Meaning
Inorganic alkaline compound often incorporated into recycled polymer streams to neutralize residual moisture. Adding calcium oxide prevents the formation of steam bubbles during the extrusion or injection moulding of damp resins. It functions as an internal desiccant that reacts chemically with water to produce calcium hydroxide.
Moisture Sequestration
The chemical reaction between the additive and water is irreversible under standard processing conditions. Moisture that would otherwise vaporize and create silver streaks or internal voids remains trapped in a solid state. This mechanism is useful for processing hygroscopic materials or contaminated regrind where pre drying is insufficient.
Compound Reactivity
High concentrations of the mineral can alter the rheological behavior of the melt and increase the wear on tool surfaces. Because calcium oxide is a basic substance, it may also interact with acidic additives or pigments in the formulation. Formulators must balance the desiccant loading against the potential for heat generation during the exothermic hydration process.
Surface Quality
Effective use of the additive eliminates the aesthetic defects associated with moisture outgassing. The resulting parts show a uniform finish without the pitting or splay marks that typically degrade the value of recycled components. Proper dispersion of the powder ensures that no visible clusters appear on the surface of the moulded product.
