Judul: Karakteristik Cross Laminated Timber (CLT) Kayu Jabon Dengan Perekat Melamin Formaldehida (MF) Modifikasi Aplikasi Kempa Dingin
Abstrak: Cross Laminated Timber (CLT) adalah papan komposit yang terbuat dari kayu berlapis-lapis yang ditumpuk tegak lurus serta ditingkatkan stabilitas dimensinya. Tujuan dari penelitian ini adalah menganalisis sifat fisis dan mekanis CLT dari kayu jabon (Anthocephalus cadamba) dengan perekat MF modifikasi. Modifikasi perekat MF dilakukan untuk penggunaan kempa dingin. Berat labur CLT terdiri atas tiga variasi yaitu 250, 280 dan 300 g/m2. Evaluasi karakteristik perekat MF modifikasi berupa kadar padatan, waktu gelatinasi, viskositas, pH, FTIR dan DMA. Evaluasi karakteristik fisis dan mekanis berupa kerapatan, kadar air, delaminasi, MOE sejajar serat muka dan tegak lurus serat muka (flatwise & edgewise), MOR sejajar serat muka dan tegak lurus serat muka (flatwise & edgewise), tekan sejajar serat, tekan tegak lurus serat dan keteguhan rekat. Berat labur CLT hanya berpengaruh nyata terhadap nilai delaminasi dan keteguhan rekat. CLT dengan berat labur 300 g/m2 memiliki karakteristik sifat fisis mekanis yang paling optimum. Semakin tinggi berat labur perekat, semakin tinggi sifat fisis dan mekanisnya. Kualitas produk kurang baik karena tekanan kempa yang minim pada saat pengempaan CLT., Cross Laminated Timber (CLT) is a composite board made of multilayered timber that is stacked perpendicularly and its dimensional stability is enhanced. The objective of this research was to analyze the physical and mechanical properties of CLT from jabon wood (Anthocephalus cadamba) with modified MF adhesive. Modified MF adhesive was carried out for cold pressing applications. The glue spreads of CLT consist of three variations, namely 250, 280, and 300 g/m2. Evaluation of the characteristics of modified MF adhesive in the form of solids content, gelation time, viscosity, pH, FTIR, and DMA. Evaluation of the physical and mechanical properties was carried out including density, moisture content, delamination, MOE parallel and perpendicular to the face grain (flatwise & edgewise), MOR parallel and perpendicular to the face grain (flatwise & edgewise), compression parallel to the grain, compression perpendicular to the grain, and bonding strength. The glue spreads of CLT only significantly affected the value of delamination and bonding strength. CLT with a glue spread of 300 g/m2 has the most optimum mechanical and physical properties. The higher the glue spread, the higher the physical and mechanical properties. The poor product quality because of minimal compression pressure during CLT compression.
Keyword: CLT, glue spreads, jabon wood, melamine formaldehyde, modification

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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