Question

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. ar{M}_n = frac{sum_{i=1}^N N_i M_i}{sum_{i=1}^N N_i} = frac{sum_{i=1}^N W_i}{sum_{i=1}^N (W_i / M_i)} (1.3) ar{M}_w = frac{sum_{i=1}^N N_i M_i^2}{sum_{i=1}^N N_i M_i} = frac{sum_{i=1}^N W_i M_i}{sum_{i=1}^N W_i} (1.5)

          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.
ar{M}_n = frac{sum_{i=1}^N N_i M_i}{sum_{i=1}^N N_i} = frac{sum_{i=1}^N W_i}{sum_{i=1}^N (W_i / M_i)} (1.3)
ar{M}_w = frac{sum_{i=1}^N N_i M_i^2}{sum_{i=1}^N N_i M_i} = frac{sum_{i=1}^N W_i M_i}{sum_{i=1}^N W_i} (1.5)

$1. (a) A polydisperse sample of polystyrene is prepared by mixing three monodisperse samples in the following proportions: 1 g | 10,000 molecular weight 2 g | 50,000 molecular weight 2 g | 100,000 molecular weight Using this information, calculate the number-average molecular weight, weight-average molecular weight, and PDI of the mixture. (b) Also, explain what does PDI mean? Based on that fact, do you think that this mixture is well mixed? You have to use the following relations to calculate these numbers. arMn = fracsumi=1^N Ni Misumi=1^N Ni = fracsumi=1^N Wisumi=1^N (Wi / Mi) (1.3) arMw = fracsumi=1^N Ni Mi^2sumi=1^N Ni Mi = fracsumi=1^N Wi Misumi=1^N Wi (1.5)$

Added by Matthew S.

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