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MATS68301 Principles of Polymers – Coursework 2024 Dr Steve Edmondson
All coursework must be submitted to Blackboard by 12:00 UK (midday) on Thursday, 7
th November 2024. 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.
Each student must submit independently produced work. You are reminded that submitting text generated by AI/LLM tools (e.g. ChatGPT or other chatbots, automatic rephrasing or rewriting tools including automated translation tools) without proper citation and acknowledgement is likely to constitute academic malpractice.
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 its own would produce a syndiotactic homopolymer with a Tg of 80 °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
(6 marks total)
4. i. State the conditions for which the equationcan 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 of reaction, p for a polymer with number average degree of polymerisation, = 100for an RA 4 + R’B 4 polymerisation. 4 marks
(7 marks total)