Etiket Arşivleri: what is Rheology

Texture and Rheology

ABSTRACT:

Food rheology is the material science of food. Rheology is the science of flow and deformation of matter and describes the interrelation between force, deformation and time. In this experiment, the rheological behavior of solid pekmez with different solid contents (75.4, 71.6 and 67.1 Brixes) was studied in the temperature range of 10, 20 and 30°C using a controlled stress rheometer. Solid pekmez was found to exibit non-Newtonian behavior. However, diluted samples were Newtonian.

THEORY:

Rheology is the study of the deformation and flow of matter. In practice, rheology is principally concerned with extending the "classical" disciplines of elasticity and (Newtonian) fluid mechanics to materials whose mechanical behaviour cannot be described with the classical theories. It is also concerned with establishing predictions for mechanical behaviour (on the continuum mechanical scale) based on the micro- or nanostructure of the material, e.g. the molecular size and architecture of polymers in solution or the particle size distribution in a solid suspension.

Texture and Rheology v3

ABSTRACT

In the experiment of rheology the liquid sample’s textural characteristics have been measured. After calculations from datas the textural structre has been observed if it was newtonion or non newtonion type.Generally while measuring the rheological charecteristics, temperature was an important effective parameters. In non newtonion type of fluid there iare two type; time dependent and time independent. Also except temperature shear rate and time are the other effective parameters while measuring the flow of fluid.

THEORY

Rheology is defined as the science of deformation and flow of matter. The term itself originates from Greek rheos meaning to flow. Rheology is applicable to all types of materials, from gases to solids. The science of rheology is young, only about 70 years of age, but its history is very old. In the book of Judges in the Old Testament the prophetess Deborah declared “The mountains flowed before the Lord…”. Translated into rheological terms by professor M. Reiner, this expression means everything flows if you just wait long enough, a statement that is certainly applicable to rheology. It was also described by the Greek philosopher Heraclitus as “panta rei” – everything flows. Professor Reiner, together with Professor E. Bingham, was the founder of the science of rheology in the mid-20s. Rheology is used in food science to define the consistency of different products. Rheologically the consistency is described by two components, the viscosity (“thickness”, lack of slipperiness) and the elasticity (“stickiness”, structure). In practice, therefore, rheology stands for viscosity measurements, characterisation of flow behaviour and determination of material structure. Basic knowledge of these subjects is essential in process design and product quality evaluation.