Spinning Apparatus Research Articles

Preparation and characterization of pitch-based carbon fibers

A petroleum pitch was heated at 420 °C for 7 h in nitrogen to prepare a carbon fiber precursor with a softening point of 295 °C. The precursor was successfully melt-spun into fibers through a circular nozzle of a monofilament spinning apparatus, and these were then stabilized at 320 °C in air and finally carbonized at 1000 °C in nitrogen to produce carbon fibers. SEM, TGA, FT-IR, and XRD were performed to characterize the petroleum pitch, the precursor, the as-spun fibers, the stabilized fibers, and the carbon fibers. It is found that the precursor contains 70.5% mass fraction of mesophase that is aligned upon spinning, and aliphatic side chains that are beneficial to spinning. The carbon fibers have a radial core structure with a linear and bent type anisotropic texture. The maximum tensile strength of the carbon fiber is 650 MPa.

Silk spinning apparatuses in the cribellate spider nurscia albofasciata (Araneae: Titanoecidae)

The fine structural characteristics of the silk spinning apparatus in the titanoecid spiders Nurscia albofasciata have been examined by the field emission scanning electron microscopy (FESEM). This titanoecid spiders have a pair of medially divided cribella just in front of the anterior spinnerets, and the surface of the cribellum is covered by hundred of tiny spigots which produce numerous cribellate silk fibrils. The cribellar silks are produced from the spigots of the sieve‐like prate, and considered as a quite different sort of catching silk with dry‐adhesive properties. The other types of the silk spigots were identified as follows: ampullate, pyriform and aciniform glands. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another 1–2 pairs of minor ampullate glands supply the middle spinnerets. In addition, the pyriform glands send ductules to the anterior spinnerets, and two kinds of the aciniform spigots feed silk into the middle (A type) and the posterior spinnerets (both of A & B types), respectively.

Micro-computerized tomographic observation of the spinning apparatus in Bombyx mori silkworms

Silkworms and spiders have evolved complex spinning apparatus thought to use highly controlled conditions to optimize protein folding and crystallization to provide a tough fiber. Accordingly, the structure and function of the natural spinning apparatus has been studied with great attention as an interesting piece of biological engineering with potential for mimicry in an industrial process. However it is still not well understood. Here we used Micro-Computerized Tomographic equipment (mCT) to visualize the three-dimensional structure of the spinning apparatus in Bombyx mori silkworms. Multidirectional tomograms obtained by X-ray radioscopy provided valuable information on the detailed arrangement of each muscle of the silk press. It is suggested that the duct in the silk press part plays a part as an extrusion die whose cross-sectional area can be controlled by muscles to optimize applied stresses in the partially gelled silk within its lumen.

The sol–gel transition of mullite spinning solution in relation to the formation of ceramic fibers

Continuous mullite ceramic fibers were fabricated by a sol–gel dry spinning technique. The sol was prepared from an aqueous solution of aluminum nitrate (AN), aluminum isopropoxide (AIP) and tetraethylorthosilicate (TEOS). The sol–gel transition was investigated by measuring the volume, the solid content, the viscosity and the rheological properties of the solution. Shear viscosity η of the mullite sol varied dynamically with concentrating time and temperature. Combine size analysis of sol particles and TEM analysis on this basis, the growth character of sol particles agglomeration and its structural evolution were discussed. By adjusting the temperature, the gelling degree could stabilize at a certain value and the sol–gel transition could be transferred to the spinning line. Continuous fibers were spun from such sols immediately before gelling in a laboratory dry spinning apparatus. The spinneret contained thirty circular holes, each having a diameter of 0.2 mm. The temperature inside the spinning channel was 100–120 °C, the winding speed was 100–300 m/min. Sintering of the precursor fibers at 1,100 °C yields crack-free mullite ceramic fibers.

More data, fewer shifts: Molecular insights into the evolution of the spinning apparatus in non-orb-weaving spiders

All spiders produce silk and use it for various functions throughout their lives, but not all spiders produce the same silks, or use them for the same functions. These functions may include building shelters, protecting eggs, and trapping prey. The “RTA clade” of spiders (grass spiders, jumping-spiders, wolf spiders, hackled-band weavers, etc.) is an extremely diverse group (∼18,000 species, representing nearly half of all described species), with great variation in ecology and morphology, including variation in the cribellum, a specialized silk-producing organ. The loss of the cribellum, a structure that produces fibers contributing stickiness to prey snares and which is invariably associated with a set of accessory structures, has been studied in orb-web-weavers and shown to have been lost once during the evolutionary history of the group, but never regained. Relative to the orb-weavers, evolution of the structure remains less-thoroughly studied in the RTA clade. As the cribellum is one member of a suite of traits, the combined action of which is essential in prey-capture, its loss should have ecological correlates or physiological trade-offs of evolutionary interest. Using molecular data from nuclear genes (ribosomal DNAs 18S and 28S, and protein-coding Histone H3), as well as mitochondrial data (Cytochrome oxidase I) totaling ∼3400 base pairs, we developed a phylogenetic hypothesis for three-clawed lineages in this group, focusing on families where taxonomy and previous cladistic analyses suggest multiple losses, or possibly loss and secondary gain, of the cribellum. Results of Bayesian and direct-optimization (POY) analyses agree on a well-resolved and robust agelenid clade that includes the putative subfamilies Ageleninae, Tegenariinae, Textricinae and Coelotinae, but excludes the cribellate New Zealand genus Neoramia. Optimizing the pattern of cribellum evolution onto these trees shows that the cribellate state is conserved in large clades and has undergone fewer shifts than current taxonomy implies. The dominant pattern is one of repeated loss of the cribellum, though loss and regain remains a possibility in some groups.

Structure of the spinning apparatus of a wild silkworm Samia cynthia ricini and molecular dynamics calculation on the structural change of the silk fibroin

Silkworms have been developed over thousands years to optimize folding and crystallization of fibroin under highly controlled conditions which have resulted in their efficient fiber formation. In this paper, we reconstructed the three-dimensional architecture of the spinneret of a wild silkworm Samia cynthia ricini from approximately 1000 optical micrographs of the semi-thin cross sections. The chitin plates and muscles were observed in the silk press part together with large change in the diameter of the spinneret lumen at the press part by large shear stress. This is similar to the case of the spinneret of Bombyx mori silkworm, indicating that the structural change in the silk fibroin of S.c. ricini silkworm occurs exclusively at the silk press part due to large shear stresses. Molecular dynamics (MD) calculations were then performed to study the structural change that occurs in the crystalline region of S.c. ricini silk fibroin under shear stress. Namely, using the peptide AGGAGG(A)12GGAGAG as a model of the crystalline part of the silk fibroin under different shear stresses in the presence of water molecules and followed by molecular mechanics (MM) calculation after removal of water molecules. The simulation indicates that the Ala residues in the model peptides adopt a predominantly β-sheet structure under shear stresses of above 1.0GPa.

Some Observations on the Structure and Function of the Spinning Apparatus in the Silkworm Bombyx mori

Silkworm silk has outstanding mechanical properties despite being spun at room temperature and from aqueous solution. Although it has been proposed that fiber formation is mainly induced by shearing and extensional flow in the spinneret, the detailed structure and function of the spinning apparatus of Bombyx mori silkworms are still not fully elucidated. In this paper we describe three aspects of the functional microanatomy of the spinning apparatus: changes in the diameter of the silk gland duct with distance along the duct, how the birefringence of the fibroin changes as it flows down the duct, and the detailed three-dimensional structure of the silk press and related structures. The existence of a double escaped nematic liquid crystal texture in the fibroin in a region of the duct is described. After this region the birefringence suddenly disappeared until the start of an internal draw down taper which commenced just before the silk press. In the internal draw down taper the birefringence increased dramatically to an asymptotic value as a thread was drawn from the fibroin gel. The structure of the silk press suggests that it acts as a restriction die whose diameter can be regulated.

Microstructure of the silk spigots of the green crab spider Oxytate striatipes (Araneae: Thomisidae)

AbstractThe genus Oxytate L. Koch, 1878 comprises a homogeneous group of nocturnal crab spiders that have silk apparatuses even though they do not spin webs to trap prey. We examined the microstructure of the silk spinning apparatus of the green crab spider Oxytate striatipes, using field emission scanning electron microscopy. The silk glands of the spider were classified into three types: ampullate, pyriform and aciniform. The spigots of these three types of silk gland occur in both sexes. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pairs of minor ampullate glands supply the median spinnerets. In addition, the pyriform glands send ductules to the anterior spinnerets (45 pairs in females and 40 pairs in males), and the aciniform glands feed silk into the median (9–12 pairs in females and 7–10 pairs in males) and the posterior (30 pairs in both sexes) spinnerets. The spigot system of O. striatipes is simpler and more primitive than other wandering spiders: even the female spiders possess neither tubuliform glands for cocoon production nor triad spigots for web‐building.

Studies on spinning and rheological behaviors of regenerated silk fibroin/N-methylmorpholine-N-oxide·H2O solutions

In this paper, N-Methylmorpholine-N-Oxide (NMMO) was used as solvent for regenerated silk fibroin (RSF). Concentrated solutions with RSF content from 10 to 25 wt% were obtained by dissolving RSF film into NMMO monohydrate. The spinning and rheological properties of RSF/NMMO·H2O solutions were studied by a simple piston type single filament spinning apparatus and HAAKE RS150L rheometer, respectively. The results are discussed to understand the influences of shear rate, temperature and RSF concentration on the rheological behaviors of RSF/NMMO·H2O and to choose appropriate process condition for spinning. Spinning was performed using a dry-wet spinning process. The regenerated silk fibre was prepared successfully and the tenacity can reach to 3.07cN/dtex.

Synthesis, characterization and melt spinning of a block copolymer of L-lactide and ε -caprolactone for potential use as an absorbable monofilament surgical suture

This paper describes the synthesis and characterization of a block copolymer of L-lactide (LL) and epsilon -caprolactone (CL) and its subsequent melt spinning into a monofilament fiber. The synthesis reaction was a two-step process. In the first step, an approximately 50:50 mol% random copolymer, P(LL-co-CL), was synthesized via bulk copolymerization of LL and CL. This first-step prepolymer then became the macroinitiator in the second-step reaction in which more LL monomer was added to form a block copolymer, PLL-b-P(LL-co-CL)-b-PLL. Both the prepolymer and block copolymer were characterized by a combination of analytical techniques comprising dilute-solution viscometry, GPC, 1H and 13C NMR, DSC and TG. The block copolymer was then processed into a monofilament fiber using a small-scale melt spinning apparatus. The fiber was spun with a minimum amount of chain orientation and crystallinity so that its semi-crystalline morphology could be constructed under more controlled conditions in subsequent off-line hot-drawing and annealing steps. In this way, the fiber's tensile properties and dimensional stability were developed, as indicated by the changes in its stress-strain curve. The final drawn and annealed fiber had a tensile strength (>400 MPa) approaching that of a commercial PDS II suture of similar size. It is considered that this type of block copolymer has the potential to be developed further as a lower-cost alternative to the current commercial monofilament surgical sutures.

Spinneret Microstructure of the Silk Spinning Apparatus in the Crab Spider, Misumenops tricuspidatus (Araneae: Thomisidae)

ABSTRACTThe silk spinning apparatus in the crab spider, Misumenops tricuspidatus was studied with the field emission scanning electron microscope (FESEM) and the main microstructural characteristics of the silk glands are presented. In spite of the fact that the crab spiders do not spin webs to trap a prey, they also have silk apparatus even though the functions are not fully defined. The crab spider, Misumenops tricuspidatus possesses only three types of silk glands which connected through the typical spinning tubes on the spinnerets. The spinning apparatus of Misumenops closely corresponds to that of wandering spiders such as jumping spiders or wolf spiders except some local variations. Anterior spinnerets comprise 2 pairs of the ampullates and 48 (±5) pairs of pyriform glands. Another 2 pairs of ampullate glands and nearly 20 (±3) pairs of aciniform glands were connected on the middle spinnerets. Additional 50 (±5) pairs of the aciniform glands were connected on the posterior spinnerets. The aggregate glands and the flagelliform glands which have the function of sticky capture thread production in orb‐web spiders as well as the tubuliform glands for cocoon production in females were not developed at both sexes of this spider, characteristically.

Preparation and properties of keratin‐poly(vinyl alcohol) blend fiber

Because of an error at the printer, the incorrect version of Figure 2 appears in the print version of the article. The online article contains the correct figure, which is shown below: Schematic diagram of wet spinning apparatus.

張力制御紡績装置の高速化(OS4-2 産業用メカトロニクス技術)

張力制御紡績装置の高速化(OS4-2 産業用メカトロニクス技術)

611 張力制御紡績装置の高速化と糸の評価

611 張力制御紡績装置の高速化と糸の評価

고 비정질 형성능을 가진 FeBSiNb 합금 리본의 자기적 특성

벌크 비정질 형성능과 큰 포화자속밀도를 가지는 FeBSiNb계 아몰퍼스 합금 리본을 22~102<TEX>$\mu\textrm{m}$</TEX>의 두께 범위에서 단롤형 액체 급냉법으로 제조하였다. 이 합금은 두께 증가에 따라 보자력이 감소하고 최대투자율 및 교류투자율이 증가하였으며, 자기이력곡선의 각형비가 감소하였다. 한편 전기 비저항은 두께와 상관없이 거의 일정한 값을 나타내었다. 또 지구 관찰 결과, 두께가 증가하면 내부 자기 이방성의 변화에 따라 자구가 미세화 되고 보다 복잡한 자구 구조를 갖는 것으로 나타났다. 두께 81<TEX>$\mu\textrm{m}$</TEX>인 합금의 경우, 24 mOe의 작은 보자력과 1KHz에서 12,000이상의 높은 실효투자율을 나타내어 일반적인 고 연자성 비정질 합금(두께 약 20<TEX>$\mu\textrm{m}$</TEX>)의 특성을 능가하였다. 이와 같은 두꺼운 FeBSiNb 비정질 합금의 우수한 연자성은 자벽이동에 대한 표면 고착 효과의 감소 및 수직자기이방성 성분의 출현과 미세화 된 자구 구조에 그 원인이 있는 것으로 평가되었다. Amorphous FeBSiNb alloy ribbons having bulk glass forming ability and high saturation magnetic flux density were produced by single-roller melt spinning apparatus in the thickness range of 22∼102㎛. With the increase of thickness, the coercive force and squareness ratio decreased, while maximum permeability and AC permeability increased. However electrical resistivity was almost constant. Furthermore refined and complex magnetic domain structure was observed in thicker ribbons owing to the change in internal magnetic anisotropy. For the alloy with the thickness of 81㎛, small coercive force of 24 mOe and high effective permeability of 12,000 at 1㎑ were obtained, those are considered to be better comparing to the conventional soft magnetic amorphous alloys (∼20 ㎛). The good soft magnetic properties of the thick FeBSiNb amorphous alloys were attributed to the decrease in surface pinning effect during wall motion, appearance of perpendicular anisotropy and resulted domain refinement.

Spinning an elastic ribbon of spider silk.

The Sicarid spider Loxosceles laeta spins broad but very thin ribbons of elastic silk that it uses to form a retreat and to capture prey. A structural investigation into this spider's silk and spinning apparatus shows that these ribbons are spun from a gland homologous to the major ampullate gland of orb web spiders. The Loxosceles gland is constructed from the same basic parts (separate transverse zones in the gland, a duct and spigot) as other spider silk glands but construction details are highly specialized. These differences are thought to relate to different ways of spinning silk in the two groups of spiders. Loxosceles uses conventional die extrusion, feeding a liquid dope (spinning solution) to the slit-like die to form a flat ribbon, while orb web spiders use an extrusion process in which the silk dope is processed in an elongated duct to produce a cylindrical thread. This is achieved by the combination of an initial internal draw down, well inside the duct, and a final draw down, after the silk has left the spigot. The spinning mechanism in Loxosceles may be more ancestral.

Dispersion and Alignment of Carbon Nanotubes in Polycarbonate

AbstractDispersion and alignment of carbon nanotubes in thermoplastic polymers such as polycarbonate have been studied. Dispersion was accomplished by mixing in a conical twin-screw extruder and alignment was carried out using a fiber spinning apparatus. The effects of mixing time and fiber draw ratios on dispersion and alignment were investigated. Uniform dispersions were produced with relatively short residence times in the extruder. Excellent alignment of carbon nanotubes in nanocomposite filaments was obtained when the fiber draw ratio was greater than 7. The ability to closely control the dispersion and alignment of carbon nanotubes in polymers is expected to lead to the development of nanocomposites with desirable electronic and structural properties.

1P1-C7 張力制御糸紡ぎ装置の開発(82. 先進繊維生産メカトロニクス)

1P1-C7 張力制御糸紡ぎ装置の開発(82. 先進繊維生産メカトロニクス)

Hollow Yarn in Friction Spinning

"Hollow" yams have been created to improve cotton yam properties, to increase the entrapped air in the yam, and to gain a stronger yam for spinning and weaving processes. Hollow yams are spun by introducing PVA filaments into the yam-forming zone of an experimental friction spinning apparatus. A 61/18-denier (6.8 tex) PVA multifilament is used as the core and cotton fibers form the sheath. The water soluble PVA in the center is removed from the yam structure in boiling water with a good extraction of more than 95%. The effect of the PVA proportion on the mechanical properties of the hollow yam is examined, and its properties are compared with those of conventional cotton yams. The results show that the strength of the yam before boiling significantly increases as the PVA percentage increases, and it is more than that of an equivalent conventional cotton yarn. The strength of the hollow yam after PVA extraction does not change with the PVA content, and it is the same as that of the equivalent cotton yam. At a high filament percentage, the breaking elongation of the hollow yam is more than that of the cotton yarn.

Structure development during melt spinning and subsequent annealing of polybutene-1 fibers

The structural development during the melt spinning and subsequent annealing of polybutene-1 fibers was studied with in situ wide-angle X-ray scattering techniques. The online spinning apparatus consisted of a vertically translating extruder that allowed different distances from the spinneret to the stationary X-ray beam to be sampled. For all take-up speeds examined, phase II crystals mainly were formed, with only a small population of phase I crystals existing. As the take-up speed was increased, the crystallinity also increased, indicating that strain-induced crystallization prevailed. The crystalline orientations observed online were very close to perfect alignment with the fiber axis. In addition, annealing studies were performed to study aspects of the gradual phase II to phase I transformation as functions of time and prior processing take-up speed. This transformation was strongly dependent on the take-up speed. The dependence appears to be connected to local stress enhancement via chains connecting crystallites. The results also seem to indicate that at low take-up speeds (17 mpm) there is a series connectivity of amorphous and crystalline components in the fiber, whereas at greater take-up speeds (100 and 250 mpm), the morphology grows into some type of three-dimensional network, possibly a shish–kebob-type morphology. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1872–1882, 2000