Judul: Evaluation of Homogenization Process in the Production of Agar-Based Hydrophobic Bioplastic Straws
Abstrak: Penggunaan alat makan sekali pakai seperti sedotan plastik berkontribusi besar pada masalah sampah di Indonesia. Pengembangan sedotan bioplastik degradable berbasis agar yang menjadi salah satu alternatif dihadapkan pada tantangan dalam proses industri. Penelitian bertujuan untuk mengoptimalkan kondisi homogenisasi dalam produksi sedotan bioplastik agar-based hydrophobic, dengan menggunakan alat homogenisasi alternatif berupa overhead stirrer. Metode penelitian mencakup eksperimen dengan desain 2k faktorial dan Rancangan Acak Kelompok (RAK). Parameter karakteristik sedotan yang diukur meliputi ketebalan, daya serap air, kekuatan tarik, elongasi, kekuatan lentur, sudut kontak, dan tingkat biodegradabilitas. Hasil penelitian menunjukkan bahwa sedotan terbaik memiliki tampilan fisik berwarna putih kecoklatan dengan tekstur permukaan yang halus dan kokoh saat ditekuk. Sedotan ini memiliki ketebalan 0,67±0,02 mm, daya absorpsi air 100,27±2,67%, kuat tarik 60,76±3,52 MPa, elongasi 38,61±5,16%, kuat lentur 1,72±0,18 MPa, serta sudut kontak permukaan 114,61±1,28º (hidrofobik). Selain itu, sedotan ini dapat terdegradasi sepenuhnya dalam tanah setelah 60 hari penanaman., Disposable cutlery like straws, significantly contributes to the waste issue in Indonesia. The development of degradable bioplastic straws based on agar, which serves as an alternative, faces challenges within the industrial process. This study aims to optimize the homogenization conditions in the production of agar-based hydrophobic bioplastic straws, utilizing an alternative homogenization tool, namely the overhead stirrer. The research methodology encompasses experiments with a 2k factorial design and a Randomized Complete Block (RCB) design. The measured straw characteristics include thickness, water absorption capacity, tensile strength, elongation, flexural strength, contact angle, and biodegradability. The research findings indicate that the optimal straw exhibits a physical appearance of light brownish white color with a smooth and robust surface texture when bent. This straw possesses a thickness of 0.67±0.02 mm, water absorption capacity of 100.27±2.67%, tensile strength of 60.76±3.52 MPa, elongation of 38.61±5.16%, flexural strength of 1.72±0.18 MPa, and a surface contact angle of 114.61±1.28° (hydrophobic). Furthermore, this straw can undergo complete degradation in the soil after 60 days of burial.
Keyword: agar, bioplastic, degradable straw, homogenization, hydrophobic

Judul: Bioplastic Formulations Based To Mixed Polymer On The Manufacture Of Degradable Water Resistant Straw
Abstrak: The type of plastic product that contributes to a significant amount of junk is a disposable plastic straw which reaches 93,2 million units per day. The solution is the manufacture of a bioplastic degradable straw in the raw materials agar can be obtained from the seaweed which has great potential for further research. The study aims to produce straws that can be untied from the ground and to feature the straw that is produced. Research procedures include the formulation of a straw, the manufacture of a straw and the analytical process for characterizing the straw produced. The general analysis that is done is, thickness, water absorption, microstructural, contact Angle, and analysis to see the clusters’ functional groups on the sample. Studies show that the best degradable drinking formula has a characteristic thickness of 0.401 ± 0.11 mm, with a straws' water absorption capacity of 87.908 ± 3.388%, a uniform composite surface, a strong pull of 44.40 MPa, an elongation of 39%, and a large hydraulic pressure point of 106.01 ± 2.69°, and a chemical occurrence of the contact point.
Keyword: degradable straw, plasticizer, polymer, agar, bioplastic

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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