a technique of increasing strenght of fibre
Answers
Air flow
High velocity primary air flow produces fine fibres with small diameter, which gives a web structure with increased fibre cover and reduced pore cover. Large air flows increase fibre entanglement, leading to decreased pore size structure, since generally the airstream controls the entire web uniformity and it should be adjusted so that fibres are uniformly distributed. The airflow determines fibre diameter, fibre entanglement, basis weight and the attenuation zone. Low air flow rate results in coarse fibres because of the limited drawing of the polymer stream. Turbulence in the airstream, if not controlled, results in defects called roping – narrow, elongated, thick streaks of fibres in the web. Ropes develop when the air flow rate is out of adjustment or insufficient, such that the attenuated fibres come into contact and are then laid down as collected aggregates. The air flow is adjusted for a fixed polymer flow rate so that they can form continuous fibres. Violent blowing of air results in a defect called fly – fine nanofibres not trapped on the drum and therefore showing up on the surface of the web (Butin et al., 1974, 1976; Bresee and Qureshi, 2006; Bresee et al., 2005; Moore et al., 2004; Sloan et al., 1981)