China
Africa
Explore chapters and articles related to this topic
Scaffold processing
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
John J. Scanlon, Joseph M. Deitzel, Dieter Mairhörmann, Roland Wölzein
Melt spinning consists of the steps of squeezing a melted polymer through a circular orifice in a spinneret, drawing the extrudate from a thicker to a thinner cross-sectional thickness and a shorter to longer length, and cooling the polymer so that it resolidifies. Wet spinning consists of the steps of producing a polymer solution by dissolving the polymer in a volatile solvent, extruding the polymer solution through a circular orifice in a spinneret, drawing the extrudate from a thicker to a thinner cross-sectional thickness and a shorter to longer length, and solidifying the polymer by evaporating the solvent. Dry spinning consists of the steps of producing a polymer solution by dissolving the polymer in a nonvolatile solvent, extruding the polymer solution through a circular orifice in a spinneret, drawing the extrudate from a thicker to a thinner cross-sectional thickness and a shorter to longer length, and solidifying the polymer by immersing the fiber in a nonsolvent that coagulates or precipitates the polymer into fibers.
Filament Formation and Recent Developments
Published in Asis Patnaik, Sweta Patnaik, Fibres to Smart Textiles, 2019
Out of the three different spinning systems, melt spinning is more popularly used for some of its advantages over the other spinning systems. Melt spinning is a relatively simple process involving only heat transfer, the control of the process is relatively easy and as it does not require any solvent, therefore, it is a relatively clean process. Melt spinning can also be effectively used as a tool to modify and generate new types of fibre such as bi-component or multi-component fibres, hollow fibres, etc. Using polymers having different structure development kinetics, fibres having a wide range of fine structure and resultant properties can also be developed (Ziabicki and Jarecki 1985).
Chemical Engineering in Polymer Processing
Published in Shintaro Furusaki, John Garside, L.S. Fan, The Expanding World of Chemical Engineering, 2019
The most common industrial spinning processes are melt spinning, dry spinning and wet spinning. In melt spinning, a polymer melt is extruded through a spinneret and then cooled through its glass transition or melting temperature to form a fiber. Melt spinning is the most economical spinning process, but can only be used when the polymer is stable at temperatures above its melting point. In dry spinning, a polymer solution is extruded through a spinneret into a chamber where the solvent is evaporated and the fiber solidifies. Wet spinning is the extrusion of a polymer solution through a spinneret into a liquid nonsolvent where the polymer precipitates to form a fiber.
Biobased polymer SF/PHBV composite nanofiber membranes as filtration and protection materials
Published in The Journal of The Textile Institute, 2023
The research on PHA fiber is mainly concentrated in the fields of melt spinning and electrospinning. The melt spinning process of PHA only exists in the laboratory stage due to its defects in crystallization and thermal stability. PHBV has been explored a lot in PHAs. Ohura et al. (1999) obtained PHBV fiber with a breaking strength of 183 MPa. Yamamoto et al. (1997) studied the influence of drafting and annealing processes on the structure and properties of PHBV fibers and obtained PHBV fibers with a breaking strength of 210 MPa. The mechanical properties of PHBV fibers obtained by the above methods were all poor. Conventional melt spinning technology can not obtain PHA fibers with good mechanical properties. Generally, it is necessary to adopt special spinning and drawing processes or through blending modification to improve the spinnability and ultimately improve the mechanical properties of the fiber. The preparation process of PHBV electrospun nanofiber is relatively simple and has many applications in biomedicine. Wu and Wang (2018) prepared a bio-based electrospun polyhydroxyalkanoate (PHA) nanofiber by dissolving PHA with dichloromethane, but the fiber-forming effect of the fiber was not particularly good; there were adhesions between each other. Castro-Mayorga et al. Castro-Mayorga et al., Castro-Mayorga et al., (2016) produced antimicrobial polyhydroxyalkanoate materials containing in situ-stabilized silver nanoparticles by electrospinning coating technique, and the fiber diameter was large and uneven. Solvent selection and spinning process parameters have a greater impact on fiber morphology.
Medical textiles
Published in Textile Progress, 2020
The nylon polymer is converted into filament form by melt spinning, which involves the polymer chips being melted and subsequently extruded through a spinneret then drawn to produce continuous filaments or, after a further step involving cutting or stretch-breaking, staple fibres [122]. Melt spinning as a process does allow for the incorporation of other polymers/molecules into the polymer melt if desired. Melt spinning of the nylon is followed by drawing of the newly-formed filaments (extending the filament by 4-5 times its length to help to align the polymer chains along the lengthwise direction of the filament and improve crystallinity), a common requirement in spinning processes; both spinning and drawing can be adjusted to alter the final filament properties to render them more-suitable not only for general use, but also for more-demanding purposes [123]. In the case of tyre cord for example, where high modulus and high strength are imperative, and for demanding medical applications, higher levels of extension are required and the temperature at which the drawing is carried out may need to be raised to enable enhanced alignment of the polyamide chains to be achieved.
Textile applications of commercial photochromic dyes: part 7. A statistical investigation of the influence of photochromic dyes on the mechanical properties of thermoplastic fibres
Published in The Journal of The Textile Institute, 2019
Basel Younes, Stephanie C. Ward, Robert M. Christie, Samantha Vettese
The technology of synthetic fibres has advanced significantly in recent decades, opening up a wide range of engineering applications. In particular, the development of fibres that incorporate smart technology has become an important goal of modern textile industries. The synthetic fibres, polypropylene, polyethylene and polyester, notably poly(ethylene terephthalate), are used in a wide range of applications, due to their good technical performance and relatively low cost of production, which involves melt extrusion (Mather & Wardman, 2011). As the molten polymer emerges from the high temperature extrusion process, it is cooled by quenching, either by air or in water. The structure of the as-spun synthetic fibres obtained, including important physicochemical features such as molecular orientation and degree of crystallinity, is developed during the melt-spinning processes. The as-spun fibres produced are required to have a structure that can be drawn easily. Drawing, which may be applied either directly after the extrusion operation or during texturing, is a vital stage in the manufacture of synthetic fibres because it stabilises the structure and strengthens the yarn by improving the molecular orientation and crystallinity (Lord, 2003), as the polymer chains move in the direction of drawing to become oriented parallel to the fibre axis. As the temperature is lowered in the relaxation stage, the polymer chains lose their freedom of movement and thus become fixed. Melt-spinning systems usually incorporate two or more drawing zones. The drawing ratio that is appropriate in a particular case depends on the drawing conditions and original structure of the filaments (Hes & Ursiny, 1994) .