M42 Double-Layer Wet Spinning Experimental Machine (Laboratory Use)

The Ollital M42 Double-Layer Wet Spinning Experimental Machine is a compact, bench-top wet spinning system specifically designed for laboratory-scale production of double-layer (core-sheath) fibers and advanced hollow fiber membranes. This experimental machine enables researchers to fabricate bicomponent fibers with distinct core and sheath materials, as well as double-layer hollow fibers for specialized filtration and biomedical applications.

Unlike single-layer spinning systems, the M42 features dual coaxial spinneret capability and independent dope delivery channels, allowing precise control over core and sheath flow rates, compositions, and solidification conditions. It is ideal for academic research, material development, and process optimization where small batch sizes (from 50 mL to 2 L) and maximum flexibility are required.

Primary Applications:
Core-Sheath Bicomponent Fibers: Functional fibers with active core and protective/sheath layer (e.g., drug-loaded core with biocompatible sheath)
Double-Layer Hollow Fiber Membranes: Advanced filtration membranes for water treatment, hemodialysis, and gas separation
Support-Reinforced Fibers: Braid-reinforced or support-layer embedded hollow fibers
Smart & Functional Textiles: Phase change materials (PCM) encapsulated fibers, conductive core fibers
Biomedical Scaffolds: Double-layer tubular scaffolds for nerve guidance or vascular grafts
Controlled Release Systems: Core-sheath fibers for sustained or triggered drug delivery

Working Principle
The M42 employs a co-axial double-layer extrusion method combined with non-solvent induced phase separation (NIPS) to produce bicomponent fibers.

Working Principle – Core-Sheath Fiber:
Two Dope Solutions: Two different polymer solutions (core and sheath) are prepared in separate reservoirs.

Co-Axial Extrusion: The solutions are simultaneously pumped through a concentric dual-nozzle spinneret. The sheath solution flows through the outer annulus, while the core solution flows through the inner channel.

Coagulation: The co-extruded filament enters a coagulation bath containing a non-solvent. The NIPS process causes both polymer layers to solidify simultaneously.

Fiber Formation: A continuous double-layer fiber is formed, with the core completely encapsulated by the sheath. For hollow fiber applications, a bore fluid (internal coagulant) is pumped through the innermost channel to create a lumen.

Key Process Parameters for Double-Layer Spinning:
Core/Sheath Flow Rate Ratio: Determines layer thickness distribution

Dope Composition & Viscosity: Affects interfacial adhesion and delamination risk

Coagulation Bath Composition & Temperature: Controls solidification rate and pore structure

Air Gap Distance (Optional): For dry-jet wet spinning mode, allows partial solvent evaporation before coagulation

Take-Up Speed: Influences fiber diameter and molecular orientation

Double-Layer Hollow Fiber Configuration:
The M42 can be configured to produce three-layer structures (bore fluid + inner layer + outer layer) or support-reinforced hollow fibers (braid or textile reinforcement embedded between layers).