1,720,956 research outputs found
Stress-cracking of PET bottle as an unpredictable factor limiting the commercial life of carbonated soft drinks
No full textThe shelf life of carbonated beverages mainly depends on the carbon dioxide retention performances of the PET bottle, however the commercial life of such products can be compromised by ruptures and crackings of the material, which can occur in certain conditions. The so-called "stress cracking" of PET bottles occurs in correspondence with the injection point, which is more susceptible due to its amorphous nature, unlike the sides of the bottles, whose strength is a result of a certain degree of orientation. Stress cracking can be a consequence of various factors, which usually act in combination and are difficult to isolate: excessive internal pressure (excess carbonation), material distribution, altered intrinsic viscosity, exposure to UV rays and/or high temperatures, but most important is the contact with caustic substances (for example, the lubricant of the conveyors belts), etc. The present contribution focuses on a case study occurred at SIBEG s.r.l., concerning the non conformity of 1.5 L PET bottles of a popular carbonated soft drink, which caused the loss of an important amount of bottles, the disposal of defective products, and the careful inspection and selection of in-house stocks. Inspections revealed no failure in the blowing process, leading to hypothesize over-carbonation and transport conditions as the triggering events. Moreover, the analysis of intrinsic viscosity (IV) of bottles and preforms revealed the non-conformity with specification. Despite the product conformity concerning thermal stability, burst test and stress cracking test performed in alkaline conditions, PET bottles quality and performances may become altered if the IV of the material does not fulfill specifications. Therefore, the IV determination plays a key role, complementary with other routine determinations, in the quality control of PET bottles addressed to carbonated soft drinks packaging. The use of such tool is fundamental for the prevention of severe problems which might occur along the distribution chain, such as claims, withdrawal and disposal of defective products
Dependance of the shelf-life of carbonated soft drinks from PET performances as required by "the Coca Cola Company"
No full textPET (Polyethyleneterephthalate) is one of the most important resins used for the package of carbonated water and soft drinks. Preforms are intermediate products which are manufactured in a wide range of designs and colours by injection moulding of PET. The cost of the resin covers a high percentage in the overall cost of the produce, especially due to the recent increments on the price of petroleum, from which PET is derived. As a consequence, according to the numerous standards fixed by " The Coca-Cola Company (R)", Sibeg S.r.l. decided to test a new cheaper PET preform which was suggested by a possible new supplier. The experiment consisted in the comparison of the main performance characteristics of the old PET bottles in comparison with the ones obtained from the new preforms. " The Coca-Cola Company (R)" requires specific test procedures to authorize a new package. Among the methods used to test new materials, the gas-barrier properties have a main importance as they are directly linked with the shelf-life of the bottled produces. Shelf-life of carbonated soft drinks is determined by the internal CO2 level, and limits for this parameter are different for different the types of beverages. Therefore a material with higher CO2-barrier property would be effective in extending the shelf-life of carbonated drinks. Results evidenced a similar behaviour of the two materials tested for what concerns the characteristics of the bottles (dimensions, appearance, distribution of the material, stress cracking test), showing, in particular, comparable CO2 internal pressure after 12 weeks of storage
Improvement of CO2 retention of PET bottles for carbonated soft drinks
No full textOne of the major aims pursued by the carbonated soft drinks industry is to extend the shelf-life of PET-packaged products, in order to guarantee the consumers with the original characteristics and quality. Most of the responsibility in the shelf-life extension of such products has to be attributed to the bottle material performances, such as the barrier properties to gases with special regards for the ability to maintain the internal CO2 through the shelf-life. Tests on carbonated soft drinks bottles are performed at every change (design, volume, etc.) of the package, in order to verify the performances of the new bottle with special regards for the CO2 retention properties.
The research aims at the evaluation of new bottles addressed to the packaging of a sugar free and a caffeine free carbonated soft drink (Coca-Cola Light e Coca-Cola Caffeine Free), recently launched on the Italian market. The start of commercialisation for these new products is the result of a project named "Silver and Gold", which takes the name from the new colours of the new bottles. Such bottles are produced using the same PET resin as the standard ones, with the only exception of master batch dyes used in the test materials. The CO2 retention performances of Silver and Gold bottles were investigated in comparison with the standard bottle used as a control. Results showed that CO2 retention was improved in the Silver and Gold bottles, which retained averagely 88% of the initial CO2 level after 14 weeks of storage, approximately 10% more than the standard bottles
Measures to prevent stress corrosion cracking of aluminum cans for carbonated beverages
No full textCommon containers for carbonated beverages are PET bottles and aluminum cans. These different materials are chosen based on marketing and convenience reasons. While the shelf life of carbonated beverages packed in PET bottles is affected by the CO2 permeation through the polymer matrix, aluminum cans allow the gas retention and guarantee a higher quality during storage. Indeed, the shelf life of canned carbonated beverages is commonly ≥1 year. While the longer commercial life is an advantage from a commercial point of view, it increases the probability of occurrence of failure due to corrosion. Stress Corrosion Cracking (SCC) occurring from the outside of the can would prejudice the integrity of the container, provoke the product loss and, what is probably worst, could determine a chain-effect on other adjacent cans if the product is spilled from the damaged can. Normally, aluminum cans are internally lacquered for protecting the metal from corrosion by the food components. Chlorine from the conditioning water bath and storage environmental moisture determines the onset of SSC, while temperature and internal gas pressure speed up the failure of cans. This study aimed at evaluating the potential of a supplementary outer enamel for preventing stress corrosion cracking, and proved that this measure, which does not imply significant process changes or supplementary costs, could effectively reduce the risk of product loss, with consequent need for damaged products withdraw and disposal, and prejudice for the image of the producer
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
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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