Judul: Physical and mechanical properties of poly ethylene glicol and polystyrene wood from mangium (acacia mangium willd.) and pine (pinus merkusii jungh. et de vries)
Abstrak: Impregnasi kayu merupakan salah satu teknologi modifikasi kayu untuk meningkatkan sifat fisis dan mekanis. Tujuan penelitian ini adalah untuk membandingkan sifat fisis dan mekanis kayu Mangium dan Tusam dengan pemberian Poly Ethylene Glicol (PEG) dan Polystyrene. Bahan baku yang digunakan yaitu kayu mangium dan tusam. Impregnasi kayu dilakukan dengan menggunakan metode vakum tekan yaitu dengan pengisian bahan kimia seperti poli etilen glikol (PEG) dan polistiren ke dalam kayu dengan proses polimerisasi pemanasan. Jenis pengujian sifat fisis dan mekanis yang dilakukan mengacu pada British Standard (BS) 373:1957 meliputi kadar air, kerapatan, kembang susut, keteguhan lentur statis, keteguhan patah, keteguhan geser, dan kekerasan. Hasil pengujian menunjukkan nilai rata-rata kadar air pada kayu mangium berkisar 7.26-10.17% dan kayu tusam berkisar 8.75-15.64%. Nilai rata-rata kerapatan pada kayu mangium berkisar 0.44-0.55 g/cm3 dan kayu tusam berkisar 0.70-0.96 g/cm3. Nilai rata-rata kembang susut pada kayu mangium berkisar 1.40-5.53% dan kayu tusam berkisar 0.61-3.96%. Nilai rata-rata keteguhan lentur statis pada kayu mangium berkisar 44678-74924 kg/cm2 dan kayu tusam berkisar 43754-69938 kg/cm2. Nilai rata-rata keteguhan patah pada kayu mangium berkisar 337-589 kg/cm2 dan kayu tusam berkisar 251-615 kg/cm2. Nilai rata-rata keteguhan geser pada kayu mangium berkisar 40-90 kg/cm2 dan kayu tusam berkisar 34-104 kg/cm2. Nilai rata-rata kekerasan pada kayu mangium berkisar 356-583 kg/cm2 dan kayu tusam berkisar 201-717 kg/cm2. Pemberian polistiren dan poli etilen glikol baik pada kayu mangium maupun tusam dapat meningkatkan kadar air, kerapatan, keteguhan lentur statis, dan kekerasan tetapi kembang susut, keteguhan patah dan keteguhan geser menurun., Impregnation of timber is one of the wood modification technology to improve the physical and mechanical properties. The research objective it was to compare physical and mechnical properties on mangium and pine timber impregnated with poly ethylene glicol (PEG) and polystyrene. The materials used were mangium and pine. Impregnation used vacuum pressure method which was by filling chemical substances of poly ethylene glicol (PEG) and polystyrene through by thermal polimerisation on the timber. The test impregnation wood conducted by refer the (British Standard (BS) 373:1957) comprised moisture content, density, shrinkage swelling, stiffness, static bending strength, shear strength and hardness. The result showed the average value of the moisture content ranged 7.26-10.17% for mangium and 8.75-15.64% for pine. The average value of the density ranged 0.44-0.55 g/cm3 for mangium and 0.70-0.96 g/cm3 for pine. The average value of the shrinkage swelling ranged 1.40-5.53% for mangium and 0.61-3.96% for pine. The average value of the stiffness ranged 44678-74924 kg/cm2 for mangium and 43754-69938 kg/cm2 for pine. The average value of static bending strength ranged 337-589 kg/cm2 for mangium and 251-615 kg/cm2 for pine. The average value of shearing strength ranged 40-90 kg/cm2 for mangium and 34-104 kg/cm2 for pine. The average value of hardness ranged 356- 583 kg/cm2 for mangium and 201-717 kg/cm2 for pine. The addition of polystyrene and poly ethylene glycol into mangium or pine are increasing the moisture content, density, stiffness and hardness, but shrinkage swelling, static bending strength and shearing strength are decreased.
Keyword: mangium, poli etilen glikol, polistiren, sifat fisis dan mekanis, tusam

Judul: Physical Properties and Color Changes in Polystyrene Impregnated Mangium (Acacia mangium) Glulam
Abstrak: Glue Laminated Timber (Glulam) merupakan salah satu produk komposit dari kayu. Tujuan penelitian ini untuk mengetahui pengaruh impregnasi polistirena terhadap sifat fisis dan perubahan warna glulam dari kayu mangium (Acacia mangium). Tujuan perlakuan impregnasi untuk peningkatan sifat fisis kayu dengan cara memasukkan monomer stirena ke dalam kayu. Evaluasi karakteristik yang dilakukan adalah polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna. Hasil penelitian menunjukkan bahwa nilai rata-rata polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna masing-masing adalah 5,25 %, 0,69-0,80 g·cm-3, 10,07-11,58 %, 6,4-19,69 %, dan 7,04. Pembuatan glulam impregnasi polistirena kayu mangium dapat meningkatkan sifat fisis pada glulam. Nilai kerapatan tertinggi dan kadar air terendah didapatkan pada glulam impregnasi polistirena. Impregnasi polistriena memberikan pengaruh yang berbeda (different colors) terhadap perubahan warna kayu mangium. Warna kayu menjadi lebih gelap setelah terimpregnasi polistirena. Nilai delaminasi glulam impregnasi polistirena tidak sesuai standar., Glue Laminated Timber (Glulam) is a composite product made of wood. The purpose of this study was to determine the effect of polystyrene impregnation on the physical properties and color changes of glulam from mangium (Acacia mangium). The purpose of impregnation treatment is to improve the physical properties of wood by incorporating styrene monomer into the wood. Characteristic evaluation carried out were polymer loading, density, moisture content, delamination, and color change. The results showed that the average values of polymer loading, density, moisture content, delamination, and color change were 5.25%, 0.69-0.80 g·cm-3, 10.07-11.58 %, 6.4-19.69%, and 7.04. The manufacture of glulam impregnation of mangium wood polystyrene can improve the physical properties of the glulam. The highest density values and the lowest water content were found in polystyrene impregnated glulam. Polystyrene impregnation has a different effect (different colors) on the color change of mangium wood. The color of the wood becomes darker after being impregnated with polystyrene. The delamination value of polystyrene impregnated glulam is not up to standard.
Keyword: fast growing wood, glulam, impregnation, isocyanate, mangium

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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