UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2015/2016 : SEMESTER 1 ACADEMIC SESSION 2015/2016 : SEMESTER 1 SCES2242/ SCES2434/SIC2005 : KIMIA POLIMER/ KIMIA POLIMER I POLYMER CHEMISTRY/ POLYMER CHEMISTRY I Dis 2016/Jan 2017 Dec 2016/Jan 2017 MASA : 2 jam TIME : 2 hours ARAHAN KEPADA CALON : INSTRUCTIONS TO CANDIDATES : Kertas soalan ini mengandungi dua bahagian, Bahagian A dan Bahagian B. This paper contains two sections, Section A and Section B. Jawab kedua-dua bahagian mengikut arahan yang diberi di bawah setiap bahagian. Answer both sections according to the instructions given in each section. (Kertas soalan ini mengandungi 6 soalan dalam 6 halaman yang dicetak) (This question paper consists of 6 questions on 6 printed pages)
BAHAGIAN A (50 MARKAH) SECTION A (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 1. Struktur dan berikut mewakili dua polimer perdagangan penting. Bagi setiap polimer, beri nama perdagangan dan IUPAC. Jika kedua polimer itu mempunyai berat molekul 400,000 g/mol, kira darjah pempolimeran bagi setiap polimer itu. Structure and represent two important commercial polymers. For each polymer, state its trade and IUPAC names. If both polymers have molecular weight of 400,000 g/mol, calculate the degree of polymerization for each one. (Jisim atom/atomic mass: H = 1; C = 12; N = 14; O = 16; F =19 g/mol) [CF 4 ] n [NH(CH 2)5 -CO] m (10 markah/marks) 2. (a) Tulis nota tentang perbezaan utama antara proses pempolimeran emulsi dan pempolimeran manik. Write a note on the main differences between emulsion and bead polymerizations. (8 markah/marks) (b) Suatu sampel poliamida diperbuat dengan memanaskan 10 mol asid 1, 6-heksanadioik dan 10 mol 1,6-hexametilena diamina di dalam sebuah reaktor pada 220-240 C. A sample of polyamide was produced by heating 10 mol of 1,6-hexanedioc acid and 10 mol of 1,6-hexamethylene diamine in a reactor at 220-240 C. (iii) Tulis persamaan tindak balas yang terlibat. Write the reaction equation involved. Apabila penukaran tindak balas mencapai 90%, kira purata darjah pempolimeran, P n. When the reaction conversion reaches 90%, calculate the average degree of polymerization, P n. Apa masalah yang akan berlaku sekiranya penukaran tindak balas mencapai 100%? What could be the problem if the reaction conversion reaches 100%? 2/6
(iv) Cadang satu cara untuk mengelakkan masalah tersebut daripada berlaku dalam tindak balas ini. Suggest one way to prevent this issue from occuring in this reaction. (12 markah/marks) 3. (a) Pengkopolimeran antara A (monomer 1) dan B (monomer 2) telah dijalankan dan hasilnya diringkaskan dalam jadual berikut. Copolymerization of A (monomer 1) and B (monomer 2) was carried out and the results are summarized in the following table. Expt. g G 1 0.49 0.30 2 0.66 0.39 3 0.96 0.50 4 1.32 0.67 5 2.12 0.89 g = [A]/[B] iaitu nisbah molar bagi monomer yang digunakan G = d[a]/d[b] iaitu nisbah [monomer 1] / [monomer 2] dalam kopolimer g = [A]/[B] is the molar ratio of the monomers used G = d[a]/d[b] is the ratio of [monomer 1] / [monomer 2] in copolymer Tulis persamaan Fineman-Ross. Write down the Fineman-Ross equation. Dengan menggunakan kaedah graf, kira nilai r 1 dan r 2. Calculate r 1 and r 2 by using a graphical method. (iii) Dari nilai r 1 dan r 2 yang diperolehi di 3a, ramal bentuk kopolimer yang akan dihasilkan dari A dan B. Based on the values of r 1 and r 2 measured in 3a, predict the structure of the copolymer made from A and B. (15 markah/marks) (b) Nisbah kereaktifan antara monomer A dan B adalah r 1 dan r 2. Apa nilai r 1 dan r 2 untuk menghasilkan kopolimer berstruktur rawak? The reactivity ratios of monomers A and B are r 1 and r 2. What should be the values of r 1 and r 2 in order to obtain a copolymer with random structure? (5 markah/marks) 3/6
BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 4. Poli(vinil asetat) disediakan daripada vinil asetat melalui pempolimeran penambahan radikal bebas. Poly(vinyl acetate) is prepared from vinyl acetate by free radical addition polymerization. (a) Lukiskan struktur vinil asetat. Draw the structure of vinyl acetate. (2 markah/marks) (b) Dengan menggunakan benzoil peroksida sebagai pemula, tunjukkan mekanisme tindak balas bagi pempolimeran vinil asetat. Using benzoyl peroxide as initiator, show the reaction mechanism for the polymerization of vinyl acetate. (6 markah/marks) Dengan mengandaikan tiada tindak balas pemindahan rantai, bincangkan bagaimana mengubah kepekatan monomer dan pemula masing-masing memberi kesan kepada: Assuming absence of chain transfer reactions, discuss how changing the concentrations of monomer and initiator respectively affect the: kadar pempolimeran. rate of polymerization. nombor purata darjah pempolimeran. number average degree of polymerization. (4 markah/marks) Jika separuh rantai dalam polimer yang disintesis mempunyai berat molekul 100,000 dan separuh lagi mempunyai berat molekul 200,000, kira: If half the chains in a synthesized polymer have a molecular weight of 100,000 and the other half have a molecular weight of 200,000, calculate: 4/6
(iii) nombor purata berat molekul number average molecular weight berat purata berat molekul weight average molecular weight polisebaran polydispersity (6 markah/marks) 5. Poli(etil terefthalat), PET, adalah poliester termoplastik digunakan secara meluas dalam bekas cecair dan gentian sintetik. Bergantung kepada pemprosesan dan keadaan termanya, PET mungkin wujud sebagai kedua-dua amorfus dan sebagai semi-hablur. Poly(ethyl terephthalate), PET, is a thermoplastic polyester widely used in liquid containers and synthetic fibres. Depending on its processing and thermal conditions, PET may exist both as amorphous and as semi-crystalline. (a) Bincangkan perbezaan dari segi struktur dan sifat antara PET amorfus dan semi-hablur. Discuss the differences in terms of structure and properties between amorphous and semi-crystalline PET. (8 markah/marks) (b) Huraikan perubahan dalam struktur polimer dan sifat PET amorfus dengan peningkatan suhu. Describe the change in polymer structure and behavior of the amorphous PET with increasing temperature. (7 markah/marks) Cadangkan dua kaedah bagaimana polimer amorfus boleh dibuat semihablur. Suggest two methods how an amorphous polymer can be made semi crystalline. (2 markah/marks) 6. Suhu peralihan kaca poli(α-metilstirena) ialah 168 o C manakala polistirena ialah 90 o C. The glass transition temperature of poly(α-methylstyrene) is 168 o C while that of polystyrene is 90 o C. 5/6
(a) Lukiskan struktur kedua-dua polimer dan menjelaskan perbezaan dalam suhu peralihan kaca di antaranya. Draw the structure of the two polymers and explain the difference in glass transition temperature between them. (4 markah/marks) (b) Cadangkan dua cara bagaimana suhu peralihan kaca poli(α-metillstirena) dapat dikurangkan. Suggest two ways how glass transition temperature of poly(α-methylstyrene) can be reduced. (4 markah/marks) Huraikan kaedah eksperimen untuk menentukan suhu peralihan kaca polistirena. Describe an experimental method to determine the glass transition temperature of polystyrene. (7 markah/marks) TAMAT END 6/6