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Abstrak :
Pertumbuhan plastik tahun ke tahun sangatlah signifikan, namun masalah limbah plastik menjadi salah satu isu yang mengiringi perkembangan dari plastik. Salah kelola limbah plastik di Indonesia menjadi faktor utama mengapa pertumbuhan limbah plastik dari tahun ke tahun semakin meningkat. Oleh karena itu, daur ulang plastik menjadi salah satu cara yang efektif untuk mengelola limbah plastik ini. Penelitian ini berfokus pada komposisi dari material virgin dan recycled serta penambahan heat stabilizer untuk meningkatkan performa dari limbah plastik yang berasal dari industri otomotif. Beberapa pengujian dilakukan seperti pengujian termal, mekanik, reologi, dan morfologi untuk melihat karakteristik dari limbah plastik dan optimalisasinya dengan variabel komposisi dan penambahan heat stabilizer. Hasil penelitian ini menunjukkan bahwa terjadinya penuruan sifat mekanik, reologi, dan termal dari limbah plastik dibandingkan dengan material virginnya. Hal ini disebabkan karena adanya degradasi termooksidatif yang dialami oleh limbah plastik pada saat diolah kembali dengan menggunakan mesin esktrusi. Penambahan material virginnya mampu untuk meningkatkan sifat mekanik dari material paduan, namun penambahannya tidak terlalu signifikan. Penambahan heat stabilizer mampu untuk meningkatkan ketahanan limbah plastik terhadap degradasi termooksidatif yang dibuktikan dengan pengujian oxidative induction time (OIT) dan pengujian tarik setelah proses heat aging. Komposisi optimum dari paduan material virgin dan recycled adalah 100% material virgin dengan penambahan heat stabilizer sebesar 0.3%. ......The growth of plastic from year to year is very significant, but the problem of plastic waste is one of the issues that accompany the development of plastic. Mismanagement of plastic waste in Indonesia is the main factor why the growth of plastic waste is increasing from year to year. Therefore, plastic recycling is an effective way to manage this plastic waste. This research focuses on the composition of virgin and recycled materials and the addition of heat stabilizers to improve the performance of plastic waste from the automotive industry. Several tests were carried out such as thermal, mechanical, rheological, and morphological tests to see the characteristics of plastic waste and its optimization with variable composition and the addition of heat stabilizers. The results of this study indicate that there is a decrease in the mechanical, rheological, and thermal properties of plastic waste compared to virgin material. This is due to the thermooxidative degradation experienced by plastic waste when it is reprocessed using an extrusion machine. The addition of virgin material is able to improve the mechanical properties of the alloy material, but the addition is not too significant. The addition of a heat stabilizer is able to increase the resistance of plastic waste to thermooxidative degradation as evidenced by oxidative induction time (OIT) testing and tensile testing after the heat aging process. The optimum composition of the blend of virgin and recycled materials is 100% virgin material with the addition of a 0.3% heat stabilizer.

Abstrak :
The rapidly growing demand for petroleum resources has become a crucial global problem. Therefore, a more realistic solution is required for oil production. Enhanced oil recovery (EOR) has become an essential technique to extract original oil content and maintain oil fields. During this process, certain viscous polymers are commonly used as mobility control agents. In this work, we introduce a new class of polymer to address the limitations of commercial EOR polymers. We successfully extracted kappa-type carrageenan from Eucheuma cottonii seaweed using demineralized water and ethanol precipitation. The amount of yield, intrinsic viscosity, and viscosity-average molecular mass of the extracted carrageenan were 18.64%, 12.77 dLg-1, and 4.716×105 gmol-1, respectively. Characterizations were done by dynamic viscosity and rheological measurement, along with a thermal degradation test. The measurements indicated that kappa-carrageenan is an attractive green substitute for polyacrylamide, as it showed relatively high resistance to temperature, shear rate, and salinity compared to polyacrylamide-based commercial EOR polymers. However, a higher concentration of carrageenan is still needed to reach the same viscosity as the commercial polymers.

Abstrak :
Drawing on years of practical on-site experience, this book presents a new method for controlling "bridge-head bumping" in soft soil ground. Based on deformation compatibility and control theory of structure, it proposes strategies for improving the design method of soft soil ground and the effective "bridge-head bumping" control method. Soft soil ground is chiefly characterized by a large void ratio, high compressibility, high water content, low impermeability, low strength, strong structure and high sensitivity. As a result, it has pronounced rheological properties, and controlling "bridge-head bumping" in soft soil ground is essential to control the amount of soil rheology-induced unstable successive settlement. The book offers extensive information on this and related topics, making it a valuable guide for engineers in Civil Engineering and Geotechnical Engineering alike.

Abstrak :
This Handbook provides researchers, faculty, design engineers in industrial R&D, and practicing engineers in the field concise treatments of advanced and more-recently established topics in thermal science and engineering, with an important emphasis on micro- and nanosystems, not covered in earlier references on applied thermal science, heat transfer or relevant aspects of mechanical/chemical engineering. Major sections address new developments in heat transfer, transport phenomena, single- and multiphase flows with energy transfer, thermal-bioengineering, thermal radiation, combined mode heat transfer, coupled heat and mass transfer, and energy systems. Energy transport at the macro-scale and micro/nano-scales is also included. The internationally recognized team of authors adopt a consistent and systematic approach and writing style, including ample cross reference among topics, offering readers a user-friendly knowledgebase greater than the sum of its parts, perfect for frequent consultation. The Handbook of Thermal Science and Engineering is ideal for academic and professional readers in the traditional and emerging areas of mechanical engineering, chemical engineering, aerospace engineering, bioengineering, electronics fabrication, energy, and manufacturing concerned with the influence thermal phenomena.

Abstrak :
Mampu bentuk (formability) material bukan hanya ditentukan oleh mikrostruktur dari material, temperatur, laju regangan (strain rate) dan regangan (strain), tetapi juga tahapan tegangan pada zona deformasi. Uji tarik panas merupakan salah satu metode pengujian yang dilakukan untuk mengevaluasi sifat mekanis dari material, memperoleh informasi plastisitas material dan sifat perpatahan (fracture). Pengujian dilakukan dengan menggunakan parameter dari persamaan konstitutif dimana tegangan alir merupakan fungsi dari regangan, laju regangan dan temperatur. Hal ini dapat menjelaskan karakteristik Rheologi dari material tersebut. Penelitian ini bertujuan untuk mempelajari karakteristik Rheologi dari material baja HSLA (ASTM A572 Gr 50) dengan menentukan parameter persamaan konstitutif menggunakan uji tarik panas, dengan variabel temperatur 700°C, 750°C, 800°C, dan 850°C. Dalam penelitian ini dapat dihasilkan parameter persamaan konstitutif untuk paduan Baja HSLA (ASTM A572 Gr 50), yaitu σ = K. ɛn. έm. eQ /RT, di mana dengan meningkatnya temperatur dari 700°C ke 800°C akan menurunkan nilai koefisien pengerasan regang (n) sebesar 47% dan menurunkan % elongasi sampel sebesar 26%. Pada laju regangan 0.1 s-1 dengan meningkatnya temperatur dari 700°C ke 850°C akan menurunkan tegangan luluh sebesar 42%. Pada laju regangan 0.1 s-1 dengan meningkatnya temperatur dari 750°C ke 850°C, akan meningkatkan nilai koefisien sensitifitas laju regangan (m) sebesar 96%. Pada temperatur konstan 850°C, dengan meningkatnya laju regangan dari 0.01 s-1 ke 0,1 s-1 akan menurunkan nilai energi aktivasi sebesar 2%. ......Formability not only determined by the microstructure of the material, temperature, strain rate and strain, but also stage the voltage on the deformation zone. Hot tensile test one method of testing conducted to evaluate the mechanical properties of the material, information material plasticity and fracture properties. Tests carried out by using the parameters of constitutive equations in which the flow stress is a function of strain, strain rate and temperature. This may explain the rheological characteristics of the material. This research aims to study the rheological characteristics of HSLA steel material (ASTM A572 Gr 50) by determining the parameters of the constitutive equation using hot tensile test, with variable temperature 700°C, 750°C, 800°C and 850°C. In this study the constitutive equation can be generated parameters for HSLA steel alloy (ASTM A572 Gr 50), namely σ = K. ɛn. έm. eQ / RT, where with increasing temperature from 700°C to 800°C will lower the value of strain hardening coefficient (n) by 47% and lower % elongation of 26% of samples. At the strain rate 0.1 s-1 with increasing temperature from 700°C to 850°C will lower the yield stress by 42%. At the strain rate 0.1 s-1 with increasing temperature from 750°C to 850°C, will increase the value of strain rate sensitivity coefficient (m) of 96%. At a constant temperature of 850°C, with increasing strain rate from 0.01 s-1 to 0.1 s-1 would lower the activation energy value of 2%.