1,720,989 research outputs found
Pengembangan proses degradasi karet alam menggunakan lindi hitam sebagai bahan tambahan aspal termodifikasi
Full text linkOne way to improve the usability of natural rubber is by modifying natural rubber, for example by giving a chemical degradation treatment. Degradation of chemical compounds taken with the aid of a polymer chain breakers, in this study used black liquor. Degradation of natural rubber aims to adjust the physical properties of natural rubber in the mechanism of mixing with asphalt to produce a modified asphalt that is expected to improve and enhance the properties of asphalt in its application in road pavement. Chemical degradation pursued through three stages. The first stage is the formation process of latex into solid rubber in the form of crepes. The second stage is the process of rubber degradation using black leachate by using two variations of the treatment, immersion time of rubber in black leachate and drying time. While the third stage is mixing of degraded rubber with asphalt. The variation of immersion time and drying time significantly affected the amount of black liquor absorbed by the rubber, plasticity (Po), and softening point of modified asphalt. The best treatment in this study were treated R7K2 (rubber immersed for 7 hours and dried in the normal time plus 2 hours)
PENGGUNAAN LINDI HITAM SEBAGAI BAHAN PELUNAK DALAM KOMPON KARET ALAM
Full text linkSifat fisika vulkanisat dan karakteristik kematangan kompon karet alam yang mengandung lindi hitam dan analisis spektrometri FTIR dari lindi hitam telah dikaji untuk mengevaluasi penggunaan lindi hitam sebagai bahan pelunak. Bahan pelunak jenis aromatik digunakan sebagai bahan pelunak kontrol. Bahan pelunak dari lindi hitam dibuat dengan perlakuan berdasarkan jenis bahan pembasa yang ditambahkan pada lindi hitam serta jumlah kadar padatannya. Hasil pengujian spektrometri FTIR dapat menyimpulkan gugus fungsi yang terikat pada struktur molekul lindi hitam dan hasil interpretasi spektra FTIR menunjukkan bahwa lindi hitam mengandung senyawa cincin aromatik pada struktur molekulnya dan mengandung gugus fungsi –OH, -C-O, serta –C=O. Berdasarkan hasil pengujian karakteristik kematangan kompon menunjukkan bahwa kompon karet yang mengandung bahan pelunak lindi hitam tanpa perlakuan ataupun dengan perlakukan penambahan bahan pembasa NH4OH dan NaOH memiliki waktu masak optimum (t90) dan waktu scorch (t2) yang lebih cepat dari pada kompon karet yang mengandung bahan pelunak kontrol (Minarex).  Hasil pengujian sifat fisika vulkanisat menunjukkan bahwa vulkanisat yang mengandung lindi hitam tanpa perlakuan penambahan bahan pembasa dengan kadar padatan sebesar 60% memiliki kinerja yang setara dengan vulkanisat yang mengandung bahan pelunak kontrol.   Diterima : 15 Februari 2013; Disetujui : 25 Mei 2013 How to Cite : Cifriadi, A. (2013). Penggunaan lindi hitam sebagai bahan pelunak dalam kompon karet alam. Jurnal Penelitian Karet, 31(1), 20-29. Retrieved from http://ejournal.puslitkaret.co.id/index.php/jpk/article/view/13
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Carbon Black and Lignin Hybrid Filler in Designing NR Based Cushion Gum Composite Formulation
Full text linkLignin has high potential to be used as rubber cushion gum compound ingredient due to its unique properties. Cushion gum is an adhesive used to bind a new tread to the surface of used tires in a retread tire factory. An experiment was carried out to evaluate the performance of hybrid filler consisting of carbon black and lignin in affecting the physical and mechanical properties of natural rubber (NR) based cushion gum composite. The composition of carbon black/lignin was arranged at 40/10 phr and 35/15 phr. Carbon black grade N220, N330, and N550 were used in this research. Meanwhile, the lignin was specifically in the form of sodium lignosulfonate. The cushion gum compound was also formulated with the addition of pine tar oil as bio-based plasticizer. Commercial cushion gum was used as a comparison. The result showed that the hybrid filled NR cushion gum composite with N330/lignin at 40/10 (coded as SP2) was the most appropriate formula. Compared to commercial cushion gum, the SP2 hybrid filled cushion gum had comparable or even better processability and mechanical properties, attributed to high crosslink density. The excellent adhesive strength of the SP2 NR cushion gum composite was due to the presence of high content of the phenolic functional group in lignin and pine tar oil
Design of Elastomeric Bridge Bearing Pad Compound Formula Based on Hydrogenated Natural Rubber
Full text linkLaminated elastomeric bearing pad which is commonly produced by natural or chloroprene rubber is functioned as isolation system in bridge or flyover structures. In the research, hydrogenated natural rubber (HNR) was evaluated its feasibility to be used as base elastomer on steel-laminated bearing pad production by designing rubber compound formula. The compounding procedures of HNR applied various vulcanization system and carbon black filler types. The physical and mechanical tests result showed that only hardness parameter could fill the standar quality requirement of commercial elastomeric bearing pad as stated in AASHTO M251 in the range of 50 "“ 70 Shore A scale. The tensile property and compression set value of the HNR vulcanizates were under the requirement. This was due to low rubber-filler interaction and rigidity of crosslink network. The low interaction was more evident with increasing carbon filler particle size. By adjusting semi efficient vulcanization system and used N220 as carbon filler in designing compound formula,HNR was regarded as alternative promosing base elastomer for elastomeric bridge bearing pad manufacture. Nevertheless, it was necessary to improve the procedure to achieve better tesile property and compression set parameter
KARAKTERISASI MINYAK JARAK TERHIDROGENASI SEBAGAI BAHAN PELUNAK KARET ALAMI
Full text linkMinyak jarak castor terhidrogenasi diharapkan dapat berfungsi sebagai bahan pelunak karet alami. Bahan pelunak harus memiliki kesesuian yang baik dengan karet agar diperoleh efektivitas pencampuran yang tinggi. Percobaan ini akan mempelajari kinerja dan pengaruh minyak jarak castor terhidrogenasi sebagai bahan pelunak karet alami pada pembuatan kompon karet SIR 20 dan EPDM 6250 terhadap karakteristik vulkanisasi kompon dan sifat fisika vulkanisat karet. Dosis bahan pelunak ditetapkan 10 dan 20 bsk. Kinerja minyak jarak castor terhidrogenasi dibandingkan dengan bahan pelunak komersial golongan parafinik yaitu HVI 60 dan HVI 650. Tahapan dalam percobaan diawali dengan pembuatan kompon, kemudian vulkanisasi kompon dan pengujian sifat fisika vulkanisat karet. Saat pembuatan kompon dilakukan pengamatan terhadap waktu dan konsumsi energi pengkomponan serta persentase kehilangan berat kompon. Hasil percobaan menunjukkan bahwa penambahan minyak jarak castor terhidrogenasi mampu menurunkan waktu dan energi pengkomponan serta persentase kehilangan berat kompon. Pengaruh minyak jarak castor terhidrogenasi pada karakteristik vulkanisasi sangat tampak pada penurunan modulus torsi sebagai akibat terputusnya rantai molekul karet. Penambahan minyak jarak castor terhidrogenasi juga menurunkan kekerasan, kekuatan tarik, dan pampatan tetap tetapi meningkatkan perpanjangan putus dan kekuatan sobek baik vulkanisat karet SIR 20 maupun EPDM 6250. Dengan demikian minyak jarak castor terhidrogenasi dapat digunakan sebagai bahan pelunak karet alami terutama dalam pembuatan kompon karet sintetik EPDM. Diterima : 19 Juli 2013; Direvisi : 27 Agustus 2013; Disetujui : 9 November 2013 How to Cite : Puspitasari, S., & Cifriadi, A. (2014). Karakterisasi minyak jarak terhidrogenasi sebagai bahan pelunak karet alami. Jurnal Penelitian Karet, 32(1), 65-73. Retrieved from http://ejournal.puslitkaret.co.id/index.php/jpk/article/view/15
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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