Polymer Testing Newsletters

2008 marks the 10th year of business for Fleming Polymer Testing and consultancy.  Arguably one of the most dramatic changes is in flow simulation. What was once considered the preserve of academics is now a reality for almost everyone.  We can now simulate almost all extrusion processes, from cable coating to film blowing, to multilayer extrusion to complex profile production.  When in 2005 Fleming PTC took on the Compuplast distributorship, it made a complimentary addition to the business portfolio. The materials testing via capillary rheometry was ideally placed to provide the crucial shear and elongational viscosity data, and with the addition of DSC, the only parameter which can't be measured in-house is thermal conductivity...watch this space!

The other notable achievements were the completion of a prestigious DTI SMART award and ISO9001:2000 registration.  The former £60,000 award saw the business funded to produce a coextrusion option for a twin bore capillary rheometer.  This patented system enables two dissimilar polymers to be coextruded on a capillary rheometer and their physical compatibility to be assessed.  Work on the elasticity part of the award continues.

ISO9001:2000 registration was also a very important award and serves to provide confidence that all areas of the business are monitored, not only in terms of the technical aspects, but also those of business and administration.  The business is monitored both internally by an independent auditor and externally by the NQA.  Despite registration taking at least 12 months to obtain, the ongoing improvemnts to the business have proved to be beneficial.

In terms of the future, it will be interesting to see how the flow simualtion side of the business will develop via Compuplast, and from what we have seen so far it will be exciting.  It may be that several of the individual programs will be linked in some way to represent an entire production line made up of for example, extruder, spiral mandrel die and down stream calibration and cooling.  Currently, these exist as stand-alone programs, but it is likely they may be joined in some way. We will be sure to keep all informed of progress.

In terms of additional complimentary techniques which can be of use to the polymer industry FlemingPTC is always on the look out, so if you feel there is an area you want to investigate, let us know.

The paper 'Capillary rheometry-a technique sensitive enough to assess the radiation tolerance of polypropylene' was presented by Don to great interest from the attendees. The work had been conducted with one of the business's oldest medical device clients and showed how, even in supposedly radiation resistant PP grades, embrittlement could still be achieved.  This was corroborated by capillary rheometry tests using polymer from sterilised and non-strilised products following product failures post-irradiation. The findings suggested that in sections of low thickness, the proportion of anti oxidant availble to effectively 'mop up' the free radicals created via radiolitic reactions, was insufficient to prevent chain scission.  It is this chain scission which in turn results in the dramatic viscosity rediuction and subsequent embrittlement.  Clearly a way of avoiding the problem is to reduce the dose and/or dose rate, however, this is not always possible.  An alternative solution is to substitute the polymer used in the said part; in this case it was shown that by using the inherently radiation resistant HIPS, provided such a solution.  For further details, please request a copy of the paper or look on the website.

Following a request from a customer the gas switching facility has now been added to the TGA. The figure shows the marked change in slope, and increased mass loss rate as the purge gas is changed from nitrogen to air.  The system was being used to investigate the degradation of a polyethylene film and was crucial in gaining an understanding of the oxidation behaviour. Now the gas switching capability has been introduced, different gasess can of course now be used, so if you have a system you need investigating, don't hesitate to call.