Nitrogen equivalent weights

TGA. Unlike the previous two sets of molding compounds, the semiconductor grade novolacs investigated in this section do not differ solely in the presence or absence of a flame retardant. However, they are considered to be relatively equivalent. Weight loss measurements for the FR formulation, sample F, and the non-FR compound, sample G, are presented in Figure 7 for both nitrogen and air. Several differences are observed in the weight loss curves for these samples. 

The reactor was purged with nitrogen and heated to 50 °C under 20 torr vacuum. The vacuum was broken and 500 ppm of stannous octoate catalyst obtained from City Chemical was added. The methanol was stripped under 20 torr vacuum at 195 °C for 4-6 hours yielding a viscous light yellow natural oil polyol with an equivalent weight of 660. 

Chain Extension of -U-Polystyrene Hiols. A two-stage chain extension of the. -kJ -polystyrene diols was accomplished by carboxylation of the diols with succinic anhydride followed by chain extension with a diepoxide. The succinic anhydride reaction was carried out 120-130°C under nitrogen. The reaction was monitored bj changes in the carbonyl bands at 1715 and 1740 cm in the infrared spectra of the reaction mixtures. The resulting dicarboxylic acid polymers were chain-extended in bulk at 130°C for 9 hours with Sow s HER diepoxide, equivalent weight =171, using bis( 3,5-diisopropylsalicylato)Cr (III) as the catalyst. 

Vacuum-still bottoms from the H-coal liquefaction process were separated into acid, neutral, and basic fractions by precipitation with acids or by extraction with bases. About one-third of the preasphaltene and one-sixth of the asphaltene fraction were precipitated by acids equivalent weights of the bases were in the range 1200-1800 for preasphaltenes and 600-800 for asphaltenes. The acidic components were obtained either by extraction with aqueous sodium hydroxide or by extraction with benzyltrimethylammonium hydroxide in methanol. About one-fifth of the asphaltene and one-fourth of the presasphaltene fractions were obtained as acids, and up to 10% as amphoteric substances. Nitrogen and sulfur were present in all fractions found. Deno axidation (CF3C02H, H202, H 04) gave dicarboxylic acids from malonic to adipic in addition to mono acids. 

This is a mixture of 3 parts of nitre with I part of sulphur, and contains approximately equivalent weights of the two components. When this mixture, which yields very little gas, is burnt, the products formed are mainly potassium sulphate, sulphur dioxide and nitrogen in accordance with the following equation —... 

The reactor was charged under a nitrogen atmosphere with an aqueous solution of initiator, buffers, and surfactant, followed by comonomer. The synthesis was then carried out at 60 C with a continuous feed of TFE to maintain the desired pressure in the stirred reactor. After the required quantity of TFE was added, the reactor was vented and the copolymer was isolated by acid coagulation, washed, and dried. The comonomer TFE ratio was adjusted to a level that would produce 80-90 grams of polymer at about 50% conversion of comonomer. The TFE pressure was controlled to produce polymers which analyzed at 1200, 1000, 800 and 600 (+-26) equivalent weight, respectively. Equivalent weights were determined by functional group hydrolysis and titration and confirmed by percent sulfur analysis. 

Materials Two commercial polypropylene glycols (polyols) of different functionality were used. The trifunctional polyol is Union Carbide NIAX 16-56, and the difunctional polyol is Union Carbide NIAX 2025. Each has an equivalent weight approximating 1.00 kg. The polyols were dried with bubbling dry nitrogen while... 

One observes that the tertiary nitrogen atoms in the polyol structure shown in Figure 4.39 have bulky substituents (the polyoxyalkylene chains with equivalent weight of around 1700-2000 daltons). This fact explains the modest catalytic activity in the foaming process. 

Each nitrogen in hydrazine is oxidized from —2 to 0 valence for a total valence change of 4 electrons per molecule. Therefore, its equivalent weight is one-fourth its formula weight. Hence,... 

In the same way, the nitrogen atom, with an atomic wei t of 14 and a valence of 3, combines with 3 hydrogen atoms. The equivalent weight of nitrogen is therefore 14/3 or about 4.7. 

PU-1. This polyether prepolymer (NCO/OH = 2) was prepared at 80°C under nitrogen. 1.5 equivalent weights of poly (tetramethylene glycol), MW = 661 (PM 660), were slowly added with stirring to three equivalent weights of tolylene diisocyanate (TDI) in a resin kettle. The reaction was allowed to proceed until the theoretical isocyanate content (determined by the di-n-butylamine method) was reached (2 hr). An equivalent weight of a... 

Equivalent weights for PFSI ionomers immediately following precipitation from the reaction medium and for membranes formed as described in section 22.5 were measured by acid-base titration. In brief, the procedure is as follows. A known amount of dried polymer (in a typical measurement, approximately 0.0670 g of polymer) and 0.10 g of NaCl were dissolved in 30 mL of deionized water, and the resulting solution was refluxed in a 150-mL conical-shaped flask at 80°C overnight with constant stirring. The flask was covered with a latex balloon and then filled with nitrogen gas through a septum. The polymer swelled up in water. A few drops of phenolphthalein were added to the solution, which was then titrated with a 0.0100 M... 

---