|
PHYWE Viscosity of Newtonian and Non-Newtonian Liquids |
Learn about:
- Shear stress
- Velocity gradient
- Internal friction
- Viscosity
- Plasticity
There are many ways to measure viscosity, including attaching a torque wrench to a paddle and twisting it in a fluid, using a spring to push a rod into a fluid, and seeing how fast a fluid pours through a hole. This experiment uses a variation of a spring method. When a thin film of a liquid is held between two parallel surfaces, moving the surfaces relative to each other requires the application of force. The liquid layers that are directly adjacent to each of the surfaces are held to them by forces of adhesion; and forces of cohesion act amongst the molecules of the liquid. On movement, a linear velocity gradient is formed within the liquid between the two surfaces. When the distance between the two surfaces is dx and the difference in velocity is d, then a force F is required to move the liquid layers. F= nA (dv/dx). This force is proportional to the area A and the velocity gradient d /dx. The factor given here is the dynamic viscosity. The quotient F/A gives the shearing stress T. The relationship for is T= (dv/dx), where A is the area of contact between the plate and the liquid and is the viscosity of the liquid and dv/dx is the velocity gradient.
In this experiment the viscosity of the liquid is determined with a rotation viscometer. A motor with variable rotation speed drives a cylinder immersed in the liquid to be investigated. The viscosity of the liquid generates a moment of rotation at the cylinder which can be measured with the aid of the torsion of a spiral spring. Torque on the spring may be read on a scale.
Use this experimental setup to:
1. Determine the gradient of the rotational velocity as a function of the torsional shearing stress for two Newtonian liquids (glycerine, liquid paraffin).
2. Investigate the temperature dependence of the viscosity of Castor oil and glycerine.
3. Determine the flow curve for a non Newtonian liquid (chocolate).
Includes 500 ml of castor oil; 250 ml of liquid paraffin; 500 ml glycerol; required glass rod and beakers; separator f magnetic bar; magnetic stirring bar; EKT Hei-Con electronic temperature controller; support rods; spring balance holder; Hei-standard magnetic stirrer; clamp; 3-6,000,000 mPas 110-240 V rotary viscometer; and instructions. Requires, but does not include 750 ml acetone.
For your convenience this experiment is available to you as a complete set.
Everything you require to perform the activities are included in the total price.
For assistance in using your new equipment we also offer professional development (WLS1808-24) on all PHYWE line products.
For customization options and pricing please contact your local Cenco representative.
 (0
customer reviews)
|
Customer Reviews
|
 and share your thoughts with other customers
|
|
|
|
|
