Influence of Processing Conditions on Melt Blown Web Structure. Part III — Water Quench

The overall goal of our recent research has been to quantitatively measure the influence of commercial processing variables on the structure of polypropylene melt blown webs. In this paper, we applied a cool water quench spray to fibers to increase their thermal quenching rate. Then, we collected webs and measured single fiber diameter, shot content, fiber bundle size, basis weight uniformity and pore structure. The structure of webs produced with and without quenching was compared to access the influence of quenching on webs.

Process Property Studies of Melt Blown Thermoplastic Polyurethane Polymers for Protective Apparel

The primary goal of this research was to determine optimum processing conditions to produce commercially acceptable melt blown (MB) thermoplastic polyurethane (TPU) non-woven fabrics. The 20-inch wide Accurate Products MB pilot line at the Textiles and Nonwovens Development Center (TANDEC), The University of Tennessee, Knoxville, was utilized for this study. MB TPU webs having small fiber diameters were obtained from film-forming and highly elastic fiber-forming TPUs and the webs were mechanically strong and durable to abrasion compared to MB PP. The basic MB process was found to be fundamentally valid for the MB TPU process; however, the MB process was more complicated for TPU than PP, because web structures and properties of MB TPUs are very sensitive to MB process conditions. Furthermore, different TPU polymers responded very differently to MB processing and exhibited different web structure and properties, although uniform elastic MB webs were produced with average fiber diameters as small as 5.0μm. Preliminary research leading to this study was funded the Army Research Office (ARO) and the findings were used by ARO towards the development of an elastic chemical protective liner with better overall comfort attributes and protection against chemical warfare agents.

Study of Repellent Finish of Filtration Ability of Surgical Face Masks

A surgical face mask is an important medical device used to protect both surgical patients and operating room personnel from the transfer of microorganisms, body fluids and particulate material. In this research, the effect of repellent finish on filtration ability of surgical face masks was studied. In determining the filtration ability of surgical face masks, a technique using Laser Scanning Confocal Microscopy (LSCM) was used to determine particle capture. Small particles present on/in nonwoven fabrics of the face masks were located using LSCM. Then, image analysis was used to quantify the small particles by total area to evaluate the filtration ability. The results showed that the filtration layer was the primary contributor to the barrier effectiveness of the surgical face mask. Statistical analysis was performed and the results showed that although repellent finish decreased the filtration ability of the cover layer, it did not affect the filtration ability of the filtration layer.

Melt-Spun Polybutylene Fibers and Nonwovens

Polybutylene (PB-1) fibers were spun at spinning speeds of 250–2500 m/min. A tensile tester was used to analyze the stress-strain behavior of these fibers. In addition, birefringence and the effect of aging were examined. A DMA (dynamic mechanical analyzer) was used to measure the storage modulus and loss modulus of the fibers. Nonwoven mats of the fibers were prepared and compression tests were run on these mats. The properties of the polybutylene fibers and mats were compared with the properties of common polypropylene fibers and mats.

Analysis of a Converging, Annular, Isothermal Melt Blowing Jet Using Computational Fluid Dynamics

An unconventional melt blowing die was analyzed using computational fluid dynamics (CFD). This die has an annular configuration wherein the jet inlet is tapered (the cross-sectional area decreases) as the air approaches the die face. It was found that the flow characteristics of this die are different from conventional slot and annular dies. In particular, for the tapered die the near-field normalized turbulent kinetic energy was found to be lower at shallow die angles. Also, it was found that the peak mean velocity behavior was intermediate between that of conventional annular and slot dies. The centerline turbulence profiles were found to be qualitatively similar to those of annular dies; quantitatively, higher values were present for tapered dies.

Submicron Filtration Media

Biopharmaceutical processes, membrane pretreatment, water purification and food and beverage applications all require fine filtration. There are many different types of filter media that can be used for these applications. The types of media vary by materials of construction, processing method and performance characteristics. Each process produces a media with unique properties that have advantages in different applications. These industries have traditionally relied on membranes for their submicron filtration needs. Nonwoven media have not been successful in finer filtration applications due to the relatively large fibers that are produced or the technical and/or operational difficulties in producing fine fiber media. A significant amount of research has been expended over the last few years on developing high efficiency wetlaid media and producing fine diameter synthetic fibers in drylaid operations. Nonwoven media have begun to compete with membranes and other separation technologies in these fine filtration applications. High efficiency nonwoven media composites have equivalent efficiency as many types of membranes but with significantly higher dirt holding capacity or life. This paper will discuss the different types of wetlaid, drylaid and membrane media available for submicron filtration and compare their methods of construction, performance and cost.

Nanofibers from Natural and Inorganic Polymers via Electrospinning

In the present work the formation of nanofibre webs from natural polymers accessible from waste materials and SiO2-precursors was studied at environmentally acceptable electro-spinning conditions, thus excluding the use of hazardous organic solvents for the preparation of spinning solutions. For these purposes water-based solutions of S-sulfo-kerateins isolated from wool, chitosan and precondensated tertraethyl orthosilicate were investigated with special regard to their propensity in nanofibre formation.

An Image Analysis for Inspecting Nonwoven Defect

Quality and uniformity in nonwoven fabrics is very important, especially when utilized for highly technical purposes. Therefore, the standards for uniformity of nonwovens are growing stricter in applications like filters and battery separators. Traditionally, uniformity evaluation for nonwovens has been the analysis of coefficient of variance (COV), which is often found to be insufficient for inspecting and identifying small defects in the fabric. This paper presents a novel technique based on image segmenting and watershed analysis to inspect defects in the nonwoven. The exact defect areas can be quantified and described through precise calculations. A number of defective nonwoven samples have been tested, showing the method's successful detection and quantification of defects. In addition, the size of investigated image does not appear to greatly affect the result of analysis. Based upon the inspiring findings above, the method should be applicable for on-line monitoring during nonwoven manufacture and promises to reduce manual inspection and costs.

Study on a Novel Material Technology for Chemical/Biological Protection

A novel chemical/biological (CB) protective material was studied in this paper. The material was designed to provide protective properties and satisfactory wearing comfort. In the fabric construction, a PET fabric was laminated with modified PTFE membrane by paste dot coating, and then coated by PU solution in a direct process. Finally, it was laminated with active carbon felt. The modified PTFE membrane completely prevents permeation of the mustard liquid and biological warfare agent, any residuals penetrating the PU will be absorbed by active carbon felt. Furthermore, the CB protective material can provide satisfactory wearing comfort.