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排序方式: 共有197条查询结果,搜索用时 15 毫秒
191.
Seung-Yeol Jeon Woong-Ryeol Yu Min Sun Kim Joon Seok Lee Jong Won Kim 《Fibers and Polymers》2014,15(6):1202-1210
As nonwoven mats are randomly oriented fiber assemblies, the tensile strength of nonwoven mats is determined by their microstructural factors, such as fiber orientation, fiber volume fraction, and fiber-fiber contact level. The complex microstructure of nonwoven mats must be reasonably simplified to properly predict their mechanical properties within affordable efforts. In this study, a new parameter, so called contact efficiency, is defined to describe the fiber-fiber contact level of nonwoven mats. Micro X-ray computer tomography (CT) is employed to characterize the microstructure of needlepunched nonwoven mats made of polypropylene short fibers. The fiber orientation and volume fraction are obtained by analyzing 2D sectional CT image of the nonwoven mat, while the contact efficiency is determined from 3D CT image. A statistical model, developed originally for staple yarns, is modified to predict the tensile strength of the nonwoven mat using the microstructural factors obtained from CT analysis. The prediction is then compared with experiments to validate that the current model incorporating the contact efficiency is highly suitable for predicting the tensile strength of nonwoven mats. 相似文献
192.
Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(N-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and ultraviolet light weakly, whereas arrays of compact shrunken particles diffract efficiently. A tunable diffracting array was also created by embedding a CCA of polystyrene spheres within a PNIPAM hydrogel that swells and contracts with temperature; thus the array lattice constant varies with temperature, and the diffracted wavelength was thermally tunable across the entire visible spectrum. These materials may find applications in many areas of optics and materials science. 相似文献
193.
Young Seok Koo 《Fibers and Polymers》2002,3(2):80-84
Tension control is an important factor in producing high quality knitted products and in maintaining good processing condition.
Yarn tension during knitting is subject to be affected from many elements of the machine and process parameters. Several factors
including yarn feeding speed, feeding angle, and needle gauge that are considered to influence on the tension variation were
investigated. Yarn feeding speed did not show high contribution to the tension variation but feeding angle of yarn did show
high correlation with the tension. No or negative correlation of the tension with needle gauge was found from the results.
In order to keep well-determined process condition in the knitting manufacturing, it is strongly suggested that all knitting
elements and parameters should be in the integrated control circumstance. 相似文献
194.
Kwan Woo Kim Keun Hyung Lee Bong Seok Lee Yo Seung Ho Seung Jin Oh Hak Yong Kim 《Fibers and Polymers》2005,6(2):121-126
Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends
with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene
chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity,
surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased,
while there was no difference in surface tension with respect to aPET composition. The characteristics of the electrospun
cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements
were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased
with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend
nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to
a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of
the morphology. 相似文献
195.
Dyebath used for metal complex dyeing of nylon microfiber was recycled to reduce the overall amounts of metal complex dyeing
effluents. Instead of discharging the dyebath after each dyeing cycle, the residual dyebath was analyzed spectrophotometrically
and reconstituted to the required concentration of dyes and auxiliaries. Dyebaths were reused eight times and the CIELAB coordinates
of dyed samples were measured after each recycling. Color difference (ΔE*) between the sample dyed in the fresh bath and that
from reused dyebath was maintained below 1.5. The levelness and fastness of dyed fabrics from recycled dyebath were not impaired
either. Chromium content of each recycled dyebath was similar to that of the first residual dyebath. 相似文献
196.
197.
Chaijan M Benjakul S Visessanguan W Lee S Faustman C 《Journal of agricultural and food chemistry》2007,55(11):4562-4568
The interaction between fish myoglobin (Mb) and natural actomyosin (NAM) extracted from fresh and frozen fish was studied. The quantity of soluble Mb in Mb-NAM extracted was less in frozen than in fresh fish (P < 0.05). However, no differences were observed in Mb that remained in solution following preparation of Mb-NAM from frozen whole fish vs frozen fillets (P > 0.05). MetMb formation in Mb-NAM was generally greater than that observed in control Mb (P < 0.05); the greatest MetMb content occurred in Mb-NAM extracted from frozen whole fish (P < 0.05). The effect of different aldehyde oxidation products on the interaction between fish Mb and NAM was also studied in vitro. The loss of soluble Mb from NAM:Mb preparations was greater in the presence of hexenal and hexanal (P < 0.05) relative to controls, and the degree of solubility loss varied with aldehyde type. Hexenal caused greater OxyMb oxidation than hexanal (P < 0.05). Whiteness of washed NAM and NAM-Mb mixtures decreased following aldehyde addition (P < 0.05). In the absence of Mb, the Ca2+ -ATPase activity of NAM was lower with added hexenal than with hexanal (P < 0.05). However, no differences in Ca2+ -ATPase activity between hexanal and hexenal-treated samples were observed when Mb was present (P > 0.05). Reducing and nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses suggested that both disulfide and nondisulfide covalent linkages contributed to aldehyde-induced cross-linking between Mb and myofibrillar proteins. 相似文献