Judul: Characteristic of Hotmelt Adhesive Using  Gondorukem as a Sustainable Tackifier
Abstrak: Penggunaan sustainable products dalam industri perekatan terus mengalami peningkatan. Salah satu jenis sustainable products tersebut adalah gondorukem. Gondorukem dalam kontribusinya pada perekat terutama perekat Hotmelt dapat dijadikan sebagai tackifier. Namun, karakteristik-karakteristik dasar dari gondorukem ini justru akan menurunkan nilai pemanfaatannya sebagai tackifier. Studi ini bertujuan untuk mempelajari karakteristik perekat hotlmelt yang menggunakan gondorukem sebagai tackifier. Hasil studi ini menunjukkan bahwa gondorukem sebagai tackifier ini dapat meningkatkan peel strength, sifat mekanis, kimia, dan menurunkan looptack. Ada beberapa permasalahan yang muncul akibat penambahan gondorukem sebagai tackifier yaitu menurunkan kekuatan adhesi dan menurunkan nilai kristalinitas perekat. Oleh karena itu, diperlukan metode modifikasi untuk mengatasi permasalahan yang muncul tersebut untuk meningkatkan kualitas produk yang dihasilkan dan perekat yang menggunakan gondorukem sebagai tackifier., The use of sustainable products in the glue industry continues to increase. One type of durable product is gondorukem. Gondorukem contributes as a Hotmelt adhesive that can be used as a tackifier. However, the essential characteristics of gondorukem will reduce the value of its use as a tackifier. This study aims to study the characteristics of hotlmelt adhesive using gondorukem as a tackifier. The results show that gondorukem as a tackifier can increase peel strength, mechanical properties, chemical properties, and decrease looptack. However, negative impacts of adding gondorukem as a tackifier are reducing adhesion strength and reducing the crystallinity of the adhesive. It needs a modification method to be able to improve the quality of the product and adhesives using gondorukem as a tackifier.
Keyword: Characteristics, Gondorukem, Hotmelt adhesive, Tackifier

Judul: Kajian Pemanfaatan Getah Pinus (Pinus merkusii) Sebagai Bahan Baku Perekat
Abstrak: Pine merkusii included to multipurpose tree species that developed and expanded continually to produce timber, gums, and as conservation land. Almost all parts of the tree can be utilized. Part of the tree that has high values is the pine gum. Processing of pine resin is widely used in printing ink industry, coating industry, and adhesive industry. Adhesive substance is a material that can be joined with the same or different type of object through bonding process or surface contact, so the body of joint object is resist to separation effort. In the production of pine gum adhesive substance, esterification process carried out to improve the adhesive power. This research aims to study the process of making adhesive substance from pine gum esters, and also to determine the effect of acid number, ester number, glycerol number and catalyst concentration on adhesive strength of the adhesive products. Stages of this research is the characterization of pine gum raw materials; esterification using KOH catalyst with concentration 1.5 and 10% by weight of pine gum, and moles of glycerol 1.1, 1.5, and 2 mol; making of the adhesive substance and determination of the best adhesive substance based on its best adhesive strength. Conducted preliminary research is the characterization of raw materials of pine gum, and then continued with the main research that is esterification of pine gum using alkaline catalyst (KOH), and making of the adhesive substance of the pine gum esterification. The treatment that used is the concentration of KOH catalyst (1%, 5%, and 10%) and the mole of glycerol (1.1 mol, 1.5 mol, and 2 mol). The esterification results of the pine gum tested through acids numbers, esters numbers, and free glycerol levels by comparing between the unwashed pine gum esters and the washed. The esterification results are made into adhesive substance. Then the surface area of adhesive strength and the adhesive strength of adhesive substance tested with shear stress (shear strength) of the adhesive strength and test. Based on preliminary research results, the characteristics of pine gum that was obtained is a liquid, slightly yellow color, soluble in ethanol solvent ratio of 90 percent with 1 ml of pine resin:1 ml of ethanol, acid number 125.66, and viscosity Cp 8693.14. The results of measurements showed that the adhesive substance with the code C22 (with KOH catalyst 5%, 1.5 mol glycerol, washed) gives a better adhesive strength. The characteristics of adhesive substance with the code C22 are: acids numbers 109.21 and esters numbers 21:18. Based on the observations, it can be concluded that the adhesive substance that was processed with 5% catalyst and 1.5 mole of glycerol with the code C22 is the best adhesive substance compared with others based on its adhesive strength.
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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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