Problem (1) Calculate the wt. % for the plasticizer with T g = -80 o C which nee

ID: 988657 • Letter: P

Question

Problem (1)

Calculate the wt. % for the plasticizer with Tg = -80 oC which need to be added to a film of nylon 66 in order for Tg of the blend to be 25 oC?

[Hint: consider that the blend follow the Fox equation]

Problem (2)

Based on your result from problem (2), calculate the decrease in melting temperature of nylon 66 after the addition of this amount of plasticizer.

The following Data are available for problem 1 and 2:

Polymer-plasticizer interaction parameter = 0.40

Heat of fusion of nylon 66 (per polymer repeat unit) = 301 J/g

Density of nylon 66 = 1.091 g/cm3

Density of the plasticizer = 1.091 g/cm3

Melting point of the pure polymer = 280 oC

Glass transition temperature of the pure polymer = 50 oC

Molar volume of the plasticizer = 200 cm3/mol

Molecular weight of the repeat unit of polymer = 226.32 g/mol

The Fox equation is

1/Tg = w1/Tg1 + w2/Tg2

1/298 = w1/323 + (w2)/193

1/298 = 193w1 + 323w2/62339

w2 = 1-w1

62339/298 = 193w1 + 323(1-w1)

209 = 193w1 + 323- 323w1

114 = 130w1

w1 = 114/130

w1 = 0.876

Nylon = 0.876

Plasticizer = 0.123

Wt% = 12.3 wt%

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