Session: Protective Textiles
Wednesday, April 2
9:45 AM – Noon
Moderator: Seshadri S. Ramkumar, Texas Tech University
Cooling Effect of Sweat Evaporation from Different Clothing Layers
Emiel A. DenHartog, North Carolina State University
In thermal comfort, a widely discussed property of moisture management is the wicking of liquid sweat away from the skin. Using a thermal manikin, the effect of sweat evaporation at different locations from the skin was investigated. A manikin was used to study dry and evaporative heat loss separately and combined, to determine the effective evaporative heat of sweat, using a series of clothing systems consisting of different combinations of materials, varying in evaporative resistance. The results resemble the theoretical equation fairly well, showing reduced effectiveness of sweat evaporation away from the skin and demonstrating some beneficial effects of condensation in the clothing system for impermeable systems. These results show the effectiveness of sweat evaporation from clothing and help optimize efficiency of sweat evaporation.
Evaluation of High Strength Fibers Extracted from Field Aged Armor
Amanda L. Forster, National Institute of Standards and Technology
The law enforcement community became concerned about the long-term stability of body armor in service after the well-publicized failure of an in-service armor in 2003. This incident led to a heightened interest on the part of many law enforcement agencies to seek ways to evaluate the performance of their armor over time. One such effort was recently conducted by a major North American police organization. In this study, hundreds of units of used body armor were tested using both ballistic testing techniques and an evaluation of mechanical properties to determine how the armor performed during its service life. This presentation will discuss the findings of this study and what lessons can be learned from this effort to inform future studies.
Impact of Firefighter Protective Equipment and Firefighting Activity on Physiology and Biomechanics of Movement
Gavin Horn, University of Illinois at Urbana
In this presentation, we will provide an overview of several of the multidisciplinary research studies conducted by the Illinois Fire Service Institute. These focused on the various Engineering, Human Factors, and Exercise Science based investigations into the effect of firefighting personal protective equipment design (PPE) and its interaction with the stresses from firefighting on the ability of a firefighter to operate in a safe and effective manner. The impact of bunker gear style PPE design on the heat stress and cardiovascular strain that results from firefighting will be described. Additional studies on the design of firefighting PPE have demonstrated the impact on the biomechanics of movement, impacting the risk for slips, trips, and falls—the leading cause of fireground injuries in the US Fire Service.
Advantages of using Systems-Level Test Methods to Evaluate the Performance of Fire/Flame Resistant Protective Clothing
Alex Hummel, North Carolina State University
Performance criteria used to certify and qualify personal protective clothing are traditionally based off measurements from bench-scale test methods such as the Thermal Protective Performance (TPP), Radiant Protective Performance (RPP), and the Conductive Heat Resistance (CHR) tests. These tests evaluate how much heat passes through small swatches (typically 5” x 5”) of protective fabric(s) representing the layers of firefighter or military uniforms. Bench-scale testing, however, does not accurately measure these fabrics’ performance when being worn in garment form, resulting in “overprotection” which negatively impacts physiological heat stress. Systems-level test methods, such as NC State’s PyroMan, RadMan, and other manikins, capture valuable information about garment fit, layering, air gaps, and shrinkage effects that can improve overall protective clothing performance, reducing deaths to firefighters and soldiers.
Session: Innovative Technologies
2:00– 4:00 PM
Moderator: Haskell W. Beckham, Exponent Inc.
The Impact of Cellulose Nanocrystal Orientation on the Enhanced Mechanical Properties and Structural Color of Bio-Nanocomposites
Christopher Kitchens, Clemson University
Cellulose nanocrystals (CNCs) are the nano-scale building blocks that provide natural fibers their unique and often unmatched properties. This work focuses on the incorporation of CNCs into polymer nanocomposites from renewable resources; taking a biomimetic approach to polymer nanocomposite design. This talk will present our recent work with CNC nanocomposites of 1) alginate fibers and 2) polylactic acid films. The results suggest that CNC alignment is a key factor influencing the mechanical properties. WAXD was used to correlate CNC orientation in the alginate nanocomposite fibers with the resulting mechanical property enhancements. Similar behavior is also observed in natural fibers where cotton, a fiber with a higher elastic modulus, possesses a higher spiral angle, while bast fibers are stronger and possess greater CNCs alignment. An increase in PLA toughness with CNC addition without compromising the film strength was also demonstrated.
Submicron Meltblown Filter Media for Enhanced Efficiency
Seshadri S. Ramkumar, Texas Tech University
Nonwoven webs with superior barrier properties and increased filtration efficiency find applications in filtration, medical, hygiene and other innovations forthcoming in the nonwovens industry. Meltblown technology is evolving to develop highly efficient submicron filters. There is no substantial data available on the filtration efficiency of single layer submicron webs and their comparison with micron sized webs. Refined dies were used to develop single layer standalone submicron fiber size webs with fiber diameters 520 nm and 590 nm. Additionally, we have used regular meltblown die to develop micron size webs ranging from 1620 nm to 2100 nm. This presentation will focus on the relationship between the fiber diameters, air permeability of the single layered standalone webs to their filtration characteristics, as well as filtration characteristics of standalone single layer submicron webs.
Multi-stimuli Responsive Conductive Polymers for Photoelectric Artificial Muscle Dressings
Tawfik A. Khattab, Kent State University
This research work addresses the need for completely flexible devices embedded into truly wearable smart fabrics, built from electroactive molecular switching polymers for functional electrical stimulation, capable of providing electrically induced muscular contractions in patients affected by neuromuscular disorders. We report a new generation of a reversible crosslinkable electroactive polyanilines, polythiophenes, and polypyrroles capable of responding to external stimulus and consequently modifying their features. In response to these external stimuli including electric field, light, and heat, these polymers can show all the required active functionalities including sensing, actuation, and mechanical flexibility - superior to those of frequently used inorganic materials. Sensorized garments able to monitor the human body kinematic variables including positions and movements of articulation segments, and physiological actions, will be developed.
Novel Low Band Gap Ru (II) Dyes for Enhanced Light Harvesting and High Efficiency Dye-sensitized Solar Cells
Maqbool Hussain, North Carolina State University
Four novel Ru (II) bipyridyl dyes MH11-MH14, containing strong electron donor ancillary ligands, were synthesized and characterized to study their structure-property relationship for dyes-sensitized solar cells. The molecular structures of MH11-MH14 were characterized using FT-IR, -ESI-MS, and 1H-NMR. All four dyes, MH11-MH14 exhibited red shifted metal-to-ligand-charge transfer (MLCT) with significantly higher molar extinction coefficient than that of the benchmark N719-dye. This impressive light harvesting capability was attributed to the strong electron donor ancillary ligands, which destabilized the Ru (t2g) and produced smaller HOMO-LUMO gap compared to that of N719. The photovoltaic performance of MH11-MH14 was measured on nanocrystalline TiO2 and compared under the same experimental condition to that of N719. Among these complexes, MH12 demonstrated the best solar-to-power conversion efficiency of 9.71% compared to 9.32% of N719.
Session: Medical Textiles
Thursday, April 3
9:00 AM – 11:45 AM
Moderator: Philip J. Brown, Clemson University
Nanofibrous Platforms for Wound Healing and Tissue Engineering Applications
Elizabeth G. Loboa, University of North Carolina at Chapel Hill and North Carolina State University
We have investigated the effects of four nanofiber morphologies: 1) single component, 2) core-sheath, 3) porous, and 4) hollow porous, on drug and compound release from nanofibrous scaffolds. Nanofibrous scaffolds comprised of these different fiber morphologies were analyzed for their ability to promote wound healing by providing antimicrobial, antibacterial, and anti-inflammatory actions while maintaining viability of human dermal fibroblasts (HDF) and human epidermal keratinocytes (HEK). We have found distinct differences in release profiles as a function of fiber morphology that significantly affect HDF and HEK fate. We have created novel scaffolds that successfully inhibit and kill multiple bacteria of critical concern in wound healing while also maintaining viability, or in some cases promoting proliferation, of HDF and HEK.
Effects of Antimicrobial Activities of Peppermint and Rosemary Oils Incorporated into Textiles
Suraj Sharma, University of Georgia
With the development of innovative technologies, textile manufactures face diverse challenges to meeting the consumers' demands, profits, and maintaining a sustainable environment. In order to uphold the quality of products, AATCC test methods should be implemented and emphatically executed. In this study, AATCC-100 and AATCC-147 test methods were used to determine the antimicrobial activities of peppermint and rosemary oils incorporated into woven, knit, and nonwoven textiles, using natural protein fibers, manufactured regenerated fibers, and synthetic fibers. Samples were tested for the microorganisms—Bacillius subtilis and Escherichia coli. The effect of oil incorporation into the textiles against microorganisms is investigated by (1) padding micro-encapsulated oil into the textiles; (2) placing oil directly over the textiles; and (3) spraying micro encapsulated oil powder over the textiles.
Materials Science of Surgical Meshes: Polypropylene for Soft Tissue Repair
Maureen T. F. Reitman, Exponent Inc.
Synthetic meshes made from polymer fibers have been used for over 50 years to augment natural tissue and restore function in abdominal, urological, urogynecological, cardio-thoracic, and orthopedic applications. One of the most common synthetic mesh types is knitted polypropylene monofilament. Based on the visual condition of some explanted fiber surfaces and chemical analyses of inappropriately cleaned fibers, some suggest that polypropylene is not a stable biomaterial and is susceptible to oxidative degradation. Mesh materials were evaluated to assess the surface and bulk properties of polypropylene fibers from surgical meshes after manufacturing and after implantation. The mesh materials were shown to be chemically inert and resistant to oxidation. Surface features on explanted fibers hypothesized to be oxidized polypropylene were found to be non-polypropylene deposits.
A New Strategy for the Woven Tubular Taper: Improvements in Weaving Vascular Grafts
Seth Winner, Secant Medical Inc.
A bio-inspired textile designer should strive to create biomimetic structures to replicate the geometric shapes and microstructures of the human anatomy. We can construct physiologically compliant structures that can permanently redirect blood flow, tethers and bands to anchor restorative devices, or provide temporary scaffolding for the body to permanently rebuild and heal itself. One of the challenges is the need to improve the design of vascular grafts for the EVAR procedure. This presentation focuses on a novel method to change the diameter without affecting the density of the fabric wall. With this new method, we are able to imagine more complex structures using the taper technology and also create thicker walls for intestinal structures. It is possible to make grafts with elastomeric yarns for pulsatile compliance.
Ecolab Medical Materials Development Pathway
Tami Mace, Ecolab Inc.
The talk will consist of a basic overview of the business platforms Ecolab Surgical is supporting and include my impressions when transitioning from personal care to health care in materials development; including challenges related to standards specific to medical devices, the evolution of the surgical suite, and meeting constantly changing needs in procedures and equipment use, as well as, finding ways to innovate while meeting regulatory and commercial needs.
Session: Innovative Technologies
2:15 – 3:45 PM
Moderator: Donald B. Thompson, North Carolina State University
New Approaches towards a Sustainable Textile Industry of Tomorrow
Anja Gerhardts, Hohenstein Institute for Textilinnovation GmbH, Germany
Reducing the impact of textile products on the environment is becoming increasingly important for the textile industry. The main interest concerns biodegradable products and fibers from sustainable sources in consumer as well as in medical applications. Current research at the Hohenstein Institutes deals with the decay of sustainable products or their resistance to micro-organisms in biologically active soil. To evaluate the biodegradation of textiles based on soil burial tests, a new assessment scheme was developed and made available to the industry. Some fiber types display a rapid degradation. Therefore, we present further research data on the production of alginate and chitosan, based on biotechnological fermentation. With this technology, we move towards a new sustainable textile industry: From micro-organisms via fibers up to textile end use.
Process Property Relationships of Synthetic Polymers Exposed to Organometallic Vapors
Jesse S. Jur, North Carolina State University
Inorganic and hybrid (organic-inorganic) modifications to synthetic fibrous materials have drawn significant interest for their ability to impart optical and mechanical properties. We will explore the luminescent, optical absorption, and barrier influence imparted upon fabrics by use of novel metallo-organic vapor exposures that react with the outer surface of the fabric. During exposure to these vapors, a reactive infiltration occurs into the bulk of the polymer, forming a hybrid material that shows unique properties. Specifically, research findings on the degree of infiltration of trimethylaluminum (TMA, a precursor commonly used in the formation Al2O3) into polyesters is provided. Process-property relationships are provided that exhibit the unique materials characteristics of the hybrid modification. TME infiltration into polyethylene terephthalate shows significant alterations in UV absorption and photoluminescence.
Single PPTA Fiber Tensile Test under High Strain Rate Loading
Jae Hyun Kim, National Institute of Standards and Technology
The mechanical properties of high strength polymer fibers are often measured at many orders of magnitude slower rates, although the fibers deform at high rates during ballistic impact. A modified Kolsky bar first proposed by Cheng et al. was used, employing a direct fiber gripping method, allowing the measurement of fiber tensile properties at high rate loading, avoiding the adhesive wicking and low throughput of the original design. A single fiber tensile test method at high rates will be introduced and the tensile strengths and failure strains measured at different rates will be discussed.