TALLER DE INTRODUCCIN A LOS POLIMEROS (NO Entregar, ejercicios para

estudiar. Recomiendo tambin teora)

UNIVERSIDAD DE CARTAGENA

1. Una solucin de estireno 2.0 M en dicloruro de etileno es polimerizada a 25

C usando acido sulfrico de 4 x 10-4 M. calcule el grado de polimerizacin inicial. Que podra ser el grado de polimerizacin si la solucin de monmero contiene isopropyl benceno a una concentracin de 8 x 10-5 M? use los siguientes datos si los necesita: Kp = 7.6 L/mol KtrM = 1.2 x 10

-1 L/mol s Kts = 4.9 x 10

-2 s-1 Kt (combinacin) = 6.7 x 10-3 s-1 Cs = 4.5 x 10-2

2. En la copolimerizacion de cloruro de vinilo (1) con acetato de vinilo (2), las

razones de reactividad valen r1 = 1.39 y r2 = 0.72

a. Cual sera la composicion de un copolimero obtenido con una mezcla de

monomeros del 30% en moles de cloruro de vinilo?

b. Que composicion de la mezcla de monomeros se necesita para producir

en las primeras etapas de la reaccion, un copolimero que contenga 50%

en moles de acetato de vinilo?

c. Que valores deberian tener las razones de reactividad para obtener un

copolimero de bloques, ideal y aleatorio

Example 10.6. From the data given below for the emulsion polymerization styrene in water at 60C: a. Calculate the rate of polymerization. b. Show that the number average degree of polymerization Xn is 3.52 x 10

3 c. Estimate the number of polymer chains in each. Data: kp = 176 l mol

1 s1 ri = 5x10

12 radicals cc1 s1

N = 1013 particles cc1 [M] = 10 M Latex particle size = 0.10 m Particle density = 1.2 g/cc Example 10.7: Calculate the time required for 10% polymerization of pure styrene at 60C with benzoyl peroxide as the initiator in a batch reactor. Assume that the initiator concentration remains constant.

Data: f = 1 kp

2/kt=0.95 x 10-3 L/mol.s

[I] = 4x10-3 mol/l kd = 1.92 x10

6 s1 Example 10.8: The production of high-pressure low-density polyethylene is carried out in tubular reactors of typical dimensions 2.5 cm diameter and 1 km long at 250C and 2500 atm. The conversion per pass is 30% and the flow rate is 40,000 kg/h. Assuming that the polymerization reaction is first order in ethylene concentration, estimate the value of the polymerization rate constant. (Taller para jovenes)

10.3. Calculate the time required for 80% conversion of pure styrene at 60C with benzoyl peroxide as the initiator in a batch reactor. Assume that the initiator concentration remains constant. Use the data given below: Data: f = 1 kp

2/kt=0.95 x 10-3 L/mol.s

[I] = 4x10-3 mol/l kd = 1.92 x10

6 s1