Advanced Materials Research Vols. 781-784

Abstract: The application of chelating agents DTPMPA (Diethylene Triamine Penta Methylene Phosphonic Acid) as cooking aids in kraft pulping of bamboo was researched. The effect of DTPMPA dosage at different alkali charge was discussed. The results showed that the cooking aids DTPMPA added in bamboo kraft pulping was able to reduce K value of pulp, improve the screened stock yield and brightness and reduce the alkali charge. The optimized bamboo kraft pulping conditions are: DTPMPA dosage 0.4%, alkali charge 19%, when sulfidity was 20%, maximum cooking temperature was 165°C and time at maximum temperature was 90min. Under optimized conditions of cooking, the screened bamboo pulp yield is higher, the K value is lower and the bamboo pulp brightness is higher.

Abstract: Ultra-high-molecular-weight polyethylene (UHMWPE) fibers were treated by low temperature oxygen-plasma. The effects of oxygen-plasma treatment time on the properties of UHMWPE have been investigated. The wetting ability and roughness were increased significantly after the treatment. While, the tensile strength at break of UHMWE fibers were decreased with the treatment time. The optimum plasma treatment time is 2min.

Abstract: The effect of molecular weight on the structure and properties of PAN precursor was studied by the combination of scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), etc. With the molecular weight increasing, the grooves on the surface become deeper and rougher, the interlayer spacing and crystallite size increase, and the exothermic reaction occurred later. The strength and breaking extension of PAN precursors increase gradually with the molecular weight increasing. The effect of molecular weight is greater than the effect of surface defects on strength for PAN precursor of high molecular weight.

Abstract: Three thiadiazolyl azo dyes were used as disperse dyes for polyester fibres. The dyeing medium was supercritical CO₂. The experiment conditions were 80 to 120°C and 2500 to 4000 psi pressures. The dyeing results were compared with traditional dyeing in water. The results shown that the disperse dyes have high substantivity towards polyester fibres and very good fastness.

Abstract: The degradation rules of glycan in reed ethanol/water cooking process were studied. The degradation rules of polydextrose and polyxylose were obtained in the cooking process by means of ion chromatography determination of glucose and xylose in the reed ethanol pulp content under different holding time. Results showed that cellulose (polydextrose) removal rate obviously was divided into two stages, rapid removal stage at the holding time of 0-90min and slow removal stage at the holding time of 90-210min; hemicellulose (xylan) removal rate was also divided into two stages, slow removal stage at the holding time of 0-60 min and rapid removal stage at the holding time from 60min until the end; meanwhile the change rules of lignin and ash content were achieved.

Abstract: This article studied the pulp contrast of reed three-stage counter-current cooking and single-stage cooking, meanwhile analyzed the regulation of the yield , the hardness of pulps and the properties of the waste liquor from each cooking stage of reed three-stage counter-current batch cooking with ethanol-water process. The SEM and IR-FT were employed to gain more understanding on the change of lignin on fiber surface and the structural change of lignin separated from waste liquor of each stage. The results show that single-stage cooking need to keep 190°C for 4.0 hours to get the best results, while the three-stage counter-current cooking need 1.5 hours more, but the highest temperature fallen by 20°C and the screened pulp yield increased by 3.9%, also the Kappa number decreased by 11. In the process of reed three-stage counter-current batch cooking with ethanol-water, the degradation and removal of lignin and glycan occurs mainly in the first stage. After the first stage cooking, most fibroblasts did not reach the fiber separation point and the screened pulp yield is only 38.7%. After the second and third stage cooking, the fiber separation became better ,the screened pulp yield increased to 49.72% and the Kappa number decreased to 25.6 . As the analysis of the results from the each-stages lignin by IR-FT, the structure of lignin had no significant difference .

Abstract: The soda pulping modified by green liquor pretreatment was adopted to explore optimal green liquor pretreatment conditions. Results shows that optimum pretreatment conditions are as follows: max temperature, 130°C; holding time, 90min; wood to liquor ratio, 1:4; and green liquor charge, 0.9L/kg. Pretreated reed was pulped under following conditions: heating-up time, 60min; maximum temperature, 160°C; holding time, 60min; NaOH charge, 20% (pretreatment alkali included). Results shows that this process produces pulp with screened yield of 49.05%, Kappa number of 14.6, and viscosity of 1274mL/g. Compared with the results of industrial simulation pulping (21% NaOH), screened yield increases by 2.14%, Kappa number decreases by 5.6 and viscosity rises by 556 mL/g. Therefore, green liquor pretreatment before soda pulping improves pulp performance and yield. Meanwhile the pretreatment utilizes material effectively, thus has practical significance to decrease alkaline consumption and pulping cost.

Abstract: Long fiber component of poplar CMP is modified by ozone to improve the paper physical performance in this paper. The condition of modification is studied by the orthogonal test method. The results show that the optimum conditions are: 2.5% ozone, pH 4,consistency 0.5%. The softness, length, swelling properties and hydrophilcity of long fibers are improved after modification. The crystallinity of fiber is improved and the lignin content is reduced. The better performance in tear index and tensile index was attained compared with unmodified CMP holo-pulp to some extent: tensile index increased from 35.8N·m·g^-1 to 44.6N·m·g^-1, tear index increased from 4.58 mN·m²·g^-1 to 8.16 mN·m²·g^-1, brightness had a slightly increase.

Abstract: Supercritical carbon dioxide (SCCO₂) containing calcium propionate or magnesium bicarbonate was used to deacidify paper. In the experiment, to compare the effects of SCCO₂ technology deacidification and immersion deacidification, two kinds of paper samples were chosen to do these two kinds of deaciditication tests respectively. And pH, alkali reserve and mechanical properties of paper samples were measured before and after these treatments. The experiments showed that the pH and alkaline reserve of paper samples treated with SCCO₂ were nearly similar to that of immersion treatments. Otherwise, compared with immersion deacidification, supercritical carbon dioxide had some advantages of strengthening the mechanical properties of paper and shortening treatment time.

Abstract: Effects of ultrasonic treatment on water-retention value of straw pulp fibers were discussed and the ultrasonic treatment conditions were optimized. The best conditions of ultrasonic treatment as follows: ultrasonic power is 400W, processing time is 90min and temperature is 40°C. SEM shows that a large number of magnetic particles were left inside the pulp fiber cells. Automated Surface Area & Pore Size Analyzer shows a good superparamagnetic behavior.