Cardanol phenol—formaldehyde resin

CF = cardanol-formaldehyde resin (cured) MCPAF = monocar-danyl phosphoric acid-formaldehyde resin (cured) BrCF = bromo derivative of CF BrMCPAF = bromoderivative of MCPAF PF = phenol-formaldehyde (cured) MPPAF = monophenyl phosphoric acid-formaldehyde (cured), BrPF = bromo derivative of PF BrMPPAF = bromoderivative of MPPAF PPF = phenol-formaldehyde resin phosphorylated (cured). 

Another compound which has been found to somewhat imitate the active site of peroxidases is the commercially available Fe(II)-salen catalyst. This catalyst was used successfully to produce phenol polymers, which could be of interest for industrial production [153,154]. For example, cardanol can be polymerized by the Fe(II)-salen catalyst [155]. Due to the unsaturated bonds in the side chain of the cardanol components, the resulting polymers could be thermally cured, or cured by use of cobalt naphthenate to give brilliant films with a high-gloss surface. This reaction proves that reactive prepolymers can be synthesized from renewable resources (cardanol is the main component obtained by thermal treatment of cashew nutshell liquid). This process could be a true alternative to conventional phenol-formaldehyde resins (Scheme 25) [ 155]. Other non-heme iron complexes have been foimd to... 

The cationic polymerization of cardanol under acidic conditions has been referred to earlier [170,171], NMR studies [16] indicated a carbonium ion initiated mechanism for oligomerization. PCP was found to be highly reactive with aldehydes, amines, and isocyates. Highly insoluble and infusible thermoset products could be obtained. Hexamine-cured PCP showed much superior thermal stability (Fig. 12) at temperatures above 500°C to that of the unmodified cardanol-formaldehyde resins. However, it was definitely inferior to phenolic resins at all temperatures. The difference in thermal stability between phenolic and PCP resins could be understood from the presence of the libile hydrocarbon segment in PCP. 

The lower thermal stability of cardanol-formaldehyde resin and their derivatives were expected because of the presence of the libile side chain in the system. Although phenolics are superior in their properties, their bromo derivatives exhibit very low char yields. Oxidation of the char by a decomposition product is suspected. Evaluation of the LOI data with char yields individually for phosphorus and bromine suggests a positive interac-... 

Cardanol is a main component of thermally treated cashew nut shell liquid (CNSL), and is a phenolic compound with a long unsaturated hydrocarbon chain substituted in the meta position (Figure 2.17a). Urushiol, which is obtained from lacquer tree, poison ivy, poison oak, and poison sumac (Toxicodendron), and used for a raw material of a lacquer (urushi) in East Asia, is also a phenolic compound of catechol with a long unsaturated or saturated hydrocarbon chain (Figure 2.17b). Cardanol-based polymers have been reported very often, while there are a few research reports on urushiol-based polymers. Research on polymers synthesized from cardanol or CNSL are reviewed elsewhere.In the late 1980s, cardanol or CNSL-based polymers began to be reported as novel phenol-formaldehyde type resins and novel epoxy resins.Thereafter, Pillai and his co-workers have vigorously studied synthesis of various type of cardanol-based polymers polymers obtained... 

Synthetic resins, such as phenoHc and cresyUc resins (see Phenolic resins), are the most commonly used friction material binders, and are usually modified with drying oils, elastomer, cardanol [37330-39-5] an epoxy, phosphoms- or boron-based compounds, or even combinations of two. They ate prepared by the addition of the appropriate phenol and formaldehyde [50-00-0] in the presence of an acidic or basic catalyst. Polymerization takes place at elevated temperatures. Other resin systems are based on elastomers (see Elastomers, synthetic), drying oils, or combinations of the above or other polymers. 

The method was extended to novolak and resol cardanol/formaldehyde copolymers. HO-protected phenolic lipids have also been reacted. Thus, cardanol methyl ether and esters have been hydrosilated with HSiClj and then reacted with methanol to afford methoxysilyl products useful as coupling agents for phenolic resins in sand cores (ref. 256). 

A particularly promising route is to treat the fiber with a phenolic resin based on cardanol formaldehyde (CF). This is a natural alkyl-phenol, in which the methylol groups are able to react with the hydroxyl groups of the cellulose, while the long C-15 alkyl group of cardanol facilitates the formation of an adhesive bond with non-polar TPs. It is concluded that Jute fiber thermoplastic RPs can bear comparison with glass fiber RPs. However, the best solution may well be a combination of treated jute with glass. 

The reaction of formaldehyde with unsubstituted phenols leads to either soluble or cross-linked resins since condensation occurs at either ortho or para positions. Monosubstituted [35] (ortho or para) phenols give cross-linking with difficulty but phenols doubly substituted in ortho or para positions yield only low molecular weight products. If only one ortho or para position is available on the phenol then the phenol cannot produce resins and reacts with difficulty with aldehydes [33]. Sometimes cresols and phenol are blended together to obtain fully cured resins. In addition to phenol, the other important phenols that are used to give phenolic resins are o-cresol, mixed cresols, / -/e/ r-butylphenol (from isobutylene and phenol), p-phenylphenol (by-product from phenol manufacture), resorcinol, and cardanol (from cashew nutshell liquid). 

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