall properties of the resultant nanocomposite blends. They calculated the preferential distribution of clays at various loadings in the blend compounds from the viscoelastic property studies from DMA. The tensile properties of the 50 50 NR/ENR and 50 50 NR/BR blend nanocomposites are shown in Table 5. It is apparent that in both the blends that the mechanical properties increase with increasing clay concentration up to a certain extent and then decrease. These results have been found to depend on matrix polarity and the viscosity of the blend compounds. 

CHINA CLAY. A commercial term, more or less identical with kaolin, as applied lo the relatively pure clay concentrated by washing from a thoroughly kaolini/cd granite. England is the chief exporter of china clay. France has unique clays from which arc made Ihe famous Sevres and Limoges potteries. 

Figure 1. Change in suspensibility with clay concentration...

Figure 4.2. Electrical conductivity as a function of (a) SWNT concentration for composites with and without 2 wt% clay (b) clay concentration for composites with 0.05 wt% SWNT. Reprinted with permission from ref (41).

In this case, I have deliberately chosen the highest r, highest c sample (d = 75 A, in the regime of pastes in disoriented clays) as an example of the phase transition because, in practical problems, the higher clay concentrations will be more important than the dilute sols we have used for theoretical comparisons. The essential feature of the freezing experiments on LOQ was that the behavior shown in Figure 10.1 was observed at all the r, c points studied. 

Table 17. Hydrogen production as a function of and clay concentration, at Constant ratio...

Smith, 1995a,b). The latter, more sensitive, technique was developed especially for samples with low clay concentrations (see Figure 13.2), where clay suspensions are precipitated onto 25 mm, 0.1 j,m membrane filters. Preconcentration amongst fine-grained minerals is reduced using this technique, which can present a problem when slide mounts are used (Gibbs, 1965). Other advantages include speed, simplicity, low cost and the fact... 

Filtration. Sample should be filtered (sO.45 /tm) to separate dissolved humic substances from particular organic carbon and colloidal clays. Concentration. Humic substances should be concentrated by an efficient method, such as sorption on XAD-8 or Duolite A-7. 

The diffraction patterns of dried zirconium sulfate pillared clay obtained after different intercalation times are presented in Fig. 2. These samples were prepared using a 0.1 mol/L zirconium acetate solution with an S04 Zr ratio = 0.5. The clay concentration was 10 g/L, with Clay Zr =10 g/mol, at pH = 4.00. The intercalation was performed at 15 °C. 

The XRD patterns of zirconium sulfate pillared clays obtained after 90 hours of intercalation with different zirconium acetate concentrations using 0.5 as sulfate to Zr ratio and the same clay concentration as used earlier are presented in Fig. 5. The diffraction data show the appearance of two first order reflections. The first one is at 23.4 A for the lowest zirconium concentration and appears as a shoulder at the same distance for 0.05 mol/L concentration. The second reflection is observed at approximately 12.3 A for the lowest concentration and at 13.7 A for 0.1 mol/L zirconium acetate. The first one results from the intercalation of sulfated zirconium species. Those species are more voluminous than the non sulfated one which gives a distance spacing at only 19.6 A. The better intercalation of sulfated zirconium species at low Zr concentration is probably due to the slow progress of polycondensation reactions. This process reduces the number of different zirconium species and gives a better cristallinity of the solid. Table 2 summarizes the textural properties of samples prepared with different zirconium concentrations. The decrease of the surface area with the decrease of the Zr concentration is probably due to the increase of the sodium clay layers by comparison with the intercalated layers. The microporous volume increases when the Zr concentration decreases. The higher microporosity is due to the important basal distance of this sample. 

The system shows a (dynamic) yield stress cr that can be obtained by extrapolation to zero shear rate [8]. Clearly, at and below cr the viscosity ri-roo. The slope of the hnear curve gives the plastic viscosity ri i- Some systems, such as clay suspensions, may show a yield stress above a certain clay concentration. 

Wang and Pinnavaia [28] determined several kinetic and thermodynamic parameters for their clay -polyether nanocomposite systems. Heats of reaction for [H3N(CH2)11COOH]+-MMT and [H3N(CH2)5COOH]+-MMT as a function of clay concentration decreased linearly with increasing clay concentration, implying that the heat of reaction was primarily due to epoxide polymerization. 

Sodium montmorillonite quickly and irreversibly deposits onto cellulose at extremely low clay concentrations [61-63], It exhibits some fiber lubrication properties. 

Figure 22. The variation in high shear viscosity with solid (clay) concentration for model system (tailings) suspensions at pH 6 (M) and 8 (%). (Reproduced with permission from reference 66. Copyright 1989 Canadian Institute of Mining, Metallurgy, and Petroleum.)...

---