Intrinsic viscosity of a polymer and its density

Fog37 for discussing the properties of polymers and their relationship to viscosity and density. In summary, the two polymers mentioned have different intrinsic viscosity (IV) and there are various definitions of viscosity. While viscosity and density are generally considered independent properties, there is no direct correlation between the two. IV is a measure of a solute's contribution to the viscosity of a solution and is often used to compare molecular weights of the same polymer. It is unclear if a higher IV also corresponds to a higher density in the polymers being melted without a solvent.
  • #1
fog37
1,569
108
Hello Forum,

I have two polymers (both in pellet form). Their spec sheet shows that the two polymers have different intrinsic viscosity IV. There are so many definitions of viscosity (dynamic, intrinsic, inherent, etc.)

In general viscosity and density are two independent properties of a fluid. Surely most common substances that have high viscosity also have high density.Regardless, it seems that the two properties are not connected. One example: Some motor oil is more viscous than water but less
dense than water.

As far as IV (intrinsic viscosity): http://en.wikipedia.org/wiki/Intrinsic_viscosity
it is defined as s a measure of a solute's contribution to the viscosity of a solution...

I would like to understand if the polymer rated with larger IV also has a higher density than the other one. I am simply melting the polymers and not putting them into a solution with a solvent...

Thanks,
Fog37
 
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  • #2
Higher iv correlates with higher molecular weight. This them correlates with higher melt viscosity. Iv is usually used to compare molecular weights for the same polymer.

Chet
 
  • #3
Thank you Chet
 

FAQ: Intrinsic viscosity of a polymer and its density

1. What is intrinsic viscosity and how is it related to polymer density?

Intrinsic viscosity is a measure of the internal resistance of a polymer solution to flow. It is directly related to the size and shape of the polymer molecules, as well as the strength of intermolecular interactions. The intrinsic viscosity of a polymer is inversely proportional to its density, meaning that a higher intrinsic viscosity corresponds to a lower polymer density.

2. How is intrinsic viscosity measured?

Intrinsic viscosity is typically measured using a viscometer, which measures the flow rate of a polymer solution under a given pressure and temperature. The intrinsic viscosity is then calculated by comparing the flow rate of the polymer solution to that of a solvent with known viscosity. The difference between the two flow rates is attributed to the contribution of the polymer, allowing for the calculation of intrinsic viscosity.

3. What factors can affect the intrinsic viscosity of a polymer?

The intrinsic viscosity of a polymer can be influenced by a variety of factors, including molecular weight, temperature, and solvent type. Generally, as molecular weight increases, so does intrinsic viscosity. Higher temperatures can also decrease intrinsic viscosity, while certain solvents may increase or decrease the measured value. Additionally, the presence of impurities or additives can also affect intrinsic viscosity.

4. How is intrinsic viscosity related to polymer solution properties and processing?

The intrinsic viscosity of a polymer is directly related to its solution properties, such as viscosity, surface tension, and elasticity. It can also impact the processing of polymers, as higher intrinsic viscosity can result in thicker and more viscous solutions, making it more difficult to process. Intrinsic viscosity is an important parameter to consider when selecting and formulating polymers for various applications.

5. What are some common applications of measuring intrinsic viscosity and polymer density?

Measuring intrinsic viscosity and polymer density is important for understanding the physical and chemical properties of a polymer, as well as for quality control and product development. These measurements are often used in industries such as plastics, textiles, and coatings to ensure product consistency and performance. Additionally, intrinsic viscosity and polymer density can provide insight into the molecular structure and behavior of polymers, aiding in research and development efforts.

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