It has been proven in previous work that rosin sizing agents are distributed relatively homogeneously on the outer surface of paper. Therefore, rosin sizing agents on paper surfaces can be characterized by macro domain measurement techniques with very thin layer from the surface. In this work, the role of rosin sizing agents on paper surface was investigated by comparing wettability from contact angle measurment with the chemical state of the outermost surface by the ESCA. Furthermore, the role of rosin on the surface of paper was discussed by the quantity of hydroxyl groups obtained from chemical modification with the TFAA-ESCA technique. It was found from the ESCA data that the fixing mechanism with soap-type rosin sizing is different from that with emulsion-type rosin sizing.
Azidodeoxychitin samples were obtained in the reactions of bromodeoxychitin and chlorodeoxychitin samples with sodium azide in polar aprotic solvents. A kinetic equation for a bimolecular reversible reaction was applicable to the azidation of 6-bromo-6-deoxychitin. The rate constant for the exchange with azide ion and the equilibrium constant were 7.36×10-3 M-1 min-1 and 57.0 at 50°C, respectively, in the binary solvent system of lithium bromide and N, N-dimethylacetamide while they were 88.5×10-3 M-1 min-1 and 0.37, respectively, for the reaction at 60°C in methyl sulfoxide. The exchange with azide ion was slower in the case of 6-chloro-6-deoxychitin samples. Azidodeoxychitin samples were reduced with sodium borohydride in methyl sulfoxide for 24h at 60°C. Azido groups were consumed almost completely and the selectivity for the reduction to amino groups was higher than 80%.
To develop a simple pulping technique for small scale papermaking, a combination of ammonium oxalate pretreatment and alkaline hydrogen peroxide treatment at normal pressure was examined for jute, kenaf and mesta bast fibers. The ammonium oxalate pretreatment seems sufficient to remove transition metal ions (Mn, Fe and Cu) and a part of Ca and Mg to give a favorable metal profile for the second alkaline hydrogen peroxide pulping. The brightnesses of the pulp samples were about 60_??_70% at 5% H202 dosage although kappa numbers were still high. The strength properties of the pulps were comparable with those of commercial softwood bleached kraft pulp except folding endurance. The pulps may have strength properties enough for some practical use in local pulp mills.
The high-speed melt spinning process of poly (ethylene 2, 6-naphthalene dicarboxylate) (PEN) was modified using a liquid isothermal bath (LIB) which was kept at a liquid temperature of 150 or 170°C. The structure and mechanical properties of the as-spun fibers thus produced in the take-up velocity range of 0.5 to 7.0 km/min were characterized. The fiber structure development in the low take-up velocity region was promoted by the use of the LIB and the promotion becomes more prominent by raising the liquid temperature. In case of the fibers produced with the LIB temperature of 170°C, initial Young's modulus of about 25 GPa and tenacity of about 800 MPa, which are equivalent to the properties for the fibers prepared in the standard high-speed spinning process of 7 to 9 km/min, were obtained at 3 to 4 km/min. On the other hand, plots of the structural and mechanical parameters against the birefringence for the LIB fibers showed a similar relation in comparison with the fibers prepared in a standard high-speed spinning process indicating that the general mechanism of fiber structure development is similar in both the spinning processes. The LIB fibers obtained in the high-speed region were found to have a large amount of β modification crystals as in the case of the common high-speed spun fibers. The amount of β form crystals in the LIB fibers increased with an increase in the take-up velocity. From these results, it was concluded that the β form crystal can be formed even at a much lower temperature than the critical temperature for the formation of β form crystals in an isotropic state, and that the formation of β form crystals can be promoted by applying a higher tensile stress in the spin-line.
Colorimetric determination method of D-galacturonic acid in reverse micellar solution has been investigated in order to assay pectinase catalyzed enzymatic hydrolysis of pectin in reverse micellar solution as a model study for bio-scouring of cotton in organic media. D-galacturonic acid produced by the hydrolysis of pectin could be detected by a specific condensation reaction with naphthoresorcinol. Condensation products showed clear blue color in reverse micellar solution that can be monitored by a spectroscopic determination method. Apparent rate of hydrolysis of pectin with pectinase enzyme in the reverse micellar solution obtained by the spectroscopic determination method was found to be slower than that in aqueous media, whereas the apparent rate of removal of the pectin from cotton fabrics by the pectinase assisted bio-scouring process in reverse micellar system was appreciably faster than that in aqueous media. The above difference between the results from the model study and from the practical bio-souring study would be attributed to the influence of cotton wax exist on actual cotton substrate that acts as gluing material for pectin and inhibit hydrolysis of pectic substances. Quick removal of cotton wax must be taken into account in the bio-scouring process to obtain effective scouring results.
Polyester (PET) fabrics were alcoholyzed at 90°C in triethylene glycol (TEG) or diethylene glycol (DEG) in the presence of 2% (wt/wt) of the corresponding sodium alkoxide, STEG or SDEG, or in ethylene glycol (EG) or glycerol (GR) in the presence of 2% (wt/wt) of sodium carbonate (SC) and the rate of the weight loss of the fabrics by the alcoholysis was studied in comparison with that by hydrolysis with a 10% (wt/wt) aqueous sodium hydroxide solution at 100°C. Alcoholysis with a EG solution in the presence of 1% (wt/wt) of calcium oxide (CO) was also studied at 100°C. The weight loss proceeded linearly with treating time (zero-order reaction) as with alkaline hydrolysis. The rate of the weight loss increased in the order: SC-GR< SC-EG<SDEG-DEG<CO-EG<STEG-TEG. Scanning electron microscopic observation of the alcoholyzed and hydrolyzed PET fibers with nearly the same level of the weight loss (29.6-33.2%) showed that finer isolated microcraters were distributed more uniformly on the fiber surface of the alcoholyzed fibers, especially with STEG-TEG and SDEG-DGE. The ζ-potentials of the untreated and alcoholyzed PET were determined from the streaming potential measurements with a dilute disperse dye solution containing sodium chloride. The absolute value of the negative ζ-potential increased gradually with increasing pH of the streaming solution. The increase was more significant for the alcoholyzed PET fibers than the untreated one, reflecting higher concentrations of the terminal carboxyl groups of the alcoholyzed PET samples.
Plastic deformation zones of deep double edge notched tension (DENT) paper specimens under in-plane stress were estimated exactly in terms of the linear elastic fracture mechanics (LEFM), and further in terms of thermal image. Comparing the size of the estimated zone with that of the circular plastic deformation zone assumed in the “Essential Work of Fracture (EWF)” method to measure fracture toughness, fracture works were corrected to correspond with the circular case. As a result, corrected experimental plots of the EWF method to obtain fracture toughness for large ligament specimens were almost on the same linear relationship obtained from the uncorrected experimental plots for small ligament specimens. The results show the uniqueness of the fracture toughness obtained from small ligament specimens, which experimentally satisfy the prerequisite of the EWF method.