Monofilament-reinforced hollow fiber membrane with scalloped lumen

An outside-in hollow fiber symmetric membrane comprising,

• tubular flexible braid of monofilament embedded as a monolayer in a tubular film of membrane polymer so as to form and reinforce a scalloped lumen of e asymmetric membrane having a periphery comprising plural outwardly convex circular segments or lobes interconnected by valleys in a cross-sectional plane perpendicular to a longitudinal axis of the asymmetric membrane, each having a nadir, the tubular flexible braid, free of multifilament yarn, comprising, from 6 to 24 separate monofilaments in the range from 25-250 denier (g/9000 meters), woven in a spiral open weave having an air permeability greater than 10 cc/sec/cm2 at 1.378, to provide contiguous rhomboids areas of the membrane polymer bounded by monofilaments, the spiral open weave being woven with the separate monofilaments at axially oppositely directed spiral angles in the range from 20°-60° from the longitudinal axis, so as to be free of a restricting circumferential filament such that the asymmetric membrane is biaxially distensible under pressure from within, prior to being damaged;
• the tubular film of membrane polymer, including the tubular flexible braid embedded therein, having a wall thickness in the range from 0.2 mm-0.6 mm,
• such that the asymmetric membrane is adapted for use as a microfiltration or ultrafiltration liquid separation membrane,
• wherein the lumen has scalloped cross-section of plural interconnected arcuate segments including adjacent, outwardly convex arcs, or segments of contiguous circles, interconnected, one to another at their circumferences,
• wherein the symmetric membrane has a wall thickness measured between the outer surface of the asymmetric membrane and the nadir of a valley, hv, greater than the wall thickness measured between the outer surface of the asymmetric membrane and the upper surface of a lobe's crest, hc, that is, hv/hc>1, and a shortest distance between the nadir of the valley and a nearest one of the monofilaments to the nadir of the valley is greater than a distance between the lobe's crest and a nearest one of the monofilaments to the lobe's crest.