Pressure / temperature realtionship in polymers

[Colnago]

Hi, these is possibly a dumb question but...

I know that with regards to gases: (P1*V1)/T1 = (P2*V2)/T2

However does this still apply to polymers in liquid state?

In an injection moulding machine if I increase the pressure will you get an increase in temperature if the volume of material is constant?

Thanks.

 

[Studiot]

No it's not a dumb question
No solid and semi solid materials do not obey the gas laws
but yes they will increase in temperature if you pressurise them whilst at the same time confining them.

The ultimate example of this is what happens to rocks at great depth (and pressure) in the earth.

There is I'm sorry to tell you, no simple relationship between temperature and pressure for these materials.

 

[johnbbahm]

Safety comment, Plastics need to be VERY dry when heated and used in compression
molding or extrusion. The water vapor does obey the gas law, and will at best create
foamed plastics.

 

[Studiot]

Safety comment, Plastics need to be VERY dry when heated and used in compression
molding or extrusion. The water vapor does obey the gas law, and will at best create
foamed plastics

Worthwhile comment.

 

[alphy]

Hello,

No, the relationship between pressure and temperature in polymers is not the same as in gases. In polymers, the pressure and temperature relationship is more complex and is affected by factors such as molecular weight, polymer structure, and processing conditions.

Increasing pressure in an injection molding machine may cause an increase in temperature, but it is not a direct relationship. The temperature increase would also depend on the type of polymer being used, the mold design, and the processing parameters.

In general, increasing pressure in a polymer will cause an increase in temperature due to the conversion of mechanical energy into thermal energy. However, the exact relationship between pressure and temperature in polymers is not as straightforward as in gases.

I hope this helps to answer your question. If you have any further inquiries, please let me know. Thank you.