Judul: Karakterisasi Komposit Karbon Berbahan Lignin dari Kayu Akasia (Acacia mangium Willd.) dan PET (Polietilena Tereftalat)
Abstrak: Serat Karbon merupakan jenis serat yang mempunyai konduktivitas termal tertinggi dengan bahan baku Polyacrylonitrile (PAN) yang bersifat non-renewable, mahal, tidak ramah lingkungan serta belum dapat di produksi di Indonesia. Lignin dari kayu akasia dan Polietilena Tereftalat (PET) menjadi alternatif pengganti PAN sebagai bahan baku serat karbon yang dapat menurunkan biaya pembuatan dan ramah lingkungan. Penelitian ini bertujuan untuk menghasilkan karbon komposit berbahan lignin kayu akasia dan PET yang murah, ramah lingkungan serta mudah didapatkan hingga mendapatkan rekomendasi produk karbon komposit yang tepat. Karakterisasi dilakukan dengan menggunakan perlakuan kadar lignin dan PET yang berbeda yaitu (Lignin 20% : PET 80%), (Lignin 30% : PET 70%), dan (Lignin 40% : PET 60%) dengan melaui tiga tahapan karakterisasi yaitu pencetakan (L), Stabilisasi (S), dan Karbonisasi (A). Penelitian karbon komposit campuran antara lignin dari kayu akasia dan PET memperoleh hasil yang optimal di setiap pengujian karakterisasi TGA, FE-SEM, XRD, dan FTIR. Namun, pengujian sifat mekanis perlu dilakukan agar dapat menentukan produk yang tepat dari komposit karbon., Carbon fiber has the highest thermal conductivity with raw materials Polyacrylonitrile (PAN), which is non-renewable, expensive, not environmentally friendly, and cannot be produced in Indonesia. Lignin from acacia wood and polyethylene terephthalate (PET) are alternatives to PAN as raw materials for carbon fibers that can reduce manufacturing costs and are environmentally friendly. This study aims to produce carbon composites made from acacia wood lignin and PET that are cheap, environmentally friendly, and readily available to get recommendations for the right carbon composite products. Characterization was carried out using different lignin and PET content treatments, namely (Lignin 20%: PET 80%), (Lignin 30%: PET 70%), and (Lignin 40%: PET 60%), by going through three characterization stages, namely Printing (L), Stabilization (S), and Carbonization (A). The research on carbon composite mixture between lignin from acacia wood and PET obtained optimal results in each TGA, FE-SEM, XRD, and FTIR characterization test. However, mechanical properties testing must be done to determine the right product from the composite carbon.
Keyword: blends, carbon, characterization, lignin, PET

Judul: The Effect of Lignin Consentration on Physical and Mechanical Properties of Bioplastic with Polylactic acid (PLA) based
Abstrak: Plastik dengan sifat biodegradable mudah dihancurkan dan ramah lingkungan. Bioplastik dapat menjadi solusi pengganti plastik karena dapat terurai oleh aktivitas mikroorganisme tanpa menyisakan residu beracun, terbuat dari bahan yang dapat diperbarui, dan dapat menjaga kualitas produk. PLA merupakan polimer alami yang mempunyai sifat biodegradable dalam pembuatan bioplastik. Penambahan lignin dalam pembuatan bioplastik dapat menjadi agen penguat yang baik dalam polimer matriks PLA dan merupakan kandidat yang potensial untuk bahan pembuatan bioplastik. Salah satu sumber lignin adalah tandan kosong kelapa sawit (TKKS). Tujuan dari penelitian ini adalah mengisolasi lignin dari TKKS dan menganalisis sifat fisik dan mekanik bioplastik PLA-lignin. Lignin diperoleh dari proses isolasi lignin dan ultrasonikasi. Bioplastik PLA-lignin dihasilkan dari campuran PLA sebagai matriks dengan penambahan konsentrasi lignin yang berbeda (0%, 2.5%, 5%, 7.5%, 10%). Pembuatan bioplastik dilakukan dengan metode solvent casting. Komposisi lignin dalam TKKS diperoleh dengan uji proksimat. Karakterisasi morfologi lignin dan film bioplastik dianalisis menggunakan scanning electron microcopy (SEM), komponen gugus fungsi dianalisis dengan fourier transform infrared (FTIR), sifat mekanik dianalisis dengan uji mekanik tensile strength, dan laju transmisi uap air pada film bioplastik dianalisis dengan uji WVTR. Bioplastik PLA-lignin menghasilkan adhesi permukaan dan kompatibilitas yang baik ketika ukuran lignin diperkecil. Lignin dengan konsentrasi 5% pada pembuatan bioplastik dapat menghasilkan adhesi permukaan dan kompatibilitas yang lebih baik dibandingkan dengan konsentrasi diatas 5%. Pencampuran PLA dan lignin dapat meningkatkan sifat fisik dan mekanik dari film bioplastik PLA-lignin seperti meningkatkan kuat tarik, elongasi, dan modulus Young dibandingkan dengan bioplastik dari PLA murni., The properties of biodegradable plastic are easily decomposed and ecofriendly. Bioplastics can be a plastic replacement solution because they can be decomposed by microorganism activity without leaving toxic residues, made from renewable materials, and maintaining the product quality. PLA is a natural polymer that has biodegradable properties in bioplastics manufacturing. The addition of lignin can be a good reinforcement agent in PLA matrix polymers and potential candidates in bioplastic manufacturing materials. One of the lignin sources is oil palm empty fruit bunches (OPEFB). The research aims to isolate the lignin from OPEFB and analyze the physical and mechanical properties of PLA-lignin. Lignin from OPEFB is obtained from isolation and ultrasonication process. PLA-lignin-based bioplastics are produced from a mixture of PLA as matrix and lignin in different concentrations (0%, 2.5%, 5%, 7.5%, 10%). The casting method was applied to produce the bioplastics. The composition of lignin in OPEFB was obtained by proximate test. Morphological structure of lignin, bioplastic films and functional group components were analyzed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR), respectively. Mechanical properties and water transmission rate of bioplastic films were analyzed by mechanical tensile strentgh and WVTR test, respectively. PLA-lignin-based bioplastics produce a good compatibility and surface adhesion when the size of lignin is reduced. The 5% of lignin concentration in bioplastics showed that the better compatibility and surface adhesion compared to the higher concentration. Compared to PLA-based bioplastics, PLA-lignin-based bioplastics can increase the mechanical and physical properties, such as tensile strength, elongation, and Young’s modulus.
Keyword: bioplastic, lignin, Polylactic acid (PLA), TKKS, physical and mechanical properties

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model