SCES2242/SCES2434 : POLYMER CHEMISTRY/ POLYMER CHEMISTRY 1 KIMIA POLIMER/ KIMIA POLIMER 1

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1 UNIVERSITY OF MALAYA UNIVERSITI MALAYA EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE PEPERIKSAAN IJAZAH SARJANA MUDA SAINS ACADEMIC SESSION 2011/2012 : SEMESTER 2 SESI AKADEMIK 2011/2012 : SEMESTER 2 SCES2242/SCES2434 : POLYMER CHEMISTRY/ POLYMER CHEMISTRY 1 KIMIA POLIMER/ KIMIA POLIMER 1 June 2012 Jun 2012 TIME : 2 hours MASA : 2 jam INSTRUCTIONS TO CANDIDATES : ARAHAN KEPADA CALON : This paper contains two sections, Section A and Section B. Kertas soalan ini mengandungi dua bahagian, Bahagian A dan Bahagian B. Answer both sections according to the instructions given in each section. Jawab kedua-dua bahagian mengikut arahan yang diberi di bawah setiap bahagian. (This question paper consists of 5 questions on 7 printed pages) (Kertas soalan ini mengandungi 5 soalan dalam 7 halaman yang dicetak)

2 SCES2242/SCES2434/02 SECTION A (50 MARKS) BAHAGIAN A (50 MARKAH) Answer ALL questions. Jawab SEMUA soalan. 1. (a) PC and Teflon are two important commercial polymers. For each one, give the name and structure of its monomer. State one application for each polymer. PC dan Teflon merupakan two jenis polimer perdangangan penting. Bagi setiap polimer itu, berikan nama serta struktur monomer. Nyatakan satu kegunaan bagi setiap polimer itu. (8 marks/markah) Write short notes on any two (2) of the following topics. Tulis nota pendek atas salah dua(2) topik berikut. i. Melamine formaldehyde resins Resin melamin formaldehid i Structures of copolymers produced from two types of monomers. Struktur kopolimer terhasil dari dua jenis monomer. Environmental pollution by the packaging industry. Kecemaran alam sekitar oleh industri pembungkusan. (6 marks/markah) (c) A sample of polyester was produced by heating 100 mol of 6-hydroxylhexanoic acid in a reactor at C. In order that the reaction produced a polyester with average molecular weight of 350,000, a certain weight of benzoic acid was added. Suatu poliester diperbuat dengan memanaskan 100 mol asid 6-hidroksiheksanoik dalam sebuah reaktor pada C. Supaya tindak balas itu dapat menghasilkan poliester dengan purata berat molekul 350,000, suatu berat tertentu asid benzoik telah ditambahkan. i. Write the equation of the reaction. Tuliskan persamaan tindak balas yang terlibat.

3 SCES2242/SCES2434/03 i iv. Calculate the degree of polymerization at the molecular weight of 350,000. Kirakan darjah pempolimeran pada berat molekul 350,000. What is the function of benzoic acid? Apakah tindakan asid benzoic? Calculate the weight of benzoic acid required for this purpose. Kirakan berat asid benzoik yang diperlukan untuk tujuan itu. (11 marks/markah) 2. (a) Discuss briefly the various possible structures of the repeating units in the polymerization of chloroprene with a free radical initiator. What are the major uses of this polymer? Bincangkan secara ringkas struktur unit ulangan yang mungkin terhasil dalam pempolimeran kloroprena dengan suatu pemula radikal bebas. Apakah kegunaan utama polimer itu? (6 marks/markah) Write short note on any two (2) of the following topics. Tulis nota pendek bagi dua (2) topik daripada yang berikut. i. Classification of polymers according to sources Pengkelasan polimer mengikut sumber. Major differences between the processes of emulsion polymerization and solution polymerization Perbezaan utama antara proses pempolimeran emulsi dan pempolimeran larutan. i Application of anionic polymerization. Kegunaan pempolimeran anionik. (8 marks/markah)

4 SCES2242/SCES2434/04 Alfred and Price had introduced an empirical Q-e Scheme for the calculation of reactivity ratio for pair of monomers. The following table list the Q and e values for acrylonitrile and methyl methacrylate. Alfred dan Price telah mencadangkan suatu skima Q-e empirik untuk pengiraan nisbah kereaktifan antara pasangan monomer. Jadual berikut memberikan nilai Q dan e bagi monomer akrilonitril dan metil metakrilat. Monomer Q e Akrilonitril Metil metakrilat i. Explain the meaning of factor Q and e. Jelaskan maksud factor Q dan e.. i Calculate the reactivity ratio for the monomer pair of styrene and methyl methacrylate. Kirakan nisbah kereaktifan bagi pengkopolimeran metil metakrilat dan akrilonitril. From the values of r 1 and r 2, predict the structure of the copolymer made from methyl methacrylate and acrylonitrile. Dari nilai r 1 dan r 2, ramalkan bentuk kopolimer yang akan dihasilkan dari metal metakrilat dan akrilonitril. (11 marks/markah)

5 SCES2242/SCES2434/05 SECTION B (50 MARKS) BAHAGIAN B (50 MARKAH) Answer ALL questions. Jawab SEMUA soalan. 3. PS is prepared by free radical addition polymerization. This polymerization involves few steps and requires an initiator. PS disediakan melalui pempolimeran penambahan radikal bebas. Pempolimeran ini melibatkan beberapa langkah dan memerlukan satu pemula. (a) Draw chemical structure for its monomer and the resulting polymer. Lukiskan struktur kimia untuk monomer dan polimer yang dihasilkan. (2 marks/markah) Name one suitable initiator and give chemical structure. Namakan satu pemula yang sesuai dan berikan struktur kimianya. (2 marks/markah) (c) Derive the rate of polymerization equation and state the assumptions made. Terbitkan persamaan kadar pempolimeran dan nyatakan andaian-andaian yang dibuat. (6 marks/markah) (d) Assuming absence of chain transfer reactions, discuss how changing the concentrations of monomer and initiator affect the Dengan mengandaikan bahawa tiada tindak balas pemindahan rantai, bincangkan bagaimana perubahan ke atas kepekatan monomer dan pemula mempengaruhi i. rate of polymerization. kadar pempolimeran. number-average degree of polymerization. nombor-purata darjah pempolimeran.

6 SCES2242/SCES2434/06 (e) Describe the effect of chain transfer reactions on the average molar mass and microstructure of the polymer produced. Jelaskan kesan tindak balas pemindahan rantai terhadap purata jisim molar dan mikrostruktur bagi polimer yang terhasil. (4 marks/markah) 4. Explain the following polymer properties. Jelaskan sifat-sifat polimer yang berikut. (a) Define the glass transition temperature. Give ONE example of polymer with its glass transition temperature (Tg), when it is subjected to temperature (T), explain the polymer conditions when T > Tg and when T < Tg. Takrifkan suhu peralihan kaca polimer. Dengan memberikan SATU contoh polimer berserta suhu peralihan kacanya (Tg), apabila suatu suhu (T) dikenakan, terangkan keadaan-keadaan polimer tersebut apabila T > Tg dan apabila T < Tg. (5 marks/markah) Write the terms that can be used to explain the molecular weight distribution of a polymer. Then sketch an appropriate graph to illustrate the terms. Explain the relationship between polydispersity index with molecular weight distribution. Tuliskan ungkapan-ungkapan yang digunakan untuk menjelaskan taburan berat molekul suatu polimer. Seterusnya, lakarkan graf yang sesuai/sepadan yang menggambarkan ungkapan-ungkapan tersebut. Terangkan hubungkait di antara indeks polisebaran dengan taburan berat molekul polimer. (5 marks/markah) 5. (a) Three samples of monodisperse polystyrene, A, B and C are mixed together as the following proportions: 10 g of A, having a molecular weight of 40,000 and 5 g of B, having a molecular weight of 100,000 and 3 g of C, having a molecular weight of 200,000. Tiga sampel polystirena monosebar, A, B dan C dicampurkan dalam kadaran berikut: 10 g A dengan berat molekul 40,000 dan 5 g B dengan berat molekul 100,000 dan 3 g C dengan berat molekul 200,000.

7 SCES2242/SCES2434/07 i. Define (with symbols) the number-average molecular weight and the weight-average molecular weight for a polymer sample. Takrifkan (berserta simbol) bagi nombor-purata berat molekul dan berat-purata berat molekul bagi suatu sampel polimer. (2 marks/markah) Calculate the number-average molecular weight of the polymer mixture. Hitung nombor-purata berat molekul bagi campuran polimer tersebut. i Calculate the weight-average molecular weight of the polymer mixture. Hitung berat-purata berat molekul bagi campuran polimer tersebut. The following table is data on intrinsic viscosities [ ] of six fractions of polymer X of known molecular weight (M) in tetrahydrofuran (THF) at 25 o C. Calculate the Mark-Houwink parameters, K and a, for the polymer-solvent system described below: Jadual berikut adalah data kelikatan intrinsic [ ] bagi enam pecahan polimer X dengan berat molekul (M) yang diketahui, dalam tetrahidrofuran (THF) pada suhu 25 o C. Tentukan pemalar-pemalar Mark-Houwink, K dan a bagi sistem polimerpelarut tersebut: M 10-6 (g/mol) [ ] (dl/g) (12 marks/markah) END TAMAT