Judul: Characterisrics of Polyurethane Adhesive and Cross Laminated Timber Made from Puspa Wood and Coconut Trunk
Abstrak: Penelitian ini bertujuan untuk mengevaluasi karakteristik perekat poliuretan dan CLT yang terbuat dari kayu puspa, batang kelapa, dan kombinasinya. Pembuatan CLT diawali dengan karakterisasi perekat seperti kadar padatan, waktu gelatinasi, viskositas, analisis gugus fungsi FTIR dan analisis Py-GCMS, serta analisis termomekanik. Sifat dasar (fisik, kimia, dan permukaan) bahan kayu juga diuji. Panel CLT dibuat dengan dimensi 100 cm × 30 cm × 3,6 cm. Laminasi disusun menjadi tiga lapis dengan bagian muka/inti/belakang yaitu kayu puspa (PPP), batang kelapa (KKK), dan kombinasi yang saling tegak lurus menggunakan perekat poliuretan dengan olesan lem 160 g.m-2. Kemudian, panel CLT dikempa menggunakan kempa dingin dengan tekanan spesifik 0,8 MPa pada suhu 30 °C selama 200 menit. Sifat fisik dan mekanik CLT dievaluasi mengacu pada standar JAS 3079:2019. Hasil penelitian menunjukkan bahwa perekat poliuretan yang digunakan dalam penelitian ini memiliki kadar padatan 96,95%, waktu gelatinasi selama 116, 8 menit, dan dapat mengeras secara optimal pada suhu 30 °C selama 200 menit atau lebih. Kayu puspa dan batang kelapa memiliki sifat fisik dan kimia yang berbeda, tetapi memiliki sifat keterbasahan yang sama dengan perekat poliuretan. Karakteristik fisik dan mekanik CLT kelapa lebih baik dibandingkan dengan CLT Puspa. Namun, semua sampel tidak memenuhi standar delaminasi JAS 3079 (2019). Berdasarkan hasil pengujian secara keseluruhan, CLT puspa hybrid lebih baik dibandingkan dengan CLT tunggal. Berbeda dengan kelapa dalam beberapa parameter, CLT tunggal lebih baik daripada CLT hibrida., This study aims to evaluate the characteristics of polyurethane adhesives and CLT made from puspa wood, coconut stems, and their combination. The manufacture of CLT begins with adhesive characterization such as solid content, gelatinization time, viscosity, FTIR functional group analysis and Py-GCMS analysis, as well as thermomechanical analysis. The basic properties (physical, chemical, and surface) of wood materials are also tested. The CLT panels are made with dimensions of 100 cm × 30 cm × 3.6 cm. The laminate is arranged into three layers with the face/core/back, namely puspa wood (PPP), coconut trunk (CCC), and a combination that is perpendicular to each other using polyurethane adhesive with 160 g.m-2 glue applied. Then, the CLT panels were compressed using cold compression with a specific pressure of 0.8 MPa at 30 °C for 200 minutes. The physical and mechanical properties of CLT were evaluated according to the JAS 3079:2019 standard. The results showed that the polyurethane adhesive used in this study had a solids content of 96.95%, a gelation time of 116.8 minutes, and could harden optimally at a temperature of 30 °C for 200 minutes or more. Puspa wood and coconut trunks have different physical and chemical properties, but have the same wettability as polyurethane adhesives. The physical and mechanical characteristics of coconut CLT were better than Puspa CLT. However, all samples did not meet the JAS 3079 (2019) delamination standard. Based on the overall test results, the hybrid puspa CLT is better than the single CLT. In contrast to coconut in several parameters, single CLT was better than hybrid CLT.
Keyword: batang kelapa, cross laminated timber, kayu puspa, kombinasi lapisan, perekat poliuretan, coconut trunk, layer combination, polyurethane adhesive, puspa wood

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: 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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