EN ISO 3219 Rheology

The “ EN ISO 3219 Rheology” standard, which is based on a European standard and was subsequently published by the International Organization for Standardization (ISO) , consists of the following sub-sections published under the same title:

• EN ISO 3219-1 Part 1: Vocabulary and symbols for rotational and oscillatory rheometry describes common terms and definitions used in the context of rotational and oscillatory rheometry. Further terms and definitions are found in other parts of the ISO 3219 series where they are used.

For the purposes of this standard, the following terms and definitions apply:

• The absolute value of the complex shear modulus is the ratio between the amplitude of shear stress and the amplitude of shear strain. The absolute value of the complex shear modulus has units of Pascal (Pa).
• The absolute value of complex shear viscosity is the ratio of the complex shear modulus to the angular frequency. The absolute value of complex shear viscosity has units of Pascal (Pa) multiplied by seconds.⋅s).
• Amplitude sweep is an oscillatory test with variable amplitude at constant angular frequency.
• Angular displacement (angular deflection) is the angular measurement when the angle is expressed by the length of the arc. The unit of angular displacement is the radian.
• Angular frequency is the time course of change of angular displacement in oscillation. The unit of angular frequency is radians per second (rad).⋅s⁻¹) or, since rad is dimensionless (i.e., meters per meter), the reciprocal seconds (s⁻¹) is the unit.
• Angular velocity is the change in angular displacement over time during rotation. The unit of angular velocity is radians per second (rad).⋅s⁻¹).
• A continuous ramp is a type of test in which the specified variable changes monotonically and continuously from the initial value to the final value during the test. A continuous ramp is implemented with linear or logarithmic presetting. An alternative to a continuous ramp is a step ramp.
• Elastic behavior (elasticity) is the property of a material to exhibit reversible deformation and mechanical energy storage.
• The flow curve is a graphical representation of the relationship between shear stress and shear rate.
• Frequency is the number of oscillations per unit of time. The unit of frequency is hertz, where 1 Hz is 1 oscillation per second.
• Frequency sweep is an oscillatory test with variable angular frequency at constant amplitude.
• Ideal elastic behavior (Hookean behavior) is the property of a material to exhibit instantaneous, fully reversible recovery after deformation.
• The in-phase component of complex shear viscosity (dynamic viscosity) is the real part of complex shear viscosity. Dynamic viscosity has units of Pascal (Pa) multiplied by seconds.⋅s).
• Kinematic viscosity is the ratio of shear viscosity and density. Kinematic viscosity has units of square meters per second (m2)⋅s⁻¹).
• Laminar flow is flow in which infinitesimally thin layers are moving parallel to each other. All calculations of rheological parameters for absolute gauge geometries are valid only under the assumption of laminar flow.

There are rotational tests, oscillatory tests, and various step tests. Different tests can be combined. They can be performed using various types of measurements: controlled deformation, controlled rate, or controlled stress.

In the basic rotary test, the specimen is subjected to constant or variable loading in one direction. Shear viscosity is calculated from the measured data. Corresponding mechanical input and response parameters are listed in the tables provided in the standard. The basic parameters of the test can be schematically represented in terms of a two-plate model.

In the basic oscillatory test, the specimen is excited by an angular deflection or torque amplitude at a specific oscillation frequency. The resulting response oscillates at the same frequency and is characterized by an amplitude and phase shift. Relevant mechanical input and response parameters are listed in the tables provided in the standard.

Rheological properties are investigated using a measuring system consisting of a measuring device (viscometer or rheometer) and a measuring geometry (e.g., cone plate). A viscometer can only measure viscosity in rotation. This means that the viscosity function of a sample can be determined as a function of other parameters such as time, temperature, shear rate, shear stress, and pressure. A rheometer can perform all basic tests in rotation and oscillation. In addition to the viscosity function, viscoelastic properties, such as shear storage modulus and shear loss modulus, can be determined.

• The standard “EN ISO 3219-3 Part 3: Test procedure and examples for the evaluation of results when using rotational and oscillatory rheometry” is still in the development process.

Broadly speaking, rheology is the science of how materials flow and deform under applied forces. Essentially, it is the science of how materials respond to stress, particularly when they do not behave like ideal solids or ideal liquids.

The basic concepts in rheology are:

• Viscosity: Resistance to flow. For example, honey is more viscous than water.
• Elasticity: The ability of a material to return to its original shape after deformation.
• Plasticity: The ability of a material to deform and not return to its original shape.
• Shear stress and shear rate: Measures of how quickly the force applied and deformation occur.

Rheology mainly studies liquids (such as oils, syrups, blood), gels and pastes (such as toothpaste, ketchup), polymers and plastics, biological fluids and slurries and suspensions.

Rheology is critical in many industries. For example, in the food industry, it's important for texture and consistency (like spreading butter or pouring syrup), in the cosmetics industry, it's important for ensuring creams and lotions feel just right and are easy to apply, in the pharmaceutical industry, it's important for drug delivery (like how a gel spreads on skin), and in the oil and construction industry, it's important for understanding how crude oil or concrete flows.

Our organization, which has been supporting businesses across all sectors for years through a wide range of testing, measurement, analysis, and evaluation activities, has a strong team of employees who closely follow global developments in science and technology and are constantly improving themselves. In this context, we also provide testing services in accordance with the EN ISO 3219 Rheology standard.