3D Structures formed by a Robotic and Meltblowing Integrated System

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Title: 3D Structures formed by a Robotic and Meltblowing Integrated System
Author: Velu, Yogeshwar Karunakaran
Advisors: Abdelfattah M. Seyam, Committee Co-Chair
Tushar K. Ghosh, Committee Co-Chair
Behnam Pourdeyhimi, Committee Member
Marcia L. Gumpertz, Committee Member
Martin W. King, Committee Member
Donald A. Shiffler, Committee Member
Abstract: Meltblown nonwovens have been produced as 2D web structures for a variety of end uses. Investigation into the development of 3D structures, has led to the integration of meltblown and robotic technology to form the Robotic Fiber Assembly and Control System. The effects of various process parameters including the fiber stream approach angle and the curvature of the collecting surface on the structural properties of the webs such as the diameter and orientation distribution of the fibers and the pore size distribution on the webs has been investigated. The interrelationships between these structural parameters have been explored and a statistical model developed. Orientation distribution, and the fiber diameter distribution of the webs were measured on image analysis software, while the pore size distribution was measured using equipment developed on the basis of capillary flow technique. SAS was used to develop the correlations between the structural parameters of the web. In general, all the webs show a larger percentage of fibers orienting in the machine direction (MD). The webs with finer fiber diameter produced webs with smaller pore diameter. The take-up speed of the collector had a significant influence on the orientation and diameters of the fibers in the web. Finer fibers were formed which are more oriented in the machine direction as the take-up speed of the collecting surface increased resulting in the formation of a web which has pores with finer diameter. A decrease in the polymer throughput demonstrated a decrease in the fiber diameter, the pore diameter and the basis weights of the webs. The resulting webs also produced pores that are of finer diameter. Lower attenuating air pressures produced larger diameter fibers. The average pore diameter of the analyzed meltblown fabrics decreased significantly when the attenuating air pressure was increased. Increasing the die to collector distance (DCD) shows a decrease in the percentage of fibers that are oriented in the machine direction. An increase in the DCD also exhibits an initial decrease followed by an increase in the average pore size confirming the existence of different 'zones' in the space between the die and collector. The increase in fiber stream approach angle shows an initial decrease followed by significant increase in the pore size of the web. Compared to the webs formed at low approach angles, analyses of the webs formed at higher approach angles shows that the fibers are more randomly arranged at higher approach angles. The relative frequency of fiber oriented in the machine direction increased significantly when the curvature of the collecting surface increases while the average pore size of the web decreases, due to the increased orientation of fibers in the direction of collection. The pore diameter is found to be directly proportional to the fiber diameter and inversely related to the web anisotropy parameter. The relationship that was established for the 2D webs correlates to the relationship developed for the 3D web structures.
Date: 2003-04-09
Degree: PhD
Discipline: Fiber and Polymer Science
URI: http://www.lib.ncsu.edu/resolver/1840.16/5490

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