Material Drying
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ABS water content causing product bubbles and brittleness
Fenómeno del problema
Bubbles appear inside the product or at thick-wall areas, holes can be seen when cut open, and at the same time the product toughness decreases and it breaks easily when bent; appearance and performance deteriorate at the same time.
Análisis de la causa
When the raw material is wet, the moisture turns into steam in the barrel and mixes into the melt to form bubbles; more hidden is that the water vapor reacts with ABS in a catalytic cracking reaction at high temperature, destroying the molecular chain structure, causing the product to produce great strain, become brittle and crack, and this brittleness is often concurrent with bubbles.
Solución
①Fully dry at 80~100℃ for 2~4 hours to reduce the moisture content below 0.2%; ②seal and moisture-proof after drying; ③appropriately lower the barrel temperature to reduce volatilization and cracking; ④increase back pressure to discharge gas; ⑤improve mold venting to avoid gas being sealed in the product.
Conclusión clave
ABS water content = double blow of bubbles + brittleness: bubbles rely on venting and controlling volatilization, brittleness relies on thorough drying to prevent catalytic cracking; don't treat water content as only an appearance problem, its damage to molecular chains is the more fatal hidden danger.
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