Part 1 Practical Rheology Contents Page1. Introduction 22. Special Characteristics of Dispersions And Emulsions 63. Three Schools of Rheological Thinking 94. Thinking Rheo-logically 125. Definitions 146. Types of Flow Behavior 197. Characterization of Non-Newtonian Flow: 27 Mathematical Models and Experimental Methods8. Viscometry; Instrumentation and Use 499. Summary 6410. Symbols and Abbreviations 6511. References 67 1
2 Rheology Modifier Handbook 1. IntroductionIn the first section of Part 1 we introduce the basics of PracticalRheology. This includes examples of products and processes thatemploy rheological measurement as well as a concise summary ofASTM viscosity test procedures describing the characterization of abroad range of materials.The second section of Part 1 describes the more common types of flowbehavior. This includes methods for measuring rheological propertiesand describing complex flow behavior with a minimum of usefulparameters. The use of such tools and techniques allows rheologicalmeasurement to be used as an effective tool for the characterization of abroad range of industrial fluids. The discussion concludes with adescription of several of the more common viscometers.Appendix A contains a partial listing of viscometer manufacturers andcontact information as well as some of the viscometric instruments theymanufacture.A wide variety of useful industrial products and processes require tailor-made flow properties as an integral part of product performancerequirements. Effective control of such properties relies heavily on aknowledge of the effect of formulation and process variables as well asan ability to measure and characterize meaningful flow propertyinformation. Rheology modifiers play a significant role in achievingdesirable flow characteristics and this handbook describes the propertiesof all the major types as well as their practical use and application.Examples of some of the wide variety of products and processes whichrely on rheological characterization include food products,pharmaceuticals, biological fluids and a host of miscellaneous materials.In the food category, rheological phenomena are important for tomatojuice, dehydrated potato granules, soft serve ice milk andmicrocrystalline cellulose thickeners. Also included in this category aresingle cell protein concentrates, milk coagulation, chocolate, dressingsand sauces. In the biological area, work has been done on blood, serum,exocrine secretions, sweat, duodenal fluid and synovial fluid.
Practical Rheology 3Among the many miscellaneous applications for rheology we findasphalts, hevea latex, aerated poultry waste and livestock slurrycharacterization. The list continues with color cosmetics, lubricants, claygellants, black liquor (paper processing) and ceramics. Also included areone-fire glazes, enamel slips, thick film ceramic pastes and dentalimpression materials. Other examples include solder paste, molten glass,high titanium oxide slags and blast furnace slags. Coconut oil liquidsoaps are also characterized rheologically as well as vinyl plastisols,urethane foam prepolymers, inks, paper coatings, high solids coatingsand solvent based coatings.The American Society of Testing Materials (ASTM) has providedstandards of control and testing for many years. The use of PracticalRheology is clearly evident in the breadth and scope of the kinds ofproducts and processes which benefit from rheological characterization.One of the authors is a member of several standards-making committeesand is well apprised of the wide variety of industry specialists involvedin setting up useful, working standards. While the individual reader ofthis work may be specifically focused upon a certain industry, or type ofproduct, the authors feel that a succinct overview of the kinds ofmaterials which have benefited will be of value in setting the stage forgenerating a powerful view of what Practical Rheology is and can be.In the Petroleum field the ASTM provides tests for testing of rubberizedtar (D 2994-77), and coal tar (D 1665, D 1669-51 and D 5018-89). In theheavy petroleum end there are tests for unfilled asphalts (D 4402-87),asphalt emulsion resins (D 4957-95) and asphalt roof coatings (D 4479).Other rheological tests in the asphalt area include D 2170, D 3205,D 3791-90, D 244, D 2161 and D 4957. Bitumen rheology tests for non-Newtonian systems are described in D 4957. Testing of lubricatinggreases (D 3232-88), aircraft turbine lubricants (D 2532-93) and engineoils (D4684) are also covered as well as roofing bitumens in D 4989-90.ASTM has tests for hydrocarbon oils such as fuel oil pumpability(D 3245), lubricating oils (D 2270) and engine oils (D 5133 and D 5293).Testing of hydraulic fluids is described in D 6080 and automotive fluidlubricants are tested in D 2983-87. Oil standards are described inD 2162.
4 Rheology Modifier HandbookRubber testing in the carbon black industry is conducted using D 4483,rubber latexes in D 5605 and D 1417. SBR latexes are covered in D3346 and prevulcanized rubber testing in D 1646. Ammonia-preserved(concentrated) creamed and centrifuged natural rubber latex testing isdescribed in D 1076-88 while rheological testing of synthetic rubberlatexes is described in D 1417-90.The field of polymers has numerous ASTM tests for characterization andcontrol. Some of these include tests for Hydroxyethylcellulose (D 2364-85), Ethylcellulose (D 914-72), Sodium Carboxymethylcellulose (D1439-83), and Hydroxypropylcellulose (D 5400-93). Hydroxypropyl-methylcellulose testing is shown in both D 3346-90 and D 2363.Polymer-containing fluid testing is described in D 3945 while tests forpolyols are shown in D 4989-91. Polyethylene terephthalate rheologytesting is described in D 4603-96 and epoxy resin evaluation is describedin D 2393-86. Polyamide rheology testing is covered in D 789.Common products such as chemical grouts are evaluated rheologically inD 4016-81 as are printing inks and their vehicles (D 4040-96), grout forpre-placed aggregate concrete (C 939-87) and glass, above its softeningpoint (C 965-81).Paint testing is covered in D 1084-88 and D 562-81. Varnishes forelectrical testing are described in D 115-85 and emulsion polymers forfloor polishes are covered in D-3716-83. Liquid-applied neoprene andchlorosulfonated polyethylene in roofing water proofing is described inD 3468-93.Adhesives testing is available in D 1084-88 and D 4300-83. Testing ofhot melt adhesives is described in D 3236-88 and hot melts made frompetroleum waxes with additives are covered in D 2669-87. Mold powdertesting above the melting point is shown in C 1276.Miscellaneous rheological testing is available from the ASTM for tall oil(D 803), clear liquids (D 1545), crude or modified isocyanates forpolyurethanes (D 4889-93), volatile and reactive liquids (D 4486-91) andplastisols and organosols (D 1823 and D 1824). Still other ASTMrheology tests exist for solid propellants, starch and solder paste.
Practical Rheology 5Having reviewed the host of rheological testing described by the ASTM.One can see the great value of rheology evaluation across a broadspectrum of industries. We turn our attention now to the use of rheologyin the cosmetic and toiletry industry. Most of the products on the markettoday in this market are emulsions (either of the oil-in-water or water-in-oil types), aqueous suspensions or a combination of the two. Many skincare creams and lotions are oil-in-water emulsions, while liquid makeupformulations are suspensions of pigments in an oil-in-water emulsion.Antidandruff shampoos are usually suspensions. Certain organosiliconesare highly effective dispersants for pigments used in color cosmetics.