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: Formulation and Characterization of Non-Isocyanate Tanin Based  Bio-Polyurethane as Impregnating Agent for Fibers, Threads, and Ramie Fabrics
Abstrak: Industri tekstil membutuhkan alternatif pengganti serat kapas karena nilai impornya yang tinggi. Rami (Boehmeria nivea (L.) Gaudich) berpotensi untuk dikembangkan, tetapi memiliki kelemahan seperti mudah terbakar. Resin poliuretan non-isosianat berbasis tanin (T-NIPU) dapat dijadikan sebagai impregnan rami untuk meningkatkan stabilitas termal dan sifat mekanisnya. Penelitian ini bertujuan menganalisis sintesis resin T-NIPU dan menentukan karakteristiknya, serta menganalisis serat, benang, dan kain rami terimpregnasi. Resin T-NIPU dibuat dengan mencampurkan ekstrak kental tanin, dimetil karbonat, dan heksametilentetramin. Kemudian proses impregnasi rami dengan resin T-NIPU. Rendemen ekstraksi tanin yang diperoleh yaitu 22,71%. Analisis FTIR menujukkan adanya ikatan uretan pada T-NIPU maupun pada rami terimpregnasi. Interaksi jenis formula (F1, F2, F3, dan F4) dan jenis sampel (serat, benang, dan kain rami) memengaruhi nilai kuat tarik, MOE, dan flammability. Serat rami yang diimpregnasi resin T-NIPU F3 memiliki kekuatan tarik dan MOE tertinggi. Kain rami yang diimpregnasi resin T-NIPU F3 memiliki kecepatan bakar terendah. Serat rami lebih mudah terhidrolisis dibandingkan dengan benang dan kain rami., The textile industry needs a cotton fiber substitute because of its high import value. Although ramie (Boehmeria nivea (L.) Gaudich) shows potential for development, it suffers from a significant weakness such as flammability. Tanninbased non-isocyanate polyurethane resin (T-NIPU) can be used as a ramie impregnanting agnent to enhance thermal stability and mechanical properties. This study aims to analyze the synthesis of T-NIPU resins, determine their characteristics, and examine the fibers, threads, and ramie fabric that have been impregnated with T-NIPU resins. The thick extracts of tannins, dimethyl carbonate, and hexamethylentetramine were reacted to make the T-NIPU resin. Next, the TNIPU underwent the ramie impregnation process. The resulting tannin extraction yield is 22.71%. The FTIR analysis indicates that urethane bonds are present on both T-NIPU and impregnated samples. The interaction of formula types (F1, F2, F3, and F4) and sample types (fiber, thread, and fabric ramie) affects the strength values of tensile strength, modulus of elasticity, and flammability. T-NIPU F3 resin-impregnated ramie fibers have the highest traction strength and MOE. TNIPU F3 resin-impregnated ramie fabrics have the lowest burning speed. Ramie fiber is easier to hydrolyze than ramie thread and fabric.
Keyword: bio-poliuretan, impregnasi, non-isosianat, rami, tanin

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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