ANALISIS STRUKTUR MOLEKUL ACRYLOYL-LPROLINE METHYL ESTER MENGGUNAKAN FOURIER TRANSFORM NUCLEAR MAGNETIC RESONANCE

ANALISIS STRUKTUR MOLEKUL ACRYLOYL-L-PROLINE METHYL ESTERMENGGUNAKAN FOURIER TRANSFORM NUCLEAR MAGNETIC RESONANCE. Telah dilakukan analisis bahan monomer acryloyl-L-proline methyl ester denganmenggunakan spektrometer Fourier Transform Nuclear Magnetic Resonance (FT-NMR) ) untuk analisis atom karbon (13C) dengan model pengukuran Distortionless Enhancement by Polarization Transfer (DEPT) tanpa adanya coupling dari atom proton (1H). Bahan acryloyl-L-proline methyl ester disintesis dengan cara mereaksikan asam akrilat dengan L-prolin metil ester hidrokhlorida dalamtrietilamin pada suhu 90oC. Acryloyl-L-prolinemethyl estermerupakan bahan monomer yang cukup penting, karena polimer hidrogel polyacryloyl-L-proline methyl ester yang disintesis darimonomer ini banyak digunakan untuk diagnosis dan terapi penyakit tumor pembuluh darah. Dari hasil analisis spektrum DEPT FT-NMR dapat diperoleh, bahwa bahan monomer acryloyl-L-proline methyl ester telah berhasil disintesis dan dianalisis secara tepat dan akurat

CORROSION EXPERIMENT ON NON STANDARD AUSTENITIC STEEL A1, IN REACTOR COOLANT WATER

Experimental corrosion studies on non standar austenitic SS, A1, have been carried out. The samples were immersed in reactor coolant water medium with pH variation of  5.95, 6.0, 6.l5, and 6.31. The experiments were carried out using a type of M-273 EG&G potentiostate /galvanometer test instrument. The post-corrosion samples' microstructure were analyzed with the aid of EDS (energy dispersive spectroscopy) equipped SEM instrument to detect the presence of any viable corrosion products. For further verification x-ray diffraction method was also used to detect any possible emerging corrosion products type on the samples' surfaces. Experimental results confirm that non standar austenitic SS immersed in reactor coolant water corrosion medium with a variation of concentration experience very little or almost no corrosion, and that according to the so-called Fontana’s criteria these test-materials turn out to have an excellent resistance toward reactor coolant water corrosion medium.  This is also evidenced by the very low corrosion rate value measured in this study. EDS study and X-ray diffraction results indicate that the possible ensuing corrosion byproducts are chrome oxides and iron oxides. Keywords: Corrosion, non standard austenitic stainless steel, reactor coolant water Telah dilakukan percobaan korosi dari bahan austenitic baru yang non standar, A1, dalam medium air pendingin reaktor, dengan variasi pH, yaitu 5,95, 6,00, 6,15, dan 6,31. Experimen dilakukan dengan alat uji potensiostat-galvanometer tipe M-273 EG & G. Dilanjutkan dengan karakterisasi pada sampel yang telah dikorosikan, yaitu pemeriksaan struktur mikro yang dilakukan dengan SEM dilengkapi EDS (energy dispersive spectroscopy) untuk mendeteksi adanya produk korosi yang mungkin ada pada permukaan sampel. Juga dilakukan percobaan difraksi sinar-X untuk konfirmasi hasil produk korosi tersebut. Hasil eksperimen menunjukkan bahwa baja austenite non standar yang dibuat ini sangat tahan korosi terhadap air pendingin reaktor, dan hanya terjadi sedikit korosi sehingga menurut kriteria Fontana, baja austenit non standar A1 ini memiliki ketahanan korosi yang sangat baik dalam medium air pendingin reaktor. Hasil pemeriksaan dengan EDS dan difraksi sinar-X juga menunjukkan bahwa produk korosi yang paling mungkin ada adalah oksida besi dan oksida chrom. Kata kunci: Korosi, baja tahan karat austenite non standar, air pendingin reakto

CONDUCTIVITY AND DIELECTRIC PROPERTIES OF A NOVEL FERRITE ALLOY

CONDUCTIVITY AND DIELECTRIC PROPERTIES OF A NOVEL FERRITE ALLOY. The synthesis of a new ferrite alloy with a composition of Fe (73.42 w%), Cr (18.0 w%), Si(1.0 w%), Mn(1.0 w%), C(0.08 w%) and Ti(6.5 w%) has been carried out. The frequency-dependent conductivity and dielectric response of this novel material have been investigated by RLC bridge impedance spectroscopy method. It was verified that the real dielectric constant e¢ of these new F-1 materials show different dielectric behavior with respect to Koops theory of dielectric response in standard ferrite materials. In the F-1 samples, no relaxation peaks are observed for the frequency range below 10 kHz, meaning low frequency behavior such as grain- boundaries effect and space charge polarization has not taken effect. Both dielectric response- and dielectric loss curves show frequency dispersive relaxation peaks, three regions of discontinuity and relaxation peaks were identified in the applied frequency range. The low frequencies up to 10 KHz, intermediate frequencies 10 kHz to 40 KHz, the dielectric constant tend to decrease forming a curve resembling a distorted quarter circle, and higher frequency-range > 40 kHz where a semicircle forms, centered around 60 kHz. Using Nyquist- and Bode plots, these relaxation processes are identified as (beginning of) formation of oxidation-layers at the surface because of sintering, electron transfers between cations and Maxwell-Wagner interfacial polarizations. It is concluded that this is a novel material with its own distinctive dielectric properties

24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES

24-CHROMIUM FERRITIC STEEL MAGNETIC PROPERTIES. A 24-chromium ferritic stainless steel had been made by foundry methods. The purpose of this investigation is to investigate the magnetic behavior of this ferritic sample, as one of the divvy of its characteristics. Some of supporting data used to prove that the material sample was ferritic type and followed by hysteresis curve obtained from the experiment. By Vibrating Sample Magnetometer (VSM) equipment, it is found that the ferritic steel has the saturation induction around of 150 emu g-1, with the coercive force Hc is close to 3 x 10-4 T and the remanent induction Br is close to 1,1 x 10-3 emu g-1 meanwhile by permagraph equipment the saturation induction around of 3.13 kG, and the coercive force HcB is equal to 0.005 kOe and the remanent induction Br is 0.23 kG with the dissipasion energy BHmax zero, explains that the ferritic stainless steel has a relative good magnetic behavior with relative high magnetization at the relative weak external magnetic field and can be demagnetized easily, appropriate to soft magnetic materials

PENGARUH KONSENTRASI POLIVINIL ALKOHOL PADA SINTESIS MIKROSFER BERBASIS POLILAKTAT DENGAN METODE ULTRASONIK.

PENGARUH KONSENTRASI POLIVINIL ALKOHOL PADA SINTESIS MIKROSFER BERBASIS POLILAKTAT DENGAN METODE ULTRASONIK. Telah dilakukan sintesis mikrosfer berbasis polimer polilaktat (PLA) dengan menggunakan teknik ultrasonik. Mikrosfer berbasis polimer biodegradable PLA dapat digunakan sebagai bahan pengungkung radiofarmaka (drug delivery) yang dapat digunakan untuk terapi tumor. Proses emulsifikasi dilakukan dengan mencampurkan larutan PLA di dalam kloroform pada konsentrasi 3% b/v dengan larutan polivinil alkohol di dalam air sebagai larutan pengemulsi yang diragamkan pada konsentrasi 7,5%; 5,0%; 3,0% dan 2,5%b/v dengan menggunakan ultrasound bath selama 30 menit. Tahapan evaporasi dilakukan dengan mencampur sistem emulsi yang diperoleh menggunakan motor pengaduk pada kecepatan tetap 1000 rpm selama 60 menit. Hasil yang diperoleh menunj ukkan bahwa ukuran dan bentuk mikrosfer dipengaruhi oleh konsentrasi larutan pengemulsi. Hasil karakterisasi menggunakan simultaneous thermal analyzer menunjukkan bahwa bahan mikrosfer terbentuk memiliki sifat tahan panas yang tidak dipengaruhi oleh parameter proses sintesis. Karakterisasi sifat kekristalinitasan bahan dilakukan dengan menggunakan x-ray difiractometer menunj ukkan bahwa bahan mikrosfer hasil sintesis memiliki derajat kristalinitas relatif tinggi, sehingga mikrosfer terbentuk dimungkinkan tidak mengalami kerusakan ketika dilakukan iradiasi

Microstructure and Crystal Structure Analysis of F1 Ferritic Steel

Ferritic stainless steel code named F1 has been synthesized by foundry method. The F1 steel was synthesized using the crude ore materials mined in Indonesia, consisting of ferro scrap, ferro chrome, ferro manganese, and ferro silicon, all in granular form. A small quantity of titanium has also been added to this very low carbon ferritic steel. The synthesis was started by calculating the required amount of the starting materials based upon the principal predetermined ferritic composition specification. The next step involves pouring the base materials into the induction foundry furnace which is equipped with an electromagnetic inducto-thermo system. The stirring was carried out automatically by the system. The melting materials are then poured successively first into a ladle, and then into the sand casting. Some of the steels were normalized by homogenization at 1200 °C for 20 hours, and some characterization was carried out. The microstructure observation shows that the material's surface is homogeneous and the grain boundaries appear somewhat diffuse. The diffraction pattern shows that the material has the BCC crystal structure and a lattice parameter of approximately 2.8871 Å by Rietveld analysis

SINTESIS DAN KARAKTERISASI MICROSPHERE BERBASIS POLIMETIL META AKRILAT (PMMA)

SINTESIS DAN KARAKTERISASI MICROSPHERE BERBASIS POLIMETIL META AKRILAT (PMMA). Telah dilakukan studi tentang pengaruh konsentrasi PMMA terhadap bentuk dan ukuran microsphere dengan menggunakan scanning electron microscope (SEM). Sintesis microsphere dilakukan dengan metode pengadukan dan evaporasi larutan dan suatu sistem emulsi. Proses emulsifikasi dilakukan dengan mencampurkan larutan PMMA di dalam pelarut kloroform dengan variasi konsentrasi 1, 4, 8 dan 16 % (b/b) kedalam larutan PVA di dalam pelarut aquades dengan konsentrasi 1 % (b/b). Hasil yang diperoleh menunjukkan bahwa ukuran dan bentuk microsphere dipengaruhi oleh konsentrasi larutan polimer. Pada konsentrasi PMMA terlalu rendah (1% b/b) atau konsentrasi PMMA terlalu besar(16% b/b) diperoleh ukuran microsphere beragam dari 20 - 200 µm, sedangkan pada konsentrasi polimer PMMA 4% dan 8% (b/b) diperoleh ukuran microsphere yang relatif seragam sebesar 20 µm. Analisis ketahanan panas dengan menggunakan differental thermal analyzer (DTA) diperoleh titik gelas microsphere berbasis PMMA, Tg berkisar pada 256,5 °C dan entalpi gelas ∆H = 1,476 J/g. Sedangkan suhu leleh Tm = 275,8 oC dengan entalpi leleh ∆H = -12,72 J/g dan suhu dekomposisi Td = 3 73,4 oC dengan entalpi dekomposisi ∆H =-27,86 J/g