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การศึกษาสัณฐานวิทยา ความเสถียรทางความร้อน และสมบัติเชิงกลของการย่อยสลายทางชีวภาพของยางธรรมชาติดัดแปร
Full text linkStudy on Morphological, Thermal Stability and Mechanical Properties of Biodegradation of Modified Natural Rubber
Phetdaphat Boonsuk
รับบทความ: 8 กันยายน 2567; แก้ไขบทความ: 29 มกราคม 2568; ยอมรับตีพิมพ์: 16 กุมภาพันธ์ 2568; ตีพิมพ์ออนไลน์: 19 มิถุนายน 2568
บทคัดย่อ
งานวิจัยนี้ศึกษาสัณฐานวิทยา สมบัติทางความร้อน และสมบัติเชิงกลของการย่อยสลายทางชีวภาพในดินของยางธรรมชาติดัดแปร โดยนำยางธรรมชาติ (natural rubber: NR) กราฟต์แป้งมันสำปะหลังดัดแปร (cassava starch: CST) ที่มีสัดส่วน CST 50 phr (NR–g–CST 50 phr) เปรียบเทียบกับแป้งมันสำปะหลังดัดแปรร้อยละ 10 โดยน้ำหนัก (CST) ยางธรรมชาติกราฟต์กับแป้งมันสำปะหลังดัดแปรที่มีสัดส่วน CST 50 phr และผสมกลีเซอรอล (glycerol: GE) ร้อยละ 3 โดยน้ำหนัก (พอลิเมอร์ผสม NS–GE) ยางธรรมชาติผสมกับแป้งมันสำปะหลังดัดแปรที่มีสัดส่วน CST 50 phr (พอลิเมอร์ผสม NR/CST 50 phr) ยางพรีวัลคาไนซ์ (pre–valcanized rubber: PR) ผสมกับแป้งมันสำปะหลังดัดแปรที่มีสัดส่วน CST 50 phr (พอลิเมอร์ผสม PR/CST 50 phr) ยางธรรมชาติ 30%DRC (dry rubber content) ยางพรีวัลคาไนซ์ 30%DRC และถุงมือยาง จากการศึกษาโครงสร้างสัณฐานวิทยาพบว่าพื้นผิวของแผ่นฟิล์มทุกตัวอย่างมีลักษณะขรุขระ มีรู มีรูพรุนมีรอยแตกมากขึ้น และสังเกตเห็นเส้นใยราบนพื้นผิวตัวอย่างเมื่อฝังดินนานขึ้น จากการศึกษาสมบัติทางความร้อนก่อนการฝังดิน พบว่า เทอร์โมแกรมของ NR–g–CST 50 phr เลื่อนไปยังที่อุณหภูมิสูงขึ้นกว่า NS–GE, NR/CST 50 phr และ PR/ CST 50 phr ในช่วงอุณหภูมิ 330–500 องศาเซลเซียส และเมื่อศึกษาสมบัติทางความร้อนหลังการฝังดิน แผ่นฟิล์มทุกตัวอย่างทนความร้อนได้ลดลงเมื่อฝังดินนานขึ้น และจากการศึกษาสมบัติการทนทานต่อแรงดึง (tensile strength) ของ NS–GE NR/CST 50 phr และ PR/ CST 50 phr ในช่วงอุณหภูมิ 330–500 องศาเซลเซียส และเมื่อศึกษาสมบัติทางความร้อนหลังการฝังดิน แผ่นฟิล์มทุกตัวอย่างทนความร้อนได้ลดลงเมื่อฝังดินนานขึ้น และจากการศึกษาสมบัติการทนทานต่อแรงดึง (tensile strength) ของ CST NR–g–CST 50 phr NS–GE NR/CST 50 phr PR/CST 50 phr NR 30%DRC PR 30%DRC และถุงมือยาง ก่อนการฝังดินพบว่าค่าการทนทานต่อแรงดึงเท่ากับ 5±0.5, 8±0.6, 11±0.4, 6±0.6, 7±0.6, 10±0.6, 8±0.5, และ 25±0.8 และค่าความยืดสูงสุด ณ จุดขาดเท่ากับ 10±2, 200±10, 350±20, 270±30, 250±30, 300±40, 450±20 และ 750±30 ตามลำดับ สรุปได้ว่าการดัดแปรยางธรรมชาติโดยนำยางธรรมชาติ (NR) กราฟต์แป้งมันสำปะหลังดัดแปร (CST) ที่มีสัดส่วน CST 50 phr (NR–g–CST 50 phr) สามารถนำไปใช้เป็นแนวทางในการปรับปรุงและพัฒนาผลิตภัณฑ์จากยางธรรมชาติให้สามารถย่อยสลายทางชีวภาพได้ และจัดการของเสียจากผลิตภัณฑ์ยางธรรมชาติในสิ่งแวดล้อม ทนต่อความร้อน และทนทานต่อแรงดึงและความยืดสูงสุด ณ จุดขาด ได้ดี
คำสำคัญ: การย่อยสลายทางชีวภาพ ยางธรรมชาติ แป้งมันสำปะหลัง การดัดแปรโครงสร้าง ยางธรรมชาติย่อยสลายได้ทางชีวภาพ
Abstract
This research studied the morphology, thermal properties and mechanical properties of biodegradation in soil of modified natural rubber by natural rubber (NR) grafted with modified cassava starch (cassava starch: CST) at the ratio of 50 phr (NR–g–CST 50 phr) were compared with modified cassava starch 10% by weight (CST), natural rubber blended with modified cassava starch at the ratio of 50 phr (NR/CST 50 phr), natural rubber grafted with modified cassava starch at the ratio of 50 phr and glycerol 3% by weight (NS–GE), pre–vulcanized rubber blended with modified cassava starch at the ratio of 50 phr (PR/CST 50 phr), natural rubber 30%DRC (NR 30%DRC), pre–vulcanized rubber 30%DRC (PR 30%DRC) and rubber gloves. From the study of the morphological structure, it was found that the surface of every film sample was rough, had more holes, pores, cracks and fungal hyphae were observed on the surface when buried in the soil for a long time. From the study of the thermal properties before burial, it was found that thermogram of NR–g–CST 50 phr shifts to a higher temperature than NS–GE, NR/CST 50 phr, and PR/CST 50 phr in the temperature range from 330–500°C. By studying thermal properties after burial, it was found that the decomposition temperature decreased when buried in the soil for a long time. As a consequence of studying the mechanical properties, it was found that the tensile strength of CST, NR–g–CST 50 phr, NS–GE, NR/CST 50 phr, PR/CST 50 phr, NR 30%DRC, PR 30%DRC and rubber gloves were 5±0.5, 8±0.6, 11± 0.4, 6±0.6, 7±0.6, 10±0.6, 8±0.5 and 25±0.8, and the maximum elongation at break were 10±2, 200±10, 350±20, 270±30, 250±30, 300±40, 450±20 and 750±30, respectively. In conclusion, the modification of natural rubber by grafting natural rubber (NR) with modified cassava starch (CST) with a proportion of CST 50 phr (NR–g–CST 50 phr) could be used as a guideline for improvement and development natural rubber products were biodegradable and managed waste from natural rubber and its products in the environment. It was thermal stability, tensile strength and maximum elongation at break properties well.
Keywords: Biodegradation, Natural rubber, Cassava starch, Structure modification, Biodegradable natural rubbe
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
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Dispelling the Myths Behind First-author Citation Counts
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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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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