Controlled rheology

CR grades are available both as homopolymers and copolymers. Copolymer-based CR grades for injection moulding flow well and are highly resistant to warpage and internal stresses. These grades find application in thin-walled packaging for food and 

---

Because of this interaction, PVP has found appHcation in surfactant formulations, where it functions as a steric stabilizer for example to generate uniform particle-size polystyrene emulsions (110—112). In a variety of formulations, a surfactant s abiHty to emulsify is augmented by PVP s abiHty to stabilize coUoids stericaHy and to control rheology. 

Inks. Refined kaolin is a common ingredient in a large variety of printing inks (qv). In addition to extending the more expensive polymers present, ka olin also contributes to improved color strength, limits the penetration of the ink into the paper, controls rheology, and improves adhesion. Kaolin for this appHcation must usually be as white as possible and free from oversize particles. Surface treated clays are used to improve compatibiHty with oil-based ink. Clays can also be an ingredient in the newer water-based or uv-cured inks. 

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Lederer, K., Beytollahi-Amtmann, I., and Billiani, J., Determination and correction of peak broadening in size exclusion chromatography of controlled rheology polypropylene,. Appl. Polym. Sci., 54, 47, 1994. 

A computer-controlled rheology laboratory has been constructed to study and optimize fluids used in hydraulic fracturing applications. Instruments consist of both pressurized capillary viscometers and concentric cylinder rotational viscometers. Computer control, data acquisition and analysis are accomplished by two Hewlett Packard 1000 computers. Custom software provides menu-driven programs for Instrument control, data retrieval and data analysis. 

Controlled release formulations, 7 551 pesticide formulations, 7 551-553 Controlled rheology, 14 275 Controlled stress viscometers, 21 736-737 Controlled structure polymeric betaines, 20 481... 

MC is used as an adhesive in ceramics to provide water retention and lubricity in cosmetics to control rheological properties and in the stabilization of foams in foods as a binder, emulsifier, stabilizer, thickener, and suspending agent in paints, paper products, plywood as a rheology control for the adhesive in inks, and in textiles as a binder, and for coatings. 

In the second stage, cross-link formation triggers phase separation, and further cross-link fixes the unevenly localized and deformed shape of particle. Thus, the red-cell-like particles are prepared during polymerization and not formed during isooctane evaporation. The red-cell-like particles find practically use for controlling rheological and optical characteristics in the coating and paint industry. 

VIGNETTE IV RHEOLOGY IN MANUFACTURING AND QUALITY CONTROL Rheology of Chocolate... 

Gooch (1997, 2002) emulsified fatty acids and oils and autoxidized them under greater than atmospheric pressure of oxygen or air to produce a network polymer or gel that did not flow after applying the emulsion to a surface and allowing the aqueous phase to evaporate. By this method, the viscosity and crosslink density was adjusted to control rheological properties, including viscosity and flow-out. 

Fig. 11.2 The effect of the PP controlled rheology (CR) or viscracking process on the viscoelastic grid each curve represents a PP macromolecular degradation path. [Reprinted by permission from R. C. Kowalski, Fit the Reactor to the Chemistry, in Reactive Extrusion, M. Xanthos Ed., Hanser, New York, 1992.]...

C. Tzoganakis, J. Vlachopoulos, and A. E. Hamielec, Production of Controlled-rheology Polypropylene Resins by Peroxide Promoted Degradation during Extrusion, Polym. Eng. Sci., 28, 170-180 (1988). 

Table 1 Influence of visbreaking on the fracture toughness (NIS according to 179/leA) and stiffness measured in bending after ISO 178, bending. of non-nucleated and / -nucleated grades. CR means controlled rheology, PI polydispersity. AH (a) is the melt enthalpy of the a-phase (2nd scan), AH(fi) that of the -modification (2nd scan), Tc is the crystallization temperature determined by DSC with the scanning program + 10/ - 10/ + lOKmur1...

Producers normally rely on only a few source oils indigenous to their geographic area or that can be imported economically. Soybean is the primary oil used in the United States while very little palm is consumed and none is produced. Canada s major oil is canola (low-erucic-acid rapeseed). Malaysia, Indonesia, and Central America are the largest producers and users of palm oil. Eastern Europe, like Canada, relies on low-erucic-acid rapeseed (LEAR), sunflower, and soybean oils. It is apparent from Table 3 that it is virtually impossible to formulate products with controlled melting and crystalline properties using only one of these oils. Even in areas where conditions and economics justify a variety of types, modification methods other than blending are essential to adequately control rheologic properties. 

Fig. 1 Application field and dosage of organic peroxides for the production and processing of polymers ( Controlled rheology)...

Controlled degradation Controlled breakdown of to low-polymer or monomer Controlled-rheology polypropylene via peroxide reaction controlled M of PET polymers... 

Common peroxide degradants and stabilizers used in controlled-rheology reactive extrusion are shown in Table 17.2 and 17.8 of Fink (2005). 

The predominant system for controlle-rheology reactive extrusion is polypropylene (PP) with systems such as ultrahigh-melt-flow polypropylene, high-impact polypropylene blends... 

From R D to quality control, rheology measurements for each phase of the product development life cycle involve raw materials, premixes, solutions, dispersions, emulsions, and full formulations. Well-equipped laboratories with stress- and strain-controlled oscillatory/steady shear rheometers and viscometers can generally satisfy most characterization needs. When necessary, customized systems are designed to simulate specific user or process conditions. Rheology measurements are also coupled with optic, thermal, dielectric, and other analytical methods to further probe the internal microstucture of surfactant systems. New commercial and research developments are briefly discussed in the following sections. 

Himont polypropylene (controlled rheology type with a melt... 

Low viscosity and controlled rheology and flow give smooth coatings with good gloss. 

Liquid Latex. [Rhone-Poidenc/Perf. Resins Coatings] Polyvinyl acetate used in dl well cementing a >plics. fw fluid loss control, rheology modificadon, inqMXwed bonding. 

---