Grafting of Casein onto Polyacrylonitrile Fiber for Surface Modification

Jia Zhao,Du Shanyi The Korean Fiber Society 2006 Fibers and polymers Vol.7 No.3

Polyacrylonitrile (PAN) fiber was grafted with casein after alkaline hydrolysis and chlorination reactions of the original fiber. The structures and morphologies of the casein grafted fiber were characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and scanning electron microscope (SEM). Moisture absorption, specific electric resistance, water retention value, and mechanical properties were also investigated. The results showed that casein was grafted onto the surface of the PAN fiber and the grafted PAN fiber presented better hygroscopicity compared with the untreated fiber. With proper tensile strength, the modified fiber could still meet the requirement for wearing. A mechanism was proposed to explain the deposit of casein on the synthetic acrylic fiber.

Frictional and Tensile Properties of Conducting Polymer Coated Wool and Alpaca Fibers

Wang Lijing,Lin Tong,Wang Xungai,Kaynak Akif The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.3

Wool and alpaca fibers were coated with polypyrrole by vapor-phase polymerisation method. The changes in frictional and tensile properties of the single fibers upon coating with the conductive polymer are presented. Coating a thin layer of polypyrrole on the alpaca and wool fibers results in a significant reduction in the fiber coefficient of friction, as the conducting polymer layer smooths the protruding edges of the fiber scales. It also reduces the directional friction effect of the fibers. Depending on the type of fiber, the coating may slightly enhance the tensile properties of the coated fibers.

Surface Morphologies and Internal Fine Structures of Bast Fibers

Wang H. M.,Wang X. The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.1

Fiber surface morphologies and associated internal structures are closely related to its properties. Unlike other fibers including cotton, bast fibers possess transverse nodes and fissures in cross-sectional and longitudinal directions. Their morphologies and associated internal structures were anatomically examined under the scanning electron microscope. The results showed that the morphologies of the nodes and the fissures of bast fibers varied depending on the construction of the inner fibril cellular layers. The transverse nodes and fissures were formed by the folding and spiralling of the cellular layers during plant growth. The dimensions of nodes and fissures were determined by the dislocations of the cellular layers. There were also many longitudinal fissures in bast fibers. Some deep longitudinal fissures even opened the fiber lumen for a short way along the fiber. In addition, the lumen channel of the bast fibers could be disturbed or disrupted by the nodes and the spi­rals of the internal cellular layers. The existence of the transverse nodes and fissures in the bast fibers could degrade the fiber mechanical properties, whereas the longitudinal fissures may contribute to the very rapid moisture absorption and desorption.

Thermal Conductivity and Thermal Expansion Behavior of Pseudo-Unidirectional and 2-Directional Quasi-Carbon Fiber/Phenolic Composites

Cho, Donghwan,Choi, Yusong,Park, Jong Kyoo,Lee, Jinyong,Yoon, Byung Il,Lim, Yun Soo The Korean Fiber Society 2004 Fibers and polymers Vol.5 No.1

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.

Sound Characteristics according to Cross-sectional Shapes of Fibers

Kim, Chunjeong,Cho, Gilsoo,Hong, Kyoung A.,Shim, Hyun Joo The Korean Fiber Society 2003 Fibers and polymers Vol.4 No.4

In order to investigate the effects of cross-sectional shapes on the sound characteristics of polyester fibers, 10 specimens were woven into a twill structure made of round, hollow, triangular, u-shape, cruciform, and composite cross-sectional (▲/▲ ,()/▲, Y/Y) fibers. Their rustling sounds were recorded, and their sound spectra were obtained from FFT analysis. Physical sound parameters (LPT, ΔL, Δf) and Zwicker's psychoacoustic parameters of the loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z) were calculated from the sound spectra. According to noncircular cross-section fibers, the hollow shaped fiber had the highest value of LPT, ΔL, loudness(Z), and fluctuation strength(Z). The triangular shaped fiber had a lower value of LPT, ΔL, loudness(Z), and roughness(Z) than those of the round shaped fiber. Among composite cross-section fibers, C1(▲/▲) and C3 (Y/Y) had higher values of LPT, ΔL, Δf and loudness(Z) but C2(()/▲) had lower values. Also the LPT, ΔL, sharpness(Z), and roughness(Z) values of different denier were similar to each other, but the Δf and loudness(Z) values increased as the denier increased.

Dry-jet Wet Spinning of Polyhydroxyamide Fibers

Park, Seung-Koo,Cho, Seo-Hyun,Farris, Richard-John The Korean Fiber Society 2000 Fibers and polymers Vol.1 No.2

A high molecular weight polyhydroxyamide (PHA) solution in N, N-dimethyl acetamide (DMAc) was prepared from 3, 3'-dihydroxybenzidine and isophthalic chloride (IPC), which was used for spinning PHA fiber. Before spinning, the diffusion property of DMAc into various coagulants was examined. The fiber was well formed in coagulants such as water/ethanol with a composition of 5/5, ethanol, and ethanol/isopropanol with a composition of 7/3 and 5/5. However, the PHA fiber spun in the water/ethanol mixture contained voids. After the fiber spun in ethanol was annealed at over $350^{\circ}C$, the ultimate stress and initial modulus of the fiber increased from 75.5 MPa and 3.22 GPa to 369 MPa and 29.5 GPa, respectively. These properties of the PHA fiber spun by the dry spinning method were also enhanced, attaining 154 MPa and 5.56 Gpa, respectivel.

Psychoacoustic Characteristics of Fibers

Yi, Eunjou,Cho, Gilsoo The Korean Fiber Society 2000 Fibers and polymers Vol.1 No.1

In order to investigate psychoacoustic characteristics of fibers, and to compare them with sound physical parameters, each sound of 25 different fabrics consisted of a single fiber such as wool, cotton, silk, polyester, and nylon was recorded. Sounds of specimens were transformed into critical band diagram and psychoacoustic characteristics including loudness and sharpness for each sound were calculated based on Zwicker's models. Physical parameters such as the level pressure of total sound (LPT), level ranges (ΔL), frequency differences (Δf), AR coefficients (ARC, ARF, ARE) were obtained in fast fourier transform (FFT) spectrum. Nylon taffeta showed higher values for loudness than 2.5 sone corresponding to human low conversation, while most silk fibers generated less louder showing lower values for loudness than 1.0 sone. Wool fibers had higher loudness mean value than that of cotton, while the two fibers didn't differ in LPT. Loudness showed high positive correlation coefficients with both LPT and ARC. Sharpness values were higher for wool fiber group than other fibers. Sharpness was not concerned with loudness, LPT, and ARC, but the fabrics with higher values for sharpness tended to show higher ΔL.

Correlating the Fineness and Residual Gum Content of Degummed Hemp Fibres

Beltran, Rafael,Hurren, Christopher J.,Kaynak, Akif,Wang, Xungai The Korean Fiber Society 2002 Fibers and polymers Vol.3 No.4

It is well known residual gum exists in degummed or rotted hemp fibers. Gum removal results in improvement in fiber fineness and the properties of the resultant hemp yams. However, it is not known what correlation if any exists between the residual gum content in retted hemp fibers and the fiber fineness, described in terms of fiber width in this paper. This study examined the mean width and coefficient of variation (CV) of fiber width of seventeen chemically rotted hemp samples with reference to residual gum content. The mean and CV of fiber width were obtained from an Optical fiber diameter analyser (OFDA 100). The linear regression analysis results show that the mean fiber width is directly proportional to the residual gum content. A slightly weaker linear correlation also exists between the coefficient of variation of fiber width and the residual gum content. The strong linear co-relation between the mean of fiber width and the residual gum content is a significant outcome, since testing for fiber width using the OFDA is a much simpler and quicker process than testing the residual gum content. Scanning Electron Microscopy (SEM) reinforces the OFDA findings. SEM micrographs show a flat ribbon like fiber cross-section hence the term \"fiber width\" is used instead of fiber diameter. Spectral differences in the untreated dry decorticated skin samples and chemically treated and subsequently carded samples indicate delignification. The peaks at $1370cm^{-1}$, $1325cm^{-1}$, $1733cm^{-1}$, and $1600cm^{-1}$ attributed to lignin in the untreated samples are missing from the spectra of the treated samples. The spectra of the treated samples are more amine-dominated with some of the OH character lost.cter lost.

Study on Mechanical and Thermal Properties of Fiber-Reinforced Epoxy/Hybrid-silica Composite

Kim, Dongho,Chung, Ildoo,Kim, Guni THE KOREAN FIBER SOCIETY 2013 FIBERS AND POLYMERS Vol.14 No.12

Recently, carbon fiber composites have been widely used as structural reinforcement materials of buildings, replacing reinforcing bars or concrete. And the increase in use of super fibers such as aramid and high strength PE, which is aimed at improving the reinforcement properties, has resulted in a demand for a resin system with excellent mechanical and thermal properties. In this research, a fiber-reinforced composite has been produced by using the super fibers such as carbon fiber or aramid fiber, reinforcement resin and the silica hybrid compound containing epoxy group. This study was carried out to confirm the effect of the silica hybrid on mechanical properties, heat resistance and adhesion strength of a fiber-reinforced epoxy composite, which was produced by blending silica or introducing silica hybrid through covalent bonds. And the silica hybrid containing epoxy group, which may be introduced to the structure of fiber-reinforced epoxy composite through covalent bonds caused by reaction with a hardener, has been used, so that the heat resistance and adhesion strength could be improved.

Image Analysis of the Luster of Fabrics with Modified Cross-section Fibers

Shin Kyung In,Kim Seong Hun,Kim Jong Jun The Korean Fiber Society 2005 Fibers and polymers Vol.6 No.1

We have investigated the luster of modified cross-sectional fiber fabrics as one of the essential quality estimates for clothing development. We have confirmed an objective evaluation method, and have determined the experimental luster char­acteristics of modified cross-section fibers. The cross-section of the fibers in a fabric affects the appearance of a textile. We used the image analysis method to investigate the luster to determine the critical factors influencing the appearance of modi­fied cross-section fiber fabrics. For similarly structured textiles in a component fabric, clear differences were observed in the fabric weave, density, percentage, and total area of blobs, which is image region. Color played a decisive role in the luster of the textiles, and luster was not significantly influenced by the modified cross-section fabric weave. In addition, the degree of luster did not increase in the order plain to twill to satin for modified cross-sectional fiber fabrics. All the split-type microfi­bers exhibited higher numerical luster values (percentage of pixels, and number and total area of blobs) than sea-island microfibers did. The degree of luster of the modified cross-sectional fiber fabrics was not high at specular reflection angles.