Short fibers filler

In an ABS/metal composite, 10% iron powder has been admixed. The main reasons for choosing iron powder as short fiber fillers were its reasonably good mechanical and thermal properties as well as its capabilities of mixing and surface bonding with polymers (79). The shape of the iron particles was spherical. 

Copeland, J.R. and Rush, O.W. (1978) WoUastonite short fiber filler/ reinforcement, Plastic Compounding, 1,26-36 (Nov/Dec). 

The bottom or wire side of the paper exhibits a more pronounced grain and a greater opeimess, which affects ink appearance on paper, because the wire side loses short fibers, paper si2ing, and filler through the wires. Although the wire side is usually not the preferred printing side, if both sides are to be printed, the characteristics of both sides need to be considered. 

Although the linear coefficient of thermal expansion varies with temperature, it can be considered constant within typical design and processing conditions. It is especially high for polyolefins, where it ranges from 1.5 x 10 4K-1 to 2 x 10 4K 1 however, fibers and other fillers significantly reduce thermal expansion. A rule of mixtures is sufficient to calculate the thermal expansion coefficient of polymers that are filled with powdery or small particles as well as with short fibers. In this case, the rule of mixtures is written as... 

The notched Izod impact strength of the kenaf system is much lower than that of the glass fiber-filled PP but about the same as all other fillers and mica systems. Short fiber lengths present in the kenaf system due to the compounding system used and molding are probably responsible for the poor impact strengths [30]. 

Today, about 40% of newsprint is recycled and reused. In 1994 alone, recovered and recycled paper and paper products reached 40 million tons and are expected to reach 60 million by the year 2000 [108]. As more and more paper is being recycled, more and more unusable short fibers are being generated. Approximately 15 to 20% of the fibers are too short to be useful after repulping. The combination of short fibers with fillers, known as recycled paper sludge (RPS), is usually disposed of in landfills as waste paper sludge or subjected to incineration after dewatering [109]. 

Typically, recycled paper sludge is made up of approximately 50% cellulose, 10 % hemicellulose and 40 % other materials, and has a moisture content of about 60%. For example, with a dry ton of recovered paper for repulping, there is about 0.15 to 0.2 ton of dry short fibers generated. The wet weight of RPS will be up to 0.5 ton including water, short fiber and other solids known as fillers. Because of its high fiber content, RPS is the type of material that can be effectively utilized and converted into ethanol. The ideal method of producing ethanol from RPS is to use the simultaneous saccharification and fermentation (SSF) process. 

A more common and widely used process involves the preparation of short-fiber polymer composite materials and particulate composite polymeric materials, where the fibers or particles act as reinforcement of the polymer. In this particular case, when a polymer matrix is filled with fibers or particles, which in general possess higher mechanical properties than the polymer matrix, the resultant composite material presents properties that are between those of the soft polymer matrix and the rigid filler. 

The principles of compounding were reviewed earlier in this text and cover the fundamental characteristics of polymers, filler systems, and the basics of vulcanization in the context of compound development for tire applications. A compound formulation consists of four basic components the polymer network, the filler or particulate reinforcing system, the stabilizer system, and the vulcanization system (Figure 14.21). In addition a series of secondary materials such as resins, processing oils, and short fiber reinforcements may be included in a formula (Duddey, 2004 Rodgers and Waddell, 2004 Long, 1985). Elastomers used in radial tires are basically of four types ... 

---