Extrusion & Post
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PE Product ESCR Environmental Stress Cracking
Problembeschreibung
After contacting detergents, oils and industrial chemicals, HDPE containers and pipes develop brittle microcracks after a period of use, cracking without swelling or stretching.
Ursachenanalyse
PE undergoes environmental stress cracking under the combined action of internal or external mechanical stress and chemical media (surfactants, alcohols, oils, detergents); HDPE, due to its linear molecular chains and high crystallinity, is more prone than LLDPE; areas with high internal stress fail first.
Lösung
①Select ESCR-resistant grades according to the media (high molecular weight, narrow molecular weight distribution HDPE, or introducing mLLDPE blending to absorb local stress); ②reduce the product internal stress (optimize holding, cooling, eliminate sharp corners); ③conduct media immersion/ESCR verification; ④avoid interference fit assembly and sharp corners.
Wichtigste Erkenntnis
ESCR is the most common cause of 'premature death' of durable PE products: material grade, internal stress and media must superimpose to cause failure; blow molded household chemical bottles and industrial drainage pipes are disaster areas, and material selection and verification must be moved upstream.
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