Judul: Characteristics of Particle Board from Oil Palm Fronds and Water Soluble Chitosan Adhesive using Three-step Press Method
Abstrak: Mengurangi ketergantungan akan kayu dan emisi formaldehida yang berbahaya menjadi alasan utama dilakukannya studi papan partikel berperekat organik. Pelepah sawit dan kitosan larut air telah diketahui dapat dimanfaatkan sebagai bahan baku papan partikel yang ramah lingkungan. Tujuan penelitian ini adalah menganalisis pengaruh metode kempa three-step press terhadap sifat fisis, mekanis, dan akustik dari papan partikel pelepah sawit berperekat kitosan larut air. Papan partikel disintesis pada variasi suhu 180 oC dan 200 oC. Total waktu pengempaan selama 15 menit dengan breathing stage diletakkan di menit 5 dan menit 10 untuk perlakuan three-step press. Hasil penelitian menunjukkan peletakan fase breathing stage yang semakin mendekati akhir dari total waktu pengempaan meningkatkan sifat fisis dan mekanis papan. Berdasarkan hasil penelitian ini dan merujuk penelitian terdahulu, ada faktor jenis perekat yang berpengaruh pada efektifitas metode three-step press. Secara keseluruhan, variasi suhu 180 oC menghasilkan sifat papan yang lebih baik daripada suhu 200 oC. Pengujian sifat akustik menunjukkan papan yang dikempa dengan metode three-step press termasuk kedalam kategori penyerap suara kelas C menurut standar ISO 11654:1997 dengan nilai NRC sebesar 0,60., Reducing both dependence on wood and harmful formaldehyde emissions are the main reasons for the study of green adhesive particleboard. Palm fronds and water-soluble chitosan have been known to be utilized as raw materials for environmentally friendly particleboard. The purpose of this study was to analyze the effect of the three-step press method on the physical, mechanical, and acoustic properties of water-soluble chitosan-adhesive palm frond particleboard. The particleboard was synthesized at temperature variations of 180 oC and 200 oC. The total pressing time was 15 minutes with the breathing stage placed at 5 minutes and 10 minutes for the three-step press treatment. The results showed that placing the breathing stage closer to the end of the total pressing time improved the physical and mechanical properties of the board. Based on the results of this study and referring to previous research, there is a factor of adhesive type that affects the effectiveness of the three-step press method. Overall, the 180 oC temperature variation produced better board properties than the 200 oC temperature. Tests of acoustic properties show that the board forged with the three-step press method is included in the class C sound-absorbing category according to ISO 11654: 1997 standard with an NRC value of 0.60.
Keyword: Papan Partikel, Sifat Akustik, Kitosan larut air, Pelepah sawit, three-step press, acoustical properties, oil palm fronds, particleboard, water-soluble chitosan

Judul: Characteristics of Water Soluble Chitosan and Citric Acid Adhesive Corn Husk Particle Board: The Effect of Board Density and Thickness
Abstrak: Keterbatasan bahan baku industri perkayuan mendorong pemanfaatan material berlignoselulosa, kelobot jagung sebagai bahan pengganti kayu, seperti papan partikel. Penelitian ini bertujuan mengetahui pengaruh variasi kerapatan dan ketebalan terhadap sifat fisik, mekanik, akustik, dan termal papan partikel dengan perekat campuran kitosan larut air dan asam sitrat 15%. Papan memiliki variasi kerapatan (0,6 dan 0,8 g/cm3) dan variasi ketebalan (3, 6, dan 9 mm). Ukuran partikel kelobot jagung 4-14 mesh. Papan berukuran 25×25 cm diproduksi menggunakan kempa panas dengan suhu 180°C dan tekanan 5 MPa (3 mm) dan 10 MPa (6 dan 9 mm) selama 15 menit. Hasil uji kerapatan sebesar 0,65-0,84 g/cm3, kadar air 3,14-13,04%, pengembangan tebal 59,08-113,92%, daya serap air 78,18-180,74%, MOE 4029-7005 kgf/cm2, MOR 53-146 kgf/cm2, IB 0,71-6,67 kgf/cm2, SHP 42,34-103,44 kgf. Koefisien absorpsi suara (α) pada uji akustik sudah memenuhi standar ISO 11654 dan termasuk ke dalam kelas D untuk serapan normal. Papan partikel bersifat isolator panas dengan nilai KT 0,16-0,21 W/m.K. Uji wettability papan bersifat hidrofilik dengan sudut kontak 65°-89°. Variasi papan partikel kerapatan 0,8 g/cm3 dan ketebalan 6 mm menghasilkan kualitas terbaik sesuai standar SNI 03-2105-2006., The limited raw materials of the wood industry encourage the use of lignocellulose materials, corn husk as a substitute for wood, such as particle board. This study aims to determine the effect of density and thickness variations on the physical, mechanical, acoustic, and thermal properties of particle board with a mixture 15% of water soluble chitosan and citric acid. Boards have density variations (0.6 and 0.8 g/cm3) and thickness variations (3, 6, and 9 mm). The particle size of corn husk is 4-14 mesh. The 25×25 cm board is manufactured using a hydraulic hot press with a temperature of 180°C and pressures of 5 MPa (3 mm) and 10 MPa (6 and 9 mm) for 15 minutes. Test results of density 0.65-0.84 g/cm3, moisture content 3.14-13.04%, thickness swelling 59.08-113.92%, water absorption 78.18-180.74%, MOE 4029-7005 kgf/cm2, MOR 53-146 kgf/cm2, IB 0.71-6.67 kgf/cm2, SHP 42.34-103.44 kgf. The sound absorption coefficient (α) in the acoustic test has fulfilled the requirement of ISO 11654 standards and is included in class D for normal absorption. Particle board is a heat insulator with a KT value of 0.16-0.21 W/m.K. The board wettability test is hydrophilic with a contact angle of 65°-89°. Particle board variations of 0.8 g/cm3 density and 6 mm thickness produce the best quality according to SNI 03-2105-2006 standards.
Keyword: citric acid, corn husk, water soluble chitosan, particle board

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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