Resin formation

Resin additives Resin cements Resin component Resin cure systems Resin curing agents Resin formation Resin-in-pulp Resinoid Resinols Resins... 

In some resole appHcations, such as foam and foundry binders, a rapid cure of a Hquid resin is obtained at RT with strong acid. The reactions proceed in the same manner as those of novolak resin formation. Methylol groups react at ortho and para phenoHc hydrogen to give diphenyknethane units (41). 

As with the other aminoplastics, the chemistry of resin formation is incompletely understood. It is, however, believed that under acid conditions at aniline-formaldehyde ratios of about 1 1.2, which are similar to those used in practice, the reaction proceeds via p-aminobenzyl alcohol with subsequent condensation between amino and hydroxyl groups (Figure 24.10). 

Phenolic resins were the first totally synthetic plastics invented. They were commercialized by 1910 [I]. Their history begins before the development of the structural theory of chemistry and even before Kekule had his famous dreams of snakes biting their tails. It commences with Gerhardt s 1853 observations of insoluble resin formation while dehydrating sodium salicylate [2]. These were followed by similar reports on the behavior of salicylic acid derivatives under a variety of reaction conditions by Schroder et al. (1869), Baeyer (1872), Velden (1877), Doebner (1896 and 1898), Speyer (1897) and Baekeland (1909-1912) [3-17]. Many of these early reports appear to involve the formation of phenolic polyesters rather than the phenol-aldehyde resins that we think of today. For... 

Adolph Baeyer is credited with the first recognition of the general nature of the reaction between phenols and aldehydes in 1872 ([2,5-7] [18], Table 5.1). He reported formation of colorless resins when acidic solutions of pyrogallic acid or resorcinol were mixed with oil of bitter almonds, which consists primarily benzaldehyde. Baeyer also saw resin formation with acidic and basic solutions of phenol and acetaldehyde or chloral. Michael and Comey furthered Baeyer s work with additional studies on the behavior of benzaldehyde and phenols [2,19]. They studied a variety of acidic and basic catalysts and noted that reaction vigor followed the acid or base strength of the catalyst. Michael et al. also reported rapid oxidation and darkening of phenolic resins when catalyzed by alkaline materials. 

Furan-2-carboxylic acid reacts with sulfur tetrafluoride at 0 °C to give 2-furoyl fluoride, but attempts at further fluorination results in resin formation [222] A second carboxylic group and/or electron withdrawing substiments, such as the nitro or tnfluoromethyl group, stabilize the furan ring Thus, turandicar-... 

In anodic processes conducted at high potentials, radical-type intermediates often are formed that lead to a polymerization (resin formation) of the organic substances and to passivation of the anodes. 

Contact with the ethanolic base causes vigorously exothermic resin formation. 

Continued heating resulted in darkening of the resin, formation of a 1770 cm"l absorption for 6 in the IR, development of a broad absorption covering 1700-1300 cm"- -, and decrease of the absorptions due to CH2CpCo(C0)2- Evidently, 7 was not formed under these conditions. No other absorptions were noted in either the thermal or photolytic decar bony lation. It can thus be concluded that the 1% DVB matrix with 6% substitution does not maintain site-site isolation. 

Aminoquinolines, 21 185, 199 Amino resins, 16 409. See also Amino resins and plastics coating resins, 7 96-98 formaldehyde in, 12 121 Amino resins and plastics, 2 618-652 chemistry of resin formation,... 

Methylolated melamine, cotton cross-linking agent, 8 26 Methylolation, in amino acid resin formation, 2 624... 

Blow-molding processes consists of five main operations plastication of the resin, formation of the parison, inflation of the parison, solidification of the part, and removal of the part from the tooling. The best process economics will occur with a part optimized for weight and a minimum cycle time. In order to have a minimum cycle time, the cooling operation must be the rate-limiting step. For the case study... 

Some of the products and resin formation may be accounted for in this way. These heavily substituted benzene derivatives are likely to have absorption in the uv regions A < 300 nm. Since more HC1 is formed on keeping, the mode of polymerization seems to be as presented in (C) above and not by attack on another anthracene molecule by the AC1 radical. This is concluded from the low quantum yield of anthracene removal which does not predict chain reaction. 

On-resin formation of A-alkylglycines can be carried out according to the methods described in Section 10.1.3.4.2. 

As indicated by the structures of these molecules, the A ring contains resorcinol phenolic hydroxyls, while the B ring contains the catechol or adjacent phenolic hydroxy groups, both of which would be expected to be highly reactive in resin formation. This high reactivity would also hold for the condensed tannins present in the bark extract, since they are polymeric flavonoids (14). 

Alkyd Resins. Polyesters bearing pendant ester groups react with such groups on adjacent chains, resulting in alkyd resin formation. These reactions are catalyzed by titanates. Acrylic polymers are cross-linked with glycols or to hydroxyl-containing alkyds (485,486) (see Alkyd resins). 

The first step in the acid-catalyzed resin formation is production of gly-cosidic mono- and diureides, but subsequent products are numerous and still unidentified. 

Toxins and a large group of compounds (e.g. quaternary ammonium bases and dioxins) that require special isolation techniques, using ion pairs or ion exchange resins, formation of derivatives, continuous extraction, precipitation and concentration... 

Kinetics of /3-Resin Formation. Pyrolysis experiments were performed on the decant oil at 800°, 825°, 850°, and 980°F (430°, 440°, 450°, and 530°C, respectively) in a closed vessel under an inert atmosphere and under the pressure generated by the pyrolytic reactions. It has been established in a number of studies that for temperatures below about 1000°F (540°C) the pyrolysis of petroleum and related hydrocarbons can be described by first-order rate equations (14,15,16). An integrated form of the first-order rate equation is shown in Equation 3 ... 

The rate constant was calculated from the linear portion of each plot for the four temperatures used. The temperatures and rate constants are plotted in the Arrhenius equation in Figure 2. A reasonably straight-line relationship is obtained and an activation energy for / -resin formation of 49 kcal is obtained from the slope of the plot... 

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