Browse Topic: Nylon
Researchers have developed a solar-powered reactor to break down hard-to-recycle forms of plastic waste – such as drinks bottles, nylon textiles and polyurethane foams – using acid recovered from old car batteries, and converting it into clean hydrogen fuel and valuable industrial chemicals.
Certain materials — such as quartz, some ceramics, and even bone — produce an electrical charge when they are squeezed, pressed, or vibrated. This is piezoelectricity, which comes from the Greek “piezein” meaning to press. Modern vehicles rely on piezo components in fuel injectors, parking sensors, airbag systems, and other functions.
Researchers have developed a method that converts cotton into sugar that in turn can be turned into spandex, nylon, or ethanol.
The compatibilities of fuel system elastomers and plastics were evaluated for test fuels containing 16 vol.% isobutanol (iBu16) and 10 vol.% ethanol (E10). Elastomers included two fluorocarbons, four acrylonitrile butadiene rubbers (NBRs), and one type of fluorosilicone, neoprene, and epichlorohydrin/ethylene oxide. Plastic materials included four nylon grades, three polyamides, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE), polyphenylene sulfide (PPS), high-density polyethylene (HDPE), polybutylene terephthalate (PBT), polyoxymethylene (POM), flexible polyvinylchloride (PVC), polyetherimide (PEI), polyetheretherketone (PEEK), and a phenol formaldehyde reinforced with glass fiber (GFPF). For each polymer material, the volume, mass, and hardness were measured before and after drying. Dynamic mechanical analysis (DMA) measurements were also performed on the dried specimens. For the elastomer materials the measured properties were similar for both fuels. The fluorocarbons and fluorosilicone swelled the least (~20%), while more moderate (20-45%) expansion occurred for the two NBR hose grades and (ECO). HNBR, neoprene, and silicone exhibited high swelling and softening, which likely precludes their use in many fuel systems. For the plastic materials, the observed swell was low; Nylon 11 swelled around 15%, but otherwise, their measured swell was <10%. Many of the plastics also showed sensitivity to alcohol type, as the E10 test fuel often imparted appreciably higher swell than iBu16. In general, the plastic materials showed good compatibility with the iBu16 and E10 test fuels. The sole exception was the PVC material, which was structurally degraded from exposure to either fuel type. Compositional analysis showed high fuel retention in Nylon 12 and PVC. PVC also experienced a significant reduction in plasticizer compounds following exposure, which resulted in embrittlement and an increase in the glass-to-rubber transition temperature.
In recent years, the emerging technology competitions in automotive industry are improving engine efficiency and electronizing for coping with stringent fuel-economy regulations. However, fuel-economy technologies such as engine down-sizing and numerous electronic parts entrust burden plastic materials acing as mainly electric insulation and housing to have to be higher performance, especially temperature endurance. Engineering plastics (EPs) have critical limitations in terms of degradation by heat. Heat-resisting additives in EP are generally used to be anti-degradation as activating non-radical decomposition of peroxide. However, it could not be effective way to impede the degradation in long term heat aging over 1,000 hours at high temperature above 180 °C. In this study, we suggested the new solution called ‘shield effect’ that is purposeful oxidation at the surface and local crystallization of EP to stop prevent penetrating oxygen to inside of that. Ethylene diamine tetra acetic acid (EDTA) and Citric acid (CA) are used as additives for surface oxidation. We added the EDTA and CA to Nylon co-polymer of PA6T/6I-PA66 and made test specimens. Surprisingly, physical properties maintained 5% under degradation rate at 250 °C, over 1,000 hours in contrast with Nylon added general additives. We confirmed surface oxidation and local crystallization of the Nylon by using Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Diffraction Spectroscopy (XRD). Base on this result, we adopt the new materials to high temperature needed automotive parts in engine such as Battery Fuse Terminal (BFT) and Multi Fuse Terminal (MFT), in exhaust system such as Muffler.
The guarantee of long-term reliability of cars is becoming increasingly important in society. It is extremely important to confirm whether the condition of the accelerated deterioration test (for evaluating long-term reliability) is reasonable with respect to recent use environment conditions. In this paper, we propose how to promote degradation test conditions to guarantee the function of parts (resin materials of interior parts) exposed over a long period of time to a severe temperature environment inside the car. Heat-resisting grade nylon 66 fiber (hereinafter referred to as H-PA 66), which is a constituent material of parts requiring long-term reliability, was used as a specific resin material. High-temperature accelerated deterioration test of H-PA 66 fiber was carried out to obtain the time (hereinafter referred to as 90% strength time,) during which the tensile strength retention rate decreased to 90%. The relationship between this high temperature accelerated deterioration temperature and 90% intensity time could be expressed by the Arrhenius equation. The acceleration rate of deterioration was determined from the Arrhenius plot of this equation. At the same time, we propose DOE (Design of Engineering) graph which can judge deterioration by expressing accelerated deterioration temperature on the vertical axis and accelerated deterioration time on the horizontal axis. We predicted deterioration after 15 years from the temperature history of the actual environment obtained by the exposure test. Moreover, reasonable promotion deterioration condition without excess or deficiency in the case of 15 year guarantee was sought. The DOE graph (capable of expressing the relationship between the actual use environment and accelerated deterioration test condition) improves the accuracy and reliability of the accelerated deterioration condition.
The compatibility of key fuel system infrastructure plastics with 39 bio-blendstock fuel candidates was examined using Hansen solubility analysis. Fuel types included multiple alcohols, esters, ethers, ketones, alkenes and one alkane. These compounds were evaluated as neat molecules and as blends with the gasoline surrogate, dodecane, and a mix of dodecane and 10% ethanol (E10D). The plastics included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), polybutylene terephthalate (PBT), polypropylene (PP), high density polyethylene (HDPE), along with several nylon grades. These materials have been rigorously studied with other fuel types, and their volume change results were found to correspond well with their predicted solubility levels. The compatibility was assessed using Hansen solubility parameters and in many instances peak solubility occurred for blends rather than the neat fuel components. The results showed that good compatibilities can be expected for PPS, PVDF, PET, nylons, acetal, PEI, PVC, HDPE and PBT. PTFE showed potential incompatibilities at low blend concentrations, especially when E10D was used as the base fuel blend. Although, the nylons show good overall compatibility, the results do indicate that mid-range and high alcohol contents may not be suitable for Nylon 6 and Nylon 11 in applications requiring low volume swell. Poor potential compatibility was limited to two plastic types; PETG exposed to mid and high blend levels of the ethers and PP exposed to sabinene and the aromatics. In general, the data showed good compatibility for the majority of the candidate fuels and plastics.
This SAE Standard covers complete general and dimensional specifications for tube fittings of the spherical and flanged sleeve compression types for use in the piping of air brake systems on automotive vehicles. The spherical sleeve compression type Figures 1A to 5 and Tables 1 to 3 is intended for use with annealed copper alloy tubing per SAE J1149, Type 1. The flanged sleeve compression type Figures 6A to 11 and Tables 4 to 6 is intended for use with nylon tubing per SAE J844. It is not intended to restrict or preclude other designs of a tube fitting for use with SAE J844, air brake tubing. Performance requirements for SAE J844 are covered in SAE J1131. See SAE J1131 for the Performance Requirements of Reusable (Push to Connect) Fittings Intended for Use in Automotive Air Brake Systems. CAUTION: To assure satisfactory performance, tapered sleeve compression type fitting components (SAE J512) should not be intermixed with the spherical or flanged sleeve components, nor should the spherical sleeve compression type components be intermixed with the flanged sleeve compression type components when assembling connection in areas where the three types are available.
Traditionally, Knee Air Bag (KAB) is constructed of a woven nylon or polyester fabric. Recently, Ford developed an injection molded air bag system for the passenger side called Active Glove Box (AGB). This system integrates a plastic bladder welded between the glove box outer and inner doors. This new system is smaller and lighter, thus improving the roominess and other creature comforts inside the passenger cabin while providing equivalent restraint performance as traditional knee airbag system. This patented technology allows positioning of airbags in new locations within the vehicle, thus giving more freedom to designers. The first application of this technology was standard equipment on the 2015 Ford Mustang. Given that this technology is first in the industry, it was a challenge to design, test and evaluate the performance of the system as there is no benchmark to compare this technology. A CAE driven design methodology was chosen to overcome this challenge. This method gave engineers the ability to use an iterative approach to the design and the ability to analytically evaluate the performance of the system. Once a final design was validated through CAE, parts were manufactured and put through physical testing to qualify the design. Quantitative performance of the AGB was then correlated back to CAE results. The CAE prediction shows good correlation to the physical tests. Final design tweaking was performed on the Active Glove Box system to meet the crash safety and other performance requirements.
Microalgae as feedstock are the potential third generation biofuels. Microalgae are photosynthetic microorganism which requires light, carbon-di-oxide, nitrogen, phosphorous, and potassium for growth and to produce lipids, proteins and carbohydrates in large amounts over short a periods of time. The production of biofuels from microalgal is a viable alternative due to their easy adaptability to growth conditions, possibility of growing biomass either in fresh or marine waters. Hence the current project was designed to elucidate the biodiesel producing ability of blue-green algae such as Spirulina platensis and Green algae Chlorella vulgaris. The selected algae were cultivated in suitable growth media such as modified Zarrouke medium and bold basal medium, respectively. The Spirulina platensis and Chlorella vulgaris were mass cultured for 8 days then harvested using 50 micron nylon filters and dried in sunlight to obtain dry biomass. The dried microalgal biomass was extracted for bio-oil production. The extracted bio-oil was analyzed in gas chromatography mass spectrometer (GCMS) to derive its fatty acid profile. From the results, it is clear that 60oC temperature was optimum for bio-oil extraction. The bio-oil thus extracted was converted to biodiesel by trans-esterification process using methanol and NaOH. The quality parameters such as density, viscosity, flash point, iodine value, sulphur and water content of the obtained biodiesel were analysed and found to be in correlation with the EN-14214 standards. From the experiment results it was clear that the yield and analysis parameters of biodiesel were comparatively better in Chlorella vulgaris (75%). The biodiesel extracted from dried biomass of Chlorella vulgaris was tested in 3-cylinder naturally aspirated diesel engine with blend of 20%. Performance and emission parameters have been measured and analysed in this paper.
Samples of 33% glass filled and unfilled poly(butylene terephthalate) [PBT] and nylon 66 (PA66) were injection molded into bars,which were immersed in common engine and powertrain fluids: antifreeze, motor oil and automatic transmission fluid for 25 days. Fluid uptake was measured at 1, 7, 18, and 25 days by gravimetry. Both PBT samples absorbed 0.2-0.25% antifreeze and 0.05 - 0.10% motor oil and automatic transmission fluid (ATF). Both DSC and DMA analysis showed no disruption of polymer thermal transitions or storage moduli. The glass filled PA66 sample absorbed 2.5% antifreeze and 0.25-0.3% of motor oil and ATF and showed an 80°C reduction in the tan delta maximum on DMA. The unfilled PA66 sample absorbed 7% antifreeze and 0.2-0.3% of motor oil and ATF also showed a tan delta maximum 80°C less than the unexposed control. Creep analysis was conducted on the unfilled nylon sample and compared to a virgin material. The softer antifreeze-exposed sample had the expected higher instantaneous strain; however, it had a much reduced viscoelastic response and less permanent deformation. This behavior was thought to arise from hydrogen bond crosslinking of the chains by the imbibed ethylene glycol.
Creation of a structural joint for a heat shield for extreme entry environments requires structural fibers penetrating through the thickness of the shield at joint locations. The structural fibers must be made of carbon to withstand extremely high temperatures, i.e. 2000 ºC. Carbon fibers, due to their relatively high modulus (stiffness), are easily damaged and broken when handled by a conventional sewing machine. Special coatings such as nylon are required to increase the durability of the fiber to enable its use in a sewing or tufting process.
The compatibility of plastic materials used in fuel storage and dispensing applications was determined for an off-highway diesel fuel and a blend containing 20% bio-oil (Bio20) derived from a fast pyrolysis process. Bio20 is not to be confused with B20, which is a diesel blend containing 20% biodiesel. The feedstock, processing, and chemistry of biodiesel are markedly different from bio-oil. Plastic materials included those identified for use as seals, coatings, piping and fiberglass resins, but many are also used in vehicle fueling systems. The plastic specimens were exposed to the two fuel types for 16 weeks at 60°C. After measuring the wetted volume and hardness, the specimens were dried for 65 hours at 60°C and then remeasured to determine extent of property change. A solubility analysis was performed to better understand the performance of plastic materials in fuel blends composed of bio-oil and diesel. All of the plastic materials evaluated in this study exhibited higher solubility (volume swell) with the Bio20 fuel blend. This result was predicted by the solubility analysis. However, there were two notable exceptions; the volume swell results for high density polyethylene (HDPE) and polypropylene (PP) did not correlate with their respective solubility curves. HDPE and PP were also unique in that they were the only two plastics that exhibited pronounced volume expansion in the baseline diesel test fuel. The plastic materials which showed the best compatibility to the bio-oil blend were the barrier plastics polypropylene sulfide (PPS), polyethylene terephthalate (PET or Mylar™), and polytetrafluoroethylene (PTFE or Teflon™). Polyvinylidene fluoride (PVDF or Kynar™) is also used extensively as a permeation barrier material; however, it swelled over 15% when exposed to Bio20. Four grades of nylon were evaluated and the petroleum-derived nylons (Nylon 6, Nylon 6,6, and Nylon 12) showed good compatibility with the test fuels. In contrast, Nylon 11, which is derived from vegetable oil, expanded over 4% with Bio20. HDPE also swelled around 4%, but did so with both test fuels. Two acetal materials and polybutylene terephthalate (PBT) were also observed to swell to 4% with Bio20. Four fiberglass resins were included in the study and they exhibited 10-18% volume expansion. High volume swell was also noted for PP, the PET polyethylene - glycol copolymer (PETG), and polythiourea (PTU). PP also expanded over 15% following exposure to the baseline diesel test fuel.
The compatibility of plastic materials used in fuel storage and dispensing applications was determined for a test fuel representing gasoline blended with 10% ethanol. Prior investigations were performed on gasoline fuels containing 25, 50 and 85% ethanol, but the knowledge gap existing from 0 to 25% ethanol precluded accurate compatibility assessment of low level blends, especially for the current E10 fuel (gasoline containing 10% ethanol) used in most filling stations, and the recently accepted E15 fuel blend (gasoline blended with up to15% ethanol). For the majority of the plastic materials evaluated in this study, the wet volume swell (which is the parameter most commonly used to assess compatibility) was higher for fuels containing 25% ethanol, while the volume swell accompanying E10 was much lower. However, several materials, such as polyvinylidene fluoride (PVDF), fiberglass resins, and the polyethylene terephthalate co-polymer (PETG) exhibited similar volume expansions with both 10 and 25% ethanol. In the second part of this study, the compatibility performance of the infrastructure plastics in the E10 test fuel was compared to a test fuel containing 16% isobutanol (which has the same oxygen level as E10). The measured property changes (volume and hardness) in these two fuels were similar for the majority of the plastics tested. However, Nylon 6, Nylon 6,6, and the vinyl ester fiberglass resin showed much better compatibility with a 16% isobutanol blend than with a blend containing 10% ethanol.
The compatibility of plastic materials used in gasoline storage and dispensing applications was determined for test fuels representing neat gasoline (Fuel C), and blends containing 25% ethanol (CE25a), 16% isobutanol (CiBu16a), and 24% isobutanol (CiBu24a). A solubility analysis was also performed and compared to the volume swell results obtained from the test fuel exposures. The plastic specimens were exposed to each test fuel for16 weeks at 60°C. After measuring the wetted volume and hardness, the specimens were dried for 65 hours at 60°C and then remeasured for volume and hardness. Dynamic mechanical analysis (DMA), which measures the storage modulus as a function of temperature, was also performed on the dried specimens to determine the temperature associated with the onset of the glass-to-rubber transition (Tg). For many of the plastic materials, the solubility analysis was able to predict the relative volume swell for each test fuel. Those plastic materials commonly used as permeation barriers exhibited the least amount of volume and hardness change (<5%) when exposed to the test fuels. The response of other plastics (especially nylon) varied according to type and grade. Nylon 6 and Nylon 6,6 showed the lowest property changes following exposure Fuel C and the isobutanol blends, but swelled over 7% when exposed to CE25a. Acetal and polybutylene terephthalate (PBT) swelled around 5% with exposure to the test fuels, while high density polyethylene (HDPE) swelled around 10% for each test fuel. The remaining thermoplastics swelled to higher values and in the case of polypropylene, dissolution occurred with exposure to gasoline containing 25% ethanol. The fiberglass resins experienced more swelling in CE25a when compared to the baseline fuel or the two isobutanol blends. In general, the plastics exhibited a positive volume change when dried, which was attributed to fuel retention. For many plastics the Tg was not measurably affected by the test fuel exposures. However, polyethylene terephthalate (PET) and the nylons were notable exceptions. The Tg for PET was reduced by 30°C with CE25a, while the reductions observed for nylon depended on both nylon grade and oxygenate type.
The American Chemistry Council sponsored program to optimize a specimen design for use in high strain rate testing of long fiber-reinforced thermoplastics (LFRT) was experimentally validated through testing of injection molded long glass-filled polypropylene (LGFPP) and long glass filled Nylon ® (Nylon). It was demonstrated that the dynamic specimen geometry generated valid results for LFRT tensile tests in the quasi-static through 400/s regime. Optimum specimen size depended on the maximum test rates and end use of the data. The program results provide a basis to select specimen parameters to appropriately represent LFRT or similar materials for comparison or material property testing. Tests established the effects of injection technique; strain rate (nominal 0.1/s to 400/s); fiber fill content (20wt%, 30wt%, 40wt%), specimen type and width, panel thickness, distance to the fill gate, flow orientation, and material homogeneity. Not all variables were tested using material from both vendors. For a given LGFPP specimen size and vendor, the strength and modulus increased with fiber content, specimen width, and nominal strain rate. The LGFPP strength and failure strain increased between 0.001/s and 4/s but remained constant between 4/s and 45/s. Macroscopic and microscopic examinations of the fractures surfaces showed a strong mechanical bond between the fibers and the matrix. The Nylon demonstrated no difference in the strength between specimens identified with large or small amounts of fiber clusters. The ultimate strength, yield strength, and modulus of Nylon° increased between 0.001/s and 45/s. The failure strain decreased between 0.001/s and 45/s.
Changes in the automotive supply chain over the past several years were brought about by global economic pressures, and forced some materials into tight supply as the industry started its recovery. One such material is polyamide 6,6 fiber (PA 6,6) used for airbags, which was in tight supply in 2008-09. This, with the availability of new low temperature inflators caused some airbag module manufacturers to revisit the use of polyester (PET), which had been used sporadically and in small quantities since the 1970s, although the overwhelming majority of airbags used PA 6,6. Over the last several years PET has been adopted for use in a small number of airbag programs to reduce supply concerns, but this use has come with performance tradeoffs of higher weight, lower tear and seam properties, and other changes. Still, the lower polymer cost of PET has driven a wider evaluation. Polyamide 6,6 and polyester are not equivalent fibers, and differences in thermal capacity, toughness, modulus, and other properties result in different fabric performance. The purpose of this paper is to raise awareness of key property differences so that the appropriate polymer is selected for each airbag. This report is a summary of studies conducted by INVISTA S.á.r.l. to understand the potential consequences and important considerations of changing airbag cushion material from polyamide 6,6 to polyester. INVISTA is a current supplier of PA 6,6 and PET for a wide range of products including airbags, and can thus provide an unbiased view on the materials. These studies include the analysis of airbag modules that changed from PA 6,6 to PET, and laboratory tests of fibers and fabrics measuring the performance differences between these polymers.
The thermal efficiency of an internal combustion engine at steady state temperatures is typically in the region of 25-35%[1]. In a cold start situation, this reduces to be between 10% and 20% [2]. A significant contributor to the reduced efficiency is poor performance by the engine lubricant. Sub optimal viscosity resulting from cold temperatures leads to poor lubrication and a subsequent increase in friction and fuel consumption. Typically, the engine lubricant takes approximately twenty minutes [3] to reach steady state temperatures. Therefore, if the lubricant can reach its steady state operating temperature sooner, the engine's thermal efficiency will be improved. It is hypothesised that, by decoupling the lubricant from the thermal mass of the surrounding engine architecture, it is possible to reduce the thermal energy loss from the lubricant to the surrounding metal structure in the initial stages of warm-up. Using a bespoke oil flow rig described in the methodology section of this paper, it has been demonstrated that the addition of a 2 mm thick nylon tube, increases the maximum temperature differential between the lubricant and surrounding metal by 145% and reduces the energy losses from the gallery by 50%. This results from the addition of both a high thermal resistance material and a contact resistance between the polymer tube and metal. The insulating performance of nylon has been closely matched by utilising a specially designed aluminium insert with a 0.5 mm air gap. The increased contact resistance of such an insert has been shown to increase the temperature differential by 107% and reduce energy losses by 40%.
The use of acoustic cavity fillers or “baffles” to prevent the propagation of air borne and structure borne noise, water and dust into the interior spaces of vehicle structures has been in practice for many years. Continuous development of new OEM requirements has pushed the state of the art concerning the design and functionality of these cavity sealing systems. Various technologies are available to OEMs to provide sealing that will prevent water and dust penetration, maximize performance of vehicle HVAC systems, and minimize the propagation of noise from the body structure into the interior compartment under operating conditions. Generally, three types of cavity sealing systems are available: pre-formed thermoplastic-based systems that incorporate a heat reactive thermoplastic sealer applied to a nylon or steel “carrier” for attachment to the body structure; heat reactive rubber-based sealer systems that incorporate a carrier, push pin or pressure sensitive adhesive layer for attachment; and bulk applied chemically reactive two component polyurethane or expandable “foam” systems. In this case study, a challenge undertaken by this supplier was to provide a thermoplastic baffle design of equal or lesser weight compared to a competitive, die-cut rubber-based technology currently in production at a particular OEM, while achieving equivalent acoustical performance. This paper will document the alternative design proposals and development activities that were pursued to meet this particular objective.
This SAE Standard covers complete general and dimensional specifications for tube fittings of the spherical and flanged sleeve compression types for use in the piping of air brake systems on automotive vehicles. The spherical sleeve compression type Figures 1A to 5 and Tables 1 to 3 is intended for use with annealed copper alloy tubing per SAE J1149, Type 1. The flanged sleeve compression type Figures 6A to 11 and Tables 4 to 6 is intended for use with nylon tubing per SAE J844. It is not intended to restrict or preclude other designs of a tube fitting for use with SAE J844, air brake tubing. Performance requirements for SAE J844 are covered in SAE J1131. See SAE J1131 for the Performance Requirements of Reusable (Push to Connect) Fittings Intended for Use in Automotive Air Brake Systems. CAUTION: To assure satisfactory performance, tapered sleeve compression type fitting components (SAE J512) should not be intermixed with the spherical or flanged sleeve components, nor should the spherical sleeve compression type components be intermixed with the flanged sleeve compression type components when assembling connection in areas where the three types are available.
A resin coating was applied to a piston skirt for use in an internal combustion engine to reduce the frictional resistance on its surface. The purpose of the authors' study was to observe the change in surface states with the addition of nylon and graphite to the coating as solid lubricant particles in order to investigate the tribological properties of the surface. The authors observed self-formed microdimples on the resin surface when nylon particles were added to the polyamide-imide (PAI) coating material. These microdimples functioned as oil reservoirs similar in size to the nylon particles. The authors used PAI as a binder, and graphite particles (5 μm) and two different grades (5 and 10 μm) of nylon-12 particles as additives. These materials were mixed in a solvent, and an aluminum test sample was coated. The test sample was then heated in an oven to cure the PAI. Next, the texture of the surface was observed. The tribological properties were measured with a ball-on-disk tribometer under both oil lubrication and dry conditions. When only graphite particles were added to PAI, microdimples did not form on the surface of the coatings. However, the authors observed microdimples when both nylon and graphite particles were added. Sliding tests under oil lubrication showed a minimum value of the friction coefficient when 3-5 vol% of nylon was added. The addition of nylon particles to the graphite/PAI mixture decreased the friction coefficient at slow sliding speeds. Under the dry condition, the addition of a small amount of nylon did not affect the coefficient, but the friction coefficient decreased as the amount of graphite particles increased.
Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them.
Textile-based energy absorbers are under consideration for possible use as load-limiting devices for heavy payload tie-down systems in rotorcraft. In the event of a hard landing, these devices could prevent failure of the mounting system and subsequent uncontrolled motion of the payload. A series of environmental conditioning regimens were imposed on the textile load limiters, which are polyester tear webbings and nylon stitch-ripping devices. These test specimens were exposed to: ambient conditions; salt-fog spray; isopropyl alcohol; hydraulic fluid; hot-water immersion; kerosene; and either high or low temperatures. The results, based on performance measures of: specific energy absorption, volumetric energy absorption, linear energy absorption, and coefficient of variation of force, demonstrated that the high temperature conditioning caused the most prominent decrease in performance while the other conditions showed only small variations. Both devices were also tested at rates as high as 15 m/s in ambient conditions. The devices were found to have only a slight reduction in performance under dynamic testing conditions versus quasi-static conditions.
The material defined by this SAE document is an impact modified, heat stabilized, 66 nylon reinforced with glass fibers. This material is for use in dust shields for hydraulic disc brakes. NOTE—The applicability of a plastic dust shield must be evaluated for each individual brake system. Its use with solid rotors and/or high performance brake systems is not recommended.
The growing use of bio-based fuels today has created new performance and design considerations for high-performance polyamides used in a range of automotive fuel components such as fuel rails, diesel fuel filter housings, fuel sender units, flanges, fuel connectors, and quick connectors. During the material selection process, engineers need to take into account not only the basic tenets of metal-to-plastic conversion, but also the type of fuel and its impact on the performance of the materials. Conventional gasoline is being modified with aliphatic alcohols such as ethanol and methanol. In the U.S., the percentage of alcohol ranges up to 85% (E85) while in Brazil the usage of 100% ethanol (E100) is typical. Also, diesel fuel can be replaced by 100% of biodiesel sourced from sustainable resources such as soy, rape seed, sugar cane, and animal grease. In Brazil, B100 biodiesel (100% biodiesel content) isn't ready for commercial use. Currently, B5 (5% biodiesel content) is regulated for commercial use while in the U.S. and Europe auto makers are designing for components that use B20 (20% biodiesel) added to regular diesel and in some cases B30 (30% biodiesel). These bio-based fuels can have an adverse effect on the long-term performance of aliphatic polyamides such as nylon 6, nylon 66, and nylon 12. However, semi-aromatic polyamides such as polyphthalamide (PPA) have demonstrated superior performance in these bio-fuel applications, retaining their properties over the long term. Bio-based fuels can cause swelling in parts made of nylon 66, resulting in significant dimensional changes and weight gain. In addition, the alcohol's oxygen content can break down the carbon-carbon bond in the PA 66 backbone, resulting in a loss of mechanical properties such as tensile strength. Similarly, in biodiesel applications, parts made of aliphatic polyamides are significantly affected by the presence of corrosive water that can cause severe chemical attack to the polymers. Ultimately, this could lead to leaks and failures in certain applications. Based on extensive testing and commercial use, higher performing semi-aromatic nylons such as PPA offer major advantages over aliphatic nylons, delivering superior chemical resistance, lower water absorption, and better dimensional stability. They offer the most favorable performance in critical fuel component applications, retaining mechanical performance after over 5000 hours of exposure. This paper will present property comparisons and design recommendations for high-performance polyamides for bio-based fuel applications.
For several decades, aircrew working within rotary wing aircraft and some cargo aircraft (C-130) have used a simple nylon Crewmembers Aircraft Safety Belt (CASB) with an adjustable tether length, commonly referred to as a “gunner’s belt,” as their fall protection system. The CMARS AIRSAVE interface, in conjunction with either the CMARS or MARS webbing retractor, will eliminate the CASB in an effort to increase fall and crash protection. This paper discusses the U.S. Navy development of a system that provides a substantial decrease in injury loads while significantly increasing fall and crash protection. The system utilizes the lifting harness already worn as part of the AIRSAVE survival vest, thus distributing the crash or fall loads over the aircrew member’s body. This paper will also discuss the design development from initial concept to prototyping, testing, and demonstration of the CMARS AIRSAVE interface in preparation for final introduction into the Fleet.
More than twenty years have passed since we invented polymer-clay nanocomposites (PCN), in which only a few wt.-% of silicate is randomly and homogeneously dispersed in the polymer matrix. When molded, these nanocomposites show superior properties compared to pristine polymers such as tensile strength, tensile modulus, heat distortion temperature, gas barrier property, and so on. The number of papers on PCN has increased rapidly in recent years, reaching over 500 only in 2005. As the pioneers of the new technology, we will review its history highlighting our works. Epoch-making events of PCN are as follows: In 1985, The first PCN, nylon 6-clay hybrid (NCH), was invented. In 1987, NCH was first presented at the ACS Fall Meetings. In 1989, NCH was presented at the MRS Fall Meetings, firing PCN. In 1989, Toyota launched cars equipped with a NCH part. In 1996, Clay was found to cause a memory effect in liquid crystals. In 1997, Gilman of NIST et al. found revolutionary fire retardency in NCH. In 1997, PP-clay nanocomposite was prepared. In 1998, Compounding method for producing NCH was established. In 2002, Haraguchi of Kawamura Institute of Chemical Research et al. invented a nanocomposite hydrogel. So far only nylon-clay nanocomposites are used in practice, but other PCN will become increasingly useful in the future.
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