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1.
Theriodopteryx ephemeraeformis commonly known as bag worms produce ultrafine silk fibers that are remarkably different than the common domesticated (Bombyx mori) and wild (Saturniidae) silk fibers. Bag worms are considered as pests and commonly infect trees and shrubs. Although it has been known that the
cocoons (bags) produced by bag worms are composed of silk, the structure and properties of the silk fibers in the bag worm
cocoons have not been studied. In this research, the composition, morphology, physical structure, thermal stability, and tensile
properties of silk fibers produced by bag worms were studied. Bag worm silk fibers have considerably different amino acid
contents from those of the common silks. The physical structure of the bag worm silk fibers is also considerably different
compared with B. mori and common wild silk fibers. Bag worm’s silk fibers have lower tensile strength (3.2 g/denier) and Young’s modulus (45 g/denier)
but similar breaking elongation (15.3%) compared with B. mori silk. However, the tensile strength and Young’s modulus of bag worm fibers are similar to those of the common Saturniidae wild silk fibers. Bag worm silk fibers could be useful for some of the applications currently using the B. mori and wild silk fibers. 相似文献
2.
G.A. Bajwa Y. Nawab M. Umair Z. Rizwan 《Materialwissenschaft und Werkstofftechnik》2019,50(10):1287-1294
Natural silk is considered as queen of textile due to its superior traits. This study was conducted to assess technical properties of cocoon, and raw silk and mechanical properties of silk filament produced by two mulberry silkworm strains. The Chinese strain (205PO) produced dry cocoon of 0.61±0.04 g with raw silk of 0.30±0.02 g and the Japanese strain (J101) produced dry cocoon of 0.49±0.01 g with raw silk of 0.23±0.00 g. The single filament length of 205PO and J101 was 1203.1±20.42 m cocoon?1 and 1082.3±48.95 m cocoon?1, respectively. The filament was finer in the Japanese silkworm strain (1.91±0.06 denier) compared to the Chinese silkworm strain (2.26±0.15 denier). The filament tenacity, tenacity rupture and strain of J101 was 6.24 %, 24.62 % and 4.42 % greater compared to 205PO. The tensile strength of 205PO was 11.82 % greater compared to J101. The filament diameter was 22.01±0.42 μm and 21.98±0.15 μm of 205PO and J101, respectively. Based on these findings, it is recommended that silkworm strains with superior techno‐mechanical properties may be included in breeding programmes for enhancing the quality of silk textile. 相似文献
3.
In the present paper, the variability of mechanical properties of Bombyx mori silk is investigated at the intraspecific and intraindividual levels. We first reeled some complete silks of 700–1500 m in length from cocoons in a special procedure. A large number of tensile tests were performed to measure the variations of Young's modulus, ultimate tensile strength, yield stress, elongation and breaking energy of an entire silk along its length direction. Our experimental results and statistical analysis show that the diameter and mechanical properties of silk have significant variabilities at both the intraspecific and intraindividual levels. On one hand, this indicates that a single silkworm silk seems inappropriate to be applied as an engineering material to bear loading. On the other hand, however, it is interesting to note that the variability of silk does not exist as a disadvantage for a cocoon to achieve a superior ability against possible attacks from the outside. In addition, the dependence of such parameters as Young's modulus and tensile strength upon the diameter of silk was also analyzed, and distinct size effects were observed in these properties. This study not only provides a deeper understanding of the mechanical properties of silks and cocoons but is of interest for the design and tailoring of advanced biomimetic silk materials also. 相似文献
4.
The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 μm which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pKa value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both 13C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with β-sheet structure. 相似文献
5.
The effect of gauge length on tensile strength and Weibull modulus of polyacrylonitrile (PAN)- and pitch-based carbon fibers 总被引:1,自引:0,他引:1
Kimiyoshi Naito Jenn-Ming Yang Yoshihisa Tanaka Yutaka Kagawa 《Journal of Materials Science》2012,47(2):632-642
Carbon fibers are widely used as a reinforcement in composite materials because of their high specific strength and modulus.
Current trends toward the development of carbon fibers have been driven in two directions; ultrahigh tensile strength fiber
with a fairly high strain to failure (~2%), and ultrahigh modulus fiber with high thermal conductivity. Today, a number of
ultrahigh strength polyacrylonitrile (PAN)-based (more than 6 GPa), and ultrahigh modulus pitch-based (more than 900 GPa)
carbon fibers have been commercially available. In this study, the tensile strengths of PAN- and pitch-based carbon fibers
have been investigated using a single filament tensile test at various gauge lengths ranging from 1 to 250 mm. Carbon fibers
used in this study were ultrahigh strength PAN-based (T1000GB, IM600), a high strength PAN-based (T300), a high modulus PAN-based
(M60JB), an ultrahigh modulus pitch-based (K13D), and a high ductility pitch-based (XN-05) carbon fibers. The statistical
distributions of the tensile strength were characterized. It was found that the Weibull modulus and the average tensile strength
increased with decreasing gauge length, a linear relation between the Weibull modulus, the average tensile strength and the
gauge length was established on log–log scale. The results also clearly show that for PAN- and pitch-based carbon fibers,
there is a linear relation between the Weibull modulus and the average tensile strength on log–log scale. 相似文献
6.
Chun-Man Zheng Xiao-Dong Li Hao Wang Da-Fang Zhao Tian-Jiao Hu 《Journal of Materials Science》2008,43(9):3314-3319
The high-temperature resistant Si–Al–C–(O) fibers were prepared through polymer-derived method using continuous polyaluminocarbosilane
(PACS) fibers. Evolutions of the crystallization during the pyrolysis of the Si–Al–C–(O) precursor fibers were investigated
by a series analysis. The structure of the fibers transforms from organic state to inorganic state and the crystalline phases
appear during the pyrolysis. The β-SiC crystallite size increases when the temperature is higher than 1,300 °C. At the same time, the α-SiC appears. At 1,600 and 1,800 °C, the grain size of β-SiC of the fibers is 15.4 and 22.1 nm, respectively. The growth of β-SiC and the appearing of α-SiC have a great influence on the properties of the fibers. The change of the tensile strength of the pyrolysis products
is divided into three stages with the growth of the crystal. The tensile strength of the Si-Al-C fibers is higher than 1.9 GPa. 相似文献
7.
Md. Majibur Rahman Khan Yasuo Gotoh Hideaki Morikawa Mikihiko Miura 《Journal of Materials Science》2009,44(16):4235-4240
In order to investigate the graphitization behavior of Bombyx mori silk fibroin (SF) fibers, structural inspection of carbonized SF fibers treated with iodine vapor was studied at different
temperatures, from 800 to 1400 °C. Wide angle X-ray diffraction measurement suggested that both untreated and iodinated SF
fibers exhibited amorphous structure carbonized to 1200 °C. After carbonization at 1400 °C for 12 h, a graphite-like structure
was obtained. Raman spectroscopy and transmission electron microscopic observation showed that the graphite layers of SF fibers
became more ordered after iodine treatment. The carbon yield obtained at higher temperature (1400 °C) after iodine treatment
was higher, ca. 28 wt%, than that of untreated SF. 相似文献
8.
Igor Studart Medeiros Erika R. M. Andreeta Antonio C. Hernandes 《Journal of Materials Science》2007,42(11):3874-3877
9.
The fatigue behaviors of two SiC/[SiC+Si3N4] ceramic matrix composites (CMC) were investigated at 1,300°C in laboratory air and in steam. Composites consisted of a crystalline
[SiC+Si3N4] matrix reinforced with either Sylramic™ or Sylramic-iBN fibers (treated Sylramic™ fibers that possess an in situ BN coating)
woven in a five-harness satin weave fabric and coated with a proprietary boron-containing dual-layer interphase. The tensile
stress–strain behaviors were investigated and the tensile properties measured at 1,300°C. Tension–tension fatigue behaviors
of both CMCs were studied for fatigue stresses ranging from 100 to 180 MPa. The fatigue limit (based on a run-out condition
of 2 × 105 cycles) in both air and steam was 100 MPa for the CMC containing Sylramic™ fibers and 140 MPa for the CMC reinforced with
Sylramic-iBN fibers. At higher fatigue stresses, the presence of steam caused noticeable degradation in fatigue performance
of both composites. The retained strength and modulus of all run-out specimens were characterized. The materials tested in
air retained 100% of their tensile strength, while the materials tested in steam retained only about 90% of their tensile
strength. 相似文献
10.
S. Ouendadji S. Ghemid N. Bouarissa H. Meradji F. El Haj Hassan 《Journal of Materials Science》2011,46(11):3855-3861
Based on the self-consistent ab initio full potential-linearized augmented plane wave method, the structural, electronic,
optical, and thermodynamic properties of CdSe
x
Te1−x
ternary semiconductor alloys have been investigated. The exchange–correlation potential was calculated using both the generalized
gradient approximation (GGA) by Perdew–Burke–Ernzerhof (PBE) and the GGA by Engel–Vosko (EV-GGA). The ground-state properties
are determined for the cubic bulk materials CdSe, CdTe, and their mixed crystals at various concentrations (x = 0.25, 0.5, and 0.75). Deviation of the lattice parameter from Vegard’s law and the bulk modulus from linear concentration
dependence has been examined. The microscopic origins of the band-gap bowing parameter have been discussed. Moreover, the
refractive index and the optical dielectric constant for CdSe
x
Te1−x
are studied using different models. Besides, the thermodynamic stability of the alloys of interest is investigated by means
of the miscibility critical temperature. 相似文献
11.
Mingbo Yang Fusheng Pan Jia Shen Yi Zhu Caiyuan Qin 《Journal of Materials Science》2011,46(9):3094-3100
In this article, the as-cast microstructures and mechanical properties of the Mg–4Y–1.2Mn–0.9Sc and Mg–4Y–1.2Mn–1Zn (wt%)
magnesium alloys are investigated and compared. The results indicate that the Sc-containing alloy is mainly composed of α-Mg
and fine particle-like Mg24Y5, Mn12Y, and Mn2Sc phases, while the Zn-containing alloy mainly consists of α-Mg and coarse Mg12YZn phases with a continuous network. Furthermore, the grains of the Zn-containing alloy are relatively finer than those of
the Sc-containing alloy. In addition, the Sc-containing alloy exhibits relatively higher tensile properties at room temperature
and 300 °C than the Zn-containing alloy. However, the creep properties at 300 °C and 30 MPa for 100 h for the Sc-containing
alloy are relatively lower than those for the Zn-containing alloy. 相似文献
12.
Aydin E Planell JA Hasirci V 《Journal of materials science. Materials in medicine》2011,22(11):2413-2427
Novel PLLA composite fibers containing hydroxyapatite (HAp) nanorods with or without surface lactic acid grafting were produced
by extrusion for use as reinforcements in PLLA-based bone plates. Fibers containing 0–50% (w/w) HAp nanorods, aligned parallel
to fiber axis, were extruded. Lactic acid surface grafting of HAp nanorods (lacHAp) improved the tensile properties of composites
fibers better than the non-grafted ones (nHAp). Best tensile modulus values of 2.59, 2.49, and 4.12 GPa were obtained for
loadings (w/w) with 30% lacHAp, 10% nHAp, and 50% amorphous HAp nanoparticles, respectively. Bone plates reinforced with parallel
rows of these composite fibers were molded by melt pressing. The best compressive properties for plates were obtained with
nHAp reinforcement (1.31 GPa Young’s Modulus, 110.3 MPa compressive strength). In vitro testing with osteoblasts showed good
cellular attachment and spreading on composite fibers. In situ degradation tests revealed faster degradation rates with increasing
HAp content. To our knowledge, this is the first study containing calcium phosphate–polymer nanocomposite fibers for reinforcement
of a biodegradable bone plate or other such implants and this biomimetic design was concluded to have potential for production
of polymer-based biodegradable bone plates even for load bearing applications. 相似文献
13.
Sandeep Kumar 《Particulate Science and Technology》2017,35(3):304-313
The present investigation aims to study the effect of degumming time on the structural property of silk fiber obtained by silk cocoons of Bombyx mori, followed by preparation of the regenerated silk fibroin (RSF) solution which can be subsequently molded into silk nanoparticles. Silk fibers degummed with different media at different time intervals were investigated for the degumming loss and were characterized using Ffourier transform infrared (FTIR), differential scanning calorimetry (DSC), x-ray diffraction (XRD), and scanning electron microscopy (SEM). Maximum degumming was observed when the fibers were treated with sodium carbonate for 60 min. SEM and atomic force microscopy (AFM) images of RSF solution showed aggregation of silk globules resulting in formation of solvated macrochains and giving it an appearance of island-like morphology. Blank silk nanoparticles prepared from the RSF solution showed a smooth and spherical surface devoid of any adhesion using SEM, AFM, and transmission electron microscopy (TEM). The prepared silk nanoparticles may further be explored for loading drug entities and targeting. 相似文献
14.
Polycarbosilane (PCS) ceramic precursor fibers are irradiated in a nuclear reactor and pyrolyzed under inert atmosphere. Bridge
structure of Si–CH2–Si is formed in the irradiated products by the rupture of Si–H bonds and succeeding cross-linking. When irradiated at the
neutron fluence of 2.2 × 1017 cm−2 under N2 atmosphere, the gel content and ceramic yield at 1,273 K of PCS fibers are up to 80% and 94.3%, respectively, and their pyrolysis
products are still fibrous, which illuminates that the infusibility of PCS fibers has been achieved. FT-IR spectra indicate
that the chemical structure of pyrolysis products is very similar to that of pure SiC, while X-ray diffraction curves suggest
that β-SiC microcrystals are formed in the fibers, and their mean grain size is about 7.5 nm. The oxygen content (1.69–3.77 wt%)
is much lower than that of conventional SiC fibers by oxidation curing method (about 15 wt%). Tensile strength of the SiC
fibers is up to 2.72 GPa, which demonstrates that their mechanical properties are excellent. After heat-treated at 1,673 K
in air for an hour or at 1,873 K under Ar gas atmosphere for 0.5 h, their external appearance is still undamaged and dense,
and their tensile strength decreases to a small extent, which verifies that heat resistance of the SiC fibers is eximious. 相似文献
15.
Ke Liu Jinghuai Zhang Wei Sun Xin Qiu Huayi Lu Dingxiang Tang L. L. Rokhlin F. M. Elkin Jian Meng 《Journal of Materials Science》2009,44(1):74-83
Microstructures and mechanical properties of the Mg–7Y–4Gd–xZn–0.4Zr (x = 0.5, 1.5, 3, and 5 wt.%) alloys in the as-cast, as-extruded, and peak-aged conditions have been investigated by using optical
microscopy, scanning electron microscope, X-ray diffraction, and transmission electron microscopy. It is found that the peak-aged
Mg–7Y–4Gd–1.5Zn–0.4Zr alloys have the highest strength after aging at 220 °C. The highest ultimate tensile strength and yield
tensile strength are 418 and 320 MPa, respectively. The addition of 1.5 wt.% Zn to the based alloys results in a greater aging
effect and better mechanical properties at both room and elevated temperatures. The improved mechanical properties are mainly
ascribed to both a fine β′ phase and a long periodic stacking-ordered structure, which coexist together in the peak-aged alloys. 相似文献
16.
The Sn–3.5 wt% Ag eutectic alloy was directionally solidified upward with a constant growth rate (V = 16.5 μm/s) at different temperature gradients (G = 1.43–4.28 K/mm) and with a constant temperature gradient (G = 3.93 K/mm) at different growth rates (V = 8.3–500 μm/s) in a Bridgman-type directional solidification furnace. The rod spacings (longitudinal section, λ
L
and transverse section, λ
T
) and mechanical properties (microhardness, HV and ultimate tensile strength, σ
UTS
) of Sn–3.5 wt% Ag eutectic alloy were measured. The dependency of the microhardness, ultimate tensile strength on the temperature
gradient, growth rate and rod spacings were determined. According to experimental results, the microhardness and ultimate
tensile strength of the solidified samples increase with increasing G and V, but decrease with the increasing the rod spacing. 相似文献
17.
Saadi Abdul Jawad Adnan S. Abu-Surrah Mufeed Maghrabi Ziad Khattari Manar Al-Obeid 《Journal of Materials Science》2011,46(8):2748-2754
Electrical impedance technique was employed to investigate the electrical properties of ethylene-carbon monoxide/propylene-carbon
monoxide terpolymer (EPEC-69). The measurements were performed in the frequency range 0.1–105 Hz and in the temperature range 30–110 °C. The results reveal that the dielectric constant, loss factor, modulus, and ac conductivity
are dependent of frequency and temperature. A Debye relaxation peak was detected in the plot of Z″ versus frequency where the activation energy was determined and found to be 1.26 eV. When the surface phenomenon effects
were separated using the imaginary part of the complex admittance a second dielectric dispersion was observed in the low frequency
region. Two models were proposed from the impedance measurements depending on temperature range. 相似文献
18.
We have studied the effect of zirconia additions on the properties of basalt glasses and fibers. The solubility limit of ZrO2 in basalt glasses is determined to be 7.1 wt %. Fibers produced from modified basalt glass contain both tetragonal and monoclinic zirconia. The highest ZrO2 concentration in basalt fibers is 3.1 wt %. We have determined the fiber drawing temperature ranges and assessed the tensile strength and alkali resistance of the fibers. With increasing ZrO2 content, the tensile strength of the fibers (d = 11−12 μm) decreases from 1.8 to 0.6 GPa. The addition of less than 3.1 wt % ZrO2 increases the alkali resistance of the basalt fibers by 37%. The addition of more than 3.1 wt % ZrO2 to the glass batch reduces the alkali resistance and tensilestrength of the basalt fibers. 相似文献
19.
Haifeng Zhang Ziqiao Zheng Yi Lin Xianfu Luo Jing Zhong 《Journal of Materials Science》2012,47(9):4101-4109
The effects of Ag addition on the microstructure and thermal stability of 6156 Al–Mg–Si–Cu alloy were investigated by means
of hardness measurement, tensile tests, differential scanning calorimetry, and transmission electron microscopy. The results
showed that addition of small amount of Ag to 6156 alloy did not change the precipitation sequence mainly β″ and Q′ strengthening phase but slightly accelerated the age-hardening rate and increased peak hardness at the same aging condition.
The tensile properties enhanced about 30 MPa at the room temperature or thermal exposure at lower temperature (<100 °C). With
the exposed temperature and time increased to 150 °C for 1000 h, almost no difference between the Ag-containing and Ag-free
alloys. When exposed at 200 °C, the tensile strength of Ag-containing alloy became lower than that of Ag-free alloy because
of the coarsening precipitations in matrix and boundary observed by TEM observed. For both alloys, thermal exposure at temperatures
100 °C for long time periods had no significant effect on tensile properties. Loss in strength was small and large with prolonging
the exposure time at 150 and 200 °C, respectively. 相似文献
20.
J. Zhang J. Kaur R. Rajkhowa J.L. Li X.Y. Liu X.G. Wang 《Materials science & engineering. C, Materials for biological applications》2013,33(6):3206-3213
As a protective shell against environmental damage and attack by natural predators, the silkworm cocoon has outstanding mechanical properties. In particular, this multilayer non-woven composite structure can be exceptionally tough to enhance the chance of survival for silkworms while supporting their metabolic activity. Peel, out-of-plane compression and nano-indentation tests and micro-structure analysis were performed on four types of silkworm cocoon walls (domesticated Bombyx mori, semi-domesticated Antheraea assamensis and wild Antheraea pernyi and Antheraea mylitta silkworm cocoons) to understand the structure and mechanical property relationships. The wild silkworm cocoons were shown to be uniquely tough composite structures. The maximum work-of-fracture for the wild cocoons (A. pernyi and A. mylitta) was approximately 1000 J/m2, which was almost 10 times the value for the domesticated cocoon (Bombyx mori) and 3 ~ 4 times the value for the semi-domesticated cocoon (A. assamensis). Calcium oxalate crystals were found to deposit on the outer surfaces of the semi-domesticated and wild cocoons. They did not show influence in enhancing the interlaminar adhesion between cocoon layers but exhibited much higher hardness than the cocoon pelades. 相似文献