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Benzyl methacrylate (BzMA) was graft copolymerized onto wool fibers by using ammonium peroxydisulphate as the initiator. Grafted samples with different polymer add ons (from 7 to 180%) were obtained by varying the monomer concentration in the reaction system. Following grafting with BzMA, the X-ray diffraction peak at 20.2Њ slightly moved towards higher spacing values. Birefringence decreased, indicating a lower degree of molecular orientation of grafted wool fibers. The equilibrium regain values of grafted wool decreased with increasing add on. Tensile strength increased in the range 45-77% add on, while elongation at break decreased. Differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements showed a higher thermal stability for grafted wool. Following grafting, the drop of dynamic storage modulus (E) shifted to a lower temperature. Accordingly, the intensity of the loss modulus (EЉ) peak decreased, indicating that the thermally induced molecular motion was enhanced by grafting. Thermomechanical analysis (TMA) confirmed the increase in chain mobility for the grafted wool fibers. Above 35-40% add on, the presence of homopolymer on the surface of the wool fibers was identified by scanning electron microscopy.

SYNOPSISThe structural changes and the thermal behavior of silk fibers grafted with methacrylamide (MAA) were investigated as a function of the weight gain. The refractive index parallel to the fiber axis decreased with increasing weight gain, whereas that perpendicular remained almost unchanged. Accordingly, birefringence decreased with a steeper slope in the weight gain range 0-80%, suggesting a lower degree of average molecular orientation. Only small changes in the isotropic refractive index were detected, suggesting that the crystallinity of the fibers remained essentially unaffected by MAA grafting, as confirmed by the X-ray diffraction data. The molecular orientation in the crystalline regions remained unchanged in the weight gain range 0-60%, then sharply decreased. The strength and the initial tensile resistance of grafted silk fibers decreased both in the dry and wet states, while elongation at break increased in the dry state and remained almost constant in the wet state. The results of the thermal behavior, investigated by differential scanning calorimetry, thermomechanical and thermogravimetric analysis, and dynamic mechanical measurements, were consistent with an increased thermal stability conferred on silk fibers by MAA grafting. The cross-sectional area of MAA-grafted silk fibers increased. Moreover, ion-etched cross sections of the grafted silk fiber showed the presence of fibrils with a diameter larger than that of the untreated control. 0 1993 John Wiley & Sons, Inc.

A variety of vertically aligned multiwalled carbon nanotube (MWCNT) electrodes, which maintain their original morphology prepared by a chemical vapor deposition technique, has been successfully fabricated by a transfer methodology from a seedbed substrate to a current collector. No ohmic potential drop on a galvanostatic discharge was observed for an electric double-layer capacitor (EDLC) containing electrodes with not only a MWCNT length of 10μm but also a length of 200μm . Cyclic voltammograms for electrodes with MWCNT lengths of both 10 and 200μm showed no distorted current response, even at an extremely high scan rate of 50Vnormals−1 . These results demonstrate that the present EDLC with the MWCNT electrodes can provide an outstanding rate capability irrespective of the MWCNT length when prepared by our transfer methodology. To find suitable MWCNT electrodes for high-performance EDLCs, we investigated several relationships among the specific capacitances of aligned MWCNT electrodes and their major properties, i.e., their gravimetric and volumetric capacitances, length, diameter, and number density.