PENGARUH WAKTU PERENDAMAN SERAT PADA LARUTAN NATRIUM BIKARBONAT (NaHCO₃) TERHADAP KEKUATAN TARIK DAN STRUKTUR MIKRO KOMPOSIT SERAT KULIT BATANG KERSEN -  POLIESTER

THE EFFECT OF FIBER SOAKING TIME ON THE SOLUTION OFNATRIUM  BICARBONATE (NaHCO3) ON THE TENSILE STRENGTH AND MICRO STRUCTURE OF KERSEN STEM SKIN FIBER COMPOSITE- POLYESTER

Pengembangan teknologi dibidang industri material yang semakin maju menuntut pembaharuan jenis material dengan berat jenis (density) rendah, kuat dan ramah lingkungan seperti jenis material komposit serat alam. Penggunaan Laminate composite material kayu maple pada papan skateboard masih kurang efektif karena sering terjadi patah dan rusak akibat panas matahari serta air hujan. Perlu dilakukan inovasi material pada aplikasi papan skateboard salah satunya dengan menggunakan jenis komposit serat kersen (Muntingia calabura). Masalah yang sering terjadi pada material komposit serat alam yaitu lemahnya ikatan serat dengan matriks dan cacat akibat produksi yang menyebabkan sifat mekanis kurang sesuai dengan aplikasinya, proses perlakuan alkalisasi serat kersen dengan larutan alkali Natrium Bikarbonat (NaHCO3) diharapkan mampu memperbaiki ikatan serat dengan matriks. Penelitian ini dilakukan untuk mengetahui pengaruh serat kersen tanpa perendaman dan serat kersen dengan lama perendaman selama 24 jam, 96 jam dan 192 jam pada larutan Natrium Bikarbonat (NaHCO₃) dengan matriks poliester terhadap kekuatan tarik dan foto mikro kegagalan komposit. Metode penelitian yang digunakan yaitu eksperimen serat kersen tanpa perendaman dan serat kersen dengan variasi lama perendaman selama 24 jam, 96 jam dan 192 jam pada larutan  Natrium Bikarbonat (NaHCO₃). Serat kersen dimasukkan pada larutan Natrium Bikarbonat (NaHCO₃) dengan konsentrasi 12% pada wadah selama 24 jam, 96 jam dan 192 jam. Pembuatan spesimen komposit menggunakan metode hand lay up. Fraksi volume serat kersen dengan poliester sebesar 30%. Pengujian tarik menggunakan standar ASTM D638 . Hasil penelitian menunjukkan adanya perbedaan kekuatan tarik antara komposit serat kersen tanpa perlakuan dengan jenis komposit serat kersen variasi lama perendaman 24 jam, 96 jam dan 192 jam pada larutan Natrium Bikarbonat (NaHCO₃). Lama perendaman serat menentukan kemampuan interlocking antara serat dan matriks yang dipengaruhi akibat hilangnya senyawa lignin, hemiselulosa, lilin dan minyak yang terdapat pada serat alam, Dapat dilihat dari hasil pengujian kekuatan tarik tertinggi didapat pada komposit serat kersen lama perendaman 96 jam sebesar 57.55 Mpa, serat kersen lama perendaman 192 jam sebesar 54.76 Mpa, serat kersen lama perendaman 24 jam sebesar 45.38 Mpa dan kekuatan tarik terendah pada komposit serat tanpa perendaman sebesar 37.78 Mpa. Dari Pengamatan makro dan mikro pada spesimen uji tarik dominan menunjukkan kegagalan fiber pull out, yaitu kegagalan akibat ketidakmampuan matrik menahan beban yang diterimanya sehingga menyebabkan serat terlepas kemudian patah karena gaya searah yang diterimanya.

The development of technology in the increasingly advanced material industry requires renewal of material types with low density, strong and environmentally friendly such as natural fiber composite materials. The use of laminate maple wood composite material on a skateboard is still ineffective because it often occurs broken and damaged by the sun's heat and rainwater. Material innovation needs to be done on the skateboard board application, one of them by using a type of kersen fiber composite (Muntingia calabura). The problem that often occurs in natural fiber composite materials is the weak bonding of the fiber with the matrix and defects due to production which causes mechanical properties that are less appropriate with its application, the process of alkalising treatment of kersen fiber with an aqueous solution of Sodium Bicarbonate (NaHCO₃) is expected to improve the bonding of the fiber with the matrix. This research was conducted to determine the effect of kersen fiber without soaking and kersen fiber with soaking time for 24 hours, 96 hours and 192 hours on sodium bicarbonate (NaHCO₃) solution with polyester matrix on tensile strength and micro-photographic composite failure. The method of research that is used is experimental kersen fiber without soaking and kersen fiber with a variation of the soaking time for 24 hours, 96 hours and 192 hours in a solution of sodium bicarbonate (NaHCO₃). Kersen fiber was put into a solution of Sodium Bicarbonate (NaHCO₃) with a concentration of 12% in a container for 24 hours, 96 hours and 192 hours. Making composite specimens using the hand lay up method. Fraction volume of kersen fiber with polyester by 30%. Tensile testing using the ASTM D 638 standard.The results showed a difference in tensile strength between the kersen fiber composites without treatment with the type of kersen fiber composites with 24 hours, 96 hours and 192 hours immersion variation in Sodium Bicarbonate (NaHCO₃) solution. Soaking time fiber determines the ability of the interlocking between the fibers and the matrix are affected due to the loss of compound lignin, hemicellulose, wax and oil are contained in the natural fibers, can be seen from the results of testing the strength of attraction of the highest obtained at the kersen fiber composite soaking time 96 hours of 57.55 MPa, kersen fiber soaking time 192 hours of 54.76 MPa, kersen fibesrs soaking time 24 hours amounted to 45.38 MPa and strength tensile lows on composite fiber without soaking of 37.78 MPa. From the macro and micro observations on the dominant tensile test specimens, it shows the failure of the fiber pull out, which is a failure due to the inability of the matrix to withstand the load it receives, causing the fiber to be released then broken due to the directional force it receives.