Judul: Characteristics of Polyurethane Adhesive and Cross Laminated Timber made with a Combination of Mangium and Puspa
Abstrak: Tujuan dari penelitian ini adalah untuk mengevaluasi karakteristik CLT dari mangium, puspa, dan kombinasinya menggunakan perekat poliuretan (PU 1.2). Pembuatan CLT dimulai dengan dasarkarakterisasi perekat, FTIR, Py-GCMS, dan analisis termo-mekanis (DMA). Sifat dasar bahan kayu juga diuji dengan responnya terhadap keterbasahan PU 1,2. Panel CLT (100 × 30 × 3,6) cm3 diproduksi dengan olesan lem 160 g.m-2, pada tekanan 0,80 MPa untuk 200 menit. Panel CLT dicirikan mengacu pada standar JAS 3079 (2019). Hasilnya menunjukkan bahwa PU 1.2 memiliki waktu gelatinisasi 182,10 menit pada suhu 25 °C, mampu membentuk ikatan uretan dari analisis FTIR dan Py-GCMS, dan mengalami peningkatan modulus penyimpanan pada suhu 35 °C. Kayu mangium dan kayu puspa memiliki sifat fisik dan kimia yang berbeda, namun memiliki pengaruh yang cenderung sama terhadap keterbasahan PU 1,2. Panel CLT Puspa memiliki kerapatan yang lebih tinggi dari mangium, tetapi lebih rendah stabilitas dimensi. Sifat lentur PMP CLT mampu menandingi CLT PPP dan memiliki satu sampel kekuatan geser yang memenuhi JAS 3079 (2019) di kedua arah butir. Oleh karena itu, hibrida CLT PMP memiliki potensi untuk dikembangkan untuk meningkatkan stabilitas dimensi dan kekuatan mekanisnya., The objective of this study is to evaluate the CLT characteristics from mangium, puspa, and their combination using polyurethane (PU 1.2) adhesives. Manufacture of CLT begins with basic adhesive characterization, FTIR, Py-GCMS, and thermo-mechanical analysis (DMA). Basic properties of wood material were also tested with its response to the PU 1.2 wettability. The CLT (100 × 30 × 3.60) cm3 was manufactured with 160 g.m-2 glue spread, at pressure of 0.80 MPa for 200 minutes. The CLT panels were characterized refers to JAS 3079 (2019) standard. The results show that PU 1.2 had a gelatinization time of 182.10 minutes at 25 °C, was able to form bound urethane groups from FTIR and Py-GCMS analysis, and experienced an increase in storage modulus at 35 °C. Mangium and puspa wood have different physical and chemical properties, but they have the same interaction with PU 1.2 wettability. Puspa CLT panel has a higher density than mangium, but lower dimensional stability. Bending properties of PMP CLT were able to match PPP CLT and have one sample of shear strength that met JAS 3079 (2019) in both grain directions. Therefore, PMP hybrid CLT has the potential to be developed to improve its dimensional stability and mechanical strength.
Keyword: kombinasi lapisan, mangium, papan laminasi silang, perekat poliuretan, puspa, cross-laminated timber, layer combination, polyurethane adhesive

Judul: Influence of Layer Combination of Pine and Coconut on Characteristic of  Cross Laminated Timber Bonded With Polyurethane Adhesive
Abstrak: Tujuan dari penelitian ini adalah untuk mengevaluasi karakteristik kayu laminasi silang (CLT) yang terbuat dari kayu pinus, batang kelapa dan kombinasinya menggunakan perekat poliuretan. Pembuatan CLT diawali dengan karakterisasi bahan perekat dan kayu yang digunakan dalam penelitian ini. Panel CLT dibuat dengan dimensi 100 cm x 30 cm x 3,6 cm, masing-masing panjang, lebar, dan tebal. Laminasi disusun menjadi tiga lapis dengan muka/inti/belakang yaitu PPP, KKK, PKP, dan KPK, saling tegak lurus menggunakan perekat poliuretan dengan sebaran lem 160 g.m-2. Sifat fisis dan mekanis CLT dinilai mengacu pada standar JAS 3079 (2019). Hasil penelitian menunjukkan bahwa perekat poliuretan yang digunakan pada penelitian ini mampu mengeras secara optimal pada suhu 30 °C selama 200 menit. Kayu pinus dan kelapa memiliki sifat fisis dan kimia yang berbeda, tetapi memiliki keterbasahan yang mirip dengan perekat poliuretan. CLT pinus hibrida memiliki karakteristik yang lebih baik daripada CLT pinus tunggal. Sebaliknya, CLT kelapa tunggal memiliki karakteristik yang lebih baik dibandingkan dengan CLT kelapa hibrida. Semua sampel CLT tidak memenuhi standar JAS 3079 (2019) untuk delaminasi (≤10%) dan kerusakan kayu (≥90%)., The aims of this study was to evaluated characteristic of cross laminated timber (CLT) made from pine wood, coconut trunk, and their combination using polyurethane adhesive. The manufacturing of CLT begins with the characterization of the adhesive and wood materials used in this study. The CLT panels are made with dimensions of 100 cm by 30 cm by 3.6 cm, in length, width, and thickness, respectively. The laminate was organized into three layers with the face/core/back, namely PPP, CCC, PCP, and CPC, perpendicular to each other using polyurethane adhesive with a glue spread of 160 g.m-2. The physical and mechanical properties of the CLT were assessed alluding to the JAS 3079 (2019) standard. The results showed that the polyurethane adhesive used in this study was able to curring optimally at a temperature of 30 °C for 200 minutes. Solid pine and coconut had different physical and chemical properties, but had similar wettability to polyurethane adhesives. Hybrid pine CLT has better characteristics than single pine CLT. In contrast, single coconut CLT has better characteristics than hybrid coconut CLT. All samples of CLT didn’t meet the JAS 3079 (2019) standard for delamination (≤10%) and wood failure (≥90%).
Keyword: Coconut trunk, Cross Laminated Timber, Layer combination, Pine wood, Polyurethane adhesive

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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