Studi Eksperimental Pengaruh Ukuran Partikel Serbuk Tempurung Kelapa Terhadap Kekuatan Tarik dan Bending Nanokomposit Polipropilen Berpenguat Serbuk Tempurung Kelapa

Material komposit banyak dikembangkan untuk memenuhi kebutuhan industri karena keunggulannya yang kuat dan ringan. Namun pada pengembangannya ditemukan bahwa kekuatannya menurun karena partikel pengisi belum dicuci. Pengembangan nanokomposit dinilai berpotensi meningkatkan kekuatan suatu komposit sehingga penelitian ini akan berfokus pada komposit dengan pengisi nanopartikel. Studi eksperimen dilakukan dengan persiapan STK (Serbuk Tempurung Kelapa) berukuran nano dengan cara STK berukuran kurang dari 40 um diproses pada mesin ball mill selama 8 h dan 16 h. Setelah selesai selanjutnya sampel STK 8 h waktu milling dan 16 h waktu milling dilakukan pengujian XRD (X-ray Diffraction) untuk mengetahui ukurannya. Selanjutnya membuat spesimen dengan mencampur polipropilen dan STK (Serbuk Tempurung Kelapa) yang sudah diproses pada ball mill selama 8 h dan 16 h dengan fraksi berat 8,5%. Kemudian, spesimen dicetak sesuai standar uji dan dilakukan pengujian tarik, bending, dan SEM (Scanning Electron Microscopy). Dari hasil pengujian XRD untuk masing masing sampel STK didapatkan ukuran kristal 66 nm untuk variasi 8 h waktu milling dan 62 nm untuk 16 h waktu milling. Ukuran STK berkurang seiring dengan bertambahnya waktu milling. Dari hasil pengujian tarik didapatkan kekuatan tarik dan modulus elastisitas polipropilen meningkat setelah penambahan nano STK. Kekuatan tarik dan modulus elastisitas pada variasi 62 nm mendapat nilai 26,48 MPa dan 860,77 MPa. Sedangkan untuk variasi 66 nm mendapat nilai 27,10 MPa dan 1034,35 MPa. Angka tersebut meningkat dari komposit polipropilen dengan pengisi STK berukuran micro yang bernilai 16,17 MPa. Dari hasil pengujian bending didapatkan kekuatan bending dan flexural modulus polipropilen meningkat setelah penambahan nano STK. Kekuatan bending dan flexural modulus pada variasi 66 nm mendapat nilai 105,56 MPa dan 1985,16 MPa. Sedangkan untuk variasi 62 nm mendapat nilai 80,35 MPa dan 1699,08 MPa. Dari hasil SEM (Scanning Electron Microscopy) ditemukan adanya aglomerasi dan void yang jumlahnya lebih banyak dan ukurannya lebih besar pada variasi 16 h waktu milling. Hal tersebut yang menyebabkan menurunnya kekuatan dan modulus pada variasi 62 nm. Di sisi lain dari hasil SEM dapat dilihat tidak ada partikel yang lepas atau tidak menyatu dengan matriksnya. Hal tersebut yang menyebabkan meningkatnya kekuatan komposit polipropilen berpenguat nano STK dari komposit polipropilen berpenguat STK berukuran micro. =============================================================================================================================== Composite materials have been developed to meet industrial needs because of their superior strength and light weight. However, during its development it was found that the strength decreased because the filler particles had not been washed. The development of nanocomposites is considered to have the potential to increase the strength of a composite so that this research will focus on composites with nanoparticle fillers. Experimental studies were carried out with the preparation of nano-sized STK (Coconut Shell Powder) by means of STK measuring less than 40 um processed in a ball mill machine for 8 h and 16 h. After completion, the STK samples were tested for 8 h milling time and 16 h milling time by conducting XRD (X-ray Diffraction) tests to determine their size. Next, make specimens by mixing polypropylene and STK (Coconut Shell Powder) which have been processed in a ball mill for 8 h and 16 h with a weight fraction of 8.5%. Then, the specimens were printed according to test standards and subjected to tensile, bending and SEM (Scanning Electron Microscopy) tests. From the results of the XRD test for each STK sample, a crystal size of 66 nm was obtained for the 8 h variation of milling time and 62 nm for 16 h of milling time. STK size decreases with increasing milling time. From the results of the tensile test, it was found that the tensile strength and modulus of elasticity of polypropylene increased after the addition of nano STK. Tensile strength and modulus of elasticity at 62 nm obtained values of 26.48 MPa and 860.77 MPa. As for the 66 nm variation, the values were 27.10 MPa and 1034.35 MPa. This figure has increased from the polypropylene composite with micro-sized STK fillers which is worth 16.17 MPa. From the bending test results, it was found that the bending strength and flexural modulus of polypropylene increased after the addition of nano STK. The bending strength and flexural modulus for the 66 nm variation were 105.56 MPa and 1985.16 MPa respectively. As for the 62 nm variation, the values are 80.35 MPa and 1699.08 MPa. From the results of SEM (Scanning Electron Microscopy) it was found that there were agglomerations and voids which were more in number and larger in size at the 16 h variation of milling time. This causes a decrease in strength and modulus at 62 nm variations. On the other hand, from the SEM results, it can be seen that there are no loose particles or not integrated with the matrix. This has led to an increase in the strength of nano STK reinforced polypropylene composites from micro sized STK reinforced polypropylene composites