Judul: Quality of Kenaf (Hibiscus cannabinus L.) Cored Particleboard by Using Recycled Polypro
Abstrak: Kelangkaan bahan baku untuk industri papan partikel terjadi akibat kurangnya pasokan kayu yang selama ini berasal dari hutan alam fungsi produksi atau hutan tanaman. Pasokan kayu yang berasal dari kawasan tersebut diketahui sudah mengalami penurunan pasokan yang diakibatkan sistem pemanenan yang kurang lestari dan permintaan kayu yang semakin meningkat. Hal tersebut mendorong pemikiran-pemikiran untuk mencari bahan berlignoselulosa lain sebagai pengganti kayu, salah satunya adalah dengan memanfaatkan core kenaf (Hibiscus cannabinus L.). Tanaman kenaf telah banyak diteliti untuk menjadi substitusi bahan baku papan partikel yang dikomposisikan dengan menggunakan perekat formaldehida (Puspita 2004; Susanta 2004; Ronaldi 2004). Penggunaan formaldehida sebagai bahan perekat dinilai menimbulkan emisi formaldehida yang berdampak negatif bagi lingkungan. Untuk mengurangi dampak negatif dari penggunaan formaldehida, maka perekat yang digunakan dapat berasal dari limbah plastik seperti polipropilena yang dinilai lebih ramah lingkungan, memiliki potensi yang besar untuk dimanfaatkan dan menghasilkan stabilitas dimensi produk yang lebih baik. Pembuatan papan partikel dilakukan dengan mencampur serbuk kenaf (Hibiscus cannabinus L.) dengan plastik polipropilena. Pencampuran kedua bahan tersebut terdiri dari beberapa komposisi campuran serbuk kenaf/polipropilena yaitu 50:50, 40:60 dan 30:70. Pengujian sifat fisis yang dilakukan antara lain kerapatan, kadar air, daya serap air dan pengembangan tebal. Sifat mekanis yang diuji antara lain MOE, MOR dan kuat pegang sekrup. Dari hasil penelitian yang dilakukan, penggunaan komposisi serbuk kenaf/polipropilena dari 50/50 sampai dengan 30/70 pada pembuatan papan partikel menghasilkan nilai kerapatan, MOE, MOR dan kuat pegang sekrup yang sama. Namun, untuk sifat fisis yaitu kadar air, daya serap air dan pengembangan tebal menghasilkan nilai yang berbeda, dimana komposisi 40/60 dan 30/70 merupakan komposisi terbaik dari papan partikel serbuk kenaf/polipropilena.
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Judul: Kualitas Papan Partikel Core Kenaf (Hibiscus cannabinus L.) dengan Menggunakan Polipropilena Daur Ulang.
Abstrak: INTRODUCTION : Scarcity of raw materials for particleboard industry was occurred which is caused by the lack of wood supply that up till now comes from production functioned natural forest or planted forest. Wood supply from those areas has been decreased which is caused by less sustainable harvesting system and increasing of wood demands. Those conditions courage the ideas to find other ligno-cellulosed materials to replace wood; one of them are by using kenaf (Hibiscus cannabinus L.) core. Kenaf plant has been researched as substitute for particleboard raw material which composited by using formaldehyde adhesive (Puspita 2004; Susanta 2004; Ronaldi 2004). Utilization of formaldehyde adhesive has been appreciably produce negative impact to environment. To decrease negative impact from formaldehyde utilization, adhesive, which is used, could originate from plastic waste such as polypropylene which appreciable more eco-friendly, has high potential to be used, and produce better product dimensional stability. MATERIALS AND METHOD: Particleboard was made by mix kenaf (Hibiscus cannabinus L.) powder with polypropylene plastic. Mixture of those two materials consists of some kenaf powder/polypropylene mixture composition; those are 50:50, 40:60 and 30:70. Examined physical characters are density, moisture content, water absorption rate and thickness swelling rate. Examined mechanical characters are MOE, MOR, and screw holding power. RESULTS : From research results, utilization of kenaf powder/polypropylene mixture composition from 50:50 to 30:70 for particleboard production produce density, MOE, MOR and screw holding power with similar values. But, for physical character such as moisture content, water absorption rate and thickness swelling has different value, where the best kenaf powder/polypropylene mixture composition are 40:60 and 30:70.
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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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