Material Drying
14 مشاهدة
Bubbles/pores on the surface of homopolymer polypropylene extruded products
ظاهرة المشكلة
Bubbles or pores appear on the extrudate surface or cross-section, reducing product density.
Bubbles not only affect appearance but also reduce mechanical strength and pressure resistance; common in pipe and profile extrusion.
تحليل الأسباب
(1) Raw material moisture content exceeds standard; moisture vaporizes at high temperature producing bubbles
(2) Poor screw venting; air entrained in the melt
(3) Barrel temperature too high; material thermal degradation produces gas
(4) Screw rotation speed too fast, insufficient venting time
(5) High low-molecular volatile content in raw material
الحل
(1) Fully dry the raw material; control homopolymer polypropylene moisture content below 0.02%
(2) Check venting section design; use a vented extruder when necessary
(3) Appropriately reduce barrel temperature to a reasonable value within the 200-280°C range
(4) Reduce screw rotation speed, increase material residence time in the venting section
(5) Select raw material grades with low volatile content
الخلاصة الأساسية
Bubbles are caused by moisture vaporization or gas entrainment; they need to be solved from raw '2079851475616104451 and the venting system.
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