This dataset consists of shear-mechanical data taken on
Polyisobutylene (PIB680)

These data were published in : 
Bo Jakobsen, Kristine Niss, Claudio Maggi, Niels Boye Olsen, Tage
Christensen, and Jeppe C. Dyre Beta relaxation in the shear mechanics
of viscous liquids: Phenomenology and network modeling of the
alpha-beta merging region . Journal of Non-Crystalline Solids,
357:267, 2011. 

All experimental information can be found in this paper.

This electronic version of the data was published on the
"Glass and time - Data repository" found at http://glass.ruc.dk/data

The authors have copyright to these data. 
The authors have given permission to "Glass and Time" to publish the
data on the "Glass and time - Data repository" web site. 

You are very welcome to use the data for further analysis, but
are requested to cite the original publication whenever use is made of
the data in publications, presentations, etc. 

Any questions regarding the data can be addressed
to boj@ruc.dk who would also appreciate a mail if you find the data useful.

____________________________________________________________________
The data format is defined as described below:

The raw shear mechanical data are found in the directory
      Polyisobutylene_PIB680_shear	

     The directory contains 4 data files:
     Temp.dat : the temperatures in Kelvin 
     Fr.dat   : the frequencies in Hertz 
     Im.dat   : the imaginary part of the shear modulus in GPa
     Re.dat   : the real part of the shear modulus in GPa 

     The last two files contain the data. Each column corresponds to a
     temperature, each row corresponds to a frequency. 

     For example: Re(n,m)+i*Im(n,m) is the total complex shear modulus at
     temperature Temp(m) and frequency Fr(n), for the shear data 

     If a value in one of the data arrays is 0, it means that no data is
     taken at this frequency/temperature. 

     Beside the data files, plots of the data exist as png images for
     reference. 

Beside the raw data the fitting parameters from fitting Eq 7 (in the
original paper) to the PIB data are given. 

The results are found in the directory Fit
     Eq7.png : The equation
     pib_fit_eq7.dat : The data file

     Beside this figures of the varying parameters exists. 

     The format of pib_fit_eq7.dat is one row per temperature with the
     following contents:
     [T G_inf tau_alpha q alpha G_beta tau_{beta,j} beta]
     Notice that alpha, q, beta are keep fixed in this fit, see the
     original paper for details. 

	   Last edited September 2010, Bo Jakobsen