Soft rubber compounding

[AzizolWahab]

Hi everyone,

I am trying to help my colleague on this issue. He developed a very soft EPDM compound (approx. 25 Mooney) by using 1.6 liter Banbury (tangential) and able to reach dump temperature of 130C around 10 minutes (with 90% fill factor).

However, when he tried the same on a bigger equipment, 91 liter K4 (intermeshing), he could not reach the dump temperature within the same time (took longer, almost double the Banbury time). By the way, he converted the fill factor for K4 = 0.85 (Banbury fill factor). He need to reach the dump temperature within 7 - 8 minutes to suit factory process requirement.

Any suggestion? Thanks.

 

[tom1953]

Increase the batch size a little? Very soft compounds probably have a lot of plasticizer which doesn't use up as much volume as polymer, so higher batch sizes are often needed.

 

[GrahamBennett]

Hi Azizol. Hope all is well with you and your family.

Soft compounds are notoriously bad for mixing as they rarely get very high in temperature.

Tom is right. Your colleague should try a 0.90 fill factor. If possible, increase the temperature of the cooling water to around 70°C as well to slow down heat extraction from the mix.

forumtowers.com

 

[AzizolWahab]

Thank you both Tom and Graham,

Will suggest that to him. Previously I suggested to him to increase rotor speed RPM and TCU (temperature) but seems there is restriction as factory would like to maintain existing setting as much as possible (existing compound is based on same rubber type but different manufacturer/ supplier).

I didn't say anything about fill factor yet since he is following that 0.85 conversion. Anyway now I got this suggestion from both of you I would ask him to try this too. He is going to run another trial at the factory next month, so let see.

Note: Hi Graham, long time since we last communicate. Hope you are keeping well. Keep in touch.

 

[GrahamBennett]

Oh dear - another company that likes to change compounds around to suit existing mixer parameters instead of the other way round. I like your idea of increasing the rotor speed AW. Get him to try that too. If it works then his company will just have to accept a change in parameters for that particular compound.

forumtowers.com