Rheologic modifier

In modem industrial practice, compositions often contain pigments, reinforcements, rheological modifiers, surfactants, and other materials in addition to fillers. These materials can function synergisticaHy in the system. Hence, more complex models are needed to predict the optimal filler loading. ExceUent discussions of filler loading and selection in plastics are given (9,10). 

Other. A large variety of additives are used in paper-coatiag colors primarily to modify the physical properties of the colors (102). At high soHds concentrations in water, mineral pigment particles tend to associate and form viscous pastes. Dispersants (qv) are used to prevent this and to provide low viscosity slurries. Common dispersants include polyphosphates and sodium polyacrylate [9003-04-7]. Various water-soluble polymers are added to coatiag colors and act as water-retention agents and as rheology modifiers. 

Other Applications. PEO has also been used as an antistat additive (178,179), water-soluble packaging material of seeds and fertilizers (180), and rheology modifier in aqueous flexographic printing inks (qv) (181). 

The net effect is that tackifiers raise the 7g of the blend, but because they are very low molecular weight, their only contribution to the modulus is to dilute the elastic network, thereby reducing the modulus. It is worth noting that if the rheological modifier had a 7g less than the elastomer (as for example, an added compatible oil), the blend would be plasticized, i.e. while the modulus would be reduced due to network dilution, the T also would be reduced and a PSA would not result. This general effect of tackification of an elastomer is shown in the modulus-temperature plot in Fig. 4, after the manner of Class and Chu. Chu [10] points out that the first step in formulating a PSA would be to use Eqs. 1 and 2 to formulate to a 7g/modulus window that approximates the desired PSA characteristics. Windows of 7g/modulus for a variety of PSA applications have been put forward by Carper [35]. 

To solve this problem, modern pesticide formulations use a variety of additives (adjuvants) to improve the mass efficiency. Surfactants and polymeric rheology modifiers are used to reduce spray drift, surfactants are used to modify surface tension and reduce... 

Schulz DN, Glass JE (1991) Polymers as rheology modifiers. American Chemical Society, Washington, DC, p 322... 

These materials have possible utility in a number of specialty applications and are being explored by Guan et al. [37], They have used these catalysts, and their unique chain-walking characteristics to synthesize a variety of dendritic materials (Fig. 4), which could find potential application as processing aids, rheological modifiers, and amphiphilic core-shell nanoparticles for drug delivery and dye formulation. 

Fig. 4 Dendritic materials made via chain-walking mechanism. Left processing aid, rheology modifier. Right ampiphilic core-shell...

Other NAD microspheres are composed of styrene, MMA, hydroxyethyl acrylate, acrylic acid and acrylonitrile and are blended with acrylic copolymers and melamine/formaldehyde resins [341,342]. Particles of this polymer are used as rheology modifiers to prevent sagging in automotive coatings and for controlling the orientation of metal flake pigments. 

Rheological modifiers (LD, DW, ADW, HC, FC) Improve flow properties of product, enhance consumer appeal, assist manufacturing Rheological behavior Clays Polymers Sodium silicate Sodium sulfate Solvents 0.5-2% 0.5-2% 3-15% 0-5%... 

A. Farooq, Rheological Modifiers for Aqueous Solutions, in G. Broze, (ed.), Handbook of Detergents, Marcel Dekker, New York, 1999. 

There are many other forms of clay including synthetic clays such as laponite, a synthetic hectorite. Suitable tuning of the properties of these systems can produce similar structures. These systems have the advantage of small particle size and a relatively improved level of particle monodispersity over their naturally occurring counterparts and are being increasingly used as rheology modifiers. 

The lack of mechanical strength for thermoplastic hyperbranched polymers makes them more suitable as additives in thermoplast applications. Hyperbranched polyphenylenes have been shown to act successfully as rheology modifiers when processing linear thermoplastics. A small amount added to polystyrene resulted in reduced melt viscosity [31]. (Sect> 3.1). 

Blends of poly (ethylene terephthalate) (PETP) and polypropylene (PP) with different rheological properties were dry blended or compounded, and extrusion foamed using both physical blowing and chemical agents, and the foam properties compared with those of foam produced from the individual components in the absence of compatibilisers and rheology modifiers. The foams were characterised by measurement of density, cell size and thermal properties. Low density foam with a fine cell size was obtained by addition of a compatibiliser and a co-agent, and foamed using carbon dioxide. The presence of PP or a polyolefin-based compatibiliser did not effect... 

The synthesis of various multi-arm star polymers has long been of growing practical and theoretical interest to a variety of industries. Star polymers have shown to be useful as surfactants, lubricants, rheology modifiers, and viscosity modifiers. Actually, star polymers are considered as viscosity modifiers and oil additives (15). 

G. D. Shay, Thickeners and rheology modifiers, in Paint and Coating Testing Manual, J. V. Koleske, ed., 14th edition of the Gardner-Sward Handbook, ASTM, Philadelphia (1995). 

Methacrylic acid and methacrylic esters are used in a wide variety of polymers with a broad spectrum of applications Polyl methacrylic acid) or Us neutralized salts are used as additives for detergent builders and rheology modifiers. Methacrylic osiers, lire most important ol which is melhyl nieihacrylale. yield hard. lough polymers in contrast lo the softer... 

WATER SOLUBLE POLYMERS. Water-soluble polymers find application in a wide variety of areas that include polymers as food sources, plasma substitutes, and as diluents in medical prescriptions. Other areas of importance for water-soluble polymers include detergents, cosmetics, sewage treatment, stabilizing agents in the production of commodity plashes, rheology modifiers in the various processes for petroleum, textile, paper, and latex coatings production. The water-soluble polymers discussed in this article have significant commercial impact. 

An important group of surface-active nonionic synthetic polymers (nonionic emulsifiers) are ethylene oxide (block) (co)polymers. They have been widely researched and some interesting results on their behavior in water have been obtained [33]. Amphiphilic PEO copolymers are currently of interest in such applications as polymer emulsifiers, rheology modifiers, drug carriers, polymer blend compatibilizers, and phase transfer catalysts. Examples are block copolymers of EO and styrene, graft or block copolymers with PEO branches anchored to a hydrophilic backbone, and star-shaped macromolecules with PEO arms attached to a hydrophobic core. One of the most interesting findings is that some block micelle systems in fact exists in two populations, i.e., a bimodal size distribution. 

---