Molds & Tooling
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Phase separation problem in blending PEOX with other materials
Problembeschreibung
When PEOX is blended with PVA or PLA to prepare composite water-soluble film, cloud-like opaque areas and micro-phase separation streaks appear on the film surface, and the film strength is significantly lower than expected.
Ursachenanalyse
The solubility parameters of PEOX and PVA/PLA differ greatly (Δδ>2 MPa½) and they are thermodynamically incompatible; the blending process (temperature and shear) is insufficient to form a uniform dispersion; PEOX aggregates at the blend phase interface after absorbing water, forming weak points.
Lösung
Add compatibilizer (such as PVA-g-PEOX graft copolymer or citrate ester) 0.5-2% to reduce interfacial tension; optimize the blending screw combination to enhance shear dispersion (use distributive mixing elements such as Maddock elements); strictly control the moisture content of raw materials (all <0.1%); perform DSC to verify the Tg of the blend system to judge the degree of compatibility.
Wichtigste Erkenntnis
PEOX blend systems are inherently prone to phase separation; compatibilizer selection and strong shear dispersion are the prerequisites for obtaining homogeneous materials.
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