Pengaruh Waktu Sulfonasi terhadap Karakteristik Polistiren dan Polyblend-nya dengan Kitosan
SKRIPSI
Lelly Dwi Ambarini NIM 10504018
PROGRAM STUDI KIMIA FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM INSTITUT TEKNOLOGI BANDUNG 2008
Pengaruh Waktu Sulfonasi terhadap Karakteristik Polistiren dan Polyblend-nya dengan Kitosan (The Effect of Sulfonation Time in Polystyrene Characteristics and Its Polyblend with Chitosan)
SKRIPSI
Lelly Dwi Ambarini NIM 10504018
PROGRAM STUDI KIMIA FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM INSTITUT TEKNOLOGI BANDUNG 2008
Abstract Energy conserving problems have motivated many researches to find efficient fuel cell. Proton Exchange Membrane Fuel Cell (PEMFC) is one of the systems that work based on electrochemistry principle which converts chemical energy to electricity. In PEMFC, electrolyte polymer membrane is used as proton transfer medium. In this research, electrolyte membranes are prepared from polyblends between polystyrene (PS), sulfonated polystyrene (PSS), and chitosan prepared by mechanical technique (hot-pressed). The sulfonation of polystyrene was carried out by reaction with acetyl sulphate for 15, 30, 45, and 60 minutes to add SO3H group in polystyrene to enable those membranes conduct H+ ion. Membranes prepared in this research are PS:Chitosan (8:2) membrane and four other PS:PSS:Chitosan (8:1:1) membranes with different sulfonation degree. Those membranes were characterized by Fourier Transform Infra Red (FTIR), Thermal Gravity Analysis/Differential Thermal Analysis (TGA/DTA), swelling test, Ion Exchange Capacity (IEC) test, conductivity measurement, and mechanical test. Optimum swelling and conductivity were obtained from PSS sulfonated for 45 minutes while optimum IEC was obtained from PSS sulfonated for 60 minutes. Mechanical properties of polyblends prepared in this research were almost the same, but thermal stabilization of polyblends decrease with increasing PSS and chitosan component.
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Abstrak Permasalahan energi mendorong penelitian mengenai sistem sel bahan bakar yang dapat menghasilkan energi secara efisien. Proton Exchange Membrane Fuel Cell (PEMFC) merupakan sistem yang bekerja dengan prinsip pengubahan energi kimia menjadi listrik. Pada PEMFC, membran polimer elektrolit digunakan sebagai media pentransfer proton. Pada penelitian ini telah dibuat membran polyblend antara polistiren (PS), polistiren tersulfonasi (PSS) dan kitosan dengan metoda hot-pressed. Sulfonasi polistiren dilakukan menggunakan asetil sulfat dengan empat variasi waktu sulfonasi, yaitu 15, 30, 45, dan 60 menit, dengan tujuan agar polistiren memiliki gugus SO3H, sehingga dapat mentransfer H+. Membran polyblend yang dibuat adalah membran PS:Kitosan (8:2), dan empat membran PS:PSS:Kitosan (8:1:1) dengan variasi derajat sulfonasi polistiren. Karakterisasi dilakukan melalui analisis Fourier Transform Infra Red (FTIR), swelling, Ion Exchange Capacity (IEC), konduktivitas, uji tarik, dan TGA/DTA. Hasil analisis menunjukkan bahwa hasil optimum berdasarkan uji swelling dan konduktivitas didapatkan dari membran yang menggunakan PSS yang disulfonasi selama 45 menit, sedangkan berdasarkan nilai IEC diperoleh pada membran yang menggunakan PSS yang disulfonasi selama 60 menit. Kekuatan mekanik semua polyblend yang dibuat pada penelitian ini relatif sama, akan tetapi semakin banyak komponen PSS dan kitosan dalam polyblend, maka stabilitas termal polyblend semakin menurun.
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Program Studi Kimia Fakultas Matematika dan Ilmu Pengetahuan Alam Institut Teknologi Bandung
Menerangkan bahwa Skripsi yang disusun oleh : Nama : Lelly Dwi Ambarini NIM
: 10504018
telah disetujui sebagai persyaratan untuk mendapatkan gelar Sarjana Kimia
Pada tanggal ……………………
Pembimbing
Dr. I Made Arcana
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Mom, Dad,, It’s a gift for your 25th wedding anniversary...
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Ucapan Terimakasih Bismillaahirrahmaanirrahiim
Puji dan syukur penulis panjatkan kehadirat Allah SWT karena atas rahmat dan hidayah-Nya lah penelitian tugas akhir dan skripsi ini dapat diselesaikan. Pada kesempatan ini, penulis pun ingin mengucapkan banyak terima kasih kepada: 1. Allah SWT. 2. Bapak Dr. I Made Arcana selaku dosen pembimbing, atas topik penelitian yang telah diberikan dan segala nasihatnya yang sangat bermanfaat. 3. Pimpinan serta staf pengajar Program Studi Kimia Institut Teknologi Bandung, atas semua ilmu yang telah diberikan.
4. Seluruh karyawan Program Studi Kimia Institut Teknologi Bandung, atas semua bantuannya sehingga penulis mendapatkan kemudahan dalam melaksanakan studi di Program Studi Kimia ITB. 5. Bapak, Mama dan kakakku tersayang atas segala dorongan dan semangat yang tidak ada hentinya. 6. Robert Kuncoro atas segala semangat, nasihat, dan suka duka selama ini. 7. Bapak Dr. Veinardi atas izin yang diberikan untuk melakukan penelitian di Laboratorium Kimia Fisik Material. 8. Ibu Entin dan Pak Wahyo atas bantuan yang diberikan selama penelitian di Laboratorium Kimia Fisik Material. 9. Bapak Sutoto atas bantuan yang diberikan untuk memenuhi kebutuhan bahan-bahan penelitian. 10. Bapak Aminudin atas bantuan yang diberikan untuk memenuhi kebutuhan penggunaan alat FTIR. 11. Laboratorium Polimer LIPI untuk pengukuran bantuannya dalam pengukuran TGA/DTA. 12. Astri, Rian, Anti, Linda, Riris, Febi, terima kasih untuk persahabatan dan segala suka duka selama empat tahun ini.
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13. Teman-teman Laboratorium Kimia Fisik, Mutif, Hana, Herlina, Anti, Eryth, Adit, Fahri, Veli, Pak Bambang, Pak Dani, Pak Masykuri, Pak Hadi, dan lain-lain. 14. Sahabat-sahabat SMA-ku, Wulan, Mae, Ima, Sherry. 15. Febrinaldo Eka, atas bantuannya, sehingga spektrum-spektrum lucu itu bisa ada di skripsi ini. 16. Teh Aida, Tari, Lia, untuk pencerahan dan inspirasi yang diberikan setiap minggunya. 17. Teman-teman Kimia 2004 dan rekan-rekan AMISCA atas segala dorongan dan doanya 18. Pihak-pihak lain yang telah membantu baik moril maupun materi dalam pelaksanaan Tugas Akhir ini. Laporan ini seperti layaknya pepatah mengatakan, “Tak ada gading yang tak retak”. Penulis menyadari bahwa masih banyak kekurangan yang terdapat dalam laporan ini. Oleh karena itu, penulis memohon maaf yang sebesar-besarnya dan mengharapkan saran agar penelitian dan laporan yang akan dilakukan ke depannya dapat lebih baik lagi. Semoga laporan ini dapat bermanfaat bagi para pembaca.
Bandung,
Juli 2008
Penulis
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DAFTAR ISI Abstract .................................................................................................................................. ii Abstrak.................................................................................................................................. iii Ucapan Terimakasih ............................................................................................................. vi DAFTAR ISI ...................................................................................................................... viii DAFTAR GAMBAR ............................................................................................................ xi DAFTAR TABEL .............................................................................................................. xiii DAFTAR LAMPIRAN ........................................................................................................xv 1 Pendahuluan.........................................................................................................................1 1.1 Latar Belakang ................................................................................................................. 1 1.2 Tujuan Penelitian ............................................................................................................. 2 1.3 Ruang Lingkup Penelitian ............................................................................................... 2 2 Tinjauan Pustaka ................................................................................................................. 3 2.1 Proton Exchange Membrane Fuel Cell (PEMFC)........................................................... 3 2.2 Polistiren .......................................................................................................................... 5 2.3 Polistiren Tersulfonasi ..................................................................................................... 6 2.4 Kitin ................................................................................................................................. 7 2.5 Kitosan ............................................................................................................................. 8 2.6 Polyblend ......................................................................................................................... 9 2.7 Analisis Polyblend ......................................................................................................... 10 2.7.1 Analisis Sifat Fisik ...................................................................................................... 10 2.7.2 Analisis Gugus Fungsi ................................................................................................ 13 2.7.3 Analisis Mekanik ........................................................................................................ 14 2.7.4 Analisis Termal ........................................................................................................... 15 3 Metodologi Penelitian ....................................................................................................... 16
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3.1 Alat ................................................................................................................................ 16 3.2 Bahan ............................................................................................................................. 17 3.3 Metode Kerja ................................................................................................................. 18 3.3.1 Sintesis Polistiren ........................................................................................................ 19 3.3.2 Sintesis Polistiren Tersulfonasi ................................................................................... 19 3.3.3 Sintesis Kitosan........................................................................................................... 20 3.3.4 Penentuan Massa Molekul Polimer ............................................................................ 20 3.3.5 Penentuan Derajat Sulfonasi Polistiren Tersulfonasi .................................................. 21 3.3.6 Penentuan Derajat Deasetilasi Kitosan ....................................................................... 21 3.3.7 Pembuatan Membran Polyblend ................................................................................. 22 3.3.8 Karakterisasi ............................................................................................................... 22 4 Hasil dan Pembahasan ...................................................................................................... 24 4.1 Sintesis Polistiren ........................................................................................................... 24 4.1.1 Analisis Gugus Fungsi ................................................................................................ 24 4.1.2 Analisis Termal ........................................................................................................... 25 4.2 Sintesis Polistiren Tersulfonasi ..................................................................................... 26 4.2.1 Analisis Gugus Fungsi ................................................................................................ 28 4.3 Sintesis Kitosan ............................................................................................................. 29 4.3.1 Analisis Gugus Fungsi ................................................................................................ 30 4.4 Pembuatan Membran Polyblend ................................................................................... 32 4.5 Karakterisasi Polyblend ................................................................................................. 32 4.5.1 Analisis Gugus Fungsi ................................................................................................ 32 4.5.2 Analisis Swelling, Ion Exchange Capacity (IEC), dan Konduktivitas ........................ 35 4.5.3 Analisis Kekuatan Mekanik ........................................................................................ 36 4.5.4 Analisis Termal ........................................................................................................... 37 5 Penutup ............................................................................................................................. 40 5.1 Kesimpulan .................................................................................................................... 40 5.2 Saran .............................................................................................................................. 40
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DAFTAR PUSTAKA .......................................................................................................... 41 LAMPIRAN ........................................................................................................................ 43
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DAFTAR GAMBAR Gambar 2.1 Alat PEMFC....................................................................................................... 3 Gambar 2.2 Struktur Nafion .................................................................................................. 4 Gambar 2.3 Unit ulang polistiren........................................................................................... 5 Gambar 2.4 Polistiren dalam bentuk foam ............................................................................. 5 Gambar 2.5 Reaksi pembentukan dua senyawa radikal dari benzoil peroksida .................... 5 Gambar 2.6 Mekanisme reaksi adisi pada sintesis polistiren................................................. 6 Gambar 2.7 Reaksi sintesis polistiren tersulfonasi: ............................................................... 6 Gambar 2.8 Struktur kitin ...................................................................................................... 7 Gambar 2.9 Struktur kitosan .................................................................................................. 8 Gambar 2.10 Kurva distribusi massa molekul polimer........................................................ 11 Gambar 2.11 Skema umum alat uji tarik ............................................................................. 14 Gambar 2.12 Kurva stress-strain ......................................................................................... 14 Gambar 2.13 Kurva DSC ..................................................................................................... 15 Gambar 2.14 Kurva TGA Nilon .......................................................................................... 15 Gambar 3.1 Diagram alir penelitian secara umum .............................................................. 18 Gambar 3.2 Spektrum FTIR untuk penentuan derajat deasetilasi kitosan ........................... 21 Gambar 4.1 Spektrum FTIR polistiren ................................................................................ 25 Gambar 4.2 Termogram polistiren....................................................................................... 26 Gambar 4.3 Spektrum FTIR PSS 4 ...................................................................................... 29 Gambar 4.4 Spektrum FTIR kitin ........................................................................................ 31 Gambar 4.5 Spektrum FTIR kitosan .................................................................................... 31 Gambar 4.6 Spektrum FTIR PS:Kitosan (8:2) ..................................................................... 33 Gambar 4.7 Spektrum FTIR PS:PSS1:Kitosan (8:1:1) ........................................................ 34 Gambar 4.8 Spektrum FTIR PS:PSS4:Kitosan (8:1:1) ........................................................ 34
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Gambar 4.9 Termogram PS:Kitosan (8:2) ........................................................................... 37 Gambar 4.10 Termogram PS:PSS1:Kitosan (8:1:1) ............................................................ 38 Gambar 4.11 Termogram PS:PSS4:Kitosan (8:1:1) ............................................................ 38 Gambar A.1 Spektrum FTIR PSS 1 ..................................................................................... 43 Gambar A.2 Spektrum FTIR PSS 2 ..................................................................................... 43 Gambar A.3 Spektrum FTIR PSS 3 ..................................................................................... 44 Gambar A.4 Spektrum gabungan PSS 1, PSS 2, PSS 3, dan PSS 4 ................................... 44 Gambar A.5 Spektrum FTIR PS:Kitosan (8:2) .................................................................... 45 Gambar A.6 Spektrum FTIR PS:PSS 1:Kitosan (8:1:1) ...................................................... 45 Gambar A.7 Spektrum FTIR PS:PSS 4:Kitosan (8:1:1) ...................................................... 46 Gambar B.1 Spektrum FTIR kitosan (untuk perhitungan derajat deasetilasi) ..................... 47 Gambar D.1 Kurva ηred terhadap konsentrasi polistiren ...................................................... 50 Gambar D.2 Kurva ηred terhadap konsentrasi polistiren tersulfonasi ................................... 52 Gambar D.3 Kurva ηred terhadap konsentrasi kitosan .......................................................... 53
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DAFTAR TABEL Tabel 3.1 Komposisi polimer dalam polyblend ................................................................... 22 Tabel 4.1 Puncak serapan FTIR polistiren ........................................................................... 25 Tabel 4.2 Data TGA polistiren ............................................................................................ 26 Tabel 4.3 Data rendemen polistiren tersulfonasi ................................................................. 27 Tabel 4.4 Derajat sulfonasi polistiren tersulfonasi .............................................................. 28 Tabel 4.5 Rendemen proses pembuatan kitosan .................................................................. 30 Tabel 4.6 Komposisi polimer penyusun polyblend.............................................................. 32 Tabel 4.7 Puncak serapan FTIR polyblend .......................................................................... 32 Tabel 4.8 Data swelling, Ion Exchange Capacity (IEC), dan konduktvitas......................... 35 Tabel 4.9 Data uji tarik ........................................................................................................ 36 Tabel 4.10 Data TGA polyblend .......................................................................................... 38 Tabel C.1 Hasil titrasi untuk perhitungan derajat sulfonasi polistiren tersulfonasi ............. 48 Tabel D.1 Data waktu alir pelarut dan larutan polistiren…………………………………..50 Tabel D.2 Data hasil perhitungan ηr, ηsp, dan ηred polistiren ................................................ 50 Tabel D.3 Data waktu alir pelarut dan larutan polistiren tersulfonasi ................................. 51 Tabel D.4 Data hasil perhitungan ηr, ηsp, dan ηred polistiren tersulfonasi ............................ 51 Tabel D.5 Data waktu alir pelarut dan larutan kitosan ........................................................ 52 Tabel D.6 Data hasil perhitungan ηr, ηsp, dan ηred kitosan ................................................... 53 Tabel E.1 Data analisis swelling…………………………………………………………...54 Tabel F.1 Data volum titran titrasi Ion Exchange Capacity (IEC)…………………………55 Tabel F.2 Data analisis Ion Exchange Capacity (IEC) ........................................................ 56 Tabel G.1 Data konduktivitas membran di 1 kHz …………………….…………………57 Tabel G.2 Data konduktivitas membran di 50 Hz ............................................................... 59 Tabel G.3 Data konduktivitas membran .............................................................................. 60
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Tabel H.1 Data analisis kekuatan mekanik (uji tarik)…………………………………… 63
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DAFTAR LAMPIRAN LAMPIRAN A Spektrum Hasil Analisis FTIR ................................................................... 43 LAMPIRAN B Perhitungan Derajat Deasetilasi Kitosan .................................................... 47 LAMPIRAN C Perhitungan Derajat Sulfonasi Polistiren Tersulfonasi............................... 48 LAMPIRAN D Perhitungan Massa Molekul Polimer ......................................................... 50 LAMPIRAN E Perhitungan Swelling .................................................................................. 54 LAMPIRAN F Perhitungan Ion Exchange Capacity (IEC)................................................. 55 LAMPIRAN G Perhitungan Konduktivitas ......................................................................... 57 LAMPIRAN H Perhitungan Analisis Kekuatan Mekanik (Uji Tarik)................................. 62
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