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Abstrak :
The objective of this research was to reduce coconut sugar melting by enhancing glass transition temperature (Tg). Silicone dioxide (SiO2) and magnesium carbonate (MgCO3) were added before the coconut sugar was formed. Concentrations of SiO2 and MgCO3 were 0.5 %, 1.0 %, and 1.5 % respectively. Analysis was conducted for solidification temperature, moisture content, water activity, and glass transition temperature of coconut sugar. In this research, the glass transition temperature or coconut sugar was measured with differential thermal analyzer (DTA). The result showed that the addition of SiO and MgCO3 was not influenced toward moisture content of coconut sugar, but water activity was decreased. The solidification temperature and glass transition temperature were increased. The best coconut sugar was produced by addition of 1.5 % SiO3 with solidification temperature 72.67 °C, water activity 0.5, and glass transition temperature 70.45 °C

Abstrak :
Studi ini menganalisa pengaruh temperatur dan durasi pemanasan terhadap kekuatan composite wrapping di industri minyak dan gas bumi. Material komposit yang digunakan untuk penelitian adalah glass-kevlar reinforced-composite wrapping. Beberapa kondisi pemanasan dipilih untuk sampel pengujian; temperatur ruang, 127, dan 255°F. Variasi waktu tahan pemanasan pada 2, 6, 12, 24, dan 48 jam dilakukan bagi komposit matriks polimer (KMP) pada temperatur 255°F. Perubahan kekuatan KMP dianalisa dengan menggunakan pengujian tarik berdasarkan ASTM D3039. Analisa hasil permukaan patahan sampel setelah pengujian tarik dilakukan bagi seluruh variasi parameter pemanasan sampel. Nilai temperatur transisi gelas KMP juga dianalisa dengan menggunakan differential scanning calorimetry berdasarkan ASTM D3418. Hasil pengujian tarik menunjukkan bahwa KMP mengalami penurunan kekuatan tarik dan tensile modulus dengan peningkatan temperatur pada variabel pengujian. Penambahan durasi pemanasan juga menunjukkan pola penurunan tensile modulus KMP. Hal ini dikarenakan pelemahan ikatan antara fiber dan matriks epoksi KMP yang dapat diamati pada hasil fraktografi sampel pada kenaikan temperatur dan durasi pemanasan. Hasil analisa termal menunjukkan bahwa KMP memiliki nilai Tg yang berada pada kisaran temperatur 257°F. Perkiraan waktu penurunan kekuatan KMP hingga menyentuh angka minimum yang dibutuhkan pada kondisi operasi pipa dilakukan dengan iterasi penurunan tensile modulus KMP pada variasi pemanasan pada temperatur pengujian.

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The effect of temperature and holding time on the mechanical properties of composite wrapping were investigated. Material being used for the study is glass-kevlar reinforced-composite wrapping. Various heating at temperatures ranging from 85°F to 255°F was applied. Several holding times for 2, 6, 12, 24, and 48hours were selected in temperature of 255°F. The effect on mechanical properties was investigated by means of tensile test according to ASTM D3039. Fractography analysis on the tension tested samples was conducted using scanning electron microscope. The polymer grass transition temperature was investigated utilizing differential scanning calorimetry according to ASTM D3418. Tensile test results showed that the tensile strength and tensile modulus of the composite were decreased with increasing temperature. Increasing heating duration also resulted in a decrease in tensile modulus of composite. This was related with the weakening in fiber and matrix interface bonding of the composite as evidenced in the fractography results of samples with increasing test temperature and heating duration. Thermal analysis showed that the composite has glass transition temperature around 257°F. In addition, the time of which the strength of the wrapping will drop to a minimum required strength on the operating condition was estimated by iteration of tensile modules decreament in the tested holding times.

Abstrak :
Drug-polymer miscibility is a prerequisite for a stable solid dispersion. In this study, the miscibility of ibuprofen and the polymers, i.e., Eudragit® RL (ERL) and ethylcellulose (EC), were investigated by DSC. Ibuprofen in ERL solid dispersion at 0 - 100 %w/w was examined by the heating program: 25 - 140 °C, 10 K/min; 140 - (-60) °C, -10 K/min; and (-60) - 140 °C, 5 K/min. Solid dispersion of ibuprofen in EC at the same concentration range was examined by the heating program: 25 - 180 °C, 10 K/min; 180 - (-60) °C, -10 K/min; and (-60) - 180 °C, 5 K/min. The melting point depression and the variation of a single glass transition temperature (Tg) as a function of composition were presented in solid dispersion of ibuprofen in either ERL or EC, indicating the miscibility between blend components. Fitting the melting point of ibuprofen in either ERL or EC (Tmb) to Nishi-Wang equation by nonlinear regression analysis gave R2 equal to 0.8768 and 0.9667, respectively. Fitting experimental Tg to Gordon-Taylor and Kwei equations gave R2 equal to 0.9796 and 0.9851 for ibuprofen in ERL and 0.9753 and 0.9793 for ibuprofen in EC. The Kwei equation seemed to be better for describing the Tg of the blends, indicating the interaction between ibuprofen and the polymers, i.e., ERL and EC, which was confirmed by FTIR analysis. However, the non-randomness of residuals suggested that Nishi- Wang, Gordon-Taylor, and Kwei could not completely explain the Tmb and Tg of the blends.

Abstrak :
Dalam penelitian ini dilakukan pembuatan komposit semikonduktor dengan menggunakan matriks akrilik yang ditambahkan dengan dua jenis filler yakni ZnO dan serat nata de coco. Tujuan dari penelitian ini adalah untuk mendapatkan material komposit semikonduktor yang memiliki kekuatan mekanik, serta ketahanan termal yang baik. Metode yang digunakan adalah polimerisasi in situ dimana filler dan monomer matriks yang berupa resin dicampurkan kemudian ditambahkan katalis sebanyak 1% berat resin untuk mempercepat polimerisasi sehingga didapat komposit dengan filler yang terdistribusi di dalam polimer akrilik setelah didiamkan selama 12 jam. Komposit ini kemudian diukur modulus elastisitas, suhu transisi gelas, serta konduktivitas listriknya. Penambahan filler nata de coco mampu meningkatkan modulus elastisitas dan suhu transisi gelas dari akrilik. Modulus elastisitas serta suhu transisi gelas tertinggi dicapai oleh komposit akrilik/nata de coco dengan persen volume sebesar 30% yakni 2,68 GPa dan 199,47oC. Secara umum penambahan filler ZnO dan nata de coco meningkatkan konduktivitas dari komposit. Komposit yang dihasilkan dapat dinyatakan sebagai material semikonduktor karena berada pada rentang konduktivitas 10-8-103 S/cm. Komposit dengan sifat semikonduktor yang paling baik adalah komposit akrilik/ZnO dengan persen volume ZnO sebesar 30% dengan konduktivitas sebesar 2,7 x 10-7 S/cm. Komposit dengan kombinasi filler ZnO sebesar 20% dan nata de coco 10% volume memberikan modulus elastisitas serta suhu transisi gelas yang lebih tinggi dari komposit akrilik/ZnO yakni mencapai 1,79 GPa dan 175,73oC. Sementara konduktivitas dari komposit tersebut lebih tinggi dari konduktivitas akrilik/nata de coco yakni mencapai 1,9 x 10-7 S/cm. ......Synthesis of semiconductor composite using acrylic matrix filled with ZnO and nata de coco fiber has been conducted in this research. The purpose of this research is to obtain semiconductor composite material that have a good mechanical strength and thermal resistance. In situ polymerization method is used in this research where fillers and matrix monomer are mixed and then 1%wt of catalyst is added into the mixture to make it polymerizes faster. After 12 hours, the composite with acrylic matrix and filler is ready to be characterized. Three parameters are characterized in this research such as elastic modulus, glass transition temperature, and electric conductivity of the composite. The addition of nata de coco filler can increase the elastic modulus and glass transition temperature of the acrylic. The highest elastic modulus and glass transition temperature is obtained from acrylic/nata de coco composite with 30% filler volume percentage that reach 2,68 GPa and 199,47oC. In general the addition of ZnO and nata de coco filler can increase the conductivity of the composite. The composites that has been made in this research can be classified as semiconductor material because the conductivity is in the range of 10-8-103 S/cm. Composite that has a high semiconductor characteristic is obtained from acrylic/ZnO composite with 30% filler volume percentage that reach 2,7 x 10-7 S/cm. The composite with 20% volume of ZnO filler and 10% volume of nata de coco gives a higher elastic modulus and glass transition temperature than those in acrylic/ZnO composite that reach 1,79 GPa and 175,73oC. In addition, the conductivity of this composite is 1,9 x 10-7 S/cm which is higher than the conductivity of acrylic/nata de coco composite.;

Abstrak :
Pada penelitian ini dilakukan sintesis polimer suspensi poli[stirena-ko-(butil akrilat)] melalui polimerisasi radikal bebas untuk mempelajari pengaruh komposisi monomer stirena dan butil akrilat terhadap temperatur transisi gelas (Tg) kopolimer, serta mempelajari pengaruh konsentrasi inisiator benzoil peroksida terhadap solid content, viskositas dan ukuran partikel kopolimer. Dari hasil penelitian diperoleh bahwa, komposisi monomer mempengaruhi nilai Tg kopolimer, dengan semakin banyak komposisi monomer stirena yang digunakan, semakin tinggi nilai Tg kopolimer yang dihasilkan. Komposisi monomer optimum diperoleh pada saat perbandingan komposisi antara stirena dengan butil akrilat 55:45, dengan Tg yang dihasilkan sebesar 38,18ºC. Konsentrasi inisiator mempengaruhi nilai solid content dan viskositas, akan tetapi tidak mempengaruhi ukuran partikel kopolimer. Konsentrasi inisiator optimum diperoleh pada saat konsentrasi inisiator 1% dari berat monomer total, dengan nilai solid content yang dihasilkan sebesar 39,34% dan viskositas kopolimer sebesar 781,25 centiPoise. Karakterisasi menggunakan FTIR, GPC dan DSC menunjukkan bahwa polimer suspensi poli[stirena-ko-(butil akrilat)] telah berhasil disintesis.

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In this research, suspension polymers of poly[styrene-co-(butyl acrylate)] synthesis was done by using free radical polymerization method to study not only the effects of various monomer composition of styrene and butyl acrylate on the glass transition temperature (Tg), but also to study the effects of various initiator concentration of benzoyl peroxide on the solid content, viscosity and particle size of copolymer. The result showed that monomer composition affected the Tg of copolymers. The more amount of styrene used, the higher value of Tg copolymers produced. Optimum monomer composition was obtained when the composition ratio between styrene and butyl acrylate 55:45, with the value of Tg of 38,18ºC. Initiator concentration affected the value of solid content and viscosity, but didn?t affect the particle size of copolymer. Optimum initiator concentration was obtained when the initiator concentration 1% from the total weight of monomers, with the value of solid content of 39,34% and the viscosity of 781,25 centiPoise. The FTIR, GPC and DSC result showed that suspension polymers of poly[styrene-co-(butyl acrylate)] has been successfully synthesized.

Abstrak :
Kondisi lingkungan dapat memberikan efek yang sangat besar dalam bentuk kegagalan komposit karbon/epoksi. Kondisi lingkungan menjadi perhatian dalam dunia penerbangan karena dapat mempengaruhi kekuatan mekanik dan sifat termal dari material yang dijadikan bahan penyusun struktur pesawat. Penelitian ini dilakukan untuk mengetahui pengaruh kondisi lingkungan, khususnya kemampuan penyerapan kadar air, kekuatan mekanik, sifat termal, dan jenis kerusakan dari komposit karbon/epoksi unidirectional. Komposit ini dibuat dengan metode dry hand lay-up. Untuk mengetahui hal tersebut, komposit karbon diberikan kondisi lingkungan yang berbeda, yaitu keadaan tanpa perendaman, direndam dalam air panas, dan air laut dalam waktu tertentu. Dari hasil pengamatan penyerapan kadar air dari, didapatkan kandungan kadar air maksimum yang terserap ke dalam komposit karbon/epoksi dalam lingkungan air panas 0,89 selama 1100 jam dan air laut 0,57 selama 1200 jam perendaman. Uji mekanik short-beam shear menunjukkan persentase penurunan nilai kekuatan antarlamina dari hasil uji mekanik pada keadaan air panas dan air laut berturut-turut sebesar 9,66 dan 0,92 dibandingkan dengan bahan tanpa perendaman. Suhu transisi gelas relatif sama dari tiap kondisi lingkungan. Hasil pengamatan mikroskop optik dan Scanning Electron Microscope tidak memperlihatkan perbedaan yang berarti dari ketiga komposit. Jadi material komposit karbon/epoksi unidirectional tidak mengalami perubahan berarti pada sifat termal dan kerusakan permukaan akibat pengaruh air panas dan air laut. ...... Environmental conditions can result a profound effect in a forms of carbon epoxy composite failures. Environmental conditions are one of the main considerations in the aerospace industry as they can affect the mechanical strength and thermal properties of the materials that be used as aircraft structures. This study was aimed to determine the effect of environmental conditions, especially the moisture absorption, mechanical strength, thermal properties, and types of damage of unidirectional carbon epoxy composites. The composites were fabricated by a dry hand lay up process. The composites were conditioned in different environment which were normal condition or without immersion, soaked in both hot water, and seawater within a certain time. The maximum moisture content that was absorbed in the composites was 0.89 for 1100 hours in hot water and was 0.57 in seawater for 1200 hours of immersion. Furthermore, short beam shear test results showed that the interlaminate strength values reduced 9.66 and 0.92 in hot water and sea water conditions respectively compared to composites in normal condition. The glass transition temperature of hot water and sea water conditioned materials were relatively similar compared to materials in normal condition. According to optical microscope and Scanning Electron Microscope observations, there was no visible difference on the surface of three materials. Thus, the thermal property and the appearance of the unidirectional carbon epoxy composites did not change in hot water and sea water.