Poly supply chain

Figure 5.2, also taken from Schwarz et al. [21], illustrates how metrics for ethylene, chlorine, vinyl chloride and poly(vinyl chloride) (PVC) can be stacked to obtain metrics for the production of PVC, beginning with naphtha and brine. The metrics calculated with the mass denominator can be readily combined. Impact per dollar can also be calculated for a supply chain by combining the single values along the chain in... 

Samples. Linear polurethane block copolymers with hard segments composed of 2,4- or 2,6-TDI, and 1,4-butanediol, BD, and either 1040 or 2060 molecular weight poly (tetramethylene oxide), PTMO, soft segments were supplied through the courtesy of N. S. Schneider of the Army Materials and Mechanics Research Center, Watertown, MA. These polymers were prepared by a two-step process, first an endcapping of the PTMO with a 5% molar excess of TDI, followed by chain extension... 

The absorbed vitamin must be converted to the coenzyme form. This requires adding back a five- to seven-member glutamate chain and commercial folic acid must undergo the two-step reduction to tetrahydrofolic acid. There are two common abbreviations for the reduced form, FH4 and THF. These reactions apparently occur in a wide variety of tissues. The liver contains about a 3- to 6-month supply of the vitamin, presumably in the poly glutamate form. 

Two emulsifier systems were used for the preparation of O/W emulsions. The first emulsifier was Synperonic PEE 127, an A-B-A block copolymer of poly(ethylene oxide), PEO (the A chains, were about 100 EO units each) and propylene oxide PPO (the B chain was about 55 PO units), supplied by UNIQEMA. The second emulsifier system was Arlatone V-100 (supplied by UNIQEMA), a nonionic emulsifier system composed of a blend of Steareth-100 (stearyl alcohol with 100 EO units), Steareth-2 (stearyl alcohol with 2 EO units), glyceryl stearate citrate, sucrose, and a mixture of two polysaccharides, namely mannan and xanthan gum (Keltrol F, supplied by Kelco). In some emulsions, xanthan gum was used as a thickener. AH emulsions contained a preservative (Nipaguard BPX). 

Polyurethane. [This polymer was supplied by R. A. Auerbach, Lord Corporation.] The polyurethane was composed of a soft segment of poly(tetramethylene glycol) with a molecular weight of 1000 and a hard segment of p-diphenylmethane 4,4 -diisocyanate (MDI), and was chain extended with ethylenediamine (7). A solution of 7 wt % polyurethane in N,N-dimethylacetamide was used to cast the films. The phase-separated samples (ANN) were prepared by annealing the film at 135°C for 90 min in a helium atmosphere, and the mixed, nonphase-separated samples (NEQ)... 

An alternative (and perhaps more efficient) polymeric surfactant is the am-phipathic graft copolymer consisting of a polymeric backbone B (polystyrene or poly(methyl methacrylate)) and several A chains ( teeth ) such as poly(ethylene oxide). The graft copolymer is referred to as a comb stabiliser - the polymer forms a brush at the solid/liquid interface. The copolymer is usually prepared by grafting a macromonomer such as methoxy poly(ethylene oxide) methacrylate with poly(methyl methacrylate). In most cases, some poly(methacrylic acid) is incorporated with the poly(methyl methacrylate) backbone - this leads to reduction of the glass transition of the backbone, making the chain more flexible for adsorption at the solid/liquid interface. Typical commercially available graft copolymers are Atlox 4913 and Hypermer CG-6 supplied by ICI. 

Silicone defoamers are composed mainly of hydrophobic silicone oil (polydimethylsiloxanes). Pure silicone oil is effective, but overdose often leads to surface defects. Therefore, polyether modified poly-siloxanes have been preferably used to give effective defoaming with negligible effect on appearance of the films. MW and side chain modifications are important considerations in their selection. For ease of incorporation, they are often supplied as emulsions. They may also contain hydrophobic silica to make them more effective. Possible adverse effects are poor intercoat adhesion or craters. 

Ex. 3 Verona (Bayer) supplies Impranil 4496 (DLN) color stable, 40% solids, thermoplastic, aliphatic poly (ester-urethane), anionic, aqueous dispersion. Samples have appeared to contain a trace of solvent (acetone, MEK ). Presumably Impranil 4496 (DLN) contains a polyurethane ionomer and is prepared without added emulsifier, the polyurethane itself having its own emulsifier function. The incorporation of this function in the polyurethane chains as sodium (A) sulfonate or (B) caiboxylate groups is seen in the following equations " ... 

The fiber used in this study was Twaron 2200 a poly(p-phenylene terephthalamide) (PPTA) aramid fiber, supplied by Akzo Nobel Research (Arnhem). The fibers have modulus Ef= 136 GPa, tensile strength, thermoplastic elastomer, polyether amide block copolymer supplied by Atofma known commercially as Pebax . These thermoplastic elastomers (TPE) consist of linear chains of hard polyamide (PA) blocks covalently linked to soft polyether (PE) blocks via ester groups. The grade of Pebax used was Pebax 7033, with a modulus Eva. = 128 MPa, yield stress ay = 32 MPa, Yield strain ey = 25 %, ultimate failiue stress a m = 67 MPa and an ultimate strain e m = 400 %. 

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