| It is always a significant point to study how to balance the conflict between the bonding strength and absorbility of cellulose fibers in making fluff pulp.Bleached sulfate coniferous wood pulp was uesd as the raw cellulose fiber.A pertreatment process was carried out with some mechanical equipment.t.Meanwhile,the infiuence of weak bond agent on the fluff pulp fiber was discussed in this paper.On this basis, the mechanism of fluff pulp was analyzed by SEM,FT-IR,XPS and Morfi Compact.The optimum mechanical pertreatment conditions were as following:pretreatment mode is using high consistency PFI refining; pulp concentration,30%.The pretreatment results were as following: absorption,0.8229g/g;WRV,35.01%;internal bond strength,192J/m2; absorbility,9.0367g/g;bulk,11.784cm3/g.After a pretreatment with PFI at high consistency,on the one hand,it could contribute to increase the internal fibrillation and the absorption properties of the fiber,on the other hand,it would not be harm to fiber strength,and would not cause too much negative impact on fiber bonding force in the fluff pulpboard.The results of the weak bond research showed that the optimum agent was Varisoft3696,with the agent dosage of 0.5%,which was used to make fluff paperboard.The results were as the following:tightness, 0.23g/m3;burst strength index,0.29KPa·m2/g;absorptionspeed,0.72s/g; absorbility,7.82g/g; bulk,17.2cm3/g.Fiber surface hydroxyl test was processed under the the following condition:temperature,50℃;reaction time,3h;ratio of fiber andreaction reagent,1/3.As a consequence,the surface hydroxyl number of bleached softwood pulp is 155mg KOH/g,hardwood fiber 167mg KOH/g, cotton fiber 180mg KOH/g,bamboo fiber, 100mg KOH/g. After PFI treatment,the number of fiber surface hydroxyl,bonding force between the fibers,tightnessburst index and absorbility increased at the same time.However,the number of fiber surface hydroxyl reduced,the bonding force between fibre was abated,which was advantageous to the subsequent fluffing process,after applied weak-bonding agent.SEM micrographs showed that Valley beating process did more contribution to fibre surface fibrillation,and PFI refining process was beneficial to dislodged the outer layer on the surface of fiber.For high concentration PFI refininng process,when refining revolution reached 1500r,it could be observed that the outer layer of fiber surface began to split,and a small amount of fiber broom appeared.It was found though Morfi Compact that fiber curl increased by 12.5% at most,which largen the distance between the fibers,was not conducive to the formation of hydrogen bonds.With the analysis of FT-IR,there were apparent-OH absorption peak,with wide absorption band and strong absorption strength,showed hydrophilic group-OH exist in weak-bongding agent as well as cellulose.Consequently,the hydroxyl on fiber surface were shielded, bonding force between the fiber decreased,the absorbition of fiber would not fall down as it should be.During the research of hydroxy measurement,with the analysis of XRD,the crystallinity of fiber decreased with the increase of reaction time,indicated that the number of hydroxyl participated in the reaction increased,considering the reaction was carried out,partial hydrogen bond ruptured,fiber crystalline region was destroyed,which lead to the decrease of fiber crystallinity.FT-IR showed that reaction reagent dosage had no effect on the measurement results,so the ratio of raw material and the reaction reagent was 1:3.Compared with untreated fiber,intramolecular hydrogen bonding of the fiber after reaction increased,which proved that more free hydroxyl group had been reacted.The analysis of XPS full spectrum scanning also showed that the fiber surface free-OH has to participate in the reaction. |
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