Journal Majalah Kulit, Karet, dan Plastik

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Emiliana Kasmudjiastuti, Gresy Griyanitasari, Dona Rahmawati, Sugihartono Sugihartono
Majalah Kulit, Karet, dan Plastik, Volume 34, pp 19-26; doi:10.20543/mkkp.v34i1.3893

Abstract:Fungsi minyak pada proses peminyakan kulit untuk menjaga agar serat kulit tetap terpisah selama proses pengeringan dan untuk mengurangi gaya gesekan dalam tenunan serat, sehingga kulit menjadi fleksibel. Tujuan penelitian untuk mensintesis minyak kelapa sawit menjadi minyak sulfat melalui proses sulfatasi dan karakterisasi minyak kelapa sawit dan minyak sulfat yang dihasilkan dari proses sulfatasi. Metode yang dilakukan meliputi sintesis minyak kelapa sawit menggunakan 25% H2SO4 selama 3 jam, suhu <20ºC, kecepatan 300 rpm. Hasil karakterisasi minyak kelapa sawit menunjukkan angka Iodin 49,95 mg I2/minyak; asam lemak bebas 0,05%; kadar air 0,18%; angka peroksida 16,23 mg/kg; angka asam 0,19 mg KOH/gr. Asam lemak jenuh yang dominan adalah metil palmitat dan metil butirat, sedangkan asam lemak tidak jenuh yang dominan cis-9-oleic methyl ester dan metil linoleat. Minyak sulfat yang dihasilkan mempunyai kadar air 6,47%; pH 8; kadar minyak 81,28%; total alkalinitas 0,25%, angka penyabunan 192,74%; kadar abu 2,77% dan kadar SO3 terikat 7,68%. Hasil uji kekuatan tarik kulit tersamak adalah 286,50 kg/cm2 dan kemuluran 63,33%.Kata kunci: minyak kelapa sawit, asam sulfat, sulfonasi, minyak sulfat, peminyakan.
Tjahjono Herawan, Meta Rivani, Halimatudahliana Halimatudahliana, Suryo Irawan
Majalah Kulit, Karet, dan Plastik, Volume 34, pp 33-40; doi:10.20543/mkkp.v34i1.3634

Abstract:Besides producing oil, oil palm is also produces huge amount of biomass such as empty fruit bunch. Both of those products had a potential to be used as a source of plastic raw materials called bio-plastics. Long-chain fatty acid source can be obtained from crude palm oil (palmitic acid and oleic acid) and palm kernel oil (lauric acid) while cellulose can be obtained from oil palm empty fruit bunch waste (OPEFB). Cellulose was produced from OPEFB by alkaline process on pilot plant scale. The yield of α-cellulose obtained as much as 32-38% of the OPEFB processed. The cellulose ester was synthesized by esterification reaction between cellulose of OPEFB and modified fatty acid from palm oil in a mild condition. Conversion of cellulose ester produced reached 92.7% with percent increase weight reach 460%, Degree Substitution (DS) 2.21 and melting point 201 oC. The tensile strength of the cellulose ester film was lower than tensile strength of petroleum-based plastics (Low Density Poly Ethylene/LDPE), which averaged 73 kg/cm2 versus 108 kg/cm2, so it was necessary to add additives to increase tensile strength and elasticity properties.
Muhammad Sholeh, Ihda Novia Indrajati, Arum Yuniari
Majalah Kulit, Karet, dan Plastik, Volume 34, pp 27-32; doi:10.20543/mkkp.v34i1.3460

Abstract:The knowledge of how rubber breakdown on heating in oxidative environment is important in processing and using the material. In the present work, we performed thermogravimetric analysis and utilized three iso-conversional kinetic models to get apparent activation energies of thermal degradation of natural rubber/butyl rubber. Blending of RSS/butyl and additives was done using a laboratory two-roll mill. Cure time of the blended compound was determined by a moving die rheometer. The compound was compression moulded at 160°C with a pressure of 150 kg/cm2 using a laboratory hot press. Thermogravimetric analysis was carried out from 30°C to 800°C in air flow of 200 ml/min with heating rates of 5, 10, 15, and 20°C/min. The kinetic parameters were determined by three isoconversional models (Kissinger, Doyle, and Flynn–Wall–Ozawa model). The result revealed that the thermal decomposition of the blend occurs in two stages, DTG peaks tends to shift to a higher temperature and the values of DTG peaks increase with the increase of heating rate, and the three isoconversional models gave similar apparent activation energies. The activation energy obtained can be used to predict thermal lifetime of the material.
Dewi Kusuma Arti, Riastuti Fidyaningsih, Amilatin Rohmah, Lies A Wisojodharmo, Henny Purwati
Majalah Kulit, Karet, dan Plastik, Volume 34, pp 1-8; doi:10.20543/mkkp.v34i1.3437

Abstract:Sifat reologi dan viskoelastis pada kompon karet, terutama kompon tread ban, sangat dipengaruhi oleh jenis karet serta bahan pengisi yang digunakan. Kedua sifat ini sangat mempengaruhi hasil akhir dari produk karet terutama dalam hal sifat mekanisnya. Dalam pengembangan suatu produk, penelitian mengenai kedua sifat ini sangatlah penting untuk memperoleh formulasi yang optimum. Penelitian ini bertujuan untuk mengetahui sifat reologi dan viskoelastis dari kompon tread ban menggunakan bahan dasar karet alam (NR) dan butadiene rubber (BR) dengan memvariasikan komposisi bahan pengisi yaitu carbon black dan silika. Bahan dasar NR dan BR dengan rasio 85/15 phr dicampur dengan menggunakan alat kneader, sementara rasio bahan pengisi carbon black/silika adalah: 50/0, 40/10, 25/25, 10/40, dan 0/50 phr. Sifat reologi dan viskositas diuji dengan menggunakan rubber process analyzer (RPA) TA Instrument Elite dan dynamic mechanical analyzer (DMA) 7100 Hitachi. Pengujian RPA dilakukan dengan menggunakan variasi frekuensi dari 0.01-50 Hz pada suhu 1000C dengan amplitudo tetap 10 dan variasi amplitude dari 0,05-3,59 pada suhu 900C dengan frekuensi tetap 1 Hz. Sedangkan pengujian viskoelastis dengan DMA dilakukan menggunakan metode tension-compression dengan rentang suhu pengujian pada -800 – 800C. Hasil uji RPA menunjukkan penambahan silika mempengaruhi interaksi antar bahan pengisi yang ditunjukkan dengan perbedaan pada efek Payne. Energi disipasi juga menunjukkan kecenderungan menurunkan heat build up, meningkatkan sifat mekanis dan memperbaiki ketahanan abrasi pada produk karet dengan tambahan silika sebagai bahan pengisi. Hal ini juga didukung oleh hasil uji DMA yang menunjukkan wet skid resistance pada penggunaan silika yang sebanding dengan penggunaan carbon black saja dan rolling resistance yang meningkat signifikan dengan penambahan silika.
Desak Gede Sri Andayani, Nuri Astrini, Lik Anah
Majalah Kulit, Karet, dan Plastik, Volume 34, pp 9-18; doi:10.20543/mkkp.v34i1.3435

Abstract:Kitosan (poli-ß-1,4-glukosamin) merupakan polimer alami bersifat tidak larut dalam air dan pelarut organik, hidrofilik, biocompatible dan biodegradable. Gugus amino pada kitosan lebih mudah berubah menjadi kation dalam larutan asam sehingga sangat kuat menyerap anion dengan daya tarik elektrostatik. Dengan menambahkan dan mencampur polimer sintetik pada rasio yang tepat akan meningkatkan sifat-sifat kitosan sebagai biopolimer dalam menangani permasalahan lingkungan. Tujuan penelitian ini adalah untuk mengkaji kapasitas penyerapan air dan pembentukan hidrogel pada berbagai variasi kitosan terhadap polimer sintetis. Percobaan dilaksanakan dengan metode respon permukaan menggunakan perangkat lunak Design Expert 6,06, 46 variasi percobaan, dan delapan center point dengan kapasitas penyerapan air (g/g) sebagai respon. Proses dilakukan pada sistem batch, inert atmosphere, skala reaktor 1 L dengan kondisi operasi adalah suhu 90°C dan waktu proses selama 4 jam. Variasi biopolimer dan polimer sintetis sebagai berikut: kitosan (CTS): (0,15-1,2) g, acrylic acid (AA): (2-4,5) g, polyvinylalcohol (PVA): (0,5-3) g, benzoylperoxide (BPO): (0,03-0,13) g, methylene bis-acrylamide (MBA): (0,01-0,21) g. Data dianalisis menggunakan ANOVA pada taraf signifikan 95%. Kapasitas penyerapan air (WAC) selama 24 jam diukur dengan teknik gravimetri. Hasil penelitian menunjukkan bahwa variasi campuran kitosan sebagai biopolimer dengan polimer sintetis mempengaruhi kapasitas penyerapan air dan pembentukan hidrogel. Kapasitas penyerapan air optimum adalah 18,6 (g/g) pada komposisi (g): CTS 0,67; AA 3,25; PVA 1,75; BPO 0,08 dan MBA 0,11. Terbentuknya hidrogel sangat dipengaruhi oleh rasio campuran antara polimer alam, monomer, polimer sintetis, inisiator dan agen ikatan silang.
Ahmed Ibrahim Nasr
Majalah Kulit, Karet, dan Plastik, Volume 33, pp 99-107; doi:10.20543/mkkp.v33i2.3139

Abstract:The objective of this study is to investigate the influence of using some mechanical finishing processes on final properties of produced leather types. Nappa, nubuck, pigmented and corrected grain leather types were produced by applying some of the following operations: hang drying, vacuum drying, molissa staking, drum milling, buffing, spraying and/or embossing surface with extreme pressure. Hydrophobic-hydrophilic status, scanning electron micrographs, organoleptic and mechanical properties were determined on all finished leather types. Results showed that water behavior was hydrophobic for nappa leathers, while it was hydrophilic with the rest of produced leather types. Buffing surface in nubuck leather increases the water absorption and water vapor permeability, while the opposite was found when applying external coat layer in pigmented and corrected grain leathers. Applying vacuum drying in nappa leathers increases surface smoothness and surface water contact angle while decreases tensile and tearing strengths. These results elucidate that all studied leather types are suitable for manufacturing purposes except nubuck leather which is not recommended for footwear uppers manufacturing due to its high water absorption. The present study emphasized that while mechanical finishing processes could have profound effects on leathers surface behavior, they must be adequate to the requirements and properties of the end products.
Arum Yuniari, Hesty Eka Mayasari, Ike Setyorini
Majalah Kulit, Karet, dan Plastik, Volume 33; doi:10.20543/mkkp.v33i2.3265

Abstract:The use of methyl methacrylate butadiene styrene (MBS) as a compatibilizer for natural rubber (NR) and nitrile butadiene rubber (NBR) blends has been investigated. Research on the cure characteristics, mechanical properties, swelling, and morphology (SEM) has been conducted to determine the compatibility of NR/NBR blends in the presence of MBS. Based on the cure characteristics, it is indicated that the presence of MBS was affected significantly by maximum and minimum torque. The addition of MBS improved the mechanical properties and the oil resistance of NR/NBR blends due to the compatibility and better interfacial adhesion between rubber phases. The experiment showed that MBS loading by 2.5 phr was the optimum level for NR/NBR blends.
Ike Setyorini, Arum Yuniari
Majalah Kulit, Karet, dan Plastik, Volume 33; doi:10.20543/mkkp.v33i2.3345

Abstract:Different ethylene propylene diene monomer (EPDM) composite with the carbon black (CB) variation of 50, 60, and 70 phr (per hundred rubbers) is compounded by using an efcient (EV), semi-efcient (SEV), and conventional (CV) sulfur vulcanization systems. This research aims to investigate the effect of vulcanization systems and carbon black content on the vulcanization rate constant, the crosslink density, and the free sulfur content. This research shows the EV system resulting in the fastest vulcanization rate constant (0.0191/second), the lowest overallcrosslink density (0.0022 mol.cm-3), and the highest percentage of free sulfur content in the EPDM vulcanization (0.40 %). The CV system provides the slowest vulcanization rate constant (0.0061/second) and the highest overall crosslink density (0.0034 mol/cm-3). The percentage of free sulfur content in the EPDM vulcanization of CV system is between EV and SEV systems. The SEV system provides the vulcanization with the characteristic of vulcanization rate constant and overall crosslink density between EV and CV systems as well as provides the lowest percentage of free sulfur content (0.29 %). The higher carbon black loading in each vulcanization systems means the lower rate constant of vulcanization and the higher overall crosslink density.
Prayitno Prayitno, Dona Rahmawati, Gresy Griyanitasari
Majalah Kulit, Karet, dan Plastik, Volume 33; doi:10.20543/mkkp.v33i2.3336

Abstract:Sheep wool waste discharged from leather tanning industry recently has posed a problem in relation to its treatment because of its sizeable quantity and its difficulty to degrade. Wool is composed mainly of keratin. It is a protein with a high content of disulfide bonds which cause the protein keratin cannot dissolve in water and resist of diluted acids and alkalis. Keratin can be hydrolyzed to produce keratin hydrolysates which have many benefits such as for cosmetic additives. Research into the use of waste wool of sheep originated from the sheep leather tanning industry had been performed by using a hydrolyzed system to produce protein keratin. The waste wool used came from unhairing by painting and conventional unhairing. Hydrolysis was done using hydrogen peroxide 50% amounting to 70 ml for every 40 gr of wool. Hydrogen peroxide was added to wool immersed in the 0.5 M NaOH solution for three hours. The length of hydrolysis ranged from 4, 5, to 6 hours and the mix was stirred shortly every 1 hour followed by filtration using a coarse sieve. To precipitate the hydrolyzed keratin, the pH was decreased to 4-5 using the 2 M HCl solution and after separation of the precipitation, it was dried in the oven at a temperature not more than 50 oC for 2 days. The research findings showed that a maximum of 69.19% of keratin hydrolysates was generated using the raw material of waste wool through a conventional process with a total of hydrolysis time by 6 hours, whereas the maximum protein generated was 66.99% using waste wool through a conventional process with a total of hydrolysis time by 4 hours. The FTIR test showed the presence of groups of amides, cysteic acids, and cystine-S-monoxide.
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