Study towards the recycling of PET waste has arisen in the last decades. One of the most widely used methods was the mechanical recycling process due to its simplicity and low cost of production. In this research, PET waste obtained from the disposable water gallon containers was used to produce recycled PET fibers for textile applications. The PET fibers were prepared using the extrusion technique by varying the processing temperatures, i.e., 200, 210, 220, 230, and 240°C. The diameter, FTIR analysis, XRD analysis, and mechanical properties of the PET fibers at various processing temperatures were studied. The results showed that the optimum processing temperature for preparing recycled PET fibers was 210°C with a diameter of 0.23 mm, a degree of crystallinity of 8.9%, a tensile strength of 70.4 MPa, and an elongation at break of 83.6%. In conclusion, PET waste shows a promising application to be processed as recycled PET fibers for textile applications.
This study aims to use the hand-painting method in designing and fabricating a metamaterial based on a circular shape that exhibits a negative refractive index over the microwave spectrum. Hand painting is a simple and inexpensive fabrication method. This study applies silver ink as a periodic conductor to glossy paper as the dielectric substrate. The spectrum of investigation in this study is 3–6 GHz, and the experimental results obtained are compared with the simulation results. The slight error obtained between transmission results from the simulation and the experiments reflects limitations in the fabrication methods used. Overall, the experimental results present good agreement with the simulation results. The electrical properties of the metamaterial are retrieved from the transmission and reflection simulation results. The simulation results are employed instead of the experimental results because of the fluctuating data provided by the latter. The refractive index presents a negative value at 3–3.6 GHz.
Spray cooling merupakan aplikasi dari droplets yang digunakan sebagai salah satu teknik pendinginan. Pemanfaatan dari multiple droplets ini banyak dikaji sebagai sistem pendinginan pada peralatan elektronik dan pembuatan material quenching. Dinamika tumbukan multiple droplets pada permukaan bidang miring yang dipanaskan akan dikaji pada penelitian ini. Material uji yang digunakan adalah stainless steel 304 . Temperatur permukaan yang diamati adalah 120 ºC, 180 ºC dan 220 ºC pada bilangan Weber medium 70 dengan variasi bidang kemiringan adalah sebesar 10º, 20º dan 30º. Dinamika droplet selama tumbukan diamati menggunakan high-speed camera dengan kecepatan 4000 fps kemudian hasilnya diolah menggunakan image processing. Telah diperoleh hasil bahwa spreading ratio tertinggi terjadi saat temperatur permukaan 180 ºC pada sudut kemiringan 30 º dan terendah pada temperatur 220 ºC. Fenomena secondary droplet dapat meningkatkan nilai spreading ratio. Adapun fenomena bounching terjadi pada temperatur 220 ºC
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