MATS68301 Principles of Polymers – Coursework 2022
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MATS68301 Principles of Polymers – Coursework 2022
Each student must submit an independently written report – plagiarism will be dealt with in accordance with University of Manchester regulations. All coursework must be submitted to Blackboard by 12:00 UK (midday) on Friday, 11th November 2022. Late work will be subject to the department penalty policy. Submit your answers using the online text boxes at the submission link. You can save your answers and return later by pressing Save All Answers but you must press Save and Submit to submit your answers before the deadline. You can make additional submissions before the deadline – only the last one will be marked.
Feedback will be provided in accordance with University of Manchester policy; i.e. marked answers will be returned through Blackboard within 15 working days after the submission deadline. (Note that working days are Monday-Friday inclusive only).
1. A sample of semicrystalline syndiotactic polymer with Tg = 100 °C and Tm = 200 °C is produced by cooling very slowly from above the Tm down to 25 °C. The Young’s modulus (stiffness) is measured immediately at 25 °C. Qualitatively describe and briefly explain how the following independent modifications might change the Young’s modulus at 25 °C:
i. Changing the polymer from syndiotactic to atactic 4 marks
ii. Instead cooling very quickly from above the Tm down to 100 °C, then cooling slowly to 25 °C. 4 marks
iii. Changing to a random copolymer with 50 mol% of a monomer which on it’s own would produce a syndiotactic homopolymer with a Tg of 120 °C 4 marks
(12 marks total)
2. For thermoplastic extrusion:
i. Describe the temperature changes relative to Tm of a polymer during the extrusion process, starting with solid granules at room temperature. 4 marks
ii. Describe how heating or cooling is achieved at each step 3 marks
iii. Explain why the profile of the part might be different to that of the die. 4 marks
(11 marks total)
3. In the context of free-radical polymerisation:
i. Describe the effect of exact termination mechanism on molecular weight 2 marks
ii. Describe the effect of initial initiator concentration on molecular weight, and state TWO assumptions required for your answer to be valid. 4 marks
4.
i. State the conditions for which the equation can be used to
predict the number average degree of polymerisation, , considering particularly
polymerisation mechanism and monomer reactivity. 3 marks
ii. Assuming the equation above is valid, calculate the extent ofreaction, p for a polymer with number average degree of polymerisation, = 100 for an RA4 + R’B4 polymerisation. 4 marks
(7 marks total)
2022-11-11