Polymers suspensions

The discovery of PTFE (1) in 1938 opened the commercial field of perfluoropolymers. Initial production of PTFE was directed toward the World War II effort, and commercial production was delayed by Du Pont until 1947. Commercial PTFE is manufactured by two different polymerization techniques that result in two different types of chemically identical polymer. Suspension polymerization produces a granular resin, and emulsion polymerization produces the coagulated dispersion that is often referred to as a fine powder or PTFE dispersion. 

Polymer Suspensions. Poly(ethylene oxide) resins ate commercially available as fine granular soHds. However, the polymer can be dispersed in a nonsolvent to provide better metering into various systems. Production processes involve the use of high shear mixers to disperse the soHds in a nonsolvent vehicle (72—74). 

The system shown is heavily used in food processing applications such as milk or chocolate crumb production, sugar substitutes, modified starch, and alginates. In addition to food processing applications, such a system is used in the processing of heat-sensitive pharmaceuticals, polymer suspensions like latex, in processing pigments and dyestuffs, and pesticides. 

The polymer chain concentration and the polymer chain radius were employed to assess the rotational mobility of a molecule within a swollen gel [14]. To this purpose the gel is considered a thick, viscous polymer suspension. Its viscosity can be evaluated with the following equation, proposed by Nicodemo and Nicolais for concentrated suspensions of polymeric fibers [147] ... 

Fluidized aqueous suspensions of 15% by weight or more of hydroxyethyl-cellulose, hydrophobically modified cellulose ether, hydrophobically modified hydroxyethylcellulose, methylcellulose, hydroxypropylmethylcellulose, and polyethylene oxide are prepared by adding the polymer to a concentrated sodium formate solution containing xanthan gum as a stabilizer [278]. The xanthan gum is dissolved in water before sodium formate is added. Then the polymer is added to the solution to form a fluid suspension of the polymers. The polymer suspension can serve as an aqueous concentrate for further use. 

C. L. Burdick and J. N. Pullig. Sodium formate fluidized polymer suspensions process. Patent US 5228908, 1993. 

W. M. Harms and L. R. Norman. Concentrated hydrophilic polymer suspensions. Patent US 4772646,1988. 

K. W. Smith, L. V. Haynes, and D. F. Massouda. Solvent free oil soluble drag reducing polymer suspension. Patent US 5449732, 1995. 

Polymer surfaces, preparation of, 11 846 Polymer suspensions, poly(ethylene oxide) resin, 10 683... 

Recently, a method has been developed to microinject cell-polymer suspensions into 3-D collagen matrices in a 96-well plate format. This was used to perform a proof-of-principle screen of known signaling pathway inhibitors in murine breast cancer cells. The cells were visualized by staining of the actin cytoskeleton and effects of the compounds measured using multiparametric imaging. The system also proved amenable to the use of enzymatically... 

Truong HH, de SormeviUe J, Ghotra VP et al (2012) Automated microinjection of cell-polymer suspensions in 3D ECM scaffolds for high-throughput quantitative cancer invasion screens. Biomaterials 33 181-188... 

Non-Newtonian Polymer Suspensions Containing Rigid Fillers... 

Styrene and/or acrylonitrile have been grafted on Nylon 66 to improve its resistance to heat, water, chemicals and radiation, by gamma-irradiation of the polymer suspension in the monomer phase (8-11). 

Add the pigment suspension I to the well stirred polymer suspension II. Stir the obtained suspension during the entire coating process. 

This work reports rheological measurements of food polymer suspensions and emulsions. These are typical of a large number of foods and their rheological behaviors. 

This unit describes a method for measuring the viscosity (r ) of Newtonian fluids. For a Newtonian fluid, viscosity is a constant at a given temperature and pressure, as defined in unit hi. i common liquids under ordinary circumstances behave in this way. Examples include pure fluids and solutions. Liquids which have suspended matter of sufficient size and concentration may deviate from Newtonian behavior. Examples of liquids exhibiting non-Newtonian behavior (unit hi. i) include polymer suspensions, emulsions, and fruit juices. Glass capillary viscometers are useful for the measurement of fluids, with the appropriate choice of capillary dimensions, for Newtonian fluids of viscosity up to 10 Pascals (Newtons m/sec 2) or 100 Poise (dynes cm/sec 2). Traditionally, these viscometers have been used in the oil industry. However, they have been adapted for use in the food industry and are commonly used for molecular weight prediction of food polymers in very dilute solutions (Daubert and Foegeding, 1998). There are three common types of capillary viscometers including Ubelohde, Ostwald, and Cannon-Fenske. These viscometers are often referred to as U-tube viscometers because they resemble the letter U (see Fig. HI.3.1). 

The parameter r2 is independent of the initiator type for the emulsion, however, and is slightly higher than that obtained in benzene (r2=1.23) (Table 3). This behavior results from good compatibility of the macromonomer with poly-BzMA. Therefore the reactivity of the macromonomer does not depend so much on the reaction medium type. In contrast, reversed apparent reactivity was observed in heptane in which the clear solution of monomer turned into a polymer suspension upon polymerization. Since BzMA is soluble in the medium, it has been suggested that the polymerization occurs preferentially on the (inverse) micelle surface which is enriched by the macromonomers. 

The method for the manufacture of polypropylene by the Ziegler-Natta process, which has been in widespread use for several decades, involved some years ago a polymerization in a relatively volatile solvent, for example a light petroleum fraction. That was the drawback of this process, since in the separation and subsequent drying of the polymer formed the solvent could not be completely recovered. Problems are thus experienced in fulfilling environmental protection requirements. An additional obstacle was the large volume of aqueous waste that is generated during workup of the polymer suspension. 

Pokrovskii VN (1978) Statisticheskaya mekhanika razbavlennykh suspenzii (Statistical mechanics of dilute suspensions, in Russian). Nauka, Moscow. Available via http //ecodynamics.narod.ru/polymer/Suspension.pdf. Cited 1 Feb 2009 Pokrovskii VN (2005) Extended thermodynamics in a discrete-system approach. Eur J Phys 26 769-781... 

Prior to this discovery, in 1954 Silberberg and Kuhn (62) were first to study the polymer-in-polymer emulsion containing ethylcellulose and polystyrene in a nonaqueous solvent, benzene. The mechanisms of polymer emulsification, demixing, and phase reversal were studied. Wetzel and Hocks discovery would then equate the pressure-sensitive adhesive to a polymer-polymer emulsion instead of a polymer-polymer suspension. Since the interface is liquid-liquid, the adhesion then becomes one type of R-R adhesion (35, 36). According to our previous discussion, diffusion is not operative unless both resin and rubber have an identical solubility parameter. The major interfacial interaction is physical adsorption, which, in turn, determines adhesion. Our previous work on the wettability of elastomers (37, 38) can help predict adhesion results. Detailed studies on the function of tackifiers have been made by Wetzel and Alexander (69), and by Hock (20, 21), and therefore the subject requires no further elaboration. 

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