The R/S Plus Soft Solids Tester is a controlled rate/controlled stress rotational rheometer featuring vane spindles designed to measure “lumpy” or viscoelastic materials and is ideal for characterizing gels, pastes and slurries because of its ability to preserve sample structure with the use of vane spindles. Controlled stress tests provide important information on startup flow behavior (viscoelasticity, yield stress and creep).

R/S Plus Soft Solids Tester

Features & Benefits

Vane spindle geometry allows spindle insertion without compromising sample structure
Easy-to-test method for materials with particulates, slurries, and stiff pastes
Provides data that relates to viscoelastic characteristics such as yield stress, shear modulus (stiffness of material structure when intact) and creep
Quantifies meaningful properties like wobbliness, sloppiness, consistency and texture
Automated data analysis under PC control
Rugged design for years of trouble-free operation in QC and R&D applications
Can also be used with coaxial cylinders for flow curve analysis
Optional Rheo3000 software with Soft Solids Module allows you to program the R/S Plus Soft Solids Tester and generate data such as yield point, shear modulus, creep and relaxation

Principle of Operation

The flow properties of these materials are not easily measured using traditional coaxial cylinder or cone & plate equipment. Vane spindle geometry provides a solution. The vane spindle is lowered into the test sample with minimal disruption. The test is easily run in the sample's original container.

There are two significant Test Methods easily accomplished by the Soft Solids Tester:

Constant Rate Yield Test

For Products Like

Stiff pastes, slurries, set gels, waxes

Properties Measured

Yield Stress, Yield Strain, Modulus

Test Description

This is a Constant Shear Rate Test. The vane is rotated at a constant low rotational rate and the Stress (torque) is measured against Time, Rotational Angle or Strain.

Example Method for Mayonnaise

Constant Rotation at 0.2 rpm, 60 data points are taken in 60 seconds

Typical Results Plot
The Creep/Recovery Test

For Products Like

Gels, lumpy products like custard, gravy, sauces and jams

Properties Measured

Instantaneous Strain, Viscous Creep, Elastic Recovery, Permanent Flow

Test Description

This is a Constant Stress Test. The Stress (torque) is applied to the sample for a fixed time period, usually from one to five minutes. The degree of sample movement is recorded against time as Angular Displacement, Strain or Compliance. The Stress is removed and the Elastic Recovery and Permanent Flow is determined.

Example Method for Fruit Preserves

Constant Stress of 1,250 Pa is applied over 120 seconds and 60 data points are taken. The stress is then removed and 60 data points are taken for another 120 seconds.

Typical Results Plot