Preparation For Polyamide 6/66 Filaments Of Nanofibers By Electrospinning And Analysis Of The Structures And Properties

Currently, the shapes of electrospun nanofibers mainly exist in three styles: random orientation, uniaxial alignment and continuous fiber bundles. When a grounded conductive plate is used as the collector in electrospinning, electrospun fibers are often collected in the form of nonwoven mat. This mat can apply in the following area: filtration, tissue engineering, wound dressing and sensor. The preparation for uniaxially aligned fibers is relatively difficult and accomplished by employing electrostatic or mechanical force on fibers by introduced modified electric field or changing the shape of collector. Well-aligned nanofibers exhibit a variety of potential applications in biomedicine, optics, electronics, and device fabrication. Four methods to make continuous fiber bundles by electrospinning have been achieved, bath solution, double electrodes, rotating drum and twist. Continuous filament is one of the most common materials in textile industry. Filament constructed by nanofibers has important effect on enlarging the electrospun product style and the application areas.Polyamide6/66 solution in formic acid was electrospun into nanofibers and then collected on the surface of active solution, stretched and rotated into continuous filament with even morphology, well-properties, and steady structure with a homemade electrospinning instrument. The time for continuous electrospinning was up to several hours. The main contents of this paper are as follows: Investigation on a technique for electrospinning continuous filaments constructed of nano-scale fibers, effect of spinning parameters such as rotating speed on the structure and properties of fibers and filaments, the structure and properties of the filaments at optimized spinning parameters, and effect of post-treated technique on the structure and properties of the fiber bundles.Investigation on a technique for electrospinning continuous filaments constructed of nano-scale fibers: Six factors and three levels for each factor were taken into account in orthogonal experimental design. These factors included voltage (V), solution flow rate (FR), tip-to-collector distance (TD), rotation speed (RS), bath solution concentration (BC), and inner-diameter of spinneret (ID). Electrospinning time was the standard of spinnability and influences of theses factors on the spinnability were analyzed. Initial optimized spinning parameters were determined by orthogonal design: V 13kv, RS 100rpm, TD 6cm, FR 0.06ml/h, BC 9‰and ID 0.35mm.Effect of TD, BC, RS on the structure and properties of the filament: Effect of TD and BC on the alignment of fibers, fineness unevenness of filament and fiber, crystalline degree of fiber, tensile property of filament was discussed. Effect of RS on the crystalline degree and orientation degree of fiber, and dynamic thermal mechanical and tensile properties of yarn was mainly investigated. Some conclusions can be drawn: With TD increasing, parallel-aligned degree between fibers, the crystalline degree of fiber and tensile property of fiber bundles were improved, but too longer distance interrupted the roll of yarn. The higher aligned degree between fibers and even filament can be obtained in BC of 5‰. With RS increasing, the diameter of fiber decreased, the crystalline degree of fiber and the tensile property of yarn were improved.Structure and properties of filament at optimized parameters: when considering the effect of the result of orthogonal design and independent experiments on the structure and properties of the electrospun PA6/66 nanofiber bundles, optimized parameters were obtained: V 13kv, RS 100rpm, TD 9cm, FR 0.06ml/h, BC 5‰, and ID 0.35mm. In this condition, even filaments with well-mechanical properties and stabilities were obtained.Effect of post-treated technique on structure and properties of filament: In order to improving the properties of the filament, post-treatment was performed under different heating temperature, the length of cooling area and stretch time. The conclusions were as follows: structure and properties of the filament were improved at 100℃of heating temperature, 60cm of cooling area and higher stretch time. In this condition, stress and strain at break of the yarn were 2.95cN/dtex and 19.1% respectively.