Rayon fiber reinforcements

In one of the first reports on fiber reinforcement of rubber, natural rubber (NR) was used by Collier [9] as the rubber matrix, which was reinforced using short cotton fibers. Some of the most commonly used rubber matrices for fiber reinforcement are NR, ethylene-propylene-diene monomer (EPDM) rubber, styrene-butadiene rubber (SBR), polychloroprene rubber, and nitrile rubber [10-13]. These rubbers were reinforced using short and long fibers including jute, silk, and rayon [14—16]. 

The reinforcement of rubbers using nylon, rayon, vinyl, and polyester fibers was reported by various authors [10,58,73-75]. Because of the design flexibility and suitable end-use applications, high-performance fibers such as glass, carbon, and aramid also find extensive applications in short fiber-reinforced mbbers. A brief description of some of the major high-performance fibers commonly used in short fiber-rubber composites is given below ... 

Use of coupling agents for internally reinforced rayon fibers... 

Coupling agents can enhance the adhesion in internally reinforced rayon fibers. This improvement over fibers coated without a coupling agent is dependent on... 

Carbon and graphite fibers are made by the pyrolysis of certain naturally occurring and man-made fibers, such as regenerated cellulose (rayon) fibers. A wide range of physical, mechanical and chemical properties may be obtained dependent on amount of dehydration. This product is one of the most structurally efficient reinforcements. Unlike any other reinforcement, it retains its 2,800 MPa (400,000 psi) tensile strength when tested up to a temperature of 2700 C (4800F). 

Rayon-based reinforcing fibers, as a result of their high price of > 800 DM/kg, are only of minor importance. A comparison of the production figures for high performance C-fibers and standard C-fibers shows that the importance of the high performance HT- and HM-C-fibers has steadily increased (see Table 5.2-11). 

If rayon fibers are dipped in alkali silicate solutions prior to decomposition, then silica-carbon fibers are produced which are also suitable for reinforcing plastics. 

CFRPs are strong and light fiber-reinforced polymers. Carbon fibers are a new breed of high-strength materials. Carbon fiber contains at least 90% carbon prepared by controlled pyrolysis of rayon fibers [34]. The subsistence of carbon fiber came into use in 1879 when Edison took a patent for the fabrication of carbon filaments used in electric lamps [35]. The composites manufactured using carbon fiber reinforcements exhibit a range of mechanical properties suitable for many constructional, industrial, and automobile applications. 

The existence of carbon liber (CFs) came into being in 1879 when Thomas Edison recorded the use of carbon fiber as a filament element in electric lamp. Fibers were first prepared from rayon fibers by the US Union Carbide Corporation and the US Air Force Materials Laboratory in 1959 [41 ]. In 1960, it was realized that carbon fiber is very usefirl as reinforcement material in many applications. Since then a great deal of improvement has been made in the process and product through research work carried out in USA, Japan and UK. In 1960s, High strength Polyacrylonitrile (PAN) based carbon fiber was first produced in Japan and UK and pitch based carbon fiber in Japan and USA. 

Fig. 18.25 Selected mechanical properties of PLA (black) and its rayon composites with standard (blue) and weak green) interphase in comparison to glass fiber reinforced PP (red)...

Koo et al. [71] compared the ablative properties of carbon phenolic composite (MX-4926) to laboratory produced carbon nanofibers (CNFs)/phenolic nanocomposites (CNF-NRAMs). Three CNF loadings, namely 20 %, 24 % and 28 wt% were dispersed in the phenolic matrix without rayon-carbon fiber reinforcement. A subscale rocket motor (heat flux 1140 W/cm ) was used to study the ablation and insulation characteristics of the ablatives. According to the experimental results, when compared to the MX-4926, all the CNF-NRAMs exhibited lower ablation rates and the lower maximum backside heat-soaked temperature increase. Peak... 

Raman et al. reported the preparation of silicon carbide wiskers, SiCw, which can be employed as reinforcing fillers of ceramic-based composite materials, by pyrolyzing rayon fibers impregnated with TEOS or alkly-substituted alkoxysilanes-derived silica sol (Raman et al., 2000). 

Methane reacts with sulfur to produce carbon disulfide, which is used to make rayon fiber for the manufacture of rayon tire cord for reinforcement. 

Sodium hydroxide is used in dissolving wood pulp to produce rayon fibers to make tire cord for reinforcement. 

For the MI and HI compounds, fibers are added to increase the impact strength. Cotton fibers and paper pulp fibers increase the impact strength of the MI PF by five times. Rayon yard, nylon filament, or glass fibers are used to increase the impact resistance of the HI PF up to a factor of 20. However, the fiber-reinforced compounds suffer from poorer surface finish and they require higher molding pressures. The composition of a typical PF mixture is listed in Table 7.1. ... 

For nosetip materials 3-directional-reinforced (3D) carbon preforms are formed using small cell sizes for uniform ablation and small pore size. Figure 5 shows typical unit cell dimensions for two of the most common 3D nosetip materials. Carbon-carbon woven preforms have been made with a variety of cell dimensions for different appHcations (27—33). Fibers common to these composites include rayon, polyacrylonitrile, and pitch precursor carbon fibers. Strength of these fibers ranges from 1 to 5 GPa (145,000—725,000 psi) and modulus ranges from 300 to 800 GPa. 

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