Judul: Pengaruh Jumlah Bahan Pretanning dan Minyak Biji Karet (Hevea brasiliensis) Terhadap Mutu Kulit Samoa. Di
Abstrak: Animal hides or skins are the most valuable by product of the meat industry. Most of those hides are converted into leather by leather tanning process. Chrome based tanning is the most popular tanning process. At the chrome based tanning process, a lot of amount chrome are throw away into the environment that make a significant effect to the biological and ecological environment damaged. Due to concerns over the use and disposal of chromed tanned leather, the leather industry is now facing increasing scrutiny over its use of chrome as tanning agent. The use of non-chrome tannages has gradually become pre-eminent to producing leather, particularly in the European automotive leather markets. Chamois leather is one of leather product. It is produced from animal hides/skins by oil tanning process, usually with fish oil. High price and odour problems to the chamois leather that produced using fish oil motivate to do some research to solve that problems. Rubber seed oil is an oil that predicted can substitute fish oil. Pretanning process is needed to increase the oil penetration and protects the pelt from putrefying during oxidation periods (Khrisnan et al., 2005). Relugan GT 50 is the agent that used on this research. Relugan GT 50 is an aldehyde tanning agent, produced by BASF. This research was aimed to find out the effects of Relugan GT 50 concentration (offer) and rubber seeds (Hevea brasiliensis) oil to the chamois leather’s quality. Beside that, this research is also aimed to decide the best combination of the factors to produce chamois leather also to know the chamois leather characteristics. The preliminary research was carried out by analyzing the rubber seed’s kernel and eggshell as well as physico-chemical properties of the rubber seed oil. The main research was done by tanning the skin with Relugan GT 50 in concentrations of 1.5, 3.0 and 4.5% followed by rubber seed oil concentrations of 10, 20, and 30%. The experimental design used was completely randomize factorial design. The preliminary research shows that rubber seed’s kernel was 49% and rubber seed’s eggshell was 51%. The rubber seed’s oil characterstics were density of 0.94 (g/cm3), viscosity of 48,4 centistokes, colour of 2713 PtCo units, inodine value 113 g iod/ 100 g, peroxide value of 24 miliequivalent/1000 gram oil, acid value of 15 mg KOH/g oil and FFA content of 5.8%. The research shows that Relugan GT 50 concentration significantly affected shrinkage temperature (Ts) and pH; rubber seed oil concentration significantly affect the organoleptic properties of the leather. The optimum conditions for the tanning were Relugan GT of 3.0% concentration and 10% rubber seeds oil. The physical properties of the leather were shrinkage temperature of 75oC, thickness of 0.92 mm, tensile strength of 21.50 N/mm2, elongation at break of 144%, tear strength of 55.77 N/mm, water absorption of 266% (2 hours) and 299% (24 hours). The chemical properties were oil content of 2.5%, ash content of 1.2% and pH of 8. The organoleptic properties were softness of 7–8, colour of 8-9, and odour of 8-9.
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Judul: Pengaruh Konsentrasi Natrium Perkarbonat dan Jumlah Air Terhadap Mutu Kulit Samoa Pada Penyamakan Kulit Dengan Minyak Biji Karet.
Abstrak: Chamois leather is a popular product in trading, because it has specific uses. Nowadays, chamois leather is produced with fish oil as a main oil tanning agent. The problem are odors and colour of the product as well as the expensiveness of the fish oil. To overcome the problem, subtitution of the fish oil with vegetable oil, such as rubber seed oil. May be carried out other problem is oxidation needs a long time, such as about 2 weeks. This causes production process of tanning leathers tanning chamois needs long time. The objectives of this research were to understand the effect of amounts of sodium percarbonate and water in chamois leather tanning using rubber seed oil on the quality of the chamois leather. Besides that, this research also aimed to get the best combination of the factors. The preliminary research was carried out by analyzing the physico-chemical properties of rubber seeds oil. The main research was done by tanning of sort skin pickeld pelt. In its oxidation, combination of 2%, 4%, and 6 % of sodium perkarbonat and 70%, 50% dan 30% of water were used. The experimental design used was completely random factorial design. The results of preliminary research were rubber seed consisted of 49% shell and 51% endosperm. The characteristics of the rubber seed oil were density of 0.94 (g/cm3), viscosity of 48.4 centistokes, colour of 2713 PtCo units, acid value of 15.2 mg KOH/g oil , FFA of 5.82 %, iodine number of 113 g iodine/ 100 g oil, saponification value of 350.06 mg KOH/g oil, and peroxide number of 24.13 miliekuivalen/1000 g oil. The main research show that sodium percarbonate amount significantly affected thickness and oil content; amount of water significantly affected oil content of the leather; The interaction between sodium percarbonate and water significantly affected ash content and oil content. The optimum conditions for the oxidation were amount of sodium percarbonate of 4% and water at 50%. The physical properties of the leather were shrinkage temperature of 71oC, thickness of 0.87 mm, tensile strength of 35.95 N/mm2, elongation of 129%, tear strength of 82.01 N/mm, water absorption of 226% (2 hours) and 303% (24 hours). The chemical properties were pH of 7.45, oil content of 8.1% and ash contain of 1.3%. The organoleptic properties were softness of 6 – 7, colour of 7 - 8, and odour of 7 – 8.
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf