Recycled fibers

The protonated form of poly(vinyl amine) (PVAm—HCl) has two advantages over many cationic polymers high cationic charge densities are possible and the pendent primary amines have high reactivity. It has been appHed in water treatment, paper making, and textiles (qv). The protonated forms modified with low molecular weight aldehydes are usehil as fines and filler retention agents and are in use with recycled fibers. As with all new products, unexpected appHcations, such as in clear antiperspirants, have been found. It is usehil in many metal complexation appHcations (49). 

The total production of the U.S. paper industry in 1994 was ca 85 million metric tons with a compound aimual growth rate over the previous decade of 2.7%. The domestic production of paper and board plus imports and minus exports maintains a remarkably constant ratio with real gross domestic product in the United States. One sector of the paper industry that has grown at a higher rate than GDP is recycled papers and boards which is projected to grow at 6.8% aimuaHy. Over one-half of paperboard production in the United States is from recycled fiber, and the industry as a whole is expected to achieve 50% recovery rate for paper and board products by the end of the twentieth century (see Recycling, paper). 

Retention and drainage additives are vital to the use of recycled fibers. Papermakers consider recycled fibers to behave like virgin fines, while recycled fines behave like filler. Drainage on the paper machine can be impeded and first-pass retention reduced by the use of recycled fiber (9). Additionally, the negative impact of contaminants found in recycled fibers can be minimized by the appropriate use of dispersants and other pitch-control additives. 

Secondary Fiber. Increasing costs of taw fiber, legislative mandates for recycling (qv), and avadabdity of inexpensive waste papers have contfibuted to the increased use of recycled fibers. The use of secondary fiber in the United States has grown from 22% of pulp from all sources in 1978 to close to 31% (24 x 10 metric tons) in 1993 (3). Recycled fibers ate sometimes used in special writing papers, but the principal use is for the manufacture of linetboatd, newsprint, tissue, cereal boxes, towels, and molded paper products such as paper plates and egg cartons (see Packaging materials, containers AND INDUSTRIAL materials). 

Refining and Fractionation. These processes are used to alter and select cellulose properties so the final sheet has the desired properties (51). Properties of recycled fibers differ from those of fibers prepared directly from wood. For example, recovered chemical fibers have lower freeness, an apparent viscosity leading to different water drainage characteristics on paper machines. Recovered fibers also have iacreased apparent density, lower sheet strength, iacreased sheet opacity, inferior fiber—fiber bonding properties, lower fiber sweUiag, lower fiber flexibiUty, lower water reteatioa, reduced fiber fibrillatioa, and much lower internal fiber delamination. 

Increased usage of recycled fiber in combination with system closure and Hydrogen Peroxide (HP) bleaching at moderate temperatures, has developed microbe cultures that are very effective in decomposing (HP). As this problem often comes slowly when the mills are closing their water loops and reuses their wastewater it is sometimes difficult to say when it needs to be treated. 

Schwarz M (2000) Design of recycled fiber processes for different paper and board grades. In Gottsching L, Pakarinen H (eds) Recyled fiber and Deinking. Fapet Oy, Helsinki (Chap. 6)... 

Average use by newspapers of recycled fibers seldom exceeds 50% of the total. However, die publishers of the Los Angeles Times use approximately 80% recycled fiber. 

Lassus, A. (2000), in Recycled Fiber and Deinking, Book 7, Gottsching, L., ed., Gummerus Printing, Jyvaskyla, Finland, pp. 241-264. 

Contained 65% virgin fibers and 35% recycled fibers. b 100% virgin-fiber furnish. c Machine direction. d Cross direction. 

Roll Est. Loss, Folds/hr xio-o (28.9° C) Acidity Pulp a-Cellulose Recycled Fiber... 

A major application of these types of molded products would be for interior uses in automobiles, such as head liners, door panels, and dashboards. Although this is a low-cost, low-performance application, it represents a very laige-volume market. Indeed, wood is already utilized in applications of this type, but as a finely ground flour that serves as a filler (up to 40%) in extrusion-molded polyolefin products. The use of recycled fiber in this process and the one described above offers the potential of even greater cost reductions, combined with alleviation of solid waste disposable problems. 

Many books on the market are now printed on recycled paper containing almost 80% recycled fibers produced in a de-inking plant equipped with a dispersed flotation clarifier. 

Although FRC has become widely available from concrete suppliers, its use has been limited primarily due to cost considerations. Effort to reduce the cost includes limiting the fiber dosage and developing inexpensive fibers. A very attractive alternative, however, would be to use suitable recycled fibers from industrial waste which otherwise would be discarded, the carpet industrial waste being an example. 

This paper summarizes the results of an experimental program to evaluate the effectiveness of using recycled fibers from carpet waste for concrete reinforcement. It also discusses issues that need to be addressed for the application of such FRC in large scale construction projects. It then reports on a building construction project using carpet waste fiber reinforced concrete. The results suggest that using carpet industrial waste fibers in construction would not only improve the reliability and life of the concrete structure, it but also could reduce the landfill spaces needed to dispose the waste material. 

The carpet industrial waste generated each year and that accumulated in landfills represent an abundance of useful resources, as they can provide effective reinforcement for concrete. As to be discussed in the following sections, concrete reinforced with recycled fibers from hard carpet waste is indeed a suitable material for construction. It suggests that using carpet waste in construction could be a very cost-effective way to improve the durability and performance of the concrete structure, and to reduce the needs for landfill spaces. 

The laboratory study described above demonstrated that recycled fibers from carpet industrial waste can provide effective reinforcement for concrete. However, concerns do exist that must be addressed before such FRC can be widely accepted for construction. 

Cost is another concern associated with the use of recycled carpet waste fibers in concrete. Currently a vast amount of carpet waste is disposed of each year and therefore the cost of raw material for the recycled fibers is negligible. The disassemble process to convert the waste into fibers suitable for concrete reinforcement requires only simple, inexpensive shredding operation. Therefore the cost of the recycled fibers will remain very competitive with virgin fibers for FRC. 

Besides for building constructions, the carpet waste FRC can also be used for highway construction as pavements, columns, bridge decks and barriers, and for airport construction as runways and taxiways. Recycled fibers from carpet waste could become a standard additive for concrete. 

Wang, Y., Zureick, A.H., Cho, B.S., and Scott, D.E. (1994) Properties of fiber reinforced concrete using recycled fibers from carpet industrial waste. Journal of Materials Science, Vol. 29, No. 16, pp. 4191—4199. 

---