Molecular calibration curve, PMMA

Figure 10. "Secondary" Molecular Weight Calibration Curve for a PMMA Sample (Eastman 6041).

Route 1 (a) Using the Mark-Houwink parameters of the PMMA test polymer in tetrahydrofuran, cthfia and thf A> construct the PMMA molecular weight calibration curve in tetrahydrofuran from the polystyrene HDV calibration curve by the use of Equation 2 where x is PMMA... 

Figure 2. Illustrative method for generating PMMA molecular weight and HDV calibration curves in TFE using a poly sty rene-HDV calibration curve in...

Figure 5. Molecular weight calibration curves for PMMA in TFE at 50°C...

In Table IV, the values of Mn, Mw, [77], and Mw/Mn for the PMMA fractions D and H and whole polymers 122-7 and 122-9 calculated from the direct Mv vs. PRV calibration curve are compared with the available corresponding true values. In general, the calculated values of [ ] from the direct calibration curve are larger than the true values at low molecular weights as indicated in the values for fraction D and tend to converge to the true values as the molecular weight increases as indicated... 

Using the PMMA direct molecular weight calibration curve shown in Figure 4 and the Mark-Houwink parameters for PMMA in TFE shown in Equations 26 and 27, an HDV calibration curve can be constructed as described in the theory section. Then secondary molecular weight curves can be constructed for other polymers of interest by the methods discussed in the theory section as was done in Ref. 1, using the indirect PMMA molecular weight calibration curve. 

Application of Mark-Houwink constants. It is well known that the plot of log ri2M V. Fr, the so-called universal calibration , is obeyed by structurally different polymers including random, block and graft copolymers. Therefore, the use of [rj M should be a theoretically reliable procedure for calibration. PS, PMMA, and their random and block copolymers having the same molecular massj)ut different Fr had different intrinsic viscosities [1]. The plot of log([f/]M ) v. Fr for these polymers and copolymers fitted satisfactorily on the universal calibration curve which was established using a series of PS samples of various molecular masses. 

The melt flow index, melting and crystallization temperatures, and heat of fusion of the samples are shown in Table 1. The difference in the melting point between the reference and the branched samples are caused by the presence of the branching and the reduced crystallinity. The molecular weights are shown in Table 2 based on a calibration curve determined using PMMA standards. 

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