Actual or Proposed Applications

While the preceding chapter delineated the basic engineering and mechanical behavior of IPNs, this chapter will be devoted to selected applications, actual or proposed. Many of these applications arc discussed in the patent literature. Not so surprisingly, some of the more complex and/or intricate syntheses, as well as a wealth of detailed physical properties, are contained in these patents. 

As per the definition of patentability, each patent addressed a novel method of synthesis, process, or application. Table summarizes some 21 selected patents based on chemical crosslinking. Applications range from ion exchange resins, through adhesives, to impact-resistant plastics. 

Newer on the scene are the physically crosslinked materials, which might be designated as the thermoplastic IPNs. In each of these cases, the materials can be melt processed but on cooling attain some of the characteristics of crosslinked materials. Many of these blends exhibit dual-phase continuity, as emphasized by Kresge. There are several distinct ways of forming physical crosslinks, as indicated in Table 8.2. As discussed in Section 5.7, several independent ways of forming a thermoplastic IPN exist. Some of these have been explored, as will be illustrated below. 

Strictly speaking, the use of the term network refers to the crosslinking of the single polymer chains. Therefore, an IPN implies a mutual solution of the two networks. While this problem was dealt with in Section 1.2, a brief review is instructive. 

An IPN is defined as a combination of two (or more) polymers in network form, at least one of which is synthesized and/or crosslinked in the immediate presence of each other. The term interpenetrating polymer 

---

Many properties are involved in determining a material s ultimate usefulness. For homopolymers, the temperature of the glass-rubber transition, presence or absence of crystallinity, crosslinking, molecular weight characteristics, permeability, and toughness all make a contribution. When two different polymers are mixed or joined in some fashion the mode of mixing becomes important as well. Tables 2.1-2.3 describe some of the many actual or proposed applications for two-polymer combinations. In many cases, the patent literature has been referred to, as this is an excellent source of such information. With polymer blends, blocks, and grafts, many new properties and hence uses appeared that were previously unavailable. 

This paper first gives a brief overview of the major cobalt uses, potential feeds to recycling operations the paper then reviews recycling processes applied commercially and/or proposed for application. The paper will finally review potential or actual processes to recycle cobalt from metallurgical wastes. 

The following list of patented and published methods that have been investigated for stabilizing hypochlorite bleach is given for information only and is not intended to be complete or in any preferred order. As with any chemical stabilization method, actual technical effectiveness and practicality will depend on numerous factors specific to the proposed application. 

Because of the convenient mathematical characteristics of the x -value (it is additive), it is also used to monitor the fit of a model to experimental data in this application the fitted model Y - ABS(/(x,. ..)) replaces the expected probability increment ACP (see Eq. 1.7) and the measured value y, replaces the observed frequency. Comparisons are only carried out between successive iterations of the optimization routine (e.g. a simplex-program), so that critical X -values need not be used. For example, a mixed logarithmic/exponential function Y=Al LOG(A2 + EXP(X - A3)) is to be fitted to the data tabulated below do the proposed sets of coefficients improve the fit The conclusion is that the new coefficients are indeed better. The y-column shows the values actually measured, while the T-columns give the model estimates for the coefficients A1,A2, and A3. The x -columns are calculated as (y- Y) h- Y. The fact that the sums over these terms, 4.783,2.616, and 0.307 decrease for successive approximations means that the coefficient set 6.499... yields a better approximation than either the initial or the first proposed set. If the x sum, e.g., 0.307,... 

---