Equal amounts of PLLA and PDLA were melt-mixed in a mill type mixer at 190 ̊C and further extruded at 250 ̊C. The blend obtained was compression molded into films and biaxially drawn and annealed. The changes in various physical properties such as mechanical and thermal properties and the higher-order structure of the films in the biaxial drawing and annealing processes were investigated. The biaxially drawn films showed a broad crystalline WAXD reflection similarly to the uniaxially drawn PLLA/PDLA blend fibers and the application of annealing at 190 ̊C completely changed the reflections into those of SC. The higherorder structure was completely transferred into SC after annealing at an elevated temperature. The mechanical property was improved by the biaxial drawing and the annealing for short period of time, and the films showed an excellent thermal resistance. However the annealing for a long period deteriorated the mechanical property.
In our previous publication, we discussed the ammonium persulfate oxidation conditions of an activated carbon fiber and its use for the removal of aqueous lead. Results showed that oxidation at long times and at mild oxidant concentrations gave a high adsorption capacity for Pb(II) (2.7 mmol g-1), but at the same recent results that showed that using higher concentrations of oxidant at shorter times could give similar high adsorption capacities, with the difference that the big specific surface area of the fibers remained almost amount of soluble compounds in NaOH (oxidation debris), and it was determined to be less for samples produced at shorter oxidation times. Additionally, column adsorption-desorption experiments were done for a single metal solution of Pb(II) and for a mixture solution of Pb(II), Cd(II) and Ni(II), where Pb(II) ion was found to be preferably adsorbed by the oxidized activated carbon fiber.
The tensile strength of syndiotactic polystyrene (sPS) fibers increasedwithincreasingthedrawratio from 4.3 to 4.7 despite saturation of the molecular orientation and crystallinity of the drawn fiber. To analyze the mechanism, fiber structure development was investigated by in situ wide- and small-angle X-ray scattering. By drawing the amorphous sPS fiber, the metastable mesomorphic form appeared 0.07 ms after necking, and most of this form transformed to the α'-form crystal at 1.0 ms. With this transformation, the d-spacing of the equatorial plane increased, while the d-spacing of the (002) plane decreased until 2.0 ms after necking. After the transformation, the long period, orientation factor, and crystallite size along the meridional direction increased until 10 ms, which can be explained by rearrangement of the fiber structure. By increasing the draw ratio, the higher drawing stress and higher fiber temperature should promote rearrangement, which results in the drawn fiber having higher tensile strength.
Three kinds differently high beam T-shaped 3-D integrated woven fabrics with the glass fiber filaments tows 600 tex as warp yarns and the basalt fiber filaments tows 2000 tex as weft yarns were fabricated on common loom by reasonable design with low cost processing. The T-shaped 3-D integrated woven composites were manufactured by VARTM molding process. Then, the bending properties of Tshaped 3-D integrated woven composites with differently high beam were tested throughout the universal testing machine with the velocity of 2 mm/min. And, the load-displacement curves, absorb energydisplacement curves and bending failure mode were obtained. Results were indicated that the 12 mm high beam of T-shaped 3-D integrated woven composite had the a maximum load and absorb energy. The bending failure modes were showed that the 0 mm high beam of T-shaped 3-D integrated woven composite was a typical bending failure mode with the compression failure in the front and tensile failure in the back, while the bending failure modes of 6 mm and 12 mm high beam of T-shaped 3-D integrated woven composite were compression failure in the front and shear failure in the back. Finally, the load-displacement curves, energy absorption-displacement curves and failure modes were acquired by FEM simulation with ABAQUS software. The good agreements of comparisons proved the validity of the FEM models.
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