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ABSTRACT High-performance regenerated cellulose fibers were prepared from cellulose/1-butyl-3-methylimidazolium chloride (BMIMCl) solutions via dry-jet wet spinning. The spinnability of the solution was initially evaluated using the maximum winding speed of the solution spinning line under various ambient temperatures and relative humidities in the air gap. The subsequent spinning trials were conducted under various air gap conditions in a water coagulation bath. It was found that low temperature and low relative humidity in the air gap were important to obtain fibers with high tensile strength at a high draw ratio. From a 10 wt % cellulose/BMIMCl solution, regenerated fibers with tensile strength up to 886 MPa were prepared below 22 °C and relative humidity of 50%. High strengthening was also strongly linked with the fixation effect on fibers during washing and drying processes. Furthermore, an effective attempt to prepare higher performance fibers was conducted from a higher polymer concentration solution using a high molecular weight dissolving pulp. Eventually, fibers with a tensile strength of ∼1 GPa and Young's modulus over 35 GPa were prepared. These tensile properties were ranked at the highest level for regenerated cellulose fibers prepared by an ionic liquid-based process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45551. [ABSTRACT FROM AUTHOR]

PVA is reinforced with SWCNTs using green tea extract as a dispersant to achieve good dispersion of the SWCNTs in an organic solvent and finally high-performance composite fibers. A combination of green tea extract/DMSO/SWCNT/PVA is found to disperse larger aggregates of SWCNTs to individual or thin bundles of a few nanotubes. Incorporation of 0.5 wt% SWCNTs into PVA fibers yields a tensile strength of 2.42 GPa, a Young's modulus of 46 GPa, toughness of 105 J · g−1 at a failure strain of 11%, and a loop strength of 245 MPa, much higher than the values of commercial PVA fibers. The incorporation of highly dispersed SWCNTs suppresses the fibrillation tendency of the PVA fibers. The applied load is effectively transferred from the matrix to the SWCNTs. [ABSTRACT FROM AUTHOR]

Nanocomposite fibers were prepared from chitin whiskers (ChWs) as the reinforcing phase and poly(vinyl alcohol) (PVA) as the matrix. Colloidal suspensions of ChWs, obtained by acid hydrolysis of chitin from crab shell, were thoroughly mixed with aqueous PVA. The homogeneous PVA-ChW suspensions were gel-spun into a methanol coagulating bath. Wide-angle X-ray diffraction patterns evidenced the orientation of ChWs along the fiber axis. From differential scanning calorimetry, the crystallinity of the PVA component was found to increase with ChW loading due to the possible dragging of PVA chains adhering to ChWs during vertical extrusion. The non-isothermal crystallization peak of PVA was observed to shift to lower temperature with ChW loading indicating interfacial interactions between PVA and ChW. Further interaction between PVA and ChW was evidenced by the shifting of the Fourier transform infrared bands of PVA to lower wavenumber and the dynamic tan δ peak, corresponding to α-relaxation of PVA, shifting to higher temperature. The interaction of ChWs with the matrix PVA yielded a significant enhancement in the mechanical properties of the nanocomposites. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The elastic modulus ( E l) of crystalline regions in the direction parallel to the chain axis in a new semiaromatic polyamide 9-T (PA9-T) containing a long aliphatic chain unit was measured by X-ray diffraction and the derived E l value was discussed in terms of its molecular conformation and mechanical properties. For low and high molecular weight PA9-Ts, the E l value of 40 GPa was obtained. The low E l value for PA9-T is due to the presence of aromatic groups with long crankshaft arms, which result in a greater moment of force during deformation compared with those polymers with planner zigzag molecular conformation like polyethylene and nylon 6 α-form. Another factor for the low E l is due to the contraction of its molecular chains that is likely originated from the existence of a torsional conformation. The presence of contraction causes some internal rotation in the polymer chain during extensional deformation, which results in low E l. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In order to utilize the excellent mechanical properties of cellulose whiskers (CWs) along their length, the present work was undertaken to embed CWs with highly oriented forms in a polymer matrix. Nanocomposite fibers were prepared using poly(vinyl alcohol) (PVA; degree of polymerization of 1500) as the matrix and a stable aqueous suspension of CWs extracted from tunicates as the reinforcing phase. Macroscopically homogeneous suspensions of PVA-CW were gel-spun in a methanol coagulating bath. The as-spun fibers included CWs oriented along the fiber axis and showed a significant increase in dynamic storage modulus. Hot drawing of the PVA-CW as-spun fibers to their maximal draw ratio led to extremely high orientation of the CWs together with a drastic reduction in voids in the fiber matrix. Outstanding mechanical properties of the drawn composites were obtained by the incorporation of only a small amount (1 wt% of solid PVA content) of CWs. The stress transfer mechanism in the fibers was studied using an X-ray diffraction technique by applying stress to the whole composite with in situ monitoring of stress on the incorporated CWs. The applied external stress was found to be translated efficiently to the incorporated CWs through the PVA matrix, suggesting strong interfacial bonding between filler and matrix. The strong interaction and efficient stress transfer between matrix and filler are suggested as the cause for the observed improvements in mechanical properties of the composites. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

High strength polyvinyl alcohol (PVA) fibers with a conventional degree of polymerization of 1500 were prepared by doping iodine with PVA spinning solution. The iodine-doped PVA (I-PVA) aqueous solution was extruded into cold methanol that provides dark purple PVA-iodine complex gel fibers. Only a small amount of iodine was required to enhance drawability and molecular orientation by reducing the interaction between PVA chains. An increase of ca. 10% in the maximum draw ratio of the doped fibers compared with that of undoped PVA translated into values for the tensile strength, 2.2 Giga-Pascal (GPa), and initial modulus (47 GPa) that were more than 30% higher than those of the neat PVA fiber. Easier chain slippage of molecules in the amorphous segments of the I-PVA fiber during drawing leads to increased orientation in these segments, which is believed to be the source of the improvements in mechanical properties. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article presents a study which examined the effect of iodine treatment on the carbonization behavior of tussah silk fibroin (SF) fiber from a wild cocoon, Antheraea pernyi (A. pernyi). The researchers also evaluated and the carbon yield, morphology, structural characteristics and mechanical properties of the fiber. They found that the structures of the carbon fibers obtained from both untreated and iodinated SF were almost the same and amorphous.

The article presents a study on the structure and conductivity of an organic-inorganic composite created from nylon 6 doped with fine particles of silver diode (AgI). For the study, researchers conducted the complexation of nylon 6 with polyiodide ions. They found that lower solution temperatures led to larger amounts of AgI in the composite material. They concluded that the amount of AgI was highly dependent on the temperatures of the immersion solutions.

In the present study, we focused on several factors affecting the utility of 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) for obtaining higher performance fibers. The dependence of the spinnability and tensile strength of the fibers on the zero‐shear viscosity of the spinning solutions was investigated based on differences in the molecular weight of the cellulose, pulp concentration, and the pH of BMIMCl. We demonstrated an appropriate viscosity range of 2000–4000 Pa s−1 (100 °C) for spinning dopes to obtain good spinnability and high tensile strength. The pH of the BMIMCl and the molecular weight of the cellulose clearly impacted tensile strength. The high molecular weight of cellulose contributed to high mechanical properties of the regenerated cellulose fibers. Optimizing the molecular weight and concentration of the cellulose based on the appropriate viscosity allowed us to prepare high performance cellulose fibers with a tensile strength of 1.15 GPa and a Young's modulus of 42.9 GPa. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48681. [ABSTRACT FROM AUTHOR]