Graphite-polymer composites

W C Tucker and R Brown, Moisture absorption of graphite/polymer composites under 2000 feet of seawater , / Compos Mater 1989 23(8) 787-797. 

W C Tucker, Crystal formation on graphite/polymer composites , J Compos Mater 1988 22(8) 742-748. 

W C Tucker, Degradation of graphite polymer composites in seawater , Trans ASME I Energy Resources Technol 1991 113(4) 264-267. 

Other fibers and polymers have also been used, and the trend is toward increased utilization of composites in automobiles and aircraft. For example, a composite of graphite fibers in a polymer matrix is used in the construction of the F-117 Stealth fighter and other military aircraft. Graphite-polymer composites are used in a number of sporting goods such as golf club shafts, tennis racquets, fishing rods, and skis. The F-16 military aircraft was the first... 

Graphite/polymer composite materials made of a graphite, and carbon combined with a polymeric resin, are less susceptible to corrosion, and have low contact resistance but higher bulk resistance than metals. Also the gas permeability is higher than in metals. This results in thicker plates, which may still be acceptable for stationary applications. Target values for the bulk conductivity are in the order of >10Scm [79]. 

Graphite/polymer composite PEMFC bipolar plates for higher temperatures (120 C) and automotive applications (DOE, 2009). 

Zheng, G., Wu, J., Wang, W., Pan, C., 2004. Characterizations of expanded graphite/polymer composites prepared by in situ polymerization. Carbon 42, 2839—2847. 

Mitani, T, Hayashi, T, and Miyamoto, F. (2003) Properties of graphite-polymer composites for PEFC separators, Fuel Cell Seminar 2003, 208-211. 

A composite consisting of a mixture of carbon particles (e.g., carbon black or graphite) and a polymer binder such as polyethylene or polypropylene with a surface layer of a carbon-black or carbon-felt flow-through structure serves as the Br2 electrode in Zn/Br2 batteries. Because of the low surface area of the carbon-polymer surface, an additional layer of carbon is necessary to obtain higher reaction rates. The mechanical deterioration of graphite-polymer composite... 

Electronic resistance is almost negligible, even when graphite or graphite/polymer composites are used as current collectors. Ionic and... 

All these factors make it difficult to develop a cost effective solution for the separator plates. Initial trials were with graphite polymer molded composites. The polymers that were tried includes polyvinylidenefluoride (PVDF), polyetheretherketone (PEEK), perfluoroalkoxy (PEA) etc. Although most of the graphite polymer composite passed the 200°C phosphoric acid test, few survived more than few thousand hours, when they are maintained in 200°C phosphoric acid with a potential of 1.0 V w.r.t. SHE. Of the various polymers, PFA was found to be the most suitable. However, it was observed that after long exposure to PAFC temperature, the polymers got relaxed, causing an increase in the plate electrical resistance and porosity. However, all these plates exhibited excellent gas crossover resistance at least in the initial phase. 

---