Carbon from thermosetting resin

The FRP rebars are generally manufactured by the pultrusion technique from thermosetting resins such as continuous carbon, glass or aramid fibres embedded in polyester, vinylester or epoxy matrix (Nanni, 1997 ACI, 1996 Pilakoutas, 2000 Bank, 2006). Their geometric cross-sections are typically round, square or rectangular and have smooth surfaces these must be modified to improve the bond characteristics between the concrete and the rebar. The improvements in bond characteristics are effected by forming ... 

Reinforced Plastic n (RP) A plastic composition in which are embedded fibers that are much stronger and typically much stifier than the matrix resin. The reinforcements are usually fibers, rovings, fabrics, or mats, or mixed forms of glass, carbon, asbestos, metals, ceramics, paper, sisal, cotton, or nylon. Resins most commonly used are polyesters, phenolics, aminos, siH-cones, epoxies, and various thermoplastics. The term reinforced plastic includes some forms of Laminate and molded parts in which the reinforcements are not in layered form. When the resin is thermoplastic, the term reinforced thermoplastic is often used. Methods of forming reinforced-plastics articles from thermosetting resins are defined under the entries Ksted below. 

Synthetic Resins. Various polymers and resins are utilized to produce some specialty carbon products such as glassy carbon or carbon foam and as treatments for carbon products. Typical resins include phenoHcs, furan-based polymers, and polyurethanes. These materials give good yields of carbon on pyrolysis and generally carbonize directly from the thermoset polymer state. Because they form Httle or no mesophase, the ultimate carbon end product is nongraphitizing. 

These tests were performed on materials with the same characteristics but with different thicknesses thus, the intrinsic thermal conductivity could be resolved at different temperatures and compression pressures. Through these tests, the thermal conductivity of TGP-H carbon fiber papers was measured and achieved the same value as that reported by the manufacturer. In addition, it was observed that the thermal conductivity of the CFPs decreased from 1.80 + 0.27 W m i K i (af 26°C) to 1.24 + 0.19 W m-i K i (at 73°C). This result was suggested to be due to the presence of carbonized thermosetting resin on the CFPs. The thermal conductivity of fhe resin, which is a thermosetting polymer and acts as a binder, decreases with increasing temperature. For carbon cloth (without any resin), no significant changes in thermal conductivity were noted when the temperature was increased. 

Reinforced plastics may also include fillers (qv), which are inexpensive materials such as calcium carbonate used to displace resin and reduce cost curing agents (catalysts), promoters, inhibitors, and accelerators, which affect thermosetting resin cure colorants release agents (qv) to facilitate removal from the mold and other additives which can impart a wide variety of properties to the finished part, such as fire resistance, electrical conductivity, static dissipation, and ultraviolet resistance. 

Thermosetting phenolic resins form a separate class of polymers containing aromatic rings and aliphatic carbon groups in the polymeric network. These resins are formed from the reaction of phenol (or substituted phenols) with formaldehyde. The fully crosslinked macromolecule is insoluble and infusible. Other thermosetting resins are known in practice, some derived from the reaction of melamine or of urea with formaldehyde. Because these have a different chemical structure, containing nitrogen, they are included in a different class (see Section 15.3). 

Unlike thermoplastics, which are simply melted, thermoset resins chemically react from low-viscosity liquids to solid materials during processing, a process termed curing. Structurally, thermosets differ from thermoplastics because of the presence of cross-links in the former, which means that thermosets cannot be reshaped or recycled once the chemical reaction occurs. One advantage of thermosets vs. thermoplastics is that wetting the filler becomes much easier with a low-viscosity material. By far the most common thermoset composite is automobile tires, which consist of a polymer made from styrene and butadiene monomers and carbon-black filler. The actual recipe used is much more complicated, and can include other monomers or polymers, as well as other fillers. In the absence of filler, the cured resin is rubbery at room temperature, which makes tires a... 

This process also avoids the use of methylene chloride as a solvent and the co-production of NaCl salt. Another well-established application of DMC in the field of polycarbonates relates to the production of poly[diethyleneglycol bis(allylcarbo-nate)], a thermosetting resin used in the production of optical glasses and lenses. The non-phosgene process involves the intermediate formation of diallyl carbonate from DMC - whereas the traditional process was based on the use of diethyleneglycol bis(chloroformate) that in turn was obtained from phosgene - and allows high flexibility in terms of customer-tailored products. 

Table 12.2 Moisture content of carbon fibre composites from thermosetting and thermoplastic matrices also shown is the benefit of modifying epoxy resin with thermoset and thermoplastic modifiers to reduce Mco...

A glassy carbon fiber can be produced from a melt spun phenol-hexamine thermoset resin [296,297] or a cured novalac [296,298], without the requirement of a stabilization stage. 

Kimura [37] selected three kinds of thermosetting resins—furan, diphenylether-formaldehyde and polyimide resins—as matrix precursors to fabricate carbon fiber reinforced carbon composites (C/C composites). After heat treatment at 2000-3000°C, the graphitization process of the matrix was examined by optical microscopy and X-ray diffraction. In the C/C composite derived from a polyimide, the graphite structure was not as well developed as the others. This retarded development is attributed to less internal stress between fibers and matrix as well as to less stretching of the matrix. 

A non-woven carbon fabric is made from fibers held in position by a binder, which can include melt bonding powders and meltable fibers, thermosetting resins and thermoplastic... 

Commercial bismaleimide thermoset resins are based on aromatic bismaleimides such as 4,4 -bismaleimidodiphenylmethane (Compimid MDAB, Evraiik). Compimid MDAB, also known in literature as MDA-BMT is derived from the condensation reaction between 4,4 -methylene dianiline (MDA) and maleic anhydride, both relatively low-cost monomers. The MDA-BMI is often used as a eutectic mixture with other BMIs such as TDA-BMI, to reduce its melting point for improved impregnation and tackiness in the glass and carbon-fiber-based composite prepregs. 

As a result activated carbon fiber is produced through a series of process consisting of stabilization, carbonization, and activation of precursor fibers. It is important to improve the efficiency of the production process as well as to select low cost precursors [42]. The stabilization process, air oxidation of precursor fibers at 200-300 °C, is the process required to prevent the precursor fibers from melting during the subsequent carbonization process [61, 62]. It is essential for PAN and pitches, but is not essential for phenolic resin and cellulose, because the latter precursors are thermosetting resins. Phenolic resin is known to produce higher surface area ACF as compared with other precursors. It is, therefore, very advantageous if we could improve the production efficiency of phenol resin based ACF by, possibly, simple and cost effective methods. 

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