Material Drying
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Random copolymer polypropylene pipe special material (Nordic standard） extruded products surface bubbles/pores
Problem Phenomenon
Bubbles or pores appear on the extrudate surface or cross-section, and the product density decreases.
Bubbles not only affect appearance, but also reduce product mechanical strength and pressure resistance, common in pipe and profile extrusion.
Cause Analysis
（1）The raw material moisture content exceeds the standard, moisture vaporizes at high temperature producing bubbles\
（2）Poor screw venting, air entrained in the melt\
（3）Barrel temperature too high, material thermally degrades producing gas\
（4）Screw speed too fast, venting time insufficient\
（5）The low-molecular volatile content in the raw material is high
Solution
（1）Fully dry the raw material, control the moisture content of the random copolymer polypropylene pipe special material (Nordic standard） below 0.02%\
（2）Check the venting section design, use a vented extruder if necessary\
（3）Appropriately lower the barrel temperature to a reasonable value within the 200-220°C range\
（4）Reduce screw speed, increase the material residence time in the venting section\
（5）Select raw material grades with low volatile content
Key Takeaway
Bubbles are caused by moisture vaporization or gas entrainment, and need to be solved from raw '2079851475616104451 and the venting system.
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