Fire fighter gear is required to be no melt/drip consistent with the NFPA 1975 Station Wear Standard in order to reduce the risk of injury. This standard does not address what is worn underneath the gear. Anecdotal evidence suggests that polyester or blends tend to melt. Traditional testing has been performed on upright thermal manikins fitted with sensors that determine burn injury and garment performance. To date, this has not been reported in tests that replicate an actual burn scenario. The purpose of this study is to create a model that more accurately recreates a flashover event in order to determine the effect of what is worn underneath a Fire Fighter’s gear and how it relates to injury potential. We designed three scenarios utilizing “sand” mannikins outfitted with commercially available turnout gear. Each mannikin was outfitted with 9 “puck” style sensors and 2 backups. The sensors were placed in the same locations for each manikin: center chest, center lower back, and outside under the air pack. The sensors were then modified with extended T-type thermocouple wire, fitted with fireproof insulative sheathing and tape, and the wire ends mated with ceramic plug ends to connect to a mobile data acquisition box. The mannikins were then placed into Flashover containers with infrared cameras to record the event. Data was collected at 30, 20, and 1-2 second flashover events. Our results show that the polyester and poly/cotton blends melt under commercially available turnout gear during flashover events. There is a direct correlation between the presence of melted polyester and blend materials and worsened injury to the mannikin simulating severe burn injuries when compared to cotton undergarments. Polyester and poly/cotton blends melt under turnout gear during flashover events leading to increased injury to our mannikin model. This data supports the avoidance of these materials under Firefighter gear as a way to reduce risk of significant burn injury. We are working to raise awareness of that what you wear underneath your gear matters as our Firefighters matter to us. Synthetic base layers melt during firefighting conditions. This information should be used to help inform and protect our Firefighter community. The turnout gear, Manikins, sensors, and undergarments were all donated for this study.
As electronics continue to become more compact and complex, controlling heat remains a growing challenge for circuit performance and durability. DuPont is continuously innovating new Kapton® film and Pyralux® laminate materials that can better manage these challenges by increasing or reducing heat dissipation or assisting in heat generation within a system. This combination of material capabilities allows for a thin, flexible or rigid circuit that can alleviate hot spots and promote more efficient heat control within electronic systems. DuPont has introduced two innovative laminate materials to enhance thermal management in electronics. Temprion™ ODBC is a thermally conductive laminate that complements the Pyralux® laminates product family, showcasing a Kapton® film dielectric with three times the thermal conductivity of traditional Kapton® film at 0.65 W/m-K while maintaining a dielectric strength of 6 kV/mil. It also offers twice the thermal conductivity and a 12% reduction in thermal resistance compared to traditional Pyralux® AP and TFH laminates. Alternately, Pyralux® ML is a metal-clad laminate that incorporates Kapton® all-polyimide technology and various metal alloys, such as copper-nickel and Inconel®, to address unique challenges in heat generation while providing controlled heat transfer and tailored electrical resistance properties. The information highlighted here will explain the advantages of these new thermal management and heat generating laminate materials for use in electronics supported with data and end-use application examples.
This study describes selected research studies performed for developing design rules for power transformers usingnatural esters. The presented simulation results verified adequacy of design rules and allowed for adjustments needed forimplementing the new insulation system vs. the one based on mineral oil and cellulose-based solid insulation. They were alsoused as a base for the next transformer design combining natural ester with aramid insulation.
A detailed understanding of all phenomena that determine high-rate impact response of woven polyaramid systems is needed to design more effective materials and save lives. This study investigates the detailed nanostructures of Kevlar® KM2® Plus fibers from woven systems subjected to controlled rheometric deformations and high-rate impact. The rheometric tension, axial compression following tensile failure, and transverse compression are basic deformations not previously studied by our methods and hypothesized in high-rate impact. The impact of a high-rate object causes significant, layer-dependent nanostructural changes to woven systems. Multichannel AM-FM atomic force microscopy characterizes interior fiber nanostructure with spatially-resolved topological and viscoelastic property measurements of pleat lengths, crystal misorientation angles, fibril widths, and void widths. Statistical analyses were developed to assess convergence of nanostructure feature measurement distributions and compare the correlated nanostructure feature distributions between samples. The data and analyses indicate that tension is not the only mechanism of energy transfer from the impact of a high-rate object and that compressions, both in the axial and transverse directions, are also significant. The varying localized responses to high-rate impact and the presence of both tension and compression imply better systems can be created by improving tensile and compressive properties, tailoring fabric layers to perform to specific types of mechanical deformations.
Abstract Refrigerants that were generally toxic and flammable in the early 1900s were eventually replaced with chlorofluorocarbons (CFCs) in the early 1930s. Since then, they have undergone significant evolution, mostly driven by regulatory actions. The evolution pattern involves an initial phaseout of CFCs to hydrochlorofluorocarbons (HCFCs) followed by hydrofluorocarbons (HFCs), and finally to the current products which include a double bond in their structure and are referred to as hydrofluoro‐olefins (HFOs) and hydrochlorofluoro‐olefins (HCFOs); the term hydro(chloro)fluoro‐olefins (H(C)FOs) is employed when referring to both HFOs and HCFOs. These chemicals were/are also used as foam‐blowing agents, solvents, and propellants. Unlike HFCs and HCFCs, which are saturated organic compounds, H(C)FOs are unsaturated organic compounds (olefins or alkenes) and are composed of hydrogen, fluorine, and carbon (HFOs), or hydrogen, chlorine, fluorine, and carbon (HCFOs). The evolution of these products has mostly been driven by regulatory actions that were aimed at addressing their environmental impact. Initial scrutiny was placed on their stratospheric ozone depletion effects and later on their impact on global warming. H(C)FOs are generally categorized as having zero ozone depletion potential (ODP) and low global warming potential (GWP) and are considered more environmentally friendly, making them suitable substitutes for CFCs, HCFCs, and HFCs. The H(C)FOs reviewed in this chapter have relatively low toxicity and do not pose any health concerns for humans or the environment under normal use conditions. Toxicity datasets for a select number of substances have been reviewed by external scientific committees such as WEEL and ASHRAE as well as various regulatory bodies. Toxicological summaries of five representative commercial H(C)FOs are described in this chapter.
