overmolding

Why Do Silicone Facial Brushes Get Hard and Detach? The Physics Explained Reference Standard: ASTM D1693 – Standard Test Method for Environmental Stress-Cracking of Ethylene Plastics Short Answer Silicone face washing brushes degrade primarily through alkaline chain scission, which hardens the bristles, and thermal expansion asymmetry, which shears the brush from its plastic base. By utilizing advanced overmolding (co-extrusion) techniques and validating against ASTM D1693 environmental stress-cracking standards, high-end packaging manufacturers create a permanent, molecular-level covalent bond that resists thermal hysteresis and chemical degradation. Alkaline Chain Scission: The Shore Hardness Drift Timeline When evaluating the longevity of a silicone face washing brush, consumers often notice that the initially ultra-soft bristles … 続きを読む