Relation between thermal expansion and density in Polymers

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Discussion Overview

The discussion revolves around the relationship between thermal expansion and density in polymer materials, specifically examples like PMMA and Teflon. Participants explore whether there are established laws or equations that connect these properties, as well as the potential relationship between thermal expansion and refractive index.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires about a direct relationship between thermal expansion and density in polymers, similar to the Lorentz-Lorentz law for refractive index and density.
  • Another participant presents an equation relating the coefficient of volumetric thermal expansion to density, suggesting it may address the initial inquiry.
  • A follow-up question asks if there is a relationship between thermal expansion and refractive index, seeking relevant equations.
  • One participant expresses uncertainty about the existence of a relationship between thermal expansion and refractive index, suggesting that polymer science texts may provide answers.

Areas of Agreement / Disagreement

The discussion does not reach a consensus on the existence of a relationship between thermal expansion and refractive index, and participants express differing levels of knowledge on the topic.

Contextual Notes

Some assumptions about the relationships between properties may be missing, and the discussion does not resolve whether specific equations or laws apply to the materials in question.

sjumesh
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Hello all,
Is there any direct relation ship exists between the thermal expansion and density of polymer material (eg. PMMA, Teflon) ?
Like, Lorentz- lorentz law relates directly the refractive index and density of the polymer.
similarly any laws relating (thermal expansion and density of polymer)or ( thermal expansion or refractive index) exists ?

please guide me.

Thanks in advance
 
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Yes. The coefficient of volumetric thermal expansion of any material is related to its density by:

$$\alpha=-\frac{1}{\rho}\left(\frac{\partial \rho}{\partial T}\right)_P$$

Is that what you're asking?

Chet
 
Dear Chestermiller,

At first, thank you for your message.
Yes, i was asking for these equations. And, also is there any relationship between the thermal expansion and refractive index of material.
Any equation relating thermal expansion and refractive index of material.

Can you suggest me any books or materials to study.

regards,
Umesh.S
 
I
'M not aware of such a rrlationship, but I'm not an expert. Any text on polymer science should answer your question.

Chet
 
Dear Chestermiller,

Thank you for your reply.
i will look in the polymer science for further details.

regards,
Umesh.S
 

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