Direct mixing

Several methods have been developed over the last few years to achieve an efficient dispersion of individual CNTs in a polymer matrix. The easiest method consists of directly mixing the polymer and the CNTs. One can also either modify the polymer in such a way that it can interact with the Ti-system of the CNT wall, or modify the walls of the CNTs by functionalization to improve the wetting of the filler, as well as the dispersion in the medium. It is also possible to use a third component, such as surfactant molecules, to assist the exfoliation of the CNT bundles, and the subsequent incorporation of the CNTs into the polymer matrix. All main methods reported so far are briefly discussed below, and are illustrated with representative examples. In this way, a guided tour through the tool-box for the dispersion of CNTs into highly viscous polymer matrixes is offered. 

Sandler and his coworkers developed two methods based on the direct mixing of CNTs and polymers. The easiest direct mixing procedure consists of dispersing aligned, untreated MWCNTs, 

A variant, the so-called coagulation method, is based on the difference in swellability of polymers in a good and in a poor solvent. In a sonication bath, purified SWCNTs, produced by a HiPCO process, were first purified by an acidic HCl treatment, which led to the obtaining of a CNT sample containing less than 8 wt% of metal residue, and subsequently mixed with the polymer (poly(methyl 

---

Charge-Transfer Salts. Most charge-transfer salts can be prepared by direct mixing of donors and acceptors in solution. Semiconducting salts of TCNQ have been prepared with a variety of both organic and inorganic counterions. Simple salts of the type TCNQ can be obtained by direct reaction of a metal such as copper or silver with TCNQ in solution. Solutions of metal iodides can be used in place of the metals, and precipitation of the TCNQ salt occur direcdy (24). 

Waxes. These are dispersions of polyethylenes, Fischer-Tropsh, Teflon, or vegetable waxes (qv) in a vehicle or solvent. They impart sHp and scuff resistance to ink films. Polyolefin waxes and Teflon are also available as powders that can be directly mixed into inks. 

As the outside air conditions vary from hour to hour, day to day, and month to month, to economize on the heating and cooling loads, the recirculated and fresh airsrreams are mixed in varying proportions. If the air contains toxic or inflammable gases, vapors, or dusts, no direct mixing occurs, and a hcat-tccovery device is used. 

DIRECT MIXING PROTEIN INTO MATRIX MEDIA... 

Physical isolation of reactant and product gases from direct mixing is an obvious requirement of the seal material. However, as mentioned in Section 5.1, the leak requirement is more stringent for an SOEC than an SOFC. In general, around 1%... 

John Champion patented in 1758 the process of producing brass and zinc from the common ore of zincblende (ZnS) or black jack (patent number 726). This ore had previously been considered worthless, but even with this advance it is obvious that metallic zinc was still far too expensive to use in brass production by direct mixing, a process which was patented by James Emerson in 1781 (no. 1297). Watson (1786), however, describes the use of zinc in the production of high-quality gilding brasses such as pinchbeck, tomback and Mannheim gold (see below). 

The task of a cell separator is to impede a direct mixing of anolyte and catholyte and to decrease diffusion, but at the same time the migration of ions has to be possible without a too high voltage drop. Naturally, a compromise of these requirements has to be found. 

Figure 1-1. It also provides a physical barrier to prevent the fuel and oxidant gas streams from directly mixing. 

The self-assembly of this fundamental building block of chromatin is a topic of enduring interest. DNase I digestion experiments as well as spectroscopic studies indicate that nucleosome core particles can be reconstituted by salt-jump (i.e., diluting NaCl concentration from 2.0 to 0.2 M) or by direct mixing of histones and DNA at the lower salt concentration. Daban and Cantor used the increase in eximer fluorescence to investigate the reassembly process in terms of a two-state model ... 

Mixing with other medications - Direct mixing of iloprost with other medications in the Prodose AAD system has not been evaluated. 

Step 2 required identification of source impacts by airshed modeling. Wind speed, direction, mixing height, and emission data bases designed to represent conditions on PACS sampling days were used to insure that the CMB impact estimates could be directly compared to model predictions for each sampllne site. 

As mentioned earlier, it has proven difficult to precipitate uniform metal (hydrous) oxides by direct mixing of solutions of metal salts and bases, especially of concentrated ones. Instead, it is possible to control the generation of hydroxide ions in situ, which can be achieved if certain organic compounds, such as formamide or urea, are slowly decomposed in aqueous solutions of metal salts. The rate of these processes depends on the pH, temperature, concentration of the reactants, and the presence or absence of metal complexing agents. In particular, precipitations caused by reactions in solutions of urea have been widely employed, although the products consist primarily of metal carbonates or basic metal carbonates. For this reason, this method is described in more detail in Chapter 7.1 of this volume. 

Nitric oxide release from blood vessels was first detected by chemiluminescence (Palmer et ai, 1987). In the original adaptations of the nitric oxide detector, perfusates from isolated vessels were directly mixed in a reflux chamber containing acetic acid and iodine. The iodine in the reflux chamber served to reduce any nitrites or nitroso-containing groups to nitric oxide, which was stripped from the chamber by a continuous stream of nitrogen or helium that flowed to the chemiluminescent detector. Replacement of the acetic acid with the less volatile trichloroacetic acid reduces problems with contamination of the nitric oxide detector (Dr. D. Harrison, Emory University, Atlanta, Georgia, personal communication, 1991). While extremely sensitive, the use of the acid reflux chamber also reduces the specificity of the assay, raising questions as to whether nitric oxide or a nitrosothiol is EDRF (Myers et ai, 1990). 

Blends of PC with ABS or ABS/HIPS can be prepared by direct mixing for the reclaimed materials, i.e., blending without the need of sorting before. It has been demonstrated that these mixtures can be easily processed. Furthermore, the mixtures show acceptable mechanical properties (40). 

---