How to Purge Silicone and Flexible Materials Without Thermal Degradation (Low-Temperature Processing Guide)
- UniTemp
- a few seconds ago
- 3 min read
Silicone, EPDM, and other flexible materials introduce a unique challenge in plastics processing: they do not tolerate heat mistakes.
Unlike standard thermoplastics, these materials:
degrade quickly when overheated
trap residue in screws and barrels
leave behind contamination that impacts the next production run
If your purge process isn’t dialed in, the result is predictable:
burnt material
black specks
extended downtime
unnecessary screw pulls
This guide breaks down how to purge silicone and flexible materials correctly, without thermal degradation, and without compromising your next run.
Why Silicone and Flexible Materials Are Difficult to Purge
Silicone and elastomers behave differently than rigid plastics.
They:
process at lower temperatures
have higher elasticity and adhesion
are more prone to thermal breakdown
When traditional purge methods are used:
excessive heat causes burn-off
residue carbonizes instead of clearing
contamination carries into the next material
This is where most purge failures begin.
The Core Problem: Thermal Degradation During Purging
Thermal degradation happens when:
purge temperature exceeds material tolerance
purge compounds require higher activation temperatures
operators “push heat” to speed up cleaning
This creates:
carbon buildup
odor and smoke
degraded polymer layers inside the barrel
Instead of cleaning the machine, the process adds another layer of contamination.
The Correct Approach: Low-Temperature Mechanical Purging
The solution is not more heat.
It is controlled, low-temperature mechanical purging.
Mechanical purging works by:
softening into a thermoelastic mass
physically scouring residue
encapsulating degraded material
pushing contamination out as a unified plug
This eliminates the need for:
overheating
soaking
carrier resin dilution
Step-by-Step: Purging Silicone and Flexible Materials
1. Stabilize Processing Temperature
Do not increase temperature beyond the material’s safe range.
For silicone and flexible materials:
stay within low-temperature processing windows
avoid “heat spikes” to force flow
2. Introduce a Low-Temperature Mechanical Purge
Use a purge designed for:
low-temp processing
flexible material compatibility
PEKUTHERM® ULT operates effectively from:
175°F to 625°F
This allows cleaning without exceeding material limits.
Learn more: https://www.pekutherm.org
3. Run the Purge as a Continuous Plug
Instead of mixing or diluting:
feed purge directly into the machine
allow it to form a solid, self-adhering mass
push through until output runs clean
No soaking. No waiting.
4. Observe Output for Contamination Removal
During purging, you should see:
dark streaks (carbon removal)
color transition
material displacement
Once output stabilizes:
contamination has been removed
machine is ready for the next material
5. Transition Directly Into Next Material
With mechanical purging:
no carrier resin remains
no secondary cleanup is required
You can run production material immediately.
Avoid these: Common Mistakes That Cause Degradation
Overheating the Barrel
Trying to “burn out” residue creates more contamination.
Using High-Temperature Purges
Many purge compounds require elevated temps to activate.
This is incompatible with silicone and elastomers.
Relying on Carrier Resin Dilution
Dilution spreads contamination rather than removing it.
Running Excess Incoming Material
If you need large volumes to “confirm clean,” the purge failed.
Why Low-Temperature Purging Matters for Operations
When done correctly, low-temperature purging delivers:
reduced scrap rates
faster changeovers
elimination of burn-off contamination
improved part consistency
reduced need for manual cleaning
It also supports maintenance workflows.
When to Use This Method
This approach is ideal for:
silicone processing
EPDM and rubber materials
flexible PVC
low-temperature extrusion lines
sensitive color transitions
Connecting the Process to Broader Purging Strategy
If you are seeing:
black specks
inconsistent output
long purge times
You may also want to review:
These issues are often connected.
The UniTemp Pekutherm Tips
Purging silicone and flexible materials is not about forcing the process.
It is about controlling temperature and using the right mechanism.
When you remove heat from the equation and rely on mechanical action:
contamination is physically removed
degradation is avoided
production stabilizes faster
That is the difference between:
chasing problems
and running a controlled process
Contact / Technical Support
If you are troubleshooting purge issues or evaluating low-temperature solutions: