Phenolic-type matrices composites

Carbon Composites. Cermet friction materials tend to be heavy, thus making the brake system less energy-efficient. Compared with cermets, carbon (or graphite) is a thermally stable material of low density and reasonably high specific heat. A combination of these properties makes carbon attractive as a brake material and several companies are manufacturing carbon fiber—reinforced carbon-matrix composites, which are used primarily for aircraft brakes and race cars (16). Carbon composites usually consist of three types of carbon carbon in the fibrous form (see Carbon FIBERS), carbon resulting from the controlled pyrolysis of the resin (usually phenolic-based), and carbon from chemical vapor deposition (CVD) filling the pores (16). 

The plant cell wall consists of cellulose microfibrils within a matrix of non-cellulosic polysaccharides, glycoproteins, and phenolics, the types and composition of which are related to the maturity and function of the cell and the plant type. Most non-ceUulosic cell wall components are held into the microfibrillar array by a combination of cross-links, including covalent and non-covalent ones [4]. 

Thermoset composites are made up of thermoset resin-like polyester epoxy and phenol-formaldehyde resin composites with varying fiber volume fractions and fiber length were prepared by following one of the techniques. Among polyester epoxy and phenol-formaldehyde composites, a phenolic-type resin performed as a better matrix than epoxy and polyester resins with respect to tensile and flexural properties due to the high interfacial bonding in phenolic composites [58,59,100]. 

The phenolic-type resins should remain an excellent option for therraoset-matrix composites, with these materials maintaining a prominent position in the area of composites based on their favorable cost/performance characteristics. 

Reinforced plastics are composites in which a resin is combined with a reinforcing agent to improve one or more properties of the resin matrix. The resin may be either thermosetting or thermoplastic. Typical thermosetting resins used in RPs include unsaturated polyester, epoxy, phenolic, melamine, silicone, alkyd, and diallyl phthalate. In the field of reinforced thermoplastics (RTFs), virtually every type of thermoplastic material can be, and has been, reinforced and commercially molded. The more popular grades include nylon, polystyrene, polycarbonate, polyporpylene, polyethylene, acetal, PVC, ABS, styrene-acrylonitrile, polysulfone, polyphenylene sulfide, and thermoplastic polyesters. 

Many matrix choices are available, and each type has an impact on the processing techniques, physical and mechanical properties, and enviromnental resistance of the finished part. Thermoplastic and thermoset materials can be resin matrices. Thermoplastic matrices have been developed to increase hot/wet use temperature and the fracture toughness of composites. Thermosetting resins, however, are more common. The common thermoset matrices for composites include polyester and vinyl esters, epoxy, bismaleimide, polyimide, and cyanate ester and phenolic triazine resins. 

Three carbon-plastic compositions were also included as materials for investigation. These compositions were molded by commercial plastic forming techniques. The PTFE and nylon had carbonaceous fillers present as discrete particles in the plastic matrix. The third type of material had continuous phases of both graphitic carbon and plastic (phenol-furfural),... 

Application of higher molding pressures at the gel point of a resol-type phenolic resin led to a reduction of voids in the matrix, improving the impact strength, as observed by Megiatto Jr. et al. (2009) in phenolic composites reinforced with sisal fiber. 

There are two basic types of processes used to make CAMCs. The first is chemical vapor infiltration (CVI). CVI is a process in which gaseous chemicals are reacted or decomposed, depositing a solid material on a fibrous preform. In the case of CAMCs, hydrocarbon gases like methane and propane are broken down, and the material deposited is the carbon matrix. The second class of processes involves infiltration of a preform with polymers or pitches, which are then converted to carbon by pyrolysis (heating in an inert atmo-sphere). After pyrolysis, the composite is heated to high temperatures to graphitize the matrix. To minimize porosity, the process is repeated untU a satisfactory density is achieved. This is called densification. Common matrix precursors are phenolic and furan resins, and pitches derived from coal tar and petroleum. 

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