QUESTION 9 [20 total marks] Polymerisation of methyl methacrylate is carried out in the presence of 0.02 mmol dm? of a t

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Question 9 20 Total Marks Polymerisation Of Methyl Methacrylate Is Carried Out In The Presence Of 0 02 Mmol Dm Of A T 1 (75.16 KiB) Viewed 59 times

QUESTION 9 [20 total marks] Polymerisation of methyl methacrylate is carried out in the presence of 0.02 mmol dm? of a thermal initiator with efficiency f = 0.58 at 50°C. The initial concentration of monomer is [M]o = 9.0 mol dm3. The following rate constants are available at the reaction temperature. Decomposition constant: k= 1.13x10-4 min Propagation constant: kp=3.34x104 dm'mol 'min! Termination constant: kt=1.97*10' dm?molimin! (a) Calculate the steady-state concentration of free radicals. (4 marks) (b) Develop the integrated rate law for free radical polymerisation and use it to determine the time required for 50% conversion? Assume that the initiator concentration remains constant in the course of reaction. (5 marks) (c) Decomposition of the initiator is a first order reaction. Develop a rate equation to take into account the change in initiator concentration [] with time and use it to determine the time required for 50% conversion. Briefly discuss any difference with the result from section (b). (7 marks) (d) Calculate the initial kinetic chain length (V) and explain what will be the degree of polymerization Xn if the termination reactions are governed by disproportionation. (4 marks)