Paper, properties

Because the fibers generally are anisotropic, they tend to be deposited on the wire in layers under shear. There is Htde tendency for fibers to be oriented in an out-of-plane direction, except for small undulations where one fiber crosses or passes beneath another. The layered stmcture results in the different properties measured in the thickness direction as compared to those measured in the in-plane direction. The orthotropic behavior of paper is observed in most paper properties and especially in the electrical and mechanical properties. 

It is also important to study the interactions of papermaking additives (4) in the paper machine water system some additives act synergisticaHy, so that the performance of each is enhanced by the presence of the other. However, some additives have a negative impact on the performance of other additives, or on other desirable paper properties. Thus, optimization of the addition points and usage rates of the entire additive system is necessary in order to maximize performance of the chemical additives and the paper sheet properties, and to minimize cost and negative interactions both on the paper machine and in the white-water system. This is especially tme as unanticipated additives enter the wet end of the paper machine from recycled furnishes, including coated broke (5). 

Most talc sold to paper, ceramics, and other industrial customers is manufactured to specifications agreed to between the producer and consumer. In paper, properties such as color, abrasion, surface area, and tint ate most important, whereas in ceramics, oxide chemistry, fired color, pressing characteristics, and alkaH metal content ate mote important. There ate some military specifications for talc used in corrosive coatings (6) and for cosmetic talc products used for cleaning of personnel in chemical warfare zones (7). 

Danforth DN (1986) Effect of refining parameters on paper properties. Proceedings of the International Conference on New Technologies in Refining, 2, PIRA, Birmingham, England, UK... 

Aramid fibers, 13 372-373, 395 asbestos substitute, 3 314t chemical resistance of, 19 731t consumption of, 19 735t mechanical properties of, 13 376 properties of, 1.9 729-7301 as reinforcement materials, 26 756, 760 Aramid films/papers, properties of, 1.9 7331 Aramid polymer device, 16 1 Aramid products, economic aspects of,... 

Figure 5.11 The effect of beating on various paper properties.

Mehta, V. Gupta, J.K. Biobleaching eucalyptus Kraft pulp with Phanerochaete chrysosporium and its effect on paper properties. Tappi J. 1992, 75, 151-152. 

It was shown that, in general, the paper properties could be improved by the grafting of acrylamide onto low strength pulps (like high yield and mechanical pulps) (8). It is well known that hardwood pulp fibers are considerably shorter (about 1 milli-... 

After the furnish has been prepared with the proper refining treatment and additives, it is stored in the machine chest and then fed continuously into the paper machine system. A refiner or jordan is placed in this line to give the paper machine operators the opportunity to make small adjustments in the quality of the furnish as needed to give the desired paper properties. Screens and centrifugal cleaners also are included to ensure a high-quality paper. 

The possibility of ordering in native celluloses used in papermaking, and the significance of such ordering to the paper properties were explored in an experiment designed to simulate the physical environment during a typical commercial pulping operation (3). 

Further work was carried out with Foldur Kraft. However, the presence of the unusual effect was also demonstrated with GPO JCPA-60, which is the paper used in printing the Library of Congress Information Bulletin and Allied Superior book paper. Properties of the papers are given in Table III and the results when the papers were impregnated with Kymene and sorbitol in Table V. 

Chemical Characteristics of Paper Documents. From the earliest times up to the present day, the substances used as vehicles for writing have been numerous. Ancient paper documents were basically made from rags of cotton and linters cellulose is the major chemical constituent (I). Modern papers, however, are made of wood fibers, which usually are composed of cellulose, hemicelluloses, and lignin (I). In addition, for most of the modern papers, fillers, sizing agents, and other additives are used to improve paper properties (I). 

For the above reasons, processes that involve combinations of heat and pressure are the most widely used. This is normally accomplished by hot-roll pressure devices in which at least one roll is heated with a quartz lamp (Lee, 1975 Prime. 1983 Kuo. 1984 Hiraoka et al.. 1993). Offset of the toner to the fuser roll can be avoided by the use of special oils wicked onto the surface of the roll. Most roller fusing devices use heated rolls coated with silicone or fluorocarbon elastomers. Composite layer structures with multiple layers for improved process lifetime are becoming more common. Figure 17 shows a cross-section of a typical fuser roller and Fig. 18 shows a typical fusing process. For a review of fusing materials, see Gruber et al. (1989). For a discussion of the effects of paper properties on fusing, see Sanders et al. (1996). 

The final paper property we ll discuss is the caliper (or thickness) of an individual sheet of paper. If the paper is too thick, it may jam in feed mechanisms that have several curves in the paper path. (On the other hand, a paper that s too thin may not feed at all.)... 

The main disadvantage is that web temperatures of 275-325° F are required to cure the film. These temperatures affect the paper properties adversely, and therefore higher-quality, more-expensive paper must be used. Even so, blisterii or cracking in the folder may be a problem. Moreover, the solvent emission, although reduced significantly, is not eliminated, and, as with the ultraviolet light-cured inks, paper printed with these thermally-catalyzed inks cannot be recycled in the currently used processes (8, 9). 

Wood characteristics Wood/paper properties Desired attributes and product specifications... 

Wardrop AB and DadsweU HE (1950) The swelling behaviour of conifer tracheids and the concept of a skin substance. Proceedings APPITA, 4 198-226 Watson AJ and DadsweU HE (1962) Influence of fibre morphology on paper properties. Part 2, Early wood and late wood. Appita, 15(6) 116-28 Wayman M and Parekh SR (1990) Biotechnology of biomass conversion. Prentice Hall, Englewood Cliffs, New Jersey... 

---