Thus, the reaction extent of prepolymer can be controlled by
reactant ratio. Traditionally, only 80% TPC is added into the reaction solution after PPD is dissolved in NMP with ice-water bath, and then the remained 20% TPC is dissolved in NMP and pumped into the extruder together with prepolymer solution [19].
The optimum conditions for this process were a temperature of 80[degrees]C, pH 10, and
reactant ratio 4:5 (AgN[O.sub.3] 0.001 M and 250g/L, resp.).
Figure 5 depicts the effect of initial molar reactant ratio on the propionic acid conversion.
The performance of pervaporation reactor was analyzed by studying effect of various parameters such as temperature, catalyst concentration, and reactant ratio. Using pervaporation reactor considerable enhancement was observed and the conversion of propionic acid was increased from its equilibrium value of 66% to 87% using a PVA-PES membrane.
Table 1: The ratio of reactants Sample Reactant ratio (PTMO:TDI:DDDPM:APFS) APFS wt% PUO 57:100:10.5:0 0 FSPUU1 57:100:10.5:0.78 15.0 FSPUU2 57:100:10.5:1.13 21.6 FSPUU3 57:100:10.5:1.4 26.8 FSPUU4 57:100:10.5:2.16 35.6 FSPUU5 57:100:10.5:2.82 42.6 FSPUU6 57:100:10.5:2.93 44.5 After the synthesis reaction was complete, the polymer solution was kept in Teflon pans for 2 days at ambient temperature under a constant humidity to allow the solvent to volatilize.
Table 1 shows the reactant ratios and weight percentages of APFS in the FSPUU elastomers.
Contrastina effects of agitation screed on nitric acid-toluene dispersions N u Vortex depth [N.sub.Re,I] [We.sub.I] (rpm) (m/s) (cm) a b a b a b 100 0.39 0.52 0.55 9380 11270 46 28 200 0.78 2.06 2.15 18750 22540 182 112 400 1.58 7.80 8.00 37500 45080 730 450 600 2.37 17.00 17.40 56250 67620 1640 1010 N u Percent Conv of Para/ortho (rpm) (m/s) limiting
reactant ratio a b a b 100 0.39 85.00 21.40 0.65 0.63 200 0.78 85.00 47.20 0.65 0.50 400 1.58 85.00 38.50 0.62 0.68 600 2.37 85.00 24.10 0.67 0.68 a: Toluene/nitric acid (molar ratio) = 0.85:3.66; catalyst (zeolite H-Beta S/A, 30) =10 g; temperature under reflux = 120[degrees]C, limiting reactant: toluene.
It is interesting to note that the same insoluble fraction is obtained for these two blends "processed" with the same reactant ratio r but different processing parameters and catalyst concentration.
For example, at a DBTQ content of 0.13 wt%, the insoluble fraction rises from 3% to 21% when the reactant ratio r increases from 1/8 to 1/4 (blends #5 and 6).
The effect of xylene and change of
reactant ratios to properties of depolymerization products was investigated.