Hydroxyl index values

Table I. Hydroxyl Index Values during Irradiation in a Microscal Unit for OV Cured (5% w/w Benzophenone) GPT (12 thick) after Reaction with Various Amines...

Amine lOOh Hydroxyl Index Values 200h 300h... 

The two most relevant propraties of these polyols with regard to their use as polyurethane precursors are their viscosity and hydroxyl index. Values which simulate those associated with comma-cial counterparts were readily obtained by adjusting the key process parameters, notably the PO/L ratio. 

Formulations should be based on stoichiometric considerations. Based on a knowledge of the hydroxyl value of the polyol the amount of isocyanate necessary to cause chain growth should be calculated. The gas evolved will depend on the water content and additional isocyanate must be incorporated corresponding to the water present. When the isocyanate used equals the theoretical amount the system is said to have a TDI index of 100. In practice a slight excess of isocyanate is used (TDI index 105-110) to ensure complete... 

The dielectric constant varies with coal rank (Chatterjee and Misra, 1989). The theorem that the dielectric constant is equal to the square of the refractive index (which is valid for nonconducting, nonpolar substances) holds only for coal at the minimum dielectric constant. The decreasing value of dielectric constant with rank may be due to the loss of polar functional groups (such as hydroxyl or carboxylic acid functions), but the role of the presence of polarizable electrons (associated with condensed aromatic systems) is not fully known. It also appears that the presence of intrinsic water in coal has a strong influence on the dielectric properties (Chatterjee and Misra, 1989). 

Isocyanate index (index number) = I (X)(actual amount of isocyanate used)/ (equivalent amount of isocyanate required). An excess of isocyanate groups is used in some applications like flexible foam. The analytical values required for isocyanate formulas are the isocyanate value, hydroxyl number, residual acid value (acid number), and water content. The last two parameters reflect the following reactions ... 

Flash point 321°C Hydroxyl value 8-12 Melting point —18 to —10°C Refractive index ... 

The calculated retention is compared with the experimental value in Table 1. From a statistical point of view, the improvement when using the rotamer with better fit is insignificant (Fg g = 1.26 and 1.07) and the assumption could be considered as disputable. This can be explained by the small number of compounds that are able to rotate around the cr-bond in the total matrix. Independent of the reliability of the assumption, a beneficial conclusion can be drawn from Eqs. (l)-(3). They demonstrate that the retentions of the studied benzene derivatives are governed in the studied cases only by local descriptors and predominately by the local descriptors for the — O — atom in the hydroxyl group. The connectivity index used in many studies (e.g.. Ref. 5) showed, in the studied case, a correlation coefficient of only 0.285. 

Golden yellow oil, difficult to bleach. Not affected by temporary heating to 160 . dg 0.916-0,921. nS 1.470-1.473 n J 1.465-1 468. Titer (solidification pt) 24-28. Saponification value 1S -189. Acid value 4 120 (see above comments on the lipase content of the bran). Iodine value 99-108. Thiocyanogen value 69-76. Hydroxyl value 5-14. Reichert-Meissl value <0.5. Polenskd value <0.5. Hehner value 95.3. Unsaponifiable matter 3-5%. The high refractive index is ascribed to the presence ol squalene. Also contains other antioxidants such as tocopherols. Miscible frith hexane and other fat solvents. 

Figure 3. The hydroxyl radical scaveugiiig activity of uine difiereiit spices all bclongiug to the fkinily Labiatae. The activity was measured by using electron qiin rcsonanee technique, and the indexes were calculated on the basis of top height oni (lata of refertmce (2S). A low value of the index indicates an eCGcient scavenger. Columns with different letters are dgniUcanily different at 5% level.

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