Tensile strength of paper

Figure 4.5 Relationship between tensile strength of paper (expressed as a breaking length) and the number of fibres which fail during the test.

Adsorption might be expected to create additional fibre-to-fibre bonds and/or to strengthen existing bonds, but there is evidence that the increase in tensile strength of paper is caused primarily by an increase in the bond strength per unit of optically bonded area, rather than by an increase in the extent of the relative bonded area itself (Figure 7.13). 

Accordingly, a complete book preservation program should consider (a) complete deacidification (b) improving fold endurance, tear and tensile strength of paper and (c) inhibiting oxidation. 

Figure 2. Change in degradation rate of zero span tensile strength of paper with relative humidity when aged at various devoted temperatures...

Page DH (1969) Theory for the tensile strength of paper. Tappi 52 674-681... 

Ankerfors C, Lingstrom R, Wagberg L et al (2009) A comparison of polyelectrolyte complexes and multilayers their adsorption behaviom and use for enhancing tensile strength of paper. Nord Pulp Pap Res J 24 77-86... 

Starches used to increase the internal strength of paper as measured by tensile, edge cmsh resistance, Mullen burst, and Scott bond strength are added at the wet end, whereas starch used to increase surface strength as measured by pick and resistance to Hnting are added at the size press. 

In the pulp and paper industry, anionic and cationic acrylamide polymers are used as chemical additives or processing aids. The positive effect is achieved due to a fuller retention of the filler (basically kaoline) in the paper pulp, so that the structure of the paper sheet surface layer improves. Copolymers of acrylamide with vi-nylamine not only attach better qualities to the surface layer of.paper, they also add to the tensile properties of paper in the wet state. Paper reinforcement with anionic polymers is due to the formation of complexes between the polymer additive and ions of Cr and Cu incorporated in the paper pulp. The direct effect of acrylamide polymers on strength increases and improved surface properties of paper sheets is accompanied by a fuller extraction of metallic ions (iron and cobalt, in addition to those mentioned above), which improves effluent water quality. 

Figure 7.21 Diagrammatic representation of the tensile strength of normal paper and wet strengthened paper as a function of moisture content.

Yoshikawa H., Sata T., 1960, Measurement of a tensile strength of granular brittle materials, Sci. Papers Inst. Phys. and Chem. Res., 54, 389-393. 

Runnability is often expressed as the number of paper web breaks per 100 rolls. Paper web breaks during press runs are very costly in terms of money and time. Thus, high-speed newsprint presses also require newsprint with good tensile properties. Although the tensions in newsprint presses are kept well below the average tensile strengths of the paper, breaks do occur. These are generally the result of some defect in the paper such as shives that are not removed from the mechanical pulp fraction of newsprint. 

Table 14.6 illustrates typical improvements noted in epoxy hybrid formulations with vinyl chloride, acrylic, and styrene butadiene lattices. Tensile strengths of cured, latex-saturated paper substrates are listed in absolute numbers while those of latex-epoxy hybrids are listed as percent increases in tensile strength over that of the latex alone. The mechanisms believed responsible for these improvements are (1) cocuring of the epoxy group with carboxyl and amine functional groups present on the latex backbone and/or (2) homopolymerization of the epoxy catalyzed by the tertiary amine included in some hybrid formulations. 

Ibid., Tensile Breaking Strength of Paper and Paperboard, T-404ts-66. 

The individual fiber properties which contribute to the tensile properties of paper include the following (8) fiber tensile strength mean fiber length fiber cross-sectional area perimeter of the average fiber cross section density of the fibrous material fraction of the fiber area bonded in the sheet and the shear strength per unit area of fiber-to-fiber bonds. 

The examination of fold endurance and tensile strength of a series of polymer-paper systems under thermal accelerated aging indicates that only in the most favorable of circumstances is it possible to apply the Arrhenius equation to the system. It also seems unlikely that a sample addition relationship exists between the behavior of the individual components and their behavior as a system. A straight line plot of log folding endurance vs. aging time may reflect a fortuitous composite of several experimental variables leading to pseudo-first-order deterioration. 

The basic mission of the Physics and Biology Laboratories is to test paper treated with products used in the restoration process. Physics is in an air-conditioned room, maintained at 60% relative humidity at 21°C, equipped with machines for testing folding endurance, tensile, and burst strength of paper. Biology runs tests, primarily with culture media, to determine the susceptibility of the treated paper to attack by microorganisms these are identified and a determination is made on how to avoid or eradicate them. Aging chambers are available for tests made by the laboratories. 

The thermal degradation of silk was studied by Kurup-pillai, Hersh, and Tucker ( Historic Textile and Paper Materials, ACS Advances in Chemistry Series, No. 212, 1986) by measuring the tensile strength of silk fibers at various times of exposure to elevated temperature. The loss of tensile strength follows first-order kinetics,... 

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