Calculate the number average and weight average molecular mass for a sample of polystyrene made by blending eight separate fractions, each of which has a very narrow molecular mass distribution, as follows: Polystyrene sample #1 MW 15,000 27,000 39,000 56,000 78,000 104,000 120,000 153,000 Weight (g) 0.10 0.19 0.25 0.17 0.12 0.08 0.06 0.04 Polystyrene sample #2 is manufactured by adding 0.5 wt.% of styrene monomer to the polystyrene sample #1. What is the produced effect upon Mn and Mw? Comment on comparative manufacturability and mechanical performance of the two samples (use PDI as an argument).
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Calculate the number average and weight average relative molecular mass for a sample of polystyrene made by blending eight separate fractions, each of which has a very narrow mass distribution as follows: RMM 15000 27000 39000 56000 78000 104000 120000 153000 Mass / g 0.10 0.18 0.25 0.17 0.12 0.08 0.06 0.04 What will be the effect on Ṁₙ and Ṁᵣ of adding 0.5 wt% styrene monomer to this polystyrene sample?
Supreeta N.
1. (a) A polydisperse sample of polystyrene is prepared by mixing three monodisperse samples in the following proportions: 1 g 10,000 molecular weight 2 g 50,000 molecular weight 2 g 100,000 molecular weight Using this information, calculate the number-average molecular weight, weight-average molecular weight, and PDI of the mixture. (b) Also, explain what does PDI mean? Based on that fact, do you think that this mixture is well mixed? You have to use the following relations to calculate these numbers.
Adi S.
3. A sample of polystyrene is composed of a series of fractions of different-sized molecules: Fraction A B C D E F G H Weight Fraction 0.04 0.08 0.16 0.28 0.20 0.12 0.07 0.05 Molecular weight 10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 Calculate the Mn, Mw, and PDI of this polymer sample. Draw a molecular weight distribution curve with molecular weight and weight fraction as X and Y dimensions, respectively.
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