Hollow and Microhollow Polyester Fibres
topic
Hollow polyester fibres (10–30% void fraction) spun using annular spinnerets where air or nitrogen is injected into melt stream. Lower density (0.95–1.2 g/cm³ vs. 1.38 for solid PET), improved thermal insulation (still air trapped in lumen, thermal conductivity 0.026 W/mK), and cotton-like moisture wicking behaviour (capillary action through hollow lumen). Used in: thermal insulation fill (simulates down), cotton-feel sportswear, moisture-management fabrics.
Role
Hollow fibre design is a canonical example of using spinneret geometry to engineer macrostructural properties — insulation and moisture management — without polymer chemistry changes. It is important for understanding functional fibre design.