| In pulp there are original fines(P200) and fines which produced in beating process(P'200). P200 and P'200's chemical compositions, physical shapes, surface chemical characteristics and so on are researched. Differences of their surface chemical characteristics influenced by pH value and conductivity are studied. In addition, relations between specific surface area, beating degree and Water Retention Value(WRV) are explored. Mathematical models are established.KP bleached eucalyptus pulp result in P200 after the screening, and the fragment (P'200) of long fibers(R30) which comes from beating process. All fibers are cleaned to remove metal ion. Observation to the fiber fines' physical shape is carried on. P200 mainly is the parenchyma cell and the late wood vessel element. P'200 mainly is the fragment of fibers produced in the beating process. Fiber fines' pentosan contents are mensurated by volumetric method. It is shown that pentosan content of P200 is 26.16%, P'200 only 20.06%. Content of carboxyl of P200 is 6.386mmol/100g and P'200 being 5.484mmol/100g. Ash content of P200 is 1.1730% and P'200 being 0.2056%. Fiber fines' specific surface area are mensurated by BET nitrogen adsorption method. P200' specific surface area is 14.36m2/g. P'200' specific surface area is 91.66m2/g.When the pH value is 6, P200's anion demand reaches 13.354×10-3meq/g, which is the maximum. When the pH value is 8, P'200's anions demands is most 11.462×10-3meq/g. P200 and P'200's cation demands elevate along with the pH value's escalation basically. P'200's cation demand is bigger than P200's. P200 and P'200's CTR value are smaller than 1, assuming " negative charge". CTR value are the biggest in neutral condition. Fiber fines' WRV are elevate along with the increasing of pH value. When P200's conductivity is 2940μs/cm, anion demand and cation demand reach the maximum value. When P'200's conductivity is 1871μs/cm, anion demand and cation demand are the maximum value. Then fiber fines' anion demand and cation demand assume the drop tendency when the conductivity continues to increase. CTR value are smaller than 1. P200's CTR value is bigger than P200's. Raising the conductivity of wet-end system is only little effect to WRV of P200. P200 and P'200's beating degrees assume the drop tendency and their WRV rise first then drop along with the elevation of conductivity. When the conductivity rises to 3850μs/cm, P200' WRV will achieve to high 342g. When the conductivity reaches 947μs/cm, P'200's WRV most reaching 452g.Relatives between WRV, specific surface area and beating degree are discussed. Mathematics models are established by logarithm regression. pH value - specific surface area (x) - WRV (y): y = [ 0.867(pH)2 -11.705 (pH) + 136.4]Ln(x)+[-1.4266 (pH)2 + 18.246 (pH)... |
PDF Full Text Request