Formulating the Mix

In this formulation the mixing process corresponds to a first-order reaction, which transforms unmixed (inert) reactant into mixed reactant. The rate constant for the mixing process, k, is correlated to the mixing time zm by... 

In the liquid state molecules are in intimate contact, so the energetics of molecular interactions generally make a contribution to the overall picture of the mixing process. There are several aspects of the situation that we should be aware of before attempting to formulate a theory for ... 

Cost bilizers. In most cases the alkyl tin stabilizets ate particularly efficient heat stabilizers for PVC without the addition of costabilizers. Many of the traditional coadditives, such as antioxidants, epoxy compounds, and phosphites, used with the mixed metal stabilizer systems, afford only minimal benefits when used with the alkyl tin mercaptides. Mercaptans are quite effective costabilizets for some of the alkyl tin mercaptides, particularly those based on mercaptoethyl ester technology (23). Combinations of mercaptan and alkyl tin mercaptide ate currendy the most efficient stabilizers for PVC extmsion processes. The level of tin metal in the stabilizer composition can be reduced by up to 50% while maintaining equivalent performance. Figure 2 shows the two-roU mill performance of some methyl tin stabilizers in a PVC pipe formulation as a function of the tin content and the mercaptide groups at 200°C. 

Hydrotalcite. Synthetic hydrotalcite minerals are gaining commercial acceptance for thein abiHty to costabiHze PVC ia the presence of other primary stabilizers (see Table 2). The performance of the mixed metal stabilizers are particularly boosted when an equal part level, about 2—3 phr, of hydrotalcite is added to the PVC formulation. These minerals function by trapping HCl within the layered lattice arrangement of atoms. The formula. 

Economics. As with the alkyl tin stabilizers, the market pricing of the mixed metal stabilizers tend to be directed by the particular appHcation. The calcium—zinc and barium—cadmium packages are typically used at 2.0—4.0 parts per hundred of PVC resin (phr) in the formulation. These completely formulated products are sold for 2.50— 4.40/kg for the Hquid products and 3.20— 6.50/kg for the soHds and pastes. The higher efficiency products aimed at rigid appHcations tend toward the higher end of the cost range. 

The organic and aqueous phases are prepared in separate tanks before transferring to the reaction ketde. In the manufacture of a styrenic copolymer, predeterrnined amounts of styrene (1) and divinylbenzene (2) are mixed together in the organic phase tank. Styrene is the principal constituent, and is usually about 90—95 wt % of the formulation. The other 5—10% is DVB. It is required to link chains of linear polystyrene together as polymerization proceeds. DVB is referred to as a cross-linker. Without it, functionalized polystyrene would be much too soluble to perform as an ion-exchange resin. Ethylene—methacrylate [97-90-5] and to a lesser degree trivinylbenzene [1322-23-2] are occasionally used as substitutes for DVB. 

Molybdate orange and red are pigments (qv) that contain lead(II) molybdate [10190-33-3], PbMoO, formulated in mixed phases with PbCrO and PbSO. The mixed phase is more intensely colored than any of the component phases. Concerns about lead content are lessening the use of these materials (see also Paint). Various organic dyes are precipitated with heteropolymolybdates. This process allows the fixation of the dye in various fabrics. The molybdenum anion generally imparts light stabiHty to the colorant as weU (91). 

Sulfur as an Additive for Asphalt. Sulfur-extended asphalt (SEA) binders are formulated by replacing some of the asphalt cement (AC) in conventional binders with sulfur. Binders that have sulfur asphalt weight ratios as high as 50 50 have been used, but most binders contain about 30 wt % sulfur. Greater latitude in design is possible for SEA paving materials, which are three-component systems, whereas conventional asphalt paving materials are two-component systems. Introduction of sulfur can provide some substantial benefits. At temperatures above 130°C, SEA binders have lower viscosities than conventional asphalt. The lower viscosity enables the plant to produce and compact the mix at lower temperatures than with conventional... 

Type AD-G is used in an entirely different sort of formulation. The polymer is designed for graft polymerisation with methyl methacrylate. Typically, equal amounts of AD-G and methyl methacrylate are dissolved together in toluene, and the reaction driven to completion with a free-radical catalyst, such as bensoyl peroxide. The graft polymer is usually mixed with an isocyanate just prior to use. It is not normally compounded with resin. The resulting adhesive has very good adhesion to plasticised vinyl, EVA sponge, thermoplastic mbber, and other difficult to bond substrates, and is of particular importance to the shoe industry (42,43). 

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