Judul: Analysis of Physical and Mechanical Properties of Gmelina wood (Gmelina arborea Roxb.) Modified with Furfuryl Alcohol-Tannin
Abstrak: Furfurilasi adalah teknik modifikasi kimia terkenal yang diterapkan pada kayu untuk meningkatkan sifat fisis dan mekanisnya. Penelitian ini bertujuan untuk mengetahui pengaruh modifikasi kayu dengan metode furfurilasi dan furfurilasi termodifikasi tanin terhadap sifat fisik dan mekanik kayu gmelina tropis (Gmelina arborea Roxb). Percobaan dilakukan dengan merendam kayu gmelina dalam larutan air furfuril alkohol (FA), FA 40%, dan FA 70%, serta FA 40% dan FA 70% dalam larutan tanin. Kayu yang dterimpregnasi ini kemudian dipolimerisasi pada suhu 103°C. Hasil penelitian menunjukkan bahwa selama impregnasi, larutan tanin sedikit menurunkan nilai serapan larutan dan nilai pengembangannya. Setelah dilakukan modifikasi, larutan tanin juga sedikit menurunkan persen pertambahan berat dan efek bulking kayu yang dimodifikasi. Namun pada FA 70%, penambahan tanin meningkatkan ketahanan terhadap ketercucian dan sifat mekanik kayu modifikasi. Analisis warna menunjukkan bahwa larutan tanin membuat kayu yang dimodifikasi menjadi lebih gelap dibandingkan kayu yang diberi perlakuan tanpa larutan tanin., Furfurylation is a well-known chemical modification technique applied to wood to enhance its properties. This research aims to determine the effect of wood modification using the furfurylation method and tannin-modified furfurylation on the physical and mechanical properties of tropical gmelina wood (Gmelina arborea Roxb). Experiments were carried out by impregnating gmelina wood in aqueous solutions of furfuryl alcohol (FA), FA 40%, FA 70%, and FA 40% and FA 70% in a tannin solution. These impregnated woods were then polymerized at 103°C. The results revealed that the tannin solution slightly lowered the solution uptake and swelling value during impregnation. After modification, the tannin solution also slightly decreased the modified wood's weight percent gain and bulking effect. However, at FA 70%, the addition of tannin increased leaching resistance and the mechanical properties of the modified wood. The color analysis identified that the tannin solution made the modified wood darker than the wood treated without the tannin solution.
Keyword: tanin, furfurilasi, Gmelina, modifikasi kimia, sifat fisis dan mekanis

Judul: Physical and Mechanical Properties of Sengon (Falcataria moluccana Miq.) and Mangium (Acacia Mangium Willd.) Wood Impregnated by Furfuryl Alcohol
Abstrak: Kayu yang digunakan di industri saat ini dipasok dari hutan tanaman. Kayu dari hutan tanaman secara umum memiliki sifat fisis dan mekanis yang rendah. Perlakuan furfurilasi dapat meningkatkan sifat fisis dan mekanis tersebut. Tujuan penelitian ini adalah untuk mendapatkan kayu sengon (Falcataria moluccana Miq.) dan mangium (Acacia mangium Willd.) dengan sifat fisis dan mekanis yang lebih baik melalui proses impregnasi furfuril alkohol (FA) dan menganalisis ada atau tidaknya ikatan kimia antara FA dengan komponen kayu. Kayu sengon dan mangium divakum pada 600 mmHg selama 30 menit, setelah vakum selesai, larutan FA dimasukkan ke dalam tabung impregnasi kemudian diberikan tekanan sebesar 10 kg/cm2 selama 30 menit. Contoh uji yang telah diimpregnasi kemudian dilapisi alumunium foil dan dimasukkan ke dalam oven bersuhu 103 oC selama 24 jam. Contoh uji diukur banyaknya penambahan berat setelah proses impregnasi (weight percent gain, WPG). Pengujian sifat fisis yang dilakukan pada contoh uji meliputi pengujian kadar air (KA), kerapatan, daya serap air (DSA), pengembangan dan penyusutan volume kayu, serta koefisien anti pengembangan (anti-swelling efficiency, ASwE) dan koefisien anti penyusutan (anti-shrinking efficiency, AShE). Pengujian mekanis berupa modulus of elasticity (MOE), modulus of rupture (MOR), dan kekerasan yang mengacu pada BS 373:1957. Pengujian sifat fisis dan mekanis juga dilakukan pada contoh uji tanpa perlakuan sebagai perbandingan, pengujian dilakukan sebanyak 10 ulangan tiap perlakuan. Hasil penelitian menunjukkan bahwa secara berurutan kayu sengon dan kayu mangium terfurfurilasi memiliki nilai WPG 46.49% dan 9.14%, KA berkurang sebesar 77.58% dan 66.04%, kerapatan meningkat 34.39% dan 10.07%, DSA berkurang 83.80% dan 75.99%, pengembangan volume berkurang sebesar 71.91% dan 72.46%, penyusutan volume juga berkurang sebesar 57.84% dan 52.72%, nilai ASwE 71.81% dan 71.77%, serta nilai AShE 51.23% dan 53.19%. Sifat mekanis kayu sengon dan mangium terfurfurilasi secara berurutan nilai MOE meningkat sebesar 19.89% dan 35.20%, MOR meningkat 0.90% dan 61.14%, kekerasan kayu sisi radial meningkat 51.35% dan 56.79%, kekerasan sisi tangensial meningkat 38.96% dan 84.58%, kekerasan ujung meningkat 20.00% dan 21.19%. Berdasarkan hasil tersebut dapat disimpulkan bahwa kayu sengon dan kayu mangium terfurfurilasi memiliki sifat fisis dan mekanis yang lebih baik dibanding kayu tanpa perlakuan. Hasil analisis melalui uji X-Ray Diffractometer, Fourier Transform Infra-Red, dan Gas Chromatography-Mass Spectrometry menunjukkan adanya ikatan kimia antara FA dengan kayu., The timber in industry is supplied from plantation forests. Timber from plantation forests generally has low physical and mechanical properties. Furfurylation treatment can improve physical and mechanical properties. The purpose of the study ware to obtain sengon (Falcataria moluccana Miq.) and mangium (Acacia mangium Willd.) woods with better physical and mechanical properties through the impregnation proses of furfuryl alcohol (FA) and analyze the presence of chemical bonds between FA and wood components. Sengon and mangium woods were vacuumed at 600 mmHg during 30 minutes, when the vacuum has been releasing, the FA reagent was inserted to the tank and followed with pressure at 10 kg/cm2 during 30 minutes. The specimens were wrapped with alumunium foil and heated in the oven at 103oC for 24 hours. The specimens were tested for physical properties including weight percent gain (WPG), moisture content (MC), density, water absorption (WA), swelling, shrinkage, and anti-swelling efficiency (ASwE) and
Keyword: Fast growing species, Wood modification, Furfurylated wood, Physical properties, Mechanical properties

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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