Composite membrane with compatible support filaments
View Patent ↗A filtering membrane has a supporting structure comprising filaments and is coated with a dope to produce a polymeric membrane layer. Some or all of the filaments comprise a second polymer that is soluble or swellable in a solvent of the dope. The supporting structure may be braided with yarns. One or more yarns may comprise filaments comprising the second polymer. In one example, a braided tubular support is coated with a dope based on PVDF in NMP. Some or all of the yarns of the braid are made of bi-component core-sheath PET-PVDF filaments. With as few as 4% of the yarns in the braid made of the bicomponent filaments, peel strength and pull force of the membrane is improved relative to a braid made entirely of PET yarns. In experimental examples, unpeelable composite membranes were produced. The membrane may be used, for example, for water or wastewater filtration applications.
1. An immersed membrane module comprising braid supported hollow fiber membranes, the membranes comprising a braided supporting layer and a membrane layer, the membrane layer comprising PVDF, the supporting layer comprising a plurality of yarns, wherein some of the plurality of yarns are polyester yarns and others of the plurality of yarns comprise PVDF.
2. The immersed membrane module of claim 1 wherein the yarns comprising PVDF are made up essentially entirely of PVDF.
3. An immersed membrane module comprising braid supported hollow fiber membranes, the membranes comprising a braided supporting layer and a membrane layer, the membrane layer comprising PVDF, the supporting layer comprising yarns made at least in part of filaments comprising PVDF wherein the filaments comprising PVDF are bi-component filaments having a PVDF sheath.
4. The immersed membrane module of claim 3 wherein the bi-component filaments have a core of polyester.