rFinder - Search FunctionalityAll of this information is accessible through the

rFinder interfaceA rheology search engine;

• just type to search

This includes:

▪ rSpace standard sequence

▪ Your own customer sequences

▪ rSpace recorded data

▪ Data chart & table templates

▪ Rheology application notes

Viewing Data in Tables

Table templates can be

opened to view the

data in a similar way to

the charts

Search for results data in rFinder for typical views

rFinder can be used to view other data such as model fit

coefficients

▪ Simply search for the appropriate template

Editing Charts

Charts can also be edited with the Properties box

Variables are categorised for

easy navigation

▪ Basic contains the common variables

▪ All, contains everything, even the variable field that are unfilled;

useful for setting up templates in advance

Making Analysis Easy

Any open analysis can be applied by the

same method

Remember, all sequences can be edited

Any sequences that are copy/pasted or saved in the User

Analyses are available with a right click on a data graph

▪ Just go to the Analyse menu

Model Fitting

rSpace comes with a large

selection of model fits

▪ Simply search for Analyse

in rFinder

To run a model fit, simply run analyse sequence

▪ Open the sequence and leave it in the background

▪ Open the data in a chart, and select the data

• Ensure that the mode is set to Point selection mode by right clicking

• Then goto Measure, Start Sequence and select the Analyse Sequence

Model Fitting

Model fitting can help to describe the shape of a flow curve using fitting parameters.

Parameters can be used for direct comparisons between products

Fit Models :

Ellis Model,

Newtonian Model,

Power Law Model,

Casson Model,

Sisko Model,

Moore Model,

Arrhenius Model,

Maxwell Model,

Herschel-Bulkley Model,

Bingham Model,

Linear Model,

Non-linear Model,

Polynomial Model…

Different Processes, Different shear rates!

SAMPLE STORAGE

Very low shear rates/stresses: ~ 0.001s-1

How stable is it? sample quality, perception

Storage

End use

SAMPLE DELIVERY

Medium shear rates: ~10-1000s-1

Pumpability? Scoopability?

SAMPLE APPLICATION 1

Low to high shear rates: ~1-100s-1

Flows away? Flows off hand? Spreads easily?

RUBBING

Higher shear rates: ~1000-10000s-1

Too thick to spread? Nice feel?

Viscometry test – Two Hand Creams

STORAGE

RUBBING

DELIVERY

APPLICATION

Data becomes more relevant when you know

application shear rate

What is the right shear rate?

Process Typical shear rate range (s-1)

Reverse gravure 100,000 - 1,000,000

Roller coating 10,000 - 1,000,000

Spraying 10,000 - 100,000

Blade coating 1,000 - 100,000

Mixing/stirring 10 - 1,000

Brushing 10 - 1,000

Pumping 1 - 1,000

Extrusion 1 - 100

Curtain coating 1 - 100

Levelling 0.01 - 0.1

Sagging 0.001 - 0.1

Sedimentation 0.000001 - 0.0001

Measurable

on a Rosand

capillary

rheometer

Faster processes,

squeezing

materials through

smaller gaps

Measurable

on a Malvern

rotational

rheometer

Model Fitting

Model fitting can help

to describe the shape

of a flow curve using

fitting parameters.

The appropriate

model fit will depend

on the material type

and range of data

available.

Models can give information on extent of shear thinning and an

estimation of limiting viscosities at high and low shear rates.

Parameters can be used for direct comparisons between products

η0

η∞

Model Fitting Parameters

mK )(1

1

0

+=

−

−

nk =

+= nk

CROSS MODEL

POWER LAW MODEL

SISKO MODEL

η0 is the zero shear viscosity

η∞ is the infinite shear viscosity

K is the Cross constant

m is shear thinning index

n is power law index

k is consistency index

These model fits are commonly available

in most rheological software packages

Power law model

Power law model can be used to help quantify a materials response

to shear.

▪ k is numerically equal to viscosity at 1s-1

▪ n tells us how shear thinning (0 = infinite; 1 = Newtonian)

Important to check

that correlation

coefficient suggests

a good fit (r > 0.95)

Mapping Performance

Same map can be used to compare between specific formulations or competitor products to optimise performance

Spreadability

Shear rate increases as film thickness reduces so spreading cannot

be attributed to a specific shear rate.

Power law model is therefore better for describing

spreading.

The lower the stress input required the easier to

spread.

nk =

Lower k means lower viscosity and hence lower stress input

Lower n, means more shear thinning which translates to a smaller

stress increase at higher shear rates.

THICKNESS

VELOCITYRATESHEAR =

Product comparison

Water and Syrup are both

Newtonian but water is

much thinner and easier

to spread.

Honey and body lotion

have similar consistency

index but body lotion is

more shear thinning and

easier to spread

For easier spreading follow the green arrow!

For thicker coating go the other way!

Bingham and Herschel-Bulkley Models