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The Theory Behind Dilute Solution Viscosity
In Layman's Terms

There are LOTS of ways to characterize polymers. 

As a process control measure, Dilute Solution Viscosity (DSV) leads the way.


Melt flow index (MFI) lets you know whether it will flow into the mold.

Chromatography (GPC/SEC) gives you molecular size distribution information.

Both methods are SLOW.  Neither offers the precision of solution viscosity.

How does DSV work?  Let the standards guide you.

ISO 1628 and ASTM D5225 spell out the details quite sufficiently. 

But they are highly technical. You want a simpler explanation?  Read on.

1)  Dissolve the polymer at a low enough concentration that polymer-polymer interactions are negligible. 

2)  Measure the viscosity of the solvent and the viscosity of the polymer under identical flow and temperature conditions.

3)  Let the software acquire the relevant data, run the calculations, and ensure that the system itself is performing according to minimum data quality standards before releasing the results to your database, LIMS or ERP systems.  

It seems we missed a few steps there.   Yes, the nitty-gritty details are less fun, unless you are an engineer, physicist or chemist.  Oh wait, that's you?   OK, OK... here's how it works:


 We determine the sample's relative viscosity by measuring the pressure differential across two capillaries with clearly defined and constant geometries.  First, using solvent in both capillaries.  Then using solvent in the first, and the sample solution in the second.  


Poiseuille's laws describe relationships between flow, pressure and viscosity.  There are hundreds of sites with the math(s).  Our software shows them.  And the manual has the calculations in there.  Need to see them?  Request a copy of the manual, all 86 pages of it.  But here's the gist:

The ratio of polymer solution viscosity to solvent viscosity is called relative viscosity. 


This is the core measurement of our viscometers.  Sounds simple.  But here's what's important:  

high speed

low shear

minimal solvent

extreme precision

temperature stability

flawless automation

Also important:  concentration.  More polymer, higher viscosity.

You can either run a dilution series and plot relative viscosity versus concentration OR you can run a single point low concentration sample and use one of various calculations to calculate Intrinsic or Inherent viscosity.

Inherent == Billmeyer

Intrinsic == Solomon-Gatesman

Multi-point == you are using someone else's instrument

Wait, what?  That's right.  If you have to make a multi-point measurement to ensure you are at a low enough concentration to properly run DSV, then you are probably using a glass tube viscometer.  

Glass tubes rely on a different measurement principle, and are less able to distinguish between solvent and ultra-low concentration viscosity samples.

Need any further details on how we go from polymer and solvent inputs to clean, repeatable and exquisite results with a minimum of effort and resources?  Just hit that "contact" button at the top of the page.  We're excited to share more.  

Model 575 IV Gen 2

Upset about our casual approach?  It takes a certain type to decide that it is a worthwhile use of resources and energy to copy/paste or ask AI to rewrite all the dozens and dozens of physical chemistry and rheology equations relevant to the DSV measurement.  

That's not us.  The team at Haiku are innovators.  We are modernizers.  We are focused on the critical-to-quality improvements that make our instruments what they are:

the fastest: 3x faster analysis than any other solution viscometer

the greenest:  minimum 50%, up to 80% reduced solvent use

the most reliable: [citation needed] seriously though, they're rock solid

The calculations are in the manual and are available linked via the software. 

The last thing the world needs is another webpage with copy/pasted math.  

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