SUMM method

Sodium hydroxide 2.0 M/methanol Rayon summative method 631... 

Iron-sodium tartrate solution/ Summative method 1481,1482... 

Application of the Summative-Fractionation Method to the Determination of Mw/M for Narrow-Distribution Polymers... 

The summative-fractioruition method was extended to apply to narrow-distribution polymers with polydispersity (Mw/ Mn) less than 1.12. A fractionation parameter H, previously defined and calculated for theoretical molecular weight distributions for normal polymers, was computed for narrow-distribution polymers. The calculations were made both with and without correction for fractionation errors, using the Flory-Huggins treatment. The method was applied to a well-characterized anionic polystyrene with Mw = 97,000, for which the polydispersity was estimated by this technique to be 1.02 (in the range 1.014-1.027, 95% confidence limits). 

The Summative-Fractionation Method. To review briefly (8), in the summative-fractionation method one performs a series of small-scale single-step fractional precipitations in which increasing percentages of the total polymer are precipitated. The weight fractions x and average molecular weights Mw of all the precipitates are determined. One calculates and plots against x a parameter... 

Autrata und Muller (4) schliefilich verwenden die Methode der a-Polymeren , welche bei Styrol und Methacrylat bereits ausfiihrlich beschrieben wurde. Bei Polyvinylacetat liefert sie die Summe der beiden Ubertragungskonstanten, CPo, iS+ CPolVtK. Unter Berucksichtigung der... 

The summative fractionation is a method of fractionation with the determination of the overall polymer precipitate mass in the second phase (without removing the previously precipitated polymer fractious) ou adding a due portion of non-solvent (or on decreasing temperature). I hus, the degree of phase transformation x is determined at the stage of summative fractionation. 

Formative and summative assessments are used during the course to evaluate the achievement of the learning objectives. Example assessment methods and results are discussed in the paper. Also discussed are the results of recent teaching evaluations, which show that the students value this approach to course design and organization. 

Spencer developed a method for evaluating the distribution from the experimental data obtained with his summative fractionation procedure. His method is bsised on the assumption that the separation according to molecular weight is ideally sharp, i.e. all molecules above a given size are present in the concentrated phase, whereas shorter chains are confined to the dilute phase. This assumption cannot be reconciled with the actual situation, as was pointed out by Billmeyer eind Stock-MAYER (69). 

Use embedded assessment and a variety of assessment methods. The assessment of the students should include both formative and summative evaluation and be continuous throughout the whole period of study. Teachers may assess their students traditionally via multiple choice and open-ended questions, but in addition the assessment should include, for example ... 

For the first issue, related to the summative assessment, the same gaps in teachers education that affect teaching methods applied within classrooms also affect the assessment strategies. Teachers without training tend to reproduce traditional strategies of teaching and assessment. In this way, like any other... 

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