Conductive fiber reinforced thermoplastic

Table 2A2 Typical properties of conductive fiber reinforced thermoplastics... 

There are no standard test methods specific for discontinuous fiber (or short fiber) reinforced thermoplastics. It is also not clear whether a geometry-independent fracture parameter can be measured for these nonuniformly inhomogeneous materials. However in spite of these reservations there has been considerable work conducted towards characterizing short fiber composites for fracture toughness using the standard and other procedures outlined in the previous sections. The investigators have recognized that fracture mechanics data provide much more reliable information than the customary alternative tests for material selection and also a service performance indicator for components. 

The electrical properties of pitch based semi-conductive carbon fibers have been determined by Okubo et al [191] and Gerteisen [192] examined carbon fiber reinforced thermoplastics with controlled surface resistivity. The techniques used for measuring the conductivity in carbon fibers have been described by Maslii and Panasenko [193]. 

A series of works has been done in this field of growing interest for the purposes of improving the dispersibility of nanoparticles in solvents and their compatibility in polymers [25]. Mostly, the graft polymerization is conducted via two routes (1) monomers are polymerized from active compounds (initiators or comonomers). PMMA is a commonly used thermoplastic matrix for fibers, sheets, and particles. There have been several studies on PMMA-fiber composites prepared by in situ polymerization [26], solution mixing [27], or melt blending [28]. The last one is already an industrial process for fabricating carbon fiber-reinforced thermoplastic composites. 

For many electro-technical and automotive applications plastics components have to fulfill enhanced demands on their electrical and thermal conductivity. A novel material eombination of metal fiber reinforced thermoplastics and low melting metal alloys allows a significant increase in the maximum filler content and therefore in the electrical conductivity in comparison to just solidly filled polymers, because the low-viscous alloy is already molten during manufacturing. The material can be processed economically to complex shaped parts by conventional injection molding. The material composition, the processing behavior and the resulting part characteristics will be discussed in this paper. 

Experimental results are presented that show that high doses of electron radiation combined with thermal cycling can significantly change the mechanical and physical properties of graphite fiber-reinforced polymer-matrix composites. Polymeric materials examined have included 121 °C and 177°C cure epoxies, polyimide, amorphous thermoplastic, and semicrystalline thermoplastics. Composite panels fabricated and tested included four-ply unidirectional, four-ply [0,90, 90,0] and eight-ply quasi-isotropic [0/ 45/90]s. Test specimens with fiber orientations of [10] and [45] were cut from the unidirectional panels to determine shear properties. Mechanical and physical property tests were conducted at cold (-157°C), room (24°C) and elevated (121°C) temperatures. 

Anisotropic a- nI-so- tra-pik (1879) adj. (1) A transparent particle having different refractive indices depending on the vibration direction of light. (2) Said of materials whose properties, e.g., strength, refractive index, thermal conductivity, are unequal in different directions. Oriented thermoplastics and unidirectionally fiber-reinforced... 

Conductive reinforcements in thermoplastics are a new application of composites [2891. High temperature resistant thermoplastics, such as PPS, PEI, PPO and liquid crystal polyesters, have been combined with conductive fibers, generally chopped graphite and nickel coated graphite. Fiber distribution, orientation and fracture morphology were determined by optical and SEM techniques. Poor bonding in the nickel coated graphite composite, as observed in SEM tensile fractures, resulted in lowered tensile and impact properties. 

It is common practice to add fillers, such as talc or glass fibers, to a thermoplastic matrix to achieve cost reduction and mechanical reinforcement, as well as to enhance various properties such as electrical conductivity, thermal properties, and dimensional stability. Large amoimts of conventional micron-size fillers are typically required in these formulations, which results in deterioration of processability and surface appearance. 

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