FIBRILASI PERLAKUAN DAN KARAKTERISASI SERAT PELEPAH SALAK UNTUK PEMBUATAN NANO FIBER BIOCOMPOSITE

SENO DARMANTO, Ir. Heru Santoso B.R., M.Eng., Ph.D., D.Agr.Sc. Ragil Widyorini, ST., MT.,Prof. Ir. Jamasri, Ph.D.

2018 | Disertasi | DOKTOR TEKNIK MESIN

Potensi besar limbah pertanian dan perkebunan termasuk limbah salak membutuhkan penanganan yang serius untuk diolah menjadi produk berdaya saing tinggi. Potensi limbah salak dapat bersumber dari biji, kulit buah dan pelepah. Pada penelitian ini, obyek penelitian difokuskan pada batang pelepah salak (Sallaca sp.) dengan menerapkan beberapa proses /tahapan kegiatan meliputi fibrilasi, perlakuan dan karakterisasi serat pada skala baik makrometer, mikrometer dan nanometer. Tujuan penelitian ini adalah untuk mendapatkan formulasi mengenai cara pembuatan atau fibrilasi, perlakuan, dan karakterisasi batang pelepah salak sebagai bahan untuk komposit nanofiber. Penelitian serat batang pelepah salak ini diawali dengan memberikan perlakuan fisik meliputi ukuran panjang serat, perendaman, aliran uap air, pengukusan tekanan rendah dan pengeringan dan dilanjutkan dengan beberapa pengujian meliputi komposisi kimia, kekuatan tarik, pull-out test, Fourier Transform Infra Red (FTIR) dan pengamatan foto Scanning Electron Microscope (SEM). Selanjutnya perlakuan kimia dilakukan dengan merendam pada larutannatrium hidrosida (NaOH) dengan variasi konsentrasi 2% - 8 % (w/v) dan waktu perendaman 1, 4, 6 dan 8 jam. Setelah diperoleh perlakuan alkali yang terbaik, serat dikenai perlakuan mekanik yang secara berturut-turut meliputi pengukusan, ledakan uap dan ultrasonik (sonikasi). Perlakuan mekanik diawali dengan pengukusan pada tekanan 1 - 2 bar untuk mereduksi bahan ikutan dan membantu fibrilasi. Tahap selanjutnya adalah melakukan beberapa pengujian meliputi komposisi, kekuatan tarik, pull-test, FTIR, dan foto SEM untuk mendapatkan data karakteristik serat batang pelepah salak. Tahap selanjutnya adalah optimasi perlakuan fisik, kimia dan pengukusan dan dilanjutkan perlakuan mekanis dengan ledakan uap untuk melakukan proses fibilasi serat lebih lanjut. Sebelum masuk reaktor ledakan uap, serat bundle direduksi ukurannya yakni dari panjang awal 100 mm ke 2 mm. Perlakuan ledakan uap dilakukan pada variasi tekanan 3 - 8 bar, waktu penahanan 60 - 90 detik dan jumlah ledakan 20 - 50 x (kali). Optimasifibrilasi dari serat yang dikenai perlakuan ledakan uap didasarkan pada beberapa hasil pengujian yakni komposisi, XRD, FTIR dan pengamatan SEM. Optimasi hasil fibrilasi dengan perlakuan sonikasi dipertajam dengan pengamatan TEM. Hasil penelitian menunjukkan bahwa fibrilasi serat batang pelepah salak mulai terjadi peningkatan secara nyata pada tahap aplikasi perlakuan ledakan uap dan sonikasi meskipun perlakuan alkali dan pengukusan juga berpengaruh pada tahap awal fibrilasi. Fibrilasi secara manual menghasilkan fibrilasi awal serat dengan diameter rata-rata±470 mikrometer. Perlakuan alkali dan pengukusan tekanan rendah dapat meningkatkan fibrilasi dengan capaian diameter di level ±400 mikrometer. Perlakuan ledakan uap pada serat bundle yang telah diberi perlakuan alkali dan pengukusan tekanan rendah menunjukkan hasil yang bervariasi yakni sebagian besar masih di atas 100 mikrometer, sebagian kecil di bawah 100 mikrometer dan di bawah 200 nm. Capaian serat dengan ukuran diameter nanometer yakni diameter 50 nm dicapai pada perlakuan sonikasi. Hasil uji komposisi menunjukkan bahwa ada kenaikan kandungan selulosa mencapai 58 % (penurunan kandungan hemiselulosa dan lignin) pada perlakuan alkali konsentrasi 2 % dan perendaman 6 jam dibandingkan dengan kandungan selulosa 47 % untuk serat salak tanpa perlakuan. Hasil perhitungan data pengujian tarik menunjukkan bahwa meskipun ada kecenderungan penurunan kekuatan tarik pada perlakuan alkali dengan konsentrasi yang tinggi, namun perlakuan alkali pada konsentrasi rendah yang diteruskan dengan pengukusan menunjukkan peningkatan kekuatan tarik. Kombinasi perlakuan yakni alkali-pengukusan dan ledakan uap menunjukkan hasil terbaik pada tekanan 6 bar dan jumlah ledakan 40x. Pengamatan SEM pada spesimen yang dikenai perlakuan kombinasi yakni alkali, pengukusan dan ledakan uap menunjukkan fibril dengan permukaan serat lebih bersih, tajam, jelas dan alur-alur serat nanofibril sebagian kecil sudah terbentuk. Perlakuan lanjutan dengan sonikasi dapat menghasilkan nanofibril dengan diameter di bawah 50 nm. Analisis XRD menghasilkan indeks kristaliniti dari 66 % untuk serat tanpa perlakuan ke 76 % pada serat yang dikenai ledakan uap, meskipun itu selanjutnya menurun ke 57 % setelah dikenai perlakuan sonikasi.

The large potential of agricultural and plantation waste including Snake Fruit (Sallaca) waste requires serious handling to be processed into highly competitive products. Potential of the Snake Fruit waste can be obtained from seeds, fruit shell and frond. In this study, the research object is focused on Snake Fruit frond by applying several process/activity steps including fibrillation, treatment and characterization of fibers on size both macrometer, micrometer and nanometer as well as its application for composite. The purpose of research is to obtain a formulation of the method of producing nanofiber (fibrillation), treatment and characterization of Snake Fruit frond as material for the nanofiber composite. The research of Snake Fruit frond fiber was initiated by providing physical treatment including length of fiber, immersion, steam flow, lowattpressure steaming, drying and followed by several tests including chemical composition, tensile strength, pull-out test, Fourier Transform Infra Red (FTIR) and photo observation Scanning Electron Microscope (SEM). Furthermore, chemical treatment was done by immersion in the variation of the concentration of sodium hydroxide solution (NaOH) with the duration of soaking time of 1, 4, 6 and 8 hours. After obtaining the best alkali treatment, the bundle fiber was subjected to mechanical treatment which includes steam explosion and ultrasonic (sonication). The mechanical treatment was started with steaming at a pressure of 1-2 bars to reduce impurities and increase fibrillation. The next step was to do some testing including composition, tensile strength of single fiber, pull-test, FTIR, and photo SEM to obtain data characteristic of Snake Fruit frond fiber. The next stage was optimization of physical, chemical and steam treatment and continued mechanical treatment with steam explosion to do further fibrillation of the fibers. Before entering the steam explosion reactor, the fiber was reduced in size from the initial length of 100 mm to 2 mm. The steam explosion was carried out at a pressure of 3 - 8 bar and holding time of 60 - 90 seconds and an explosive amount of 20 - 50 x (times). The next step was the fibrillation optimization of the fiber subjected to the steam explosive treatment based on several test results specifically composition, XRD, FTIR and SEM observations. Similar to the treatment of steam explosions, the optimization of fibrillation results with sonication treatment was sharpened by TEM observation. The optimization results were used as a reference to reproduce fibers with nanometer scale as material for the nanofiber composite. The results showattthat Snake Fruit frond stem fibrillation begin to increase significantly in steam explosion and ultrasonic treatment stage although alkali and steaming treatment also had an effect on the initial stage of fibrillation. Fibrillation manually can yield initial fibrillation of bundle fiber with an average diameter of ±470 mikrometer Alkali treatment and lowattpressure steaming can improve the fibrillation by achieving diameters at levels of ± 400 mikrometer. The treatment of steam explosions in alkaline treated fibers and lowattpressure steaming shows varying results namely majority above 100 mikrometer, a fraction below at 100 mikrometer and below at 200 nm. The best achievement of fibrillation is achieved by sonication treatment with the size of nanometer diameter (nanofibril) ie 50 nm. The result of the composition test shows an increase in cellulose content (alpha-cellulose) to 58 % in the alkaline treatment of 2 % concentration and 6 hours immersion compared with 47 % cellulose (alpha-cellulose) content for untreated fiber. The results of calculation of the tensile strength test data present that although there is a tendency to decrease the tensile strength on alkali treatment with high concentrations, but the combination treatment of alkali at low at concentrations continued with steaming shows an increase in tensile strength. The combination of alkali-steaming treatment and steam explosion directs the best results at 6 bar pressure and 40x of explosion amount. SEM observation on specimens subjected to combination treatment of alkali, steaming and steam explosions identifies fibrils marked on the bundle fiber surface of cleaner, sharper, clearer fibers and small portions of nanofibril fibers already formed. Further treatment with sonication can produce nanofibril fibers with diameters below at 50 nm. XRD analysis yields a crystalline index of 66 % for untreated fiber to 76 % in fibers subjected to steam explosion treatment, although it further decreases to 57 % after sonication treatment.

Kata Kunci : batang pelepah salak, alkali, pengukusan, ledakan uap, sonikasi, fibrilasi/Snake Fruit frond, alkali, steaming, steam explosion, sonication, fibrillation