Lyocell fiber is a new kind of regenerated cellulose fiber and expected to replace the Rayon fiber to be not only used in the textile field but also used in the fields of industry and aerospace after being modified. In this work, the multi-walled carbon nanotubes (MWNTs)/Lyocell composite fibers were prepared under different draw ratios by dry-wet spinning and their electrical properties, mechanical properties, and structure were investigated. It was found that an appropriate amount of MWNTs could be dispersed homogeneously in the Lyocell matrix and could improve the mechanical and thermal properties of composite fiber. The results of wide angle X-ray diffraction (WAXD) showed that the MWNTs in the composite fiber almost aligned along the axis of the fibers and the orientation of MWNTs increased with the increasing draw ratio. Furthermore, it was found that more MWNTs content and lower draw ratio could improve the electrical conductance of the composite fiber. The composite fiber containing 5 wt % MWNTs has a volume conductivity of 8.8 × 10−4 S/cm, which is five orders higher than that of pure Lyocell fiber. These results indicate that the MWNTs/Lyocell composite fiber has potential applications in the areas of precursor of carbon fiber and conductive fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
1-Butyl-3-methylimidazolium chloride ([BMIM]Cl) was used as a solvent for cellulose, the rheological behavior of the cellulose/[BMIM]Cl solution was studied, and the fibers were spun with a dry-jet–wet-spinning process. In addition, the structure and properties of the prepared cellulose fibers were investigated and compared with those of lyocell fibers. The results showed that the cellulose/[BMIM]Cl solution was a typical shear-thinning fluid, and the temperature had little influence on the apparent viscosity of the solution when the shear rate was higher than 100 s−1. In addition, the prepared fibers had a cellulose II crystal structure just like that of lyocell fibers, and the orientation and crystallinity of the fibers increased with the draw ratio increasing, so the mechanical properties of the fibers improved. Fibers with a tenacity of 4.28cN/dtex and a modulus of 56.8 cN/dtex were prepared. Moreover, the fibers had a smooth surface as well as a round and compact structure, and the dyeing and antifibrillation properties of the fibers were similar to those of lyocell fibers; however, the color of these dyed fibers was brighter than that of lyocell fibers. Therefore, these fibers could be a new kind of environmentally friendly cellulose fiber following lyocell fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
In this work, three kinds of different poly(L-lactic acid) (PLLA) materials for melt-spinning were investigated with respect to the molecular weight (MW) and molecular weight distribution (MWD), racemization, optical purity, thermal properties, and melt-spinnability. It was found that the high MW was not the only factor to affect the melt spinnability of PLLA, the racemization and the amount of residual monomer would also affect the thermal properties and melt-spinnability of PLLA. The results showed that it could be melt-spun and hot-drawn by using the general melt-spinning device for PLLA pellet with good stereoregularity and comparatively high MW. For PLLA pellet with high MW and moderate stereoregularity, it must be treated at an appropriate temperature to increase the crystallinity before dry and extrusion, which could make the pellet be spun without agglomeration, whereas the draw ability of such as-spun fiber was still poor. However, if the stereoregularity of PLLA pellet was poor, it could not be spun even it had very high MW. Only when MW, racemization, and the amount of residual monomer of the PLLA pellets all meet the requirements, PLLA fibers could be prepared by melt-spinning. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Lyocell fibers were produced from a cheap pulp with a high hemicellulose content and from a conventional pulp with a high α-cellulose content. The mechanical properties, supermolecular structure, fibrillation resistance, and dyeing properties as well as the fibril aggregation size of the high hemicellulose Lyocell fiber and high α-cellulose Lyocell fiber were compared. The results showed that the high hemicellulose spinning solution could be processed at a higher concentration, which improved the mechanical properties and the efficiency of the fiber process. Compared with the high α-cellulose Lyocell fiber, the high hemicellulose Lyocell fiber had better fibrillation resistance and dyeing properties. Therefore, it is feasible that this cheap pulp with a high hemicellulose content can be used as a raw material for producing Lyocell fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
In this work, Lyocell fibers filled with various amounts of carbon black were prepared. Wide angle X-ray diffraction (WAXD) results showed that carbon black filled Lyocell fibers still had a cellulose II crystal structure and kept the characteristic peak of carbon black at the same time. The results of mechanical properties showed a slight reduction in the carbon black filled Lyocell fiber. Moreover, the heat stabilities of the carbon black filled Lyocell fibers showed no obvious change. The residue of carbon black filled Lyocell fiber at 1000°C was higher than that of Lyocell fiber, implying higher carbon yield could be obtained for the carbon black filled Lyocell precursor. Scanning electron microscopy (SEM) experiments showed that the surface and the cross section of carbon black filled Lyocell fiber were smooth and round, which are consistent with the carbon fiber precursor. The WAXD pattern of carbon black filled Lyocell-based carbon fiber was different from that of Lyocell-based carbon fiber. The addition of carbon black transfers the diffraction peak of carbon fiber while keeping the characteristic structure of carbon black. The results of mechanical properties of carbon fibers show that, if an appropriate amount of carbon black was chosen, carbon fiber with better properties than Lyocell-based carbon fiber could be obtained by using the carbon black filled Lyocell fibers as the precursor. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 65–74, 2006
In this article, the electrospun silk fibroin (SF) fibers with an average diameter of 700 nm were prepared from a concentrated aqueous solution with an electrospinning technique. The morphology, conformation, and crystalline structure of the SF fibers were characterized by scanning electron microscopy, Raman spectroscopy, and wide-angle X-ray diffraction, respectively. The structure and morphology of the fibers were strongly influenced by the solution concentration and the processing voltage. In addition, the fiber formation parameters, including spinning velocity, elongation rate, and draw ratio, were also calculated. A kind of SF fiber with a structure between an amorphous film and a natural silk was found. We suggest that the high draw ratio was not the only factor in the transformation of SF from random-coil and α-helix conformations to a β-sheet conformation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 961–968, 2006
Lyocell fibers were heat-treated under different conditions. The tensile strength and initial modulus of the heat-treated Lyocell fibers increased sharply, whereas the elongation at break decreased. Moreover, applying tension to the fibers during the heat treatment further improved the tensile strength and initial modulus. In addition, the crystallinity of the heat-treated fibers increased slightly, and there was no obvious change with an increase in the tension; the general orientation of the heat-treated fibers increased, the crystalline orientation little changed, and the amorphous orientation improved. Also, the improved mechanical properties of the Lyocell fibers via the heat treatment could not be preserved for long. The reason may be that the crystalline structure of the Lyocell fibers was not destroyed and no new crystallites were formed during the heat-treatment process. Therefore, the heat-treated Lyocell fibers reverted to their original state with time because there was no crosslinking point to fix the orientation, although the cellulose molecules of the amorphous region of the Lyocell fibers were more oriented by the heat treatment with tension. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1738–1743, 2006
A two-step direct copolymerization process of L-lactic acid (L-LA)/glycolic acid (GA) was developed. The first step was to produce an oligomer of L-LA/GA and then the oligomer was polymerized with binary catalyst tin chloride dihydrate/p-toluenesulfonic acid. In this way, the copoly(L-LA/GA) (PLGA), without any organic solvent, was synthesized directly. The thermal properties and solubility in chloroform of PLGA were studied by DSC and NMR. The results showed that the melting point of PLGA decreases with increasing mole fraction of GA units in copolymer. In addition, the melting point of polymer also decreased with increasing degree of racemization of polymer. The solubility of PLGA in chloroform decreased with the increase of the average lengths of the glycolic acid units. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2163–2168, 2004
In this article, a rheological method that can predict the molecular weight distribution (MWD) of polymer was introduced. Using this method, the MWDs of four cellulose samples were compared from rheological data of the cellulose / N-methyl morpholine N-oxide (NMMO) / H2O solutions. The MWDs of cellulose also were determined by gel permeation chromatography (GPC) calibrated with narrow distribution polystyrene standards, using 0.5% lithium chloride (LiCl) in N,N-dimethylacetamide (DMAc) as the eluent. Comparison of the results from rheology and GPC showed that the MW and MWD of cellulose could be roughly inferred from their rheological data. Although the differential MWD obtained from the rheological method was bell shaped and can not reflect the fine characteristics of cellulose as GPC, it may be feasible to compare the MWDs of cellulose by using the rheological method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 598–603, 2004
In this work, Lyocell fibers, used as carbon fiber precursors, were investigated. Lyocell fibers used for the carbon precursors and the carbon fibers themselves were produced in our laboratory. The mechanical properties morphology and structure of the precursors and the obtained carbon fibers were studied and compared to those of rayon. The results show that Lyocell fibers have higher tenacity and modulus, and better thermal stability than rayon fibers. Scanning electron microscopy (SEM) experiments show that Lyocell precursors have round cross-sections and fewer defects in the fibers, while rayon fiber has an oval cross-section and many defects. Wide angle X-ray diffraction (WAXD) results for the Lyocell precursors indicate that the degree of crystallinity of the Lyocell precursor is higher than that of a rayon precursor. They also show that Lyocell based carbon fibers have better mechanical properties than those that are rayon-based. WAXD data of the obtained carbon fibers show that the crystallinity of Lyocell-based carbon fiber is higher than that of rayon-based carbon fiber. It is concluded that the Lyocell fibers are better precursors for carbon fibers than rayon. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1941–1947, 2003
![Acetic acid, 2-[(2,3-dihydrothieno[3,4-b]-1,4-dioxin-2-yl)methoxy]-](/data/chemimg/3240800/540803-67-6.png)
![Acetic acid, 2-[(2,3-dihydrothieno[3,4-b]-1,4-dioxin-2-yl)methoxy]-](/data/chemimg/3240800/540803-67-6_b.png)
![Aluminium hydroxybis[2,2'-methylen-bis(4,6-di-tert-butylphenyl)phosphate]](http://img.cochemist.com/ccimg/151900/151841-65-5.png)
![Aluminium hydroxybis[2,2'-methylen-bis(4,6-di-tert-butylphenyl)phosphate]](http://img.cochemist.com/ccimg/151900/151841-65-5_b.png)
![POLY[OXY[(1R)-1-METHYL-2-OXO-1,2-ETHANEDIYL]]](http://img.cochemist.com/ccimg/27000/26917-25-9.png)
![POLY[OXY[(1R)-1-METHYL-2-OXO-1,2-ETHANEDIYL]]](http://img.cochemist.com/ccimg/27000/26917-25-9_b.png)
![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2.png)
![Poly[oxy[(1S)-1-methyl-2-oxo-1,2-ethanediyl]]](http://img.cochemist.com/ccimg/26200/26161-42-2_b.png)