W-Cresol

Table 9.3 lists the intrinsic viscosity for a number of poly(caprolactam) samples of different molecular weight. The M values listed are number average figures based on both end group analysis and osmotic pressure experiments. Tlie values of [r ] were measured in w-cresol at 25°C. In the following example we consider the evaluation of the Mark-Houwink coefficients from these data. 

Evaluate the Mark-Houwink coefficients for poly (caprolactam) in w-cresol at 25°C from the data in Table 9.3. 

Phenyl sulphides 4,4 -Thiobis-(6-t-butyI-w-cresol) (IX) Very slight Not so powerful as phenylalkanes as a class but synergistic with carbon black. 

This polymer may be prepared by stirring the molten w-aminoundecanoic acid at about 220°C. The reaction may be followed by measurements of the electrical conductivity of the melt and the intrinsic viscosity of solutions in w-cresol. During condensation 0.4-0.6% of a 12-membered ring lactam may be formed by intramolecular condensation but this is not normally removed since its presence has little effect on the properties of the polymer. 

As these condensation reactions can occur at the two ortho and the para positions in phenol, w-cresol and 3,5-xylenol, cross-linked structures will be formed. It has been pointed out by Megson that because of steric hindrance the amount of cross-linking that can take place is much less than would involve the three reactive groups of all the phenolic molecules. It is now generally considered that the amount of cross-linking that actually takes place is less than was at one time believed to be the case. 

Phenoxaphosphine ring-containing poly (1,3,4-oxa-diazoles) were synthesized by cyclodehydration of poly-hydrazides obtained from (BCPO) and aliphatic and aromatic dihydrazines [152]. All these polymers are soluble in formic acid, w-cresol and concentrated H2SO4. The polyhydrazides yield transparent and flexible films when cast from DMSO solution under reduced pressure at 80-100°C. The polyhydrazides exhibit reduced viscosities of 0.24-0.40 dl/g in DMAC. Phenoxaphosphine ring-containing oxadiazole polymers showed little degradation below 400°C. 

The first polyimine was reported by Adams and coworkers [182] from terephthalaldehyde and benzidine and dianisidine. Between 1950 and 1959 Marval and coworkers [174-176] reported a number of polyimines. Suematsu and coworkers [170] reported the first successful synthesis of high molecular weight fully aromatic polyimines by solution polycondensation method using w-cresol as reaction medium. 

Guests Phenol o-cresol w-cresol p-c resol Cyclo- Cyclo-... 

Some or all of the events of this sequence are readily thrown out of balance, or even completely inhibited. Thus bacteria, particularly the rod-shaped organisms, may be induced to elongate into filaments by various treatments which apparently inhibit cell division but which do not inhibit growth. Such an effect is produced by various chemical substances, by sub-bacteriostatic concentration of certain antibacterial agents, as, for example, methyl violet, sulfonamides, /w-cresol, penicillin, irradiation, and higher temperatures of incubation. 

Amino-/w-cresol, a213 Aminocyclododecane, c340 Aminocyclohexane, c375 Aminodecane, d23... 

Room-temperature solution polycondensation is used for the preparation of hexafluoroisopropylidene-unit-containing poly(azomethine)s. At the end of the reaction, the water liberated by the reaction is thoroughly taken off as an azeotrope by vacuum distillation to allow the reaction to go to completion. Among DMF, DMSO, HMPA, NMP, and w-cresol used as reaction solvents, m-cresol yields a polymer with higher reduced viscosity in higher yield. The reaction proceeds rapidly and is essentially completed in 30 min. 

Toxieology. 4,4 -Thiobis(6-rrrr-butyl-w-cresol) (TBBC) is of low systemic toxicity in animals allergic contact dermatitis has been reported in humans. 

To a three-necked, round-bottomed flask equipped with a mechanical stirrer, dropping funnel, and condenser is added a solution of 4.95 gm (0.05 mole) of phosgene in 200 ml of dry carbon tetrachloride. The solution is vigorously stirred while the rapid addition of 5.8 gm (0.05 mole) of hexamethylenediamine and 4.0 gm (0.10 mole) of sodium hydroxide in 70 ml of water takes place. The reaction is exothermic while the polyurea forms. After 10 min, the carbon tetrachloride is evaporated off on a steam bath or with the aid of a water aspirator. The polyurea is washed several times in a blender and air-dried overnight to obtain 5.0 gm (70 %), inherent viscosity 0.90 (in w-cresol, 0.5 % concentration at 30°C), polymer melt temperature approximately 295°C. 

Although the Novolak resin of the w-cresol-benzaldehyde failed to show a marked increase in CF4 plasma etching resistance, the Novolak resins of hydroxy-naphthalene-hydroxybenzaldehyde showed a remarkable increase in the plasma etching resistance. The resist films also yielded excellent patterns when used together with a diazo-naphthoquinone sensitizer almost non-diluted AZ2401 developer had to be used for image development due to the hydrophobic nature of the naphthalene group. 

To improve the solubility of polyimides, Korshak and co-workers used l,l-dichloro-2,2-bis(4-aminophenyl)-ethylene as the starting nucleophile [17] (Scheme 3.2). The resulting polymers turned out to be of relatively high molecular weight (r = 1.2-1.4 dl/g), heat resistant > 270 °C) and fire resistant (oxygen index (OI) = 36-39) (Table 3.2). Polypyromellitimide was soluble in H2SO4 only, but polyimides based on the dianhydrides of benzophenone-3,3, 4,4 -tetracarboxylic acid and diphenyloxide-3,3, 4,4 -tetracarboxylic acid were also soluble in w-cresol and a trichloroethane (TCE)/phenol (3 1) mixture. Diphenyloxide-3,3, 4,4 -tetracarboxylic acid was soluble even in N-methyl-2-pyrrolidone (NMP) (Scheme 3.2). 

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