Static-dissipating applications, electrically

Another common reason to add a filler to a polymer is to increase either electrical conductivity or thermal conductivity. Polymers typically have electrical conductivity from 10 to 10 S/cm though the addition of a moderately conductive filler such as carbon black conductivities of lO -lO S/cm are possible highly conductive fillers such as silver can raise this value to 10 -10 S/cm. Applications include static dissipative devices and surge protectors. The impact of adding a highly thermally conductive filler to a polymer is much smaller at low-volume fractions vs. the impact of an electrically conductive filler on electrical conductivity. However, if a highly loaded stiff product is acceptable, polymer composites are capable of dissipating substantial amounts of heat. 

Coatings - Electrically conductive polysulfide/epoxy compounds for static dissipating areas intumescent coating applications, holds crystals until gas is released. 

Therefore, to minimize the effect of phase separation, the as-prepared polyblend solution is poured into an excess amount of nonsolvent such as methanol to obtain a quenched bulk powder of polymer blend. The obtained polymer blends could be molded into the desired shape by hot-pressing at 180°C for 5 min. Figure 8.43 shows the electrical conductivity of the molded blend as a function of PPy-DBSA weight fi-action [68]. The electrical conductivities of PPy-DBSA/PMMA blend exhibit a percolation threshold level at about 40%. Nevertheless, the PPy-DBSA/PMMA blends exhibit conductivities ranging from 10 to 10 S/cm with 2% PPy-DBSA, which satisfy the electrical conductivity required for static dissipative (10 to S/cm) or antistatic applications (10 to 10 S/cm). 

In addition to their primary function as mechanical property modifier, the high electrical conductivity of carbon fibers provides carbon-based composites with static dissipation and radio frequency shielding characteristics. This opens up a whole range of applications and with carbon nanotubes this can be achieved at enormously low loading levels. One application with future potential is the use of carbon... 

Anti-Static Laminates. The conventional laminates are relatively good electrical insulators and in consequence in dry conditions can accumulate static electric charges these can present problems—as when discharges take place suddenly in the course of manufacture or assembly of electronic components. It is particularly important for applications such as computer furniture and benches intended for electronic assembly that static charges will be dissipated at controlled rates. 

For some applications, particularly in packaging of sensitive electronic components, it is desirable to have a packaging material that is able to conduct electricity sufficiently to dissipate static charges, which could otherwise accumulate. As will... 

To obtain the lowest electrical volume resistivities (in the 10 to 10 ohm-cm range) and the lowest contact resistances, polymer resins must be highly Ailed with 70-80% by weight (25-30% by volume) of metal particles and must be thoroughly cured. Silver and silver alloys are the most widely used fillers but, in specific applications, other metal fillers including gold, copper, nickel, and even carbon are used. Carbon-filled polymers are often used to dissipate static electricity or to protect from electromagnetic interference (EMI). 

We next considered the dissipative system of BCPs in electric field, since virtually all polymer show some level of residual conductivi when put under an external potential. Here we are interested in the part of conductivity which is due to mobile dissociated ions. These ions are predicted to cause a phase-transition from bcc phase of spheres into hexagonal phase of cylinders in static DC field. The bcc to hex transition has just been experimentally carried-out in the group of T. Russell in Amherst (21), The surprisingly low fields used, 6-72 V/pm, cannot be explained by dielectric contrast alone, and agree with our theory and confirm our predictions. This kind of deformation should be applicable in many more ordered structures such as some of the triblock copolymer phases. 

---