ABSTRACT SURAGANI VENU, LALITH BHARGAVA. a Study on Hydroentangling Mechanisms and Structures. (Under the Direction of Dr. Behna
Total Page:16
File Type:pdf, Size:1020Kb
ABSTRACT SURAGANI VENU, LALITH BHARGAVA. A Study on Hydroentangling Mechanisms and Structures. (Under the direction of Dr. Behnam Pourdeyhimi and Dr. Eunkyoung Shim). Hydroentangling is a nonwoven mechanical bonding technique which uses a curtain of fine, high-speed water-jets to entangle fibers in a web structure. The interactions among fibers, impinging water-jets and forming surface create a strong textile-like fabric as fibers twist, turn, intermingle and penetrate through the web as a result of water-jet(s) impact. Such integrated web structures are found in diverse applications Nevertheless, the entangling characteristics like fiber movement, fiber entangling and its possible path in the integrated structures are not well understood. Thereby, the purpose of this research is to study the effect of hydroentangling parameters like jet pressure, nozzle diameter, nozzle-to-nozzle distance and number of manifolds on fiber entangling and changes occurring within the web structure. To meet the above objectives, a comprehensive hydroentangled web structure needs to be analyzed. Hydroentangled structure is three-dimensional (3D) in nature because water jet impact cause movement of fibers in all directions as well as twisting and turning of fibers. Thus, digital volumetric imaging (DVI) technique, originally used for medical imaging has been successfully employed as a means to visualize and characterize the web structures. This technique is a block-face imaging technique (based on principle of micro-tomography) and successfully employed to acquire 3D images of the hydroentangled web structure. In the first part of the study, 3D structures of hydroentangled nonwoven were comprehensively analyzed using DVI. This study focused on developing and modifying the available characterizing techniques respectively. For the very first time, key terminologies like, surface fiber transfer and its profile, 3D fiber orientation, and density/porosity variations were introduced that defined a typical hydroentangled structure. Furthermore, these techniques were also employed in other parts of the study to characterize the produced structures. In the second part of the study, to understand the fiber entangling mechanisms the study begun by analyzing the effects of impact of single water-jet on the web structure and followed by two and three jets respectively. The findings from this study disclosed the internal structure of hydroentangled nonwovens for the very first time. Besides, the study also defined a unique assessing parameter called – depth of fiber penetration which played an important role in fiber entangling. This also includes the study on the effect of nozzle diameters on the web structures. In the third part of the study, effects of hydroentangling process variables were studied by scaling-up the process. This mainly dealt the effects of multiple jets and increasing number of manifolds which changed the hydroentangled web structure during every individual impact. This study disclosed the 3D structures for multiple impacts and concluded that fiber mobility plays an important role in fiber entangling and mechanical properties. Impinging multiple jets showed formation of loops by surface penetrating fibers which were interlocked within the web structure. This is unlike one, two and three jets due to fiber interaction under the influence of adjacent water-jets. In the concluding part of this study, the effects of orifice-to-orifice distance on web structure were studied. Analyzing the produced structures disclosed increase in fiber penetration and amount of surface fiber transfer into the web structure. The key finding was increase in fiber interlocking with increase in jet spacings due to improved fiber mobility. In addition, when web structures were hydroentangled in a novel fashion the mechanical properties were retained. And most importantly, this was achieved by expending only half the amount of required hydroentangling energy. © Copyright 2012 by Lalith Bhargava Suragani Venu All Rights Reserved A Study on Hydroentangling Mechanisms and Structures by Lalith Bhargava Suragani Venu A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Fiber and Polymer Science Raleigh, North Carolina 2012 APPROVED BY: _______________________________ ______________________________ Dr. Behnam Pourdeyhimi Dr. Eunkyoung Shim Committee Chair Committee Co-Chair ________________________________ ________________________________ Dr. Nagendra Anantharamaiah Dr. Dieter Griffis DEDICATION This work is dedicated to my family, for their constant love, support and motivation; tutelage of my teachers (Gurus); greatest mathematician, Srinivasa Aiyangar Ramanujan; physicists and mathematicians Albert Einstein and Sir Isaac Newton; and to my late grandmother Mrs. Savitramma Suragani who invigorated in excelling my dreams. And to Bhoomika ii BIOGRAPHY Lalith Bhargava Suragani Venu was born to Mrs. Sree Latha Suragani and Mr. Venu Gopal Suragani on the twenty-fourth day of February, in the year 1985. Born and brought up in Hyderabad, India, he was always appreciated for his independent abilities. Lalith’s quest to succeed in the scientific society began at Vidyaniketan High School, by winning 3rd prize for exhibiting Cell-Division with sub-topic Mitosis and Meiosis, at District Level Science Fair Exhibition in 1998. Fascinated by the science around him, Lalith continued his education path at Kakatiya Junior College, Hyderabad for two years followed by attaining bachelor’s degree in Textile Technology at Osmania University, Hyderabad, India in 2008. During bachelor’s, Lalith worked on imparting flame retardant finish to cotton fabrics which formed foundations to pursue higher education. Enticed with this zeal, Lalith joined the College of Textiles, North Carolina State University (NCSU) in August 2008. Since then, Lalith has been a graduate student with the Nonwovens Cooperative Research Center (NCRC) at NCSU. As a part of his graduate research studies, he has worked on unraveling the complexity involved in hydroentangled nonwoven structures. During the course of his Ph.D., he obtained the graduate certificate in Nonwovens Science and Technology. Going further, Lalith continues to seek scientific challenges by contributing the fullest of his calibers in his journey. iii ACKNOWLEDGMENTS While I pen this section, I look back at my stint here at North State Carolina University, and, I have vivid memories of me being immersed under pile load of courses, assignments, group and research projects, and many such other deadlines. In course of time, I realized that undertaking Ph.D. is another dimension for managing pressure. And today, while this dissertation has my name as its author, I am eternally grateful to a myriad of people who helped me in my pursuit for Ph.D., and, offered their invaluable time and unconditional efforts in making this journey fruitful. First and foremost, I express my profound sense of gratitude to my advisor and mentor Dr. Eunkyoung Shim, for her constant encouragement, support and guidance throughout the entire course of my research. I also extend my heartfelt thanks to my other advisor, mentor and friend Dr. Anantharamaiah Nagendra (Nagi) who stood by me throughout the tenure of my Ph.D. I also express my eternal gratitude to other advisor and mentor, Dr. Behnam Pourdeyhimi, for providing me with all the resources required to complete this study and. I am, in perpetuity, grateful to all of them for providing me with this opportunity to work on this project, and by extension, help me hone my writing, presentation and technical skills as well as problem solving skills, in addition providing me with their timely and invaluable inputs for the successful completion of this project. I would also like to thank Dr. Dieter Griffis, for his consent to be my minor committee member and for his valuable feedback on iv my work. In addition, I would like to thank Dr. Benoît Mazé who has been a good friend and a great help with the computers. The road to this accomplishment would not have been possible without the consistent support, sacrifice and motivation of my family members, my mom Sreelatha Suragani, my dad Venu Gopal Suragani and my brother Dinesh Suragani. I would also like to thank all my relatives and friends for being with me throughout my thick and thin. I would also like to mention, it was a great pleasure working with a diverse group at NCRC including Dr. Bong Yeom, Dr. Sudhakar Jagannath, Dr. Shreya Paul, Dr. Sara Honarbaksh, Dr. Mehmet Dasdemir, Dr. Loganathan Ramasamy, Dr. Vamsi Jasti, Kendall Hollowell, Olga Ievtushenko, Syamal Tallury, Hannah Young, Ning Sun, Elham Amirnasr and Ali Kilic. My special thanks to all my friends who played an influential role. Also I would like to thank the entire Nonwovens Cooperative Research Center (NCRC) and College of Textiles staff for their support. Last but not the least, I would like to thank NCRC for funding this work and North Carolina State University for the incredible time I had during my study. v TABLE OF CONTENTS LIST OF TABLES…………………………………………………………………………...xii LIST OF FIGURES………………………………………………………………………....xiii LIST OF SYMBOLS………………………………………………………………………..xxi CHAPTER 1 INTRODUCTION................................................................................................................... 1 1.1 HYDROENTANGLING ................................................................................................