For high-quality paper that is sufficiently resistant to loads, good initial conditions are required for its production. Paper pulp consists of various types of cellulose fibres, which, to achieve different final characteristics, include both long and short fibres. Longer fibres provide greater mechanical resistance, while short fibres improve surface smoothness and paper formation. The purpose of this thesis is to present how certain physical and mechanical properties of paper change when large proportions of short fibres are included using three different industrial milling methods. The theoretical section covers paper, raw materials for its production, paper fibres and their preparation, the paper production process, and its key physicaland mechanical properties.
The experimental part of the thesis was conducted at Papirnica Vevče, where all paper samples were produced and their key physicaland mechanical properties were measured. We focused on measurements of porosity, bending stiffness, tearing resistance, bursting strength, tensile strength, and tensile strength after bending. The measurement results are presented in two sections. In the first section, we display the measured values according to the pulp grinding method, while in the second section, we present the dependence of each parameter on the composition of the paper stock and the method of grinding the initial pulp.
It was found that both the ratio of long to short fibres used and the method of pulp grinding affect the key physicaland mechanical properties of paper. The appropriate choice of starting raw materials strongly influences the properties of the final products and ensures the efficiency of the paper industry production process.
Although increasing the proportion of short fibres could contribute to better optimization of paper industry processes, their excessive use is not appropriate, as it still results in an overestimation of the properties of the final paper products.
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