Koksnes dzilas parstrades produktu iegusanas un reciklesanas izpete

Available from Latvian Academic Library / LAL - Latvian Academic LibrarySIGLEMinistry of Agriculture of the Republic of Latvia, Riga (Latvia). State Forestry ServiceLVLatvi

Microcrystalline cellulose fillers for use in hybrid composites with polyethylene and lignin

Microcrystalline cellulose (MCC) fillers were obtained for hybrid composites with high-density polyethylene and lignin. The fillers were obtained from bleached kraft pulp and cotton fibres. The raw materials were treated by the thermocatalytic destruction method and then ground in a ball mill. Treatment conditions were developed for each raw material. MCC powder samples were obtained, which contained microparticles of different shape and size. Composite samples, which contained polyethylene, 50% of lignin, 20% of MCC and a coupling agent, were produced. It was established that the mechanical properties of composites were improved to a greater extent by the MCC filler obtained from cotton fibres. This can be related to the fact that it contained longer fibre fragments in comparison with wood pulp MCC. The higher degree of crystallinity of cotton cellulose also played a part

The effect of the outermost fibre layers on solubility of dissolving grade pulp

Dissolving pulps are used to manufacture various cellulose derived products through cellulose dissolution. Solubility of cellulose pulp has been claimed to be strongly dependent on the porosity development, the degree of polymerisation and the pulp viscosity. The removal of external cell walls has been proposed to have a key role in the pulp solubility. In this paper, the effect of the outermost surface layers on the solubility of a dissolving grade pulp was studied. Furthermore the effect of mechanical peeling and combined mechanical and enzymatic treatment on pulp solubility was compared. Based on the results combined mechanical and enzymatic treatment efficiently opens up the fibre structure and has a clear positive effect on the solubility of dissolving pulp. It seems that long fibre fraction is less accessible to solvent chemicals than the other pulp fractions. Mechanical peeling of outer fibre layers does not improve fibre dissolution to NaOH/ZnO. Thus, it seems that peeling alone is not a sufficient pre-treatment prior to dissolution. The results also revealed that the peeling treatment does not enhance the effects of enzymes as the studied mechanical treatment does