2.6- Dimethylol-4- phenol

Copolymer formation by displacement reaction Solid-state chlorination of PP may lead to low levels of chlorine incorporation along the PP chain with minimal PP molecular weight degradation. Coran and Patel [1983 b] have blended (internal mixer, T = 190°C) 50 parts chlorinated PP with 45 parts NBR containing 5 parts amine-terminated NBR. The blend was characterized by mechanical properties vs. the use of unfunctionalized PP. Compatibilization resulted from copolymer formation through displacement reaction of chloride by amine groups. The blend was prepared in the presence of a vulcanization agent (3.75% of dimethylol phenol + 0.5% of SnCl ) to cause concomitant dynamic vulcanization of the rubber phase. 

TSE at 210°C / mechanical and thermal properties / DMA / ductile-brittle transition temperatures / SEM / selective solvent extraction / DSC / MFR / evidence for PP-EPDM copolymer internal mixer at 190°C / mechanical properties vs. use of unfunctionalized PP / PP and dimethylol phenol(2-4%) premixed before addition of rubber / optional addition of additional coupling agent / addition of 0-7.5% amine-terminated NBR... 

NBR (50-25)/amine-terminated NBR (0-10)/PP (45-50)/PP-MA (0-5) Internal mixer at 190 °C/mechanical properties vs. omission of functional polymers/dimethylol phenol (3.75 %) + SnCl2 (0.5 %) added as vulcanization agent for NBR Coran and Patel 1983b... 

Figure 3.18 shows the structure of the dimethylol phenolic resin [18]. Dimethylol phenolic resins are linear polymers. They contain ... 

Fig. lA-0. Chemical structures of identified sensitisers in resins based on phenol and formaldehyde. A 2-methylol phenol. B 3-methylol phenol. C 4-methylol phenol. D o-cresol. E 2,4-dimethylol phenol. F 2,6-dimethylol phenol. G 2,4,6-trimethylol phenol. H 4,4 -dihydroxy diphenyl methane. I 2,4 -dihydroxy diphenyl methane. J 2,2 -dihydroxy diphenyl methane. K 4,4 -dihydroxy-3-hydroxymethyl-diphenyl methane. L 4,4 -dihy-droxy-3,5-dihydroxymethyl-diphenyl methane. M 4,4 -dihydroxy-3,3 -dihydroxymethyl-diphenyl methane. N 2,4 -dihydroxy-3, 5 -dihydroxymethyl-diphenyl methane. O 2,4 -dihydroxy-3,3 -dihy-droxymethyl-diphenyl methane... 

Dimethylol phenol in a compound of resins based on phenol and formaldehyde. Cross reactivity is possible with other phenol derivative molecules. 

Bruze M, Zimerson E (1985) Contact allergy to 3-methylol phenol, 2,4-dimethylol phenol and 2,6-dimethylol phenol. Acta Derm Venereol Suppl (Stockh) 65 548-551... 

EPDM Dimethylol-phenolic curative, peroxide/coagents... 

HDPE -1- butadiene/acrylonitrile rubber was compatibilized by addition of dimethylol phenolic resin, which cured and compatibilized the blend [61, 62]. Cure reactions of diene rubbers with phenolic resins have been observed before [159], and probably formed an interpenetrating polymer network in this study. 

Exceptional heat resistance and low compression set can be obtained by curing butyl rubbers with dimethylol phenol resins. The curing reaction is very slow even at high temperatures and when activated by halogens. Stannous chloride, and combinations of a halogenated polymer (such as neoprene, halobutyl or brominated resin) with zinc oxide, are the most commonly used halogen-bearing activators. The systems shown in Table 5 are typical. 

Dimethylolpropyleneurea, cotton cross-linking agent, 8 26 Dimethylol-substituted phenols, 18 763 Dimethylolurea, 12 112... 

Urea (NH2CONH2) reacts with formaldehyde similarly to phenol to produce methylol derivatives that then condense further to yield a cross-linked network (Scheme 1). Actually, at a mole ratio of 1.5-2 mol of formaldehyde to urea and a pH of 7.5, a mixture of the monomethylol, dimethylol, trimethylol, and tetramethylol ureas are formed. For further extensive condensation to take place, the pH of the system must be made acidic. Thus, it is possible to concentrate the initial resin solution or spray-dry it to a soluble powder that can be dissolved and mixed with an acid catalyst at the time of application to induce the curing reaction. The ratio of formaldehyde to urea used in commercial resins varies with the manufacturer, but is always less than 2 1. 

As described above, formaldehyde exists as trimethylene glycol in aqueous solution. Phenol reacts quickly with the alkali-hydroxyl group and produces resonance structural phenoxide ion, and trimethylene glycol is added to the O and P positions in the phenoxide ion. This quinoid-transition-state is stabilized by the movement of proton. The monomethylene-derivative produced in this way reacts further with formaldehyde and produces two types of dimethylol derivative and one type of trimethyl derivative. These reactions are expressed as second-order reactions ... 

By the reaction of butenylphenols with aqueous formaldehyde under alkaline conditions dimethylol derivatives (R = H) were obtained (ref.101). Thus 4-(but-2-enyl)phenol in 10% aqueos sodium hydroxide treated with 37% aqueous formaldehyde and allowed to react during 48 hours afforded 2,6-dimethylol-4-(but-2-enyOphenol. In a similar way 2,6-dimethylol-4-(cyclopent-2-enyl)phenol,... 

The structure of the phenolic resin has been correlated with several characteristics of the adhesive. For example, benzylic ether linkages appear to prolong the tack retention time. Resins made in solvent, in the presence of catalysts (PTSA or MgO), have a lower content of 2,6-dimethylol-4-t-butylphenol, the species responsible for phasing problems. 

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