New model for predicting tensile strength and density of eucalyptus handsheets based on an activation parameter calculated from fiber distribution characteristics

Abstract The activation parameter developed is based on the fiber wall thickness distribution, fiber curl distribution, and water retention value of the unrefined fibers. The mechanical properties of paper that contain chemical pulp depend, among other things, on the free fiber segment activation between fiber-fiber crossings that is created during drying. Experimental data revealed that the degree of fiber swelling is responsible together with the fiber shape factor (curl) and fiber wall thickness for the extent of fiber network activation. The amount of bonding between fibers also affects fiber segment activation. Based on the experimental data, it was deduced that interfiber bonding ability of fibers, characterized as the water retention value, was mainly responsible for the development of handsheet density. Tensile index development was more affected by the morphology of fibers, which was the main determinant for high activation potential of fibers. Factor analysis was used to identify the main causes of variation for a refining data set of 20 Eucalyptus grandis samples. Three independent descriptors were found to be responsible for the majority of the variation: the bonding and activation factor, the factor of microcompressions, and the factor of fiber wall thickness and fiber curl. The activation parameter developed in this study can be used to determine the effect of fiber segment activation and inter-fiber bonding on the inplane mechanical properties of paper.

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Use of Cellulose-Containing Fillers in Composites with Polypropylene

Materials Science ◽

10.5755/j01.ms.17.2.484 ◽

1970 ◽

Vol 17 (2) ◽

pp. 150-154

Author(s):

Marianna LAKA ◽

Svetlana CHERNYAVSKAYA ◽

Galia SHULGA ◽

Viktor SHAPOVALOV ◽

Andrej VALENKOV ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Shear Modulus ◽

Rapeseed Oil ◽

Water Retention ◽

Raw Materials ◽

Water Retention Value ◽

Water Vapour Sorption ◽

Recycled Polypropylene ◽

Sulphate Pulp

The composites, containing recycled polypropylene and fillers, obtained from different lignocellulosics by the thermocatalytic destruction method, were investigated. Birch sawdust, newsprint wastes, cotton residues and wood bleached sulphate pulp were used as raw materials for obtaining fillers. The indices of mechanical properties (tensile strength, modulus of elasticity, deformation at break, shear modulus, toughness, twisting moment) of the composites' samples were determined. It has been found that the obtained composites have relatively good mechanical properties. Better results were obtained, using fillers from sawdust and wood pulp. After treating the fillers with rapeseed oil, their water vapour sorption and water retention value (WRV) decreased. In this case, the strength of the composites was higher.http://dx.doi.org/10.5755/j01.ms.17.2.484

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The effect of fiber dimensions on fiber network activation and tensile strength

Holzforschung ◽

10.1515/hf.2011.120 ◽

2012 ◽

Vol 66 (1) ◽

Author(s):

Iiro Pulkkinen ◽

Ville Alopaeus

Keyword(s):

Tensile Strength ◽

Wall Thickness ◽

Fiber Length ◽

Fiber Quality ◽

Pulp Fibers ◽

Fiber Network ◽

Network Activation ◽

Fiber Wall ◽

Technical Properties ◽

Comparison Of The Results

Abstract The objective of this work was to check the fiber network activation parameter developed earlier by the authors for eucalypt pulp fibers to predict technical properties of paper. The fiber size analyses were performed with an optical fiber analyzer that applies 2D image analysis techniques on single fibers. The effects of fiber length, fiber width, fiber wall thickness, and fiber curl distributions on the quality potential of eucalypt fibers were evaluated. Fiber curl and fiber wall thickness based parameters were found to have a high potential for evaluation of eucalypt fiber quality. The variations in technical properties of paper were explained with differences in fiber wall thickness and fiber curl distributions. When the model was tested against industrial long fiber pulps, a further modification for fiber length was needed. The Page tensile strength model and the shear-lag theory were applied for comparison of the results obtained by the network activation model. With the approach presented in this article, the strength characteristics of hardwood and softwood pulps can be easily evaluated based on fiber geometry and water retention value.

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The Influence of Cement Type on the Properties of Plastering Mortars Modified with Cellulose Ether Admixture

Materials ◽

10.3390/ma14247634 ◽

2021 ◽

Vol 14 (24) ◽

pp. 7634

Author(s):

Edyta Spychał ◽

Przemysław Czapik

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Portland Cement ◽

Bulk Density ◽

Water Retention ◽

High Water ◽

Cellulose Ether ◽

Cement Type ◽

Water Retention Value ◽

Mineral Additives

In this article, the effect of cement type on selected properties of plastering mortars containing a cellulose ether admixture was studied. In the research, commercial CEM I Portland cement, CEM II and CEM III, differing in the type and amount of mineral additives, and cement class, were used as binders. Tests of consistency, bulk density, water retention value (WRV), mechanical properties and calorimetric tests were performed. It was proved that the type of cement had no effect on water retention, which is regulated by the cellulose ether. All mortars modified with the admixture were characterized by WRV of about 99%. High water retention is closely related to the action of the cellulose ether admixture. As a result of the research, the possibility of using cement with additives as components of plasters was confirmed. However, attention should be paid to the consistency, mechanical properties of the tested mortars and changes in the pastes during the hydration process. Different effects of additives resulted from increasing or decreasing the consistency of mortars; the flow was in the range from 155 mm to 169 mm. Considering the compressive strength, all plasters can be classified as category III or IV, because the mortars attained the strength required by the standard, of at least 3.5 MPa. The processes of hydration of pastes were carried out with different intensity. In conclusion, the obtained results indicate the possibility of using CEM II and CEM III cements to produce plastering mortars, without changing the effect of water retention.

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