Strength enhancement of fiber network by carboxymethyl cellulose during oxygen delignification of kraft pulp
Sorption of carboxymethyl cellulose (CMC) on the fiber surface was applied during oxygen delignification to enhance the strength properties of softwood kraft pulp. Unlike many previous efforts, the focus was not set on the improvement of selectivity of oxygen delignification, i.e. retaining stable viscosity vs. decreasing kappa number. Instead, without an improved selectivity, handsheets from CMC-treated fibers exhibited a 15% improvement in tensile index and 25% improvement in tear index after a full bleaching sequence in comparison to the untreated reference pulp. Since it is demonstrated that the CMC addition can be incorporated as an integral step in the fiberline process, the method offers an effortless and viable option to produce pulp resulting in stronger paper products.
Characterization of Fiber Carboxylic Acid Development during One-Stage Oxygen Delignification
This study examines the changes in fiber carboxylate content during a series of one-stage oxygen delignification experiments using a southern United States pine kraft pulp. The carboxylic acid content of the oxygen-delignified pulps before and after holocellulose pulping was determined to establish the distribution of acid groups in lignin and pulp carbohydrates. The carboxylic acid content in residual lignin were also examined and compared with the holocellulose results in an attempt to decouple the responses from residual lignin and carbohydrate. It was found that oxygen-delignified kraft pulps exhibited an initial 4%−13% increase in total fiber carboxylic acid content in the first 10−30 min, followed by a steady state or slight decrease. In contrast, the holocellulose of oxygen-delignified pulps exhibited an initial 6%−8% decrease in carboxylic acid content in the first 10 min, followed by a small increase and then a slow decline. The residual lignin isolated from these pulps showed an initial 37% carb...
Pioneer 10 Observations of the Ultraviolet Glow in the Vicinity of Jupiter
A two-channel ultraviolet photometer aboard Pioneer 10 has made several observations of the ultraviolet glow in the wavelength range from 170 to 1400 angstroms in the vicinity of Jupiter. Preliminary results indicate a Jovian hydrogen (1216 angstrom) glow with a brightness of about 1000 rayleighs and a helium (584 angstrom) glow with a brightness of about 10 to 20 rayleighs. In addition, Jupiter appears to have an extensive hydrogen torus surrounding it in the orbital plane of Io. The mean diameter of the torus is about equal to the diameter of the orbit of Io. Several observations of the Galilean satellites have also occurred but only a rather striking Io observation has been analyzed to date. If the observed Io glow is predominantly that of Lyman-α, the surface brightness is about 10,000 rayleighs.