Polyol Ethylene oxide tipped

Sample identifi- cation Approximate molecular weight Hydroxyl number (mg KOH/g polyol) Ethylene oxide tipping moles ethylene oxide/ mole glycerol (by weight addition) Reactivity, i.e., percentage of original phenyl isocynate addition consumed in ... 

Effect of Oxyethylene Content on Stability. The processing instability of TPU elastomers based on PPG 2000 can be overcome by the use of ethylene oxide "tipped" PPG polyols, especially those containing high levels of oxyethylene groups, e.g., 30% to 45% by weight. The improved stability of the polymers based on such polyols is demonstrated in Table 2. 

Chem. Descrip. Dipropylene glycoMnitiated ethylene oxide-tipped diol Uses Polyol in flexible urethane applies, ind. caulks, sealants, coatings, encapsulants, elastomers, adhesives, and flexible foams Properties Colorless dear liq. m.w. 3740 vise. 700-850 cps hyd. no. 30 ... 

Crompton [7] applied this method to a range of glycerol/propylene oxide adducts containing varions accnrately known amounts of ethylene oxide tipping, up to 5.3 moles (Table 3.2). Figure 3.1 shows the reaction curves for each of the standard samples analysed. Increasing the ethylene oxide tip content of a polyol leads to a... 

Table 3.2 Application of reactivity method to standard ethylene oxide tipped polyols ...

As (P%)6o min nd (P%)ioo min determined under rigidly standardized test conditions these quantities are dependent upon the reactivity of the polyol sample analyzed and therefore, constitute a parameter by which it is possible to compare one batch of polyol with another. In ethylene oxide tipped condensates prepared under specified conditions, the reactivity of the polyol increases with its ethylene oxide content. 

Table 7.32 - Application of Reactivity Method to Standard Ethylene Oxide Tipped Polyols... 

The end hydroxy groups of the polymer are secondary groups and are ordinarily rather unreactive in the urethane reaction. Initially, this limitation was overcome by the preparation of isocyanate-terminated prepolymer and by the use of block copolymers with ethylene oxide. The latter products are known as tipped polyols and are terminated with primary hydroxy groups of enhanced activity. 

Since the TDI and MDI automotive polyols are highly ethylene oxide (EO) tipped the reactive hydroxyl gronp can be represented by a primary alcohol. The electronic effect of... 

When terminal primary hydroxyl groups are desired ethylene oxide may be used either as the sole alkylene oxide with the polyol initiator, or it may be employed to "cap" or "tip" the oxypropylated polyol with ethylene oxide as shown in the following scheme ... 

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