Judul: Characteristics Of Mangium Bark Tannin-Based Non-Isocyanate Bio-Polyurethane Adhesives
Abstrak: Perekat tanin non-isosianat bio-poliuretan (T-NIPU) diformulasikan sebagai altenatif perekat poliuretan isosianat. Penelitian ini bertujuan karakterisasi bahan baku T-NIPU serta mengevaluasi pengaruh jenis formula terhadap karakteristik T-NIPU. Bahan baku T-NIPU berupa tanin hasil ekstraksi kulit kayu mangium (Acacia mangium Wild) sebagai subtitusi poliol, dimetil karbonat (DMC) dengan heksametilentetraamina (HMTA) sebagai subtitusi isosianat, dan water glass (WG) sebagai filler dikarakterisasi. Bahan baku disintesis menjadi T-NIPU dalam 3 formula dengan perbedaan bobot WG. T-NIPU kemudian dikarakterisasi kadar padatan, pH, waktu gelatinasi, reologi, hidrolisis, dan FTIR. Kadar padatan ekstrak tanin sebesar 94,54% dengan rendemen 21,70%. Karakteristik bahan baku kenampakan tidak berwarna kecuali tanin dengan pH bahan HMTA dan WG cenderung basa kuat mengakibatkan perekat memiliki kenampakan hitam dengan pH basa. Peningkatan WG dalam formula T-NIPU meningkatkan kadar padatan, pH, dan reologi perekat, serta hidrolisis (mass loss (MS) dan pH larutan), tetapi mempercepat waktu gelatinasi. Analisis gugus fungsi menunjukkan terdeteksinya ikatan uretan (–NHCOO–) pada sintesis T-NIPU, penambahan water glass menunjukkan pergeseran gelombang pada wilayah fingerprint., Tannin-based non-isocyanate bio-polyurethane adhesive (T-NIPU) is prepared as an alternative to isocyanate polyurethane (PU) adhesives. This study aims to characterize T-NIPU adhesives and evaluate the influence of water glass (WG) on T-NIPU characteristics. The T-NIPU adhesives were formulated utilizing tannins extracted from mangium bark (Acacia mangium wild) as a polyol, dimethyl carbonate (DMC), hexamethylenetetramine (HMTA), and WG. The material is synthesized in three formulas with different WG weights. T-NIPU was then characterized by solid content, pH, gelation time, rheology, hydrolysis, and FTIR. The results showed that the solid content of tannin extract was 94.54%, with a yield of 21.70%. Except for tannins, the characteristics of the materials are colorless. The pH of HMTA and WG materials tends to be alkaline, resulting in adhesives that have an alkaline appearance. The addition of WG to the T-NIPU formula not only increases the solids content, pH, rheology, mass loss, and pH of the hydrolysed solutions, but also speeds up the gelation time. FTIR showed the detection of urethane bonds (–NHCOO–) in the synthesis of T-NIPU.
Keyword: mass loss, reologi, waktu gelatinasi, water glass

Judul: Characteristics of Tannin-Based Polyurethane Adhesive with Biopolyol Modification for Plywood
Abstrak: Perekat poliuretan terbentuk karena reaksi poliol dan diisosianat, namun kedua bahan ini mahal dan tidak terbarukan. Bahan subtitusi limbah tumbuhan seperti tanin merupakan solusi perekat poliuretan ramah lingkungan, murah, terbarukan, dan bebas formaldehida. Tujuan penelitian ini adalah mengkarakterisasi tanin, perekat poliuretan, dan menentukan formula efektif perekat poliuretan berbasis tanin. Perekat poliuretan dibuat dengan modifikasi polyvinyl alcohol (PVOH) tanin pada taraf konsentrasi 0%, 10%, 20%, 30%, 40%, dan 50%. Analisis dilakukan pada bahan baku, perekat, dan kayu lapis. Hasil analisis menunjukkan bahwa penambahan ekstrak tanin berpengaruh nyata terhadap viskositas, kadar padatan tanin, kerapatan, delaminasi, keteguhan rekat kering dan basah kecuali kadar air. Analisis gugus fungsi (FTIR) menunjukkan bahwa perekat poliuretan tanin cair dan padat memiliki gugus uretan, hidroksil, dan isosianat yang sama. Loss modulus DMA terendah yaitu poliuretan tanin 20%. Keteguhan rekat tertinggi adalah poliuretan tanin 20% dan sebanding dengan kerusakan kayunya. Berdasarkan hasil penelitian, PVOH/Tanin 20% merupakan formula efektif untuk perekat poliuretan berbasis tanin., The reaction of polyols and diisocyanates forms polyurethane adhesives, but these materials are expensive and non-renewable. Waste substitution bio-based materials such as tannins can be a solution caused that's environmentally friendly, cheap, renewable, and free of formaldehyde emissions. This study aimed to characterize tannins, polyurethane adhesives, and determine the effective formula of tannin-based polyurethane adhesives. Polyurethane adhesives made with modified polyvinyl alcohol (PVOH) tannins at concentration levels of 0%, 10%, 20%, 30%, 40%, and 50%. The analysis is carried out on raw materials, adhesives, and plywood. The analysis results showed that adding tannin extracts had a significant effect on viscosity, tannin solids, density, delamination, dry and wet adhesion constancy except for moisture content. Functional group analysis (FTIR) shows that liquid and solid tannin polyurethane adhesives have the same urethane, hydroxyl, and isocyanate groups. The lowest DMA loss modulus is polyurethane tannin 20%. The highest adhesion constancy is 20% tannin polyurethane and is proportional to wood damage. Based on the study's results, PVOH/Tannin 20% is an effective formula for tannin-based polyurethane adhesives.
Keyword: diisocyanates, polyol, polyurethane, PVOH, tannin

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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