UNIVERSITI MALAYA UNIVERSITY OF MALAYA PEPERIKSAAN IJAZAH SARJANA MUDA SAINS EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE SESI AKADEMIK 2014/2015 : SEMESTER 2 ACADEMIC SESSION 2014/2015 : SEMESTER 2 SCES2242/ SCES2434 : KIMIA POLIMER/ KIMIA POLIMER I POLYMER CHEMISTRY/ POLYMER CHEMISTRY I Jun 2015 June 2015 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. (a) Struktur (i) dan (ii) berikut mewakili dua polimer komersial yang penting. Bagi setiap struktur, berikan nama polimer dan kegunaannya. Jika keduadua polimer itu mempunyai berat molekul 200,000, kirakan darjah pempolimeran bagi setiap polimer itu. Structures (i) and (ii) represent two important commercial polymers. For each one, state its name and applications. If both of it have the same molecular weight of 200,000, calculate the degree of polymerization for each polymer. (i) (ii) [CH 2 -CHCl] n (10 markah/marks) Tulis nota pendek mengenai cara mengatasi pencemaran alam sekitar yang disebabkan oleh termoplastik. Write a short note regarding methods to overcome environmental pollution caused by thermoplastics. (6 markah/marks) 2. (a) Huraikan secara ringkas mengenai pertumbuhan berantai dan pertumbuhan berlangkah dalam proses pempolimeran. Describe briefly regarding chain growth and step growth in polymerization process. (8 markah/marks) 2/6
Suatu poliester disediakan dengan mencampurkan 5 mol etilena glikol (HO-CH 2 CH 2 -OH) dengan 5 mol asid adipik (HOOC-(CH 2 ) 4 -COOH). X gram asid benzoik (C 6 H 5 -COOH) telah dimasukkan bagi mengelakkan berlakunya pembentukan gel. Pada akhir pempolimeran itu, didapati bahawa purata darjah pempolimeran adalah 1000. Kirakan jumlah asid benzoik (x) yang digunakan di dalam tindak balas ini? 5 mol of ethylene glycol (HO-CH 2 CH 2 -OH) is mixed with 5 mol of adipic acid (HOOC-(CH 2 ) 4 -COOH) to prepare a polyester. To prevent gelling, x gram of benzoic acid (C 6 H 5 -COOH) was added. At the end of the polymerization, it was found that the average degree of polymerization was 1000. Calculate the amount of the benzoic acid (x) used in this reaction? (12 markah/marks) 3. (a) Bincangkan mengenai struktur kopolimer yang boleh didapati dalam pengkopolimeran dua monomer, A dan B. Discuss various possible structures in the copolymerization of two monomers, A and B. (9 markah/marks) Nisbah kereaktifan antara monomer A dan B adalah r 1 dan r 2. Apakah nilai r 1 dan r 2 untuk menghasilkan kopolimer berstruktur blok? 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 block structure? (5 markah/marks) 3/6
BAHAGIAN B (50 MARKAH) SECTION B (50 MARKS) Jawab SEMUA soalan. Answer ALL questions. 4. (a) Berikan persamaan kimia yang berkaitan untuk menjelaskan maksud bagi tindakbalas pemindahan rantai. Give a related chemical equation to explain the meaning of chain transfer reaction. (4 markah/marks) Bincangkan keadaan dimana pempolimeran radikal bebas akan berakhir dengan gel. Discuss the condition in which free radical polymerization will end up with gel. (4 markah/marks) (c) Mekanisme pempolimeran radikal bebas akan bermula dengan langkah permulaan dan berakhir dengan langkah penamatan dan tindakbalas pemindahan rantai. Tuliskan tiga tindakbalas yang akan mengurangkan kecekapan pemula semasa langkah permulaan. Berikan penjelasan mudah bagi setiap tindakbalas. Free radical polymerization mechanism would start with initiation step and end up with termination and chain transfer reaction. Give three reactions that will decrease the efficiency of initiator during the initiation step and explain briefly. (6 markah/marks) (d) Berikan tiga susunan kemungkinan bagi monomer bukan simetri. Lukiskan struktur kimia bagi polimer vinil terganti-satu berdasarkan tiga susunan kemungkinan di atas. State the three possible arrangement of non-symmetrical monomers. Give the chemical structure of monosubstituted vinyl polymer based on the above three possible arrangement. (6 markah/marks) 5. Tentukan berat molekul purata-nombor (M n ), berat molekul purata-berat (M w ), dan indeks polidispersiti (PDI) polimer berikut. Determine the number average molecular weight (M n ), weight average molecular weight (M w ), and polydispersity index (PDI) of the following hypothetical polymer. 4/6
(a) Sampel polimer hipotetikal terdiri daripada bilangan polimer yang sama dengan berat molekul 45,000 g / mol, 90,000 g / mol, 135,000 g / mol, dan 180,000 g / mol Hypothetical polymer sample that comprised of equalmolar amount of polymer with molecular weight 45,000 g/mol, 90,000 g/mol, 135,000 g/mol, and 180,000 g/mol. (5 markah/marks) Sampel polimer hipotetikal yang terdiri daripada berat komponen polimer yang sama dengan berat molekul polimer 45,000 g / mol, 90,000 g / mol, 135,000 g / mol, dan 180,000 g / mol. Hypothetical polymer sample that comprised of equal weight of polymer with molecular weight 45,000 g/mol, 90,000 g/mol, 135,000 g/mol, and 180,000 g/mol (5 markah/marks) 6. Polimer X dilarutkan dalam toluena dan masa aliran larutan polimer pada kepekatan yang berbeza diukur menggunakan meter kelikatan Ubbelohde. Diberi masa aliran toluena, t o = 216 s Polymer X was dissolved in toluene and the flow time of the polymer solution at different concentration was measured using Ubbelohde viscometer. Given the flow time of toluene, t o = 216 s Jadual 1 : Aliran masa larutan Polimer X dengan kepekatan berbeza Table 1: Flow time of Polymer X solution at various concentrations Concentration of Flow time, t / (s) Polymer X solution / (mol dm -3 ) 0.2716 459.8 0.1940 378.2 0.1509 337.9 0.1235 312.8 0.1045 296.4 Berdasarkan data yang diberikan dalam Jadual 1: Based on the data given in Table 1: 5/6
(a) Tentukan kelikatan inherent, η inh larutan polimer tersebut bagi setiap kepekatan. Determine inherent viscosity, η inh of the solution at each concentration (3 markah/marks) Tentukan kelikatan reduced, η red larutan polimer tersebut bagi setiap kepekatan. Determine reduced viscosity, η red of the solution at each concentration (3 markah/marks) (c) Plot graf yang sesuai menggunakan nilai η inh dan η red untuk mendapatkan nilai kelikatan intrinsik bagi larutan polimer tersebut. Plot relevant graphs using η inh and η red to obtain the intrinsic viscosity, η of the solution. (10 markah/marks) (d) Tentukan kelikatan molekul berat purata (M v) bagi polimer tersebut dengan menggunakan persamaan Mark-Houwink. Diberi pemalar dalam persamaan tersebut, K = 4.5 x 10-3 cm 3 g -1 dan a = 0.6. Determine viscosity average molecular weight, M v of the polymer using Mark- Houwink equation. Given the constant in Mark-Houwink equation, K = 4.5 x 10-3 cm 3 g -1 and a = 0.6. (4 markah/marks) TAMAT END 6/6