pengaruh waktu perlakuan alkali terhadap … · pengaruh waktu perlakuan alkali terhadap kekuatan...

i

PENGARUH WAKTU PERLAKUAN ALKALI TERHADAP

KEKUATAN MEKANIK KOMPOSIT rHDPE-SERAT

PELEPAH SALAK

SKRIPSI

Ditujukan sebagai salah satu syarat

Untuk memperoleh gelar

Sarjana Teknik

SYARIF HIDAYATULLOH

NIM. I0412049

PROGRAM STUDI S1 TEKNIK MESIN

FAKULTAS TEKNIK UNIVERSITAS SEBELAS MARET

SURAKARTA

2018

v

HALAMAN MOTTO

“Raihlah ilmu, dan untuk meraih ilmu belajarlah untuk tenang dan sabar.”

(Umar bin Khattab)

“Barang siapa yang keluar untuk mencari ilmu maka ia berada di jalan Allah

“hingga ia pulang.”.

(HR. Turmidzi)

“Janganlah memandang kepada siapa yang bicara, tetapi perhatikanlah apa yang ia

bicarakan.”

(Ali bin Abi Thalib)

vi

PENGARUH WAKTU PERLAKUAN ALKALI TERHADAP KEKUATAN

MEKANIK KOMPOSIT rHDPE SERAT PELEPAH SALAK

Syarif Hidayatulloh

Program Studi Teknik Mesin

Fakultas Teknik, Universitas Sebelas Maret

Surakarta, Indonesia

Email: [email protected]

Abstrak

Penelitian ini bertujuan untuk menyelidiki pengaruh perlakuan alkali

terhadap sifat mekanik komposit rHDPE-serat pelepah salak yaitu kekuatan

bending dan kekuatan impak. Material komposit yang diteliti terdiri atas serbuk

rHDPE sebagai matrik dan serat pelepah salak sebagai penguat. Variasi perlakuan

alkali menggunakan NaOH 5% dari 1 hingga 5 jam. Spesimen dicetak dengan

metode cetak tekan hot press pada tekanan 48,6 bar, temperatur 150°C dan waktu

penahanan 25 menit. Sifat mekanik komposit diketahui dengan melakukan uji

bending dan impak berturut-turut menurut ASTM D-790 dan ASTM D-5941.

Hasil penelitian komposit rHDPE-serat pelepah salak menunjukkan

kekuatan bending mengalami peningkatan pada perlakuan alkali serat pelepah

salak pada perendaman 1, 2, dan 3 jam lalu mengalami penurunan pada 4 dan 5

jam. Kekuatan bending tertinggi dimiliki komposit dengan perlakuan alkali serat

pelepah salak 3 jam yaitu sebesar 33,62 MPa sedangkan nilai kekuatan impak

komposit menurun karena perlakuan alkali serat, nilai kekuatan impak komposit

tertinggi yaitu pada komposit tanpa perlakuan alkali serat sebesar 31,36kJ/m2.

Kata kunci: alkali , kekuatan mekanik , komposit, rHDPE, serat pelepah salak

vii

EFFECT OF ALKALI TREATMENT TIME ON MECHANICAL

PROPERTIES OF rHDPE-ZALACCA FIBER COMPOSITE

Syarif Hidayatulloh

Mechanical Engineering Department

Engineering Faculty, Sebelas Maret University

Surakarta, Indonesia

Email: [email protected]

Abstract

This research aims to investigate the effect of alkali treatment on the

mechanical properties of rHDPE - zalacca midrib fibers composite. The

composite material under study consisted of rHDPE powder as a matrix and

zalacca midrib fibers as a reinforcement. Variation of alkali treatment using

NaOH 5% from 1 to 5 hours. The specimens were made by hot pressing method at

48,6 bar pressure, temperature at 150° C and 25 minutes of holding time. The

composite mechanical strength is known by conducting bending test according to

ASTM D790 and impact test according to ASTM D594

The results of composite rHDPE- zalacca midrib fibers showed that bending

strength increased in alkaline treatment of zalacca midrib fibers during

immersion of 1, 2, and 3 hours then decreased at 4 and 5 hours. The highest

bending strength of the composite has 3 hours alkaline which is 33.62 MPa while

the composite impact strength value decreases as the alkaline fiber treatment, the

highest composite impact strength value is on the composite without alkali

treatment of fiber of 31.36kJ / m2.

Keywords: alkaline, mechanical strength, composite, rHDPE, zalacca midrib

fiber

ix

DAFTAR ISI

HALAMAN JUDUL ........ ............................................................................................... i

HALAMAN SURAT PENUGASAN .............................................................................ii

PERNYATAAN INTEGRITAS PENULIS ................................................................. iii

HALAMAN PENGESAHAN ........................................................................................ iv

HALAMAN DESIMINASI ........................................................................................... v

HALAMAN MOTTO ................................................................................................... vi

ABSTRAK ....................................................................................................................vii

KATA PENGANTAR ................................................................................................... ix

DAFTAR ISI ................................................................................................................... x

DAFTAR GAMBAR .................................................................................................. xiii

DAFTAR TABEL ......................................................................................................... xv

DAFTAR RUMUS....................................................................................................... xvi

DAFTAR NOTASI .....................................................................................................xvii

DAFTAR LAMPIRAN ............................................................................................. xviii

BAB I PENDAHULUAN ....................................................................................... 1

1.1 Latar Belakang Masalah ............................................................................... 1

1.2 Rumusan Masalah ........................................................................................ 3

1.3 Batasan Masalah ........................................................................................... 4

1.4 Tujuan Penelitian .......................................................................................... 4

1.5 Manfaat Penelitian ........................................................................................ 4

1.6 Sistematika Penulisan ................................................................................... 4

BAB II TINJAUAN PUSTAKA DAN DASAR TEORI ........................................ 6

2.1 Tinjauan Pustaka .......................................................................................... 6

2.2 Dasar Teori ................................................................................................... 9

2.2.1 Komposit .............................................................................................. 9

2.2.2 HDPE (High Density Polyethylene) ................................................... 13

2.2.3 Serat Pelepah Salak ............................................................................ 13

2.2.4 Perlakuan Alkali ................................................................................. 14

2.3 Pengujian Spesimen ................................................................................... 15

2.3.1 Densitas Serat ..................................................................................... 15

x

2.3.2 Pengujian Serat Tunggal ..................................................................... 16

2.3.3 Pengujian Lentur ................................................................................. 16

2.3.4 Pengujian Impak Izod ....................................................................... 18

2.4 Variabel Penelitian ..................................................................................... 19

2.5 Hipotesis ..................................................................................................... 20

BAB III METODE PENELITIAN........................................................................ 21

3.1 Tempat Penelitian ....................................................................................... 21

3.2 Bahan Penelitian ......................................................................................... 21

3.3 Alat Penelitian ............................................................................................ 23

3.4 Alat Uji ....................................................................................................... 27

3.5 Parameter .................................................................................................... 30

3.6 Langkah Kerja Penelitian .......................................................................... 30

3.6.1 Persiapan rHDPE ................................................................................ 30

3.6.2 Persiapan Serat Pelepah Salak ............................................................ 31

3.6.3 Pembuatan Spesimen Komposit ......................................................... 32

3.6.4 Tahap Pengujian ................................................................................. 33

3.6.5 Tahap Analisis .................................................................................... 33

3.7 Bentuk dan Ukuran Spesimen Uji ............................................................. 33

3.7.1 Uji Densitas ........................................................................................ 33

3.7.2 Uji Serat Tunggal ................................................................................ 34

3.7.2 Uji Bending ......................................................................................... 34

3.7.2 Uji Impak ............................................................................................ 35

3.8 Diagram Alir Penelitian........................................................................... 35

3.9 Jadwal Penelitian ..................................................................................... 36

BAB IV HASIL DAN ANALISA ........................................................................ 39

4.1 Hasil Pengujian Serat .............................................................................. 39

4.1.1 Hasil Uji Kandungan Dan Uji Densitas Serat..................................... 39

4.1.2 Hasil Uji Foto SEM Serat Tunggal ..................................................... 40

4.1.3 Kekuatan Dan Modulus Tarik Komposit Serat Tunggal .................... 45

4.2 Hasil Pengujian Komposit Serat Pelepah Salak ...................................... 46

4.2.1 Pengaruh Penambahan Perlakuan Alkali Terhadap Kekuatan Impak

............................................................................................................ 46

xi

4.2.2 Pengaruh Penambahan Perlakuan Alkali Terhadap Kekuatan-

Bending .............................................................................................. 48

4.2.2 Pengujian SEM Komposit .................................................................. 51

BAB V KESIMPULAN ........................................................................................ 54

5.1 Kesimpulan ................................................................................................. 54

5.2 Saran ........................................................................................................... 55

DAFTAR PUSTAKA ........................................................................................... 56

LAMPIRAN .......................................................................................................... 59

xii

DAFTAR GAMBAR

Gambar 2.1 Grafik Kekuatan Tarik Serat Tunggal Kenaf- Poliester .................... 6

Gambar 2.2 Grafik Modulus Tarik Uji Tarik Serat Tunggal Kenaf- Poliester ..... 7

Gambar 2.3 Grafik Kekuatan Impak Komposit Serat Aren-Polyester .................. 7

Gambar 2.4 Kekuatan Impak Komposit Serat Rami-Polyester ........................... 8

Gambar 2.5 Grafik Kekuatan Bending Komposit Serat Kenaf-Polyester ............. 9

Gambar 2.6 Grafik Modulus Bending Komposit Serat Kenaf-Polyester .............. 9

Gambar 2.7 Pembagian Komposit ...................................................................... 11

Gambar 2.8 Pengujian Densitas ......................................................................... 15

Gambar 2.9 Spesimen Uji Tarik Serat Tunggal .................................................. 16

Gambar 2.10 Mekanisme Pengujian Three Point Bending ................................... 17

Gambar 2.11 Peletakan Spesimen Uji Impak Izod ............................................... 18

Gambar 3.1 Plastik RHDPE ................................................................................ 21

Gambar 3.2 Pelepah Salak .................................................................................. 22

Gambar 3.3 Wax Mirror Glaze ........................................................................... 22

Gambar 3.4 Kertas Karton .................................................................................. 22

Gambar 3.5 Lem Epoxi ....................................................................................... 23

Gambar 3.6 Mesin Hot Press .............................................................................. 23

Gambar 3.6 Oven ................................................................................................ 23

Gambar 3.8 Mesin Crusher ................................................................................. 24

Gambar 3.9 Ayakan ............................................................................................ 25

Gambar 3.10 Timbangan Digital........................................................................... 25

Gambar 3.11 Blender ............................................................................................ 26

Gambar 3.12 Mesin Roll ....................................................................................... 26

Gambar 3.13 Gunting ............................................................................................ 26

Gambar 3.14 Mesin Tenso .................................................................................... 27

Gambar 3.15 Universal Testing Machine ............................................................. 28

Gambar 3.16 Mesin Impak Izod............................................................................ 28

Gambar 3. 17 Mesin SEM model JOEL tipe JSM-6701F .................................... 29

Gambar 3.18 Kertas lakmus .................................................................................. 29

Gambar 3.19 Serbuk HDPE .................................................................................. 31

xiii

Gambar 3.20 Perendaman Serat ............................................................................ 31

Gambar 3.21 Serat Pelepah Salak ......................................................................... 32

Gambar 3.22 Spesimen ......................................................................................... 32

Gambar 3.23 Spesimen Uji Densitas .................................................................... 34

Gambar 3.24 Spesimen Uji Tarik Serat Tunggal .................................................. 34

Gambar 3.25 Spesimen Uji Bending ..................................................................... 34

Gambar 3.26 Spesimen Uji Impak ........................................................................ 35

Gambar 3.27 Diagram Alir Penelitian .................................................................. 35

Gambar 4.1 Grafik Uji Kandungan ....................................................................... 40

Gambar 4.2 Hasil Uji Foto SEM Serat Tanpa Perlakuan Alkali .......................... 41

Gambar 4.3 Hasil Uji Foto SEM Serat Perlakuan Alkali 1 Jam ........................... 41



Gambar 4.6 Hasil Uji Foto SEM Serat Perlakuan Alkal 4 Jam ............................ 43


Gambar 4.8 Grafik Kekuatan Tarik Serat Tunggal – Lama Perlakuan Alkali ...... 45

Gambar 4.9 Grafik Modulus Tarik Uji Tarik Serat Tunggal – Lama Perlakuan

Alkali ............................................................................................... 45

Gambar 4.10 Grafik Kekuatan Impak – Lama Perlakuan Alkali .......................... 47

Gambar 4.11 Grafik kekuatan bending – Lama Perlakuan Alkali ........................ 48

Gambar 4.12 MOE kekuatan bending – Lama Perlakuan Alkali.......................... 49

Gambar 4.13 Komposit Serat Pelepah Salak Tanpa Perlakuan RHDPE. ............. 51

Gambar 4.14 Komposit Serat Pelepah Salak Perlakuan Alkali 3 Jam RHDPE ... 52

xiv

DAFTAR TABEL

Tabel 2.1 Karakteristik HDPE .............................................................................. 13

Tabel 2.2 Komposisi Kandungan Pelepah Salak .................................................. 14

Tabel 3.1 Jadwal Penelitian................................................................................... 31

Tabel 4.1 Nilai Densitas Serat ............................................................................... 39

xv

DAFTAR RUMUS

Rumus 2.1 Perlakuan Alkali ................................................................................. 14

Rumus 2.2 Pengujian Densitas .............................................................................. 15

Rumus 2.3 Tegagan Tarik Serat Tunggal ............................................................. 16

Rumus 2.4 Regangan Serat Tunggal ..................................................................... 16

Rumus 2.5 Kekuatan Bending............................................................................... 17

Rumus 2.6 Kekuatan Impak Secara Umum .......................................................... 18

Rumus 2.7 Energi Total Yang Diserap ................................................................. 19

Rumus 2.8 Energi Total Yang Diserap ................................................................. 19

Rumus 2.9 Nilai Kekuatan Impak Benda Uji........................................................ 19



xvi

DAFTAR NOTASI

σb = Kekuatan bending (MPa)

= Nilai kekuatan impak (J/m2)

= Sudut naik awal lengan ayun (o)

= Lebar spesimen (m)

= Sudut pantul lengan ayun (o)

′ = Sudut pantul lengan ayun tanpa mengenai benda (o)

= Tebal spesimen (mm)

ℎ = Ketebalan benda uji (m)

= Panjang penumpu (mm)

R = Jarak dari pusat rotasi pendulum ke pusat massa (m)

= Beban bending maksimal (N)

w = Berat pendulum (N)

= Energi total yang diserap (J)

xvii

DAFTAR LAMPIRAN

Lampiran 1 Kekuatan Tarik Dan Modulus Serat Pelepah Salak........................... 58

Lampiran 2 Kekuatan Impak Komposit RHDPE-Serat Pelepah Salak ................. 59

Lampiran 3 Kekuatan Bending Komposit RHDPE-Serat Pelepah Salak ............. 60

Lampiran 4 Modulus Elastisitas Komposit RHDPE-Serat Pelepah Salak ............ 61

Lampiran 5 Grafik Kekuatan Bending Komposit ................................................. 62

Lampiran 6 Uji Kandungan Serat ......................................................................... 91

Lampiran 7 Data Kekuatan Tarik Serat Pelepah Salak ......................................... 93

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