Most disappointing compatibilizer trials fail for a procedural reason, not a chemical one: too many variables moved at once. The fastest path to a result you can actually interpret is a controlled dosage ladder run against an unchanged baseline.
Start with a dosage ladder
Step the loading rather than guessing a single number:
- 0.5 → 1.0 → 2.0 → 3.0 phr
The goal is to identify the optimum window. Do not assume more is better — beyond the optimum, additional compatibilizer can erode the very mechanical balance you are trying to protect.
Feed it evenly
Use pre-blending or controlled side-feeding to avoid local over-concentration. A well-chosen average dosage still fails if it arrives at the melt as hot spots and lean zones.
Hold the extrusion baseline first
Keep baseline extrusion conditions unchanged on the first pass and watch:
- Torque
- Melt pressure
- Output
- Die build-up
- Surface quality
These five readings tell you whether the compound runs stably before you start optimizing temperature or screw speed.
Control moisture
Follow the drying requirements for both filler and resin. Residual moisture distorts both processing behaviour and property comparison, quietly invalidating an otherwise clean trial.
Do not change all variables at once. If dosage, temperature, screw speed and lubricant move together, the trial cannot tell you why the result improved or failed.