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Effect of fibre treatments on tensile properties of ethylene vinyl acetate/natural rubber/mengkuang leaf fibre (EVA/NR/MLF) thermoplastic elastomer composites
No full textPreparation And Characterisation Of Ethylene Vinyl Acetate/Natural Rubber/Mengkuang Leaf Fibre Thermoplastic Elastomer Composites
Get PDFThermoplastic elastomers composites are a ternary blend, which consist of
thermoplastics and elastomers as matrix phase and natural fibre as dispersed phase.
The end performance of the composites is explained on the basis of combined
behaviour of the natural fibre, polymer matrix and fiber/matrix interface. Thus, in this
study, thermoplastic elastomer composites based on ethylene vinyl acetate (EVA),
natural rubber (NR) and mengkuang leaf fibre (MLF) were developed. Firstly, the best
blending sequences was studied to produce composites with the best end properties.
The EVA:NR ratio was fixed at 50:50 while the MLF loadings were varied from 0 to
10 phr. It was found that better enhancement in the end properties were achieved when
EVA was blended with NR first before the addition of MLF. This system produces the
composites with the best fiber dispersion in the matrix, resulting in low stabilization
torque, good tensile properties, and better thermal stability, compared with the other
systems. Secondly, fiber modification through alkaline peroxide bleaching treatments
were examined. The treatment was found to be effective in removing surface
impurities, lignin and hemicellulose, thereby producing a rougher fibre surfaces which
promote a good fibre/matrix adhesion, as depicted by Scanning Electron Microscopy
(SEM), thus resulting better tensile properties and thermal properties. Furthermore, the
treatment were resulted in the reduction of water absorption from 31% to 26%. Next,
comparison between EVA/NR/MLF and EVA/(epoxidized natural rubber) ENRxxvi
50/MLF composites were evaluated. It was found that, the EVA/ENR-50/MLF
composites showed lower stabilization toque, higher tensile and thermal properties
than EVA/NR/MLF composites. These results indicated that the EVA/ENR-50/MLF
composites had better compatibility than the EVA/NR/MLF composites. This result
was probably due the interaction between the carbonyl group of the EVA and the
epoxy group of the ENR-50 and the formation of hydrogen bonds between the MLF
and the EVA/ENR-50 matrix. However, the presence of ENR-50 had further increased
the water absorption of the blend and composites due to oxirane group present in the
ENR-50. Lastly, the influenced of different types of vulanisation system namely sulfur
and peroxide curing systems were evaluated. The stabilization torque of vulcanized
composites exhibited higher value compared to its unvulcanized counterparts as the
effect of the crosslinking. Dicumyl peroxide (DCP) cure system showed higher
improvement in tensile strength and modulus compared to sulfur vulcanizates.
However, sulfur cure system showed better resistance towards thermal degradation
compared to peroxide system. This was attributed to the DCP that was caused
degradation in polymer chain or chain scission in the composites at high temperature
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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