Judul: Coconut Coir Polymer Composites at Various Catalyst Content and Alkalisaton Time
Abstrak: Material komposit berpenguat serat alam mulai dikembangkan sebagai alternatif komposit fiberglass. Sabut kelapa berpontensi dijadikan sebagai penguat komposit polimer. Sifat hidrofilik menjadi kelemahan komposit berpenguat serat alam. Alkalisasi dan penambahan katalis dilakukan untuk meningkatkan kekuatan mekanis dan stabilitas dimensi komposit berpenguat serat alam. Penelitian ini bertujuan menganalisis pengaruh waktu alkalisasi dan kadar methyl ethyl ketone peroxide sebagai katalis terhadap sifat fisis dan mekanis papan. Papan komposit dibuat dengan target kerapatan 1 g/cm3 menggunakan serat yang diberi perlakuan alkalisasi 2, 4, 6, dan 8 jam dengan NaOH 5% serta penambahan katalis 2,4, dan 6%. Hasil penelitian menunjukkan kerapatan papan, nilai keteguhan lentur dan keteguhan patah meningkat dengan adanya peningkatan waktu alkalisasi dan penambahan kadar katalis. Waktu alkalisasi lebih dari 4 jam dan penambahan kadar katalis lebih dari 4% dapat menurunkan kekuatan mekanis papan komposit. Secara umum papan komposit polimer sabut kelapa memenuhi SNI 8154-2015. Papan komposit terbaik diperoleh dari perendaman alkalisasi 4 jam dan kadar katalis 2%., Natural fiber reinforced composite materials began to be developed as an alternative to fiberglass composites. Coconut fiber has the potential to be used as a polymer composite reinforcement. Hydrophilic nature is the weakness of natural fiber reinforced composites. Alkalization and catalyst addition were carried out to improve the mechanical strength and dimensional stability of natural fiber reinforced composites. This study aims to analyze the effect of alkalization time and methyl ethyl ketone peroxide content as catalys on the physical and mechanical properties of the board. Composite boards were made with a target density of 1 g/cm3 using fibers treated with 2, 4, 6, and 8 hours of alkalization with NaOH 5% and 2, 4, and 6% catalyst addition. The results showed that the board density, flexural and fracture strength values increased with an increase in alkalization time and the addition of catalyst content. Alkalization time of more than 4 hours and the addition of catalyst content of more than 4% can reduce the mechanical strength of the composite board. In general, the coconut fiber polymer composite board meets SNI 8154-2015. The best composite board was obtained from 4 hours alkalization soaking and 2% catalyst content.
Keyword: sifat fisis, sifat mekanis, Alkalisasi, Katalis

Judul: Characteristics of Polyester-Coconut Fiber Composite Board with the Addition of Sorghum Bagasse Powder
Abstrak: Produktivitas hutan Indonesia semakin menurun, sedangkan kebutuhan manusia akan bahan baku kayu semakin meningkat seiring dengan bertambahnya jumlah penduduk. Salah satu solusi untuk mengatasi masalah ini antara lain dengan mengembangkan pambuatan metrial papan komposit. Penelitian ini bertujuan untuk membuat papan komposit polyester berpenguat serat kelapa dengan penambahan serbuk bagas sorgum terhadap kualitas papan komposit polyester. Penelitian ini menggunakan metode dengan 2 faktor yaitu presentase kadar partikel (20%, 30%, dan 40%) dan variasi ukuran mesh sorgum (40-60 mesh dan lolos 60 mesh) dengan kadar matrik resin polyester 70% dan penambahan hardener 3%. Kerapatan target papan komposit polyester 1 g cm-3 . Secara keseluruhan kerapatan papan berkisar antara 1,10-1,15 g cm-3 . Campuran papan komposit polyester-serat kelapa dengan serbuk bagas sorgum dapat meningkatkan sifat fisis, mekanis, dan impak. Kadar partikel hanya berpengaruh nyata pada kekuatan impak papan sehingga dapat meningkatkan nilai kekuatan papan komposit. Ukuran partikel tidak berpengaruh nyata terhadap sifat fisis, mekanis dan impak papan komposit. Papan komposit dengan presentase kadar partikel yang tinggi dapat meningkatkan nilai kuat tarik dan impak pada papan., The productivity of Indonesia's forests is declining gradually everyday, while the human needs for the raw materials such as wood is increasing along with the increasing population. One possible solution for this problem is to develop composite materials manufacturing. The purpose of this study is to make polyester composite boards reinforced with coconut fiber with the addition of sorghum bagasse powder to increase the quality of polyester composite boards. This method uses 2 factors, namely the percentage of particle content (20%, 30%, and 40%) and variations in the size of the sorghum mesh (40-60 mesh and 60 mesh) with a matrix content of 70% polyester resin and the addition of 3% hardener. The target density of polyester composite board is 1 g cm-3 . Overall board density ranges from 1,10- 1,15 g cm-3 . A mixture of polyester-coconut fiber composite board with sorghum bagasse powder can increase the value of physical, mechanical and impact properties. The particle content has significant effect on the impact strength of the board, therefore it can increase the strength value of the board. Particle size has no significant effect on the physical, mechanical and impact properties of the board. Composite boards with a high percentage of particle content can increase the tensile and impact strength values of the boards.
Keyword: olyester, sorghum, coconut fiber, composite board

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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