Carboxylated phenolic resin

One example of a very special dual-component polymeric flocculant is poly (ethylene oxide) (PEO) and carboxylated phenolic resin (CPR), usually referred to as a cofactor. It has been shown that this dual flocculant can induce a richness of flocculation behavior depending on the concentration of the two components [40,41]. Flocculation, deflocculation, and reflocculation of cellulose particles were studied for various CPR PEO ratios. It was found that reflocculation is a strong function of this ratio. For low ratios, no reflocculation occurs after a few cycles, whereas for high ratios very limited flocculation and reflocculation occurs. 

The epoxy-acrylic resin referred to above is a graft copolymer prepared by the polymerisation of acrylic monomers in the presence of the epoxy resin in such a way that grafting of the acrylic onto the epoxy takes place. Water dispersibility is achieved by neutralising carboxyl groups in the acrylic polymer chain with ammonia or amine. Amino or phenolic resins are used as crosslinkers. Alternatively, solvent-borne epoxy-amino or epoxy-phenolic lacquers can be used. 

At the present time, most of the positive photoresists used in the manufacture of microcircuits consist of a low molecular weight phenolic resin and a photoactive dissolution inhibitor. This composite system is not readily soluble in aqueous base but becomes so upon irradiation with ultraviolet light. When this resist is exposed, the dissolution inhibitor, a diazoketone, undergoes a Wolff rearrangement followed by reaction with ambient water to produce a substituted indene carboxylic acid. This photoinduced transformation of the photoactive compound from a hydrophobic molecule to a hydrophillic carboxylic acid allows the resin to be rapidly dissolved by the developer. (L2,3)... 

Recent work by Russian Workers has revealed a more reasonable explanation of the photolnsolublllza-tion of a phenolic resin by the decomposed diazoquinone. The ketene Intermediate was found to be grafted onto the phenolic resin through the formation of a carboxylic acid ester oh q i... 

Phenolic adhesives are structural adhesives with specific applications, e.g. where wide gap bonding is required and where large structures need to be bonded. Phenolic resins are the product of a special reaction ratio of a phenol and formaldehyde in the presence of an organic catalyst. There are two main types of phenolic resins phenol or methylol terminated. The phenol terminated are called novalacs, while the methylol terminated are called resoles (one step resins). Modem phenolic resins are prepared in the presence of metal carboxylates and these resins contain a large number of benzylic ether linkages and have open para positions which have good temperature stability and are usually of low viscosity. 

The mechanical properties of the C3, C6, and Cl2 nanocomposites were all significantly better than those of the neat phenolic resin, even if a very small amount of the silicate was used. Among the nanocomposites prepared, the organically modified MMT-resol systems showed better mechanical properties than those of the unmodified MMT-resol system. This improvement was attributed to the formation of an end-tethered structure due to the reaction of the carboxylic acid of the organic modifier with the methylol group of the phenolic resin. Thermogravimetric analysis reported by Byun and coworkers showed that the nanocomposite systems had similar thermal stability to that of the neat polymer. 

The other organic accelerators ate carboxyl acids, formaldehyde, cationic polyesters, phenol resins and epoxy resins [54],... 

The reaction with rosin is used to modify phenolic resins and provides an alternative route to solubility in oils. The rosin carboxyl group is afterwards esterified with a polyhydric alcohol, such as pentaerythritol, to increase the resin molecular weight even further. 

Tween 81. See Polysorbate 81 Tween 85 Tween 85LM. See Polysorbate 85 Twinkling Star. See Antimony trioxide Two-stage phenolic resin. See Novolac resin Two-stage resin. See Phenolic resin Ty-lon B11. See Sodium sulfite Tylac 037 Tylac 97-422 Tylac 692 Tylac 757 Tylac 820 Tylac 936 Tylac 979-RG Tylac 68009-00 Tylac 68010-00 Tylac 68012-00 Tylac 68013-00 Tylac 68014-00. See Styrene/butadiene polymer Tylac 68060-00. See Acrylonitrile copolymer Tylac 68073-00 Tylac 68074-00 Tylac 68075-00 Tylac 68076-00. See Butadiene-acrylonitrile elastomer, carboxyl-terminated Tylac 68150-00 Tylac 68151-00. See Butadiene/acrylonitrile copolymer Tylac 68152-00. See Styrene/butadiene polymer... 

Phenolic resins are also used as tanning materials, binders for sand molds, and vulcanization additives. Ion exchange resins are obtained by condensing phenols with sulfonic, carboxylic, or amino groups. Similarly, the surfaces of space capsules have a layer of phenolic resin, which becomes carbonized by the action of heat and thus gives good thermal protection. 

The ether groups, the benzene rings, and, when present, the aliphatic hydroxyls in the cured epoxy system are virtually invulnerable to caustic attack and extremely resistant to acids. In the case of the phenolic resin, the sodium phenolate formed is readily soluble and when present will cause the ultimate disintegration of the resin chain. In the case of the polyester, the ester linkage is hydrolyzed back to the original alcohol and salt of the carboxyl group. The chemical inertness of the cured epoxy system is enhanced by the dense, closely packed structure of the resinous mass, which is extremely resistant to solvent action. 

Polyvinyl alcohol is copolymerized with cross-linkable comonomers N-methylol acrylamide is self-curing. Carboxylic acid comonomers are cured by epoxy, urea, or phenolic resins. 

The nanocomposites obtained firom phenolic resin and carboxylated MWNTs showed an improvement of the thermal stability than the neat phenolic resin. The highest thermal stability was obtained in the case of the nanocomposites obtained by in situ polymerization, due to the quality of dispersion of the functionalized MWCNTs [94]. An enhancement of the thermal stability was also obtained in the case of nanocomposites containing boron phenolic resin and MWCNTs modified with nitric acid, 4,4 -diaminodiphenyl methane and boric acid. This effect was ascribed to better interfacial interactions between modified MWCNTs and the resin matrix [95]. 

Recently a new class of heat-reactive phenolic resins has been developed, based on the anhydrous reaction of paraformaldehyde and phenol in the presence of metal carboxylates. These resins contain a large... 

Resins based on para-substituted phenols can be either one-step or two-step, but they cannot cure to a thermoset state. In the manufacture of phenolic resins, smaller quantities of acetaldehyde and furfuraldehyde are used in addition to formaldehyde. Furthermore, resorcinol, bisphenol A, and p-alkylphenols are employed, in addition to phenol, when special properties are desired. Formaldehyde concentrations of 37-50 weight % in aqueous solutions are most commonly employed. The catalysts most frequently used are acids such as oxalic, hydrochloric, sulfuric, p-toluenesul-fonic, and phosphoric and bases such as sodium, calcium, and barium hydroxide. In the weakly acidic range metal carboxylates are employed. Thermoset phenolic resins are employed as structural adhesives for laminating and bonding applications. Para-alkyl-substituted resins are employed as tackifiers in contact adhesives, pressure-sensitive adhesives, and hot-melt adhesives. 

Initially, a thermooxidative process takes place, due to the high oxygen content of phenolic resins. Conley and coworkers proposed that the first step, Eq. (24), is the formation of a hydroperoxide (36) which later fragments into phenols containing aldehyde and carboxyl groups.This is followed by a decarboxylation reaction which starts around 300°C and, finally, by a decarbonylation reaction which begins around 500°C. In addition, fragmentation reactions may occur above about 400°C, Scheme 1. 

Nitrile rubbers have been used extensively to produce phenolic adhesives with excellent properties. Nitrile rubbers contain unsaturation, nitrile groups and, in some cases, carboxyl groups (37). Reaction of the methylol groups of the phenolic resin can occur at all three positions, as indicated in Scheme 2. 

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