Weight conversion

The graft products are usually characterized by different methods. The first method is the calculation of graft parameters known as the grafting percentage (GP), grafting efficiency (GE), and weight conversion percentage (WC). These parameters can be calculated as follows ... 

Lewis acids 436 metal complex-mediated radical polymerization 484-6 molecular weight distributions 251,453-4, 458-60,490-1.499-501 molecular weight conversion dependence 452-3,455... 

Fig. 22. The effect of solvent composition on the molecular weight ( ), conversion (O), and molecular weight dispersity ( ) of PaMeSt prepared using the HSi(CH3)2CH2CH2

Figure 5. Molecular weight-conversion contour map for various concentrations of a free-radical initiator operating in a tubular-addition polymerization reactor of fixed size. Curves were constructed using varying jacket temperatures (kinetic parameters for the initiator Ea = 32.921 Kcal/mol In k/ = 26.494 In sec f = 0.5 (------------------------) optimum operating line)...

Effects of Initiator Parameters. Initiator types can best be characterized by the frequency factor (k ) and the activation energy (E ), and the effect of these parameters on the molecular weight-conversion relationship is shown in Figures 7 and 8. The curves shown are the result of choosing the jacket temperature-inlet initiator concentration combination which maximizes the reactor conversion for each initiator type investigated. 

Figure 7. Tubular plug-flow addition polymer reactor effect of the frequency factor (ka) of the initiator on the molecular weight-conversion relationship at constant activation energy (Ea). Each point along the curves represents an optimum initiator feed concentration-reactor jacket temperature combination and their values are all different, (Ea = 32.921 Kcal/mol In ka = 35,000 In sec ...

Figure 14, Molecular weight-conversion relationship (computer simulation— reactor of a fixed geometry for a given initiator system) (h) heat transfer coefficient...

The computer simulation study of the operation of the tubular free radical polymerization reactor has shown that the conversion and the product properties are sensitive to the operating parameters such as initiator type, jacket temperature, and heat transfer for a reactor of fixed size. The molecular weight-conversion contour map is particularly significant and it is used in this paper as a basis for a comparison of the reactor performances. 

The full utilization of improved heat transfer in a given reactor can only be made when the molecular weight-conversion relationships are carefully studied with various initiator types at different heat transfer levels. Then a particular initiator system must be selected for a maximum conversion improvement for a specified product. 

Optimized molecular weight-conversion relationship is related to the system heat transfer coefficient. The degree of conversion improvement from improved heat transfer depends on the average molecular weights of polymer being produced for a given initiator system. 

The ratio of monomer to initiator ranges from 1 1 to 10 1, and preferentially is set to 9 1 [126]. By setting initiator concentration, initiator type, residence time and temperature, the polymer molecular weight, conversion and solution viscosity are determined. The monomer is, e.g. acrylate-based with or without styrene. The pressure is regulated to be 2 x 10 -5 x 10 Pa in order to avoid solvent and monomer boiling. 

Source of protein Proportion of nitrogen % total weight Conversion factor... 

United States Depatment of Agriculture. 1965. Volume-weight conversion factors for milk. Consumer and Marketing Services, Dairy Division Marketing Research Rep.701 and supplement. Washington, D.C. 

Preservative Molecular formula and weight Added form Molecular formula and weight Conversion factors ... 

Shieh et al. (2003) indicated a biodiesel transesterification using soybean oil and methanol and commercial immobilized lipase from R. miehei (Lipozyme IM-77). The response surface analysis showed that the following variables were important reaction time, temperature, enzyme amount, molar ratio of methanol to soybean oil, and added water content on percentage weight conversion to soybean oil methyl ester by transesterification. The optimum yield based on ridge max analysis gave a 92.2% weight conversion. 

The RSREG procedure for SAS was employed to fit the second-order polynomial equation 1 to the experimental data—percent weight conversions (Table 5). Among the various treatments, the greatest weight conversion (96.5%) was treatment 22 (12h, 45°C, 50% enzyme, substrate molar ratio 4 1, added water 10%), and the smallest conversion (only 22.4%) was treatment 12 (16h, 55°C, 20% enzyme, substrate molar ratio 5 1, added water 5%). From the SAS output of RSREG, the second-order polynomial equation is given below ... 

Treatment Random Time (h) Xx Temperature (°C) X2 amount (%) X3 ratio (methanol/ canola oil) X4 Added H20 (% by wt of canola oil) X5 Observed yield (% weight conversion) Y... 

The analysis of variance (ANOVA) indicated that the second-order polynomial model (above) was statistically significant and adequate to represent the actual relationship between the response (percent weight conversion) and the significant variables, with very small p-value (0.0001) and a satisfactory coefficient of determination (R2 = 0.955). 

Figure 9.2. Contour plots of percent weight conversion of biodiesel. Enzyme concentration was by weight of canola oil and substrate molar ratio was methanol to canola oil. The numbers inside the contour plots indicate weight conversions at given reaction conditions.

TABLE 9.6. Estimated ridge of iiiaxiiiiuni response for variable percent weight conversion. 

Fig. 17. Dependencies of average composition of copolymer of styrene with methyl methacrylate on the weight conversion of reacted monomers p at the initial compositions x = 0.6 (7) and x = 0.35 (2). The curves are calculated experimental data, obtained by means of NMR and UV spectroscopy, are depicted by dark and P open circles, respectively [305]...

Plantwide issues of recycle and component inventory control play a significant role for polymer reactors. Because of their value, unconverted monomers are generally recovered from the polymer for recycle back to the reactor, These recycle streams most often contain impurities that can affect the polymerization (molecular weight, conversion, composition, color, etc.). In some cases a particular component impurity can be a dominant variable. If this impurity cannot be controlled and if there is no other equally dominant variable present that can be controlled, then the result will usually be an undesirable polymer product. 

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