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A new and quicker chromatographic
method for determination of xylene soluble content
of crystalline polymers like Polypropylene (PP)
has been developed. The proprietary Viscotek
Fipa technique is based upon a fast chromatographic
means of separating polymers from the low molecular
weight matrix of additives, monomers or solvent
they may be mixed with, employing triple detector
technology. The Fipa technique yields precise
and accurate average molecular weight, molecular
size, intrinsic viscosity and data on branching
or copolymer composition in only a few minutes,
without the need for elaborate sample preparation.
In a report, the authors compare
the Viscotek Fipa experimental procedures with
the traditional gravimetric method used to determine
xylene solubles in process polymers. The xylene
soluble test is designed to measure the amorphous
content of polypropylene and ethylene-propylene
rubber materials. The accuracy and precision
of the xylene soluble test are very important
to the process and product specifications of
the resultant materials.
Using an ethylene-propylene
rubber polymer, identical samples were analyzed
by both the gravimetric and Viscotek Fipa methods.
A correlation factor of 0.9998 shows a high
degree of agreement between the results obtained
by the two methods. The report demonstrates
the speed, accuracy, precision and additional
molecular weight/intrinsic viscosity information
advantages offered by the Viscotek Fipa technology
that are driving many polypropylene producers
and catalyst research organizations to adopt
the new technique as their preferred method.
When compared to the open vessel
operation of the gravimetric method, Viscotek
says the Fipa technique offers additional health
and safety benefits. Even in laboratories with
a moderate sample load, the time and labour
savings made compared to the traditional method
can easily pay for a system in less than one
year.
The Fipa system operates up to 80C - allowing
screening of most polymers including polycarbonates,
polyacrylates, olefins, rubbers, polyamides,
polystyrene and polyvinylalcohol.
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