Viscosity, resistance of a fluid liquid or gas to a change in shape, or movement of neighbouring portions relative to one another. Dunstan department of chemical engineering, university of melbourne, vic 3010, australia. In polymers like nylon it is also much sharper, with values in the region of 2. We present a general theory for the intrinsic viscosity of flexible polymers of arbitrary architecture. Density is a physical property of matter that expresses a ratio of mass to volume.
Intrinsic viscosity an overview sciencedirect topics. Environmental inorganic chemistry for engineers, 2017. The molecular mass distribution mmd is important for many physical properties of the polymer and is best expressed by a complete curve as shown in figure 28, obtained directly by a method known as gel permeation chromatography gpc box 5. For liquids, it corresponds to the informal concept of thickness. Dynamic viscosity of polymer solutions springerlink. Analysis of extensional viscosity for polymer melts by sentmanat extensional rheometer ser. The intrinsic viscosity iv is related to the molecular weight of the polymer through the markhouwink relationship 3. The viscosity of carbopol polymers will begin to decrease at a ph of 9. Intrinsic viscosity of polymers acs publications american. Due to their broad range of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Property a1535 a1536 linear linear tensile strength, mpa1,2 28 34 300% modulus, mpa1,2 7. Viscosity is a property in which an induced stress such as a pressure difference between the two ends of a tube through which the fluid is flowing is needed to overcome the internal friction to keep the fluid moving. Today, polymers are commonly used in thousands of products as plastics, elastomers, coatings, and adhesives. Viscosity control of pseudoplastic polymer mixtures for.
The increase in viscosity is caused by strong internal friction between the randomly coiled and swollen macromolecules and the surrounding solvent molecules. The viscosity of a fluid is a measure of its resistance to deformation at a given rate. The desired intrinsic viscosity of pet is dependent on its application and. Carbopol polymers must be neutralized in order to achieve maximum viscosity. The viscosity versus shear rate behavior for a range of temperature for low density polyethylene melts at a range of temperatures. Applications of rheology to polymers ta instruments. Shear viscosity, elongational viscosity, normal stress differences, stress relaxation, and some other measures and rheological phenomena, of relevance to polymer processing, are discussed. Additives in polymers plasticizer, thermal stabilizer, dye. The intrinsic viscosity is dependent upon the length of the polymer chains. Introduction the influence of temperature on the shear viscosity of polymer melts is usually expressed in terms of flow activation energy.
Singlefactor experiments were conducted to investigate the effects of ultrasonic energy on the shear viscosity. Determination of viscosity average molecular weight of. The addition of inorganic or organic fillers into polymeric materials is an effective way to attain certain desirable properties for different applications. It was observed that in many polymeric systems, the steady shear viscosity plotted against shear rate is correlated with the complex viscosity plotted. Viscosity is a tensorial quantity that can be decomposed in different ways into two independent components.
Shear viscosity of the cyclic olefin copolymer coc plasticized by ultrasonic vibration energy is characterized by high pressure capillary rheometer. The viscosity radius relationship for concentrated polymer solutions dave e. By measuring the solution viscosity we should be able to get an idea about molecular weight. The zero shear viscosity is a sensitive measure of polymer molecular weight. In the case of polystyrene it is proportional tom 0,65 which shows that. Pdf this chapter is devoted to the presentation of the fundamental rheological properties of polymers and their processing technologies. Physical properties of associative polymer solutions. Viscosity is an internal property of a fluid that offers resistance to flow. The dynamic viscosity of different long chain polymers in aroclor permits an easy extrapolation to zero concentration only in the limiting cases of newtonian, i. It was found that more rigid molecular structure results higher values. The friction factor from viscous flow and dynamic properties 335.
A basic introduction to rheology technology networks. However, it is still complicated, expensive and, more importantly, utilizes shear work to melt the polymer. Pdf viscosity study of salt tolerant polymers arne. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as dna and proteins that. At the meanfield level, these functions capture the longrange. The viscosity of polymers and their concentrated solutions.
They could even be oligomers or very long chain polymers. Polymers that are not highly crosslinked have properties that depend greatly on the forces that act between the chains. Two different plasticization modes were adopted to prepare the samples with an inhouse developed prototype machine. Branched plasticizersare more permanent than the equivalent but linear plasticizers, since branching tends to. From lab to production, providing a window into the process. Among these families, synthetic polymers, and more particularly coagulants and flocculants,are used mainly for facilitating the separation of materials in suspension in aqueous media.
Freeradical polymerizations of mma in acetone at 343 k were followed using insitu measurements of viscosity and density at different pressures from 7 42 mpa. Dynamic viscosity, also absolute viscosity, the more usual one typical units pas, poise, p. Understanding rheology of thermoplastic polymers ta instruments. A basic introduction to rheology rheology and viscosity introduction. Viscosity 5 viscosity coefficients viscosity coefficients can be defined in two ways. A consequence of these rearrangements is a decrease in.
This research investigates the physical properties of associative polymer solutions using. Inherent viscosity the effect of nylon on the viscosity of a solution of nylon and a solvent. General specification for rotational viscometers for the determination of the viscosity of polymers in the liquid or liquidlike state. The result provides a measure of the molecular weight of the nylon. Water soluble polymers cover a wide range of highly varied families of products of natural or synthetic origin,and have numerous uses. Knowledge of the resulting material function is of great importance in governing the dynamics and stability of polymer processing operations such as fiberspinning, filmblowing and blow molding.
High molecular weight polymers greatly increase the viscosity of liquids in which they are dissolved. Polymers intrinsic viscosity measurements for quality. Viscosity of a polymer solution depends on concentration and size i. However, when used in conjunction with other flow and physical property values, the solution viscosity of ethylene polymers contributes to characterizing the material. Although various studies show the violation of the noslip condition its effect on flow of colloidal particles in viscous media has been rarely explored. A high vi can be interpreted as meaning that a polymer increases the viscosity of the fluid without polymer proportionately more at high temperatures than at low temperatures. Assuming the polymers are spherical impenetrable particles, the increase in viscosity can be calculated with einsteins viscosity relationship. The rheological behavior is dependent on the amount of fillers in the liquid polymer. The theory is based on a partially permeable sphere model for which we introduce two phenomenological functions, the drag function. Extensional rheometry of polymeric fluids and the uniaxial. Miscibility, viscosity, density, and formation of polymers. Once a neutralizer is added to the dispersion, thickening gradually occurs. For polydisperse polymers, the simplest model to predict the viscosity of the system is to consider a mixture of monodisperse fractions whose viscosity can be obtained by a superposition procedure. Limiting high and low shear viscosities and the path of nonnewtonian flow may be consistently correlated for concentrated systems of linear, flexible polymers.
Maximum viscosity is typically achieved at a ph of 6. Kinematic viscosity is the dynamic viscosity divided by the density typical units m2s, stokes, st. In contrast to all of the above processing methods. Other factors influencing the viscosity of the highly filled polymers are the particle size and shape, the particle size distribution, the nature of the. Pdf effect of pressure on the viscosity of polymers. Determination of polymer melts flowactivation energy a. Viscosity data alone is potentially a limited value in predicting the processing behavior of the polymer. How polymers behave as viscosity index improvers in. Viscosity can be conceptualized as quantifying the internal frictional force that arises between adjacent layers of fluid that are in relative motion. Standard test method for dilute solution viscosity of. Blends of pmma and pcl require higher pressures than for the individual polymers for complete miscibility. Measurements and relevance in the injection molding of thermoplastics. The reciprocal of the viscosity is called the fluidity, a measure of the ease of flow. The viscosityradius relationship for concentrated polymer.
Viscosity and density measurement methods for polymer melts. Gt viscosity is a measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress. The aim of this research work has been the design, construction, and testing of a ram extruder for high viscosity polymers. Among these, the most commonly used technique is the uniaxial extension. They make up about 80% of the organic chemical industry with products produced at approximately 150 kg of polymers per person annually in the united states. Here we report unusually large reduction of effective viscosity. Pressure dependence of viscosity of polymers and its importance to. It was shown that shear viscosity and activation energy of flow of the polymers depend on the chemical structure. The technique used to perform iv measurements is described in astm d2857 and d4020. By way of example, consider a polymer such as polyethene which, in a normal commercial sample, will be made up of molecules having to 2000 ch, groups in continuous chains. Molasses, for example, has a greater viscosity than water.
1401 493 873 261 926 1529 960 1059 1185 298 929 672 1299 1108 1235 1144 173 1573 1175 382 302 1431 420 1324 910 39 572 104 1488 310 177 117 965 144 1088 1335 408 698