Selective Clay Placement within a Silicate Clay-Epoxy Blend Nanocomposite and the Effect on Physical Properties

Many epoxy systems under consideration for composite pressure vessels are composed of toughened epoxy resins. In this work, epoxy blends containing both rigid aromatic and flexible aliphatic components were prepared, to model toughened systems, and determine the optimum route of silicate addition. Compositions were chosen such that both glassy and rubbery resins were obtained at room temperature. The physical properties of the nanocomposites varied with T(g) and silicate placement, however, nanocomposite T(g)s were observed which exceeded that of the base resin by greater than 10 C. The tensile strength of the glassy resin remained constant or decreased on the dispersion of clay while that of the rubbery material doubled. Selectively placing the clay in the aliphatic component of the rubbery blend resulted in a greater than 100% increase in material toughness

Mercury trends in cormorant and great blue heron eggs from Pacific Canada: a question of local and global sources

Mercury (Hg) levels and trends in the NE Pacific Ocean are due to the convergence between natural and anthropogenic sources, with the latter broadly related to a combination of local and long-range sources. Legacy and current local point sources include chlor-alkali plants, pulp and paper mills and other mixed sources. In addition, long-range atmospheric and oceanic pathways deliver mercury to the Pacific coast, primarily from points to the west, where it is taken up by algae and bacteria and transferred through the marine food web in its inorganic form, but also its organic form, methylmercury. We present data on Hg trends in pelagic cormorant ((Phalacrocorax pelagicus) and great blue heron (Ardea herodias) eggs in Pacific Canada over a 48 year period. Temporal trends are evaluated using both diet- and non-diet-adjusted data and compared to Hg trends observed in other seabird species in the region, as well as the Atlantic and Arctic Oceans. Mercury concentrations declined alongside δ34S over time in both species, but no trend for δ13C and δ15N was apparent. The present study provides explanations for these trends in the context of local and long-range sources in the region and dietary contributions

Investigation of Hygro-Thermal Aging on Carbon/Epoxy Materials for Jet Engine Fan Sections

This poster summarizes 2 years of aging on E862 epoxy and E862 epoxy with triaxial braided T700s carbon fiber composite. Several test methods were used to characterize chemical, physical, and mechanical properties of both the resin and composite materials. The aging cycle that was used included varying temperature and humidity exposure. The goal was to evaluate the environmental effects on a potential jet engine fan section material. Some changes were noted in the resin which resulted in increased brittleness, though this did not significantly affect the tensile and impact test results. A potential decrease in compression strength requires additional investigation

Properties of PMR Polyimides Improved by Preparation of Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites

The field of hybrid organic-inorganic materials has grown drastically over the last several years. This interest stems from our ever-increasing ability to custom-build and control molecular structure at several length scales. This ability to control both the composition and structure of hybrid materials is sometimes broadly referred to as nanocomposite systems. One class of hybrid (organic-inorganic) nanostructured material is polyhedral oligomeric silsesquioxane (POSS), shown in the preceding diagram. The hybrid composition gives POSS materials dramatically enhanced properties relative to traditional hydrocarbons and inorganics. An important benefit of this technology is that it makes possible the formulations of nanostructured chemicals with excellent thermal and oxidative stability. This is largely due to the inorganic component

Brominated Flame Retardants: Spatial and Temporal Patterns and Trends in Seabird eggs from the Nearshore Pacific Coast of Canada

Brominated flame retardants (BFRs) have been widely used to reduce fire hazards. One class, the polybrominated diphenyl ethers (PBDEs), are particularly persistent bioaccumulative and toxic chemicals, now classified as POPs under the Stockholm Convention. Marine ecosystems are the ultimate sink for POPs, and thus there is a continuing need to monitor such contamination. Eggs of marine birds have proven to be an efficient and effective means of measuring and tracking xenobiotic compounds which are transferred from the female bird to the egg via yolk lipids or proteins. Here we report and discuss data from long term monitoring of and mercury in seabird eggs from the northeast Pacific. For this program, the marine system was divided, and representative species selected. The nearshore subsurface is monitored using two cormorant, Phalacrocorax, species, auritus and pelagicus, both feed on a variety of benthic and pelagic fish. The inshore and estuarine zone is monitored using the great blue heron, Adea Herodias. Nearshore data will be compared to data from the offshore subsurface monitored using the rhinoceros auklet, Cerorhinca monocerata, a feeder mainly on small pelagic fishes, and the offshore surface species, the Leach’s storm-petrel, Oceanodroma leucorhoa, which feeds mainly on surface plankton and larval fishes. At three breeding colonies each along the Pacific coast of Canada and at four year intervals 15 eggs are collected and archived. Data from a recent retrospective study, using archived samples collected from 1990 to 2011, shows, as reported for more polluted environments, that PBDEs increased in continental shelf ranging auklet eggs until the early 2000s and have declined since then, in response to restrictions on usage. In contrast, another BFR compound, HBCD (hexabromocyclododecane), increased steadily in eggs of both near and offshore species. The possible role of dietary variation, potentially related to marine regime shifts, will be examined by use of stable isotopes in variation in contaminant levels in these monitored seabirds

The Effects of Hygrothermal Aging on the Impact Penetration Resistance of Triaxially Braided Composites

An experimental study was conducted to measure the effects of long term hygrothermal aging on the impact penetration resistance of triaxially braided polymer composites. Flat panels of three different materials were subjected to repeated cycles of high and low temperature and high and low humidity for two years. Samples of the panels were periodically tested under impact loading during the two year time period. The purpose of the study was to identify and quantify any degradation in impact penetration resistance of these composites under cyclic temperature and humidity conditions experienced by materials in the fan section of commercial gas turbine engines for a representative aircraft flight cycle. The materials tested consisted of Toray T700S carbon fibers in a 2D triaxial braid with three different resins, Cycom PR520, a toughened resin, Hercules 3502, an untoughened resin and EPON 862, intermediate between the two. The fiber preforms consisted of a quasi-isotropic 0/+60/-60 braid with 24K tows in the axial direction and 12K tows in the bias directions. The composite panels were manufactured using a resin transfer molding process producing panels with a thickness of 0.125 inches. The materials were tested in their as-processed condition and again after one year and two years of aging (1.6 years in the case of E862). The aging process involved subjecting the test panels to two cycles per day of high and low temperature and high and low humidity. A temperature range of -60degF to 250degF and a humidity range of 0 to 85% rh was used to simulate extreme conditions for composite components in the fan section of a commercial gas turbine engine. Additional testing was conducted on the as-processed PR520 composite under cryogenic conditions. After aging there was some change in the failure pattern, but there was no reduction in impact penetration threshold for any of the three systems, and in the case of the 3502 system, a significant increase in penetration threshold. There was also an increase in the penetration resistance of the PR520 system impacted under cryogenic conditions

Potvrđivanje učinkovitosti testa identifikacije poremećaja uzrokovanih alkoholom (AUDIT) – verzija na Dusun jeziku u konzumenata alkohola u Sabahu, Borneo

Introduction: The Alcohol Use Disorder Identification Test (AUDIT) developed by WHO is instrumental in identifying individuals on the alcohol misuse spectrum. However there is no culturally appropriate Dusun language version in Sabahan Borneo. This study aims to develop and validate a Dusun language version of AUDIT (AUDIT-D). Methods: AUDIT was translated to Dusun and back translated to English and Malay. The first version was pilot tested in 20 participants and harmonised. The harmonised version was administered to 50 Dusun first language speakers fluent in Malay from villages in rural Sabah. Participants filled in socio-demographic questionnaires, Dusun (AUDIT-D) and Bahasa Malaysia (AUDIT-M) versions of AUDIT, and validated Bahasa Malaysia versions of the M.I.N.I. alcohol dependence subscale and CAGE. Results: ROC curves calculated AUDIT-D dependence cut-off of 9 and more, with prevalence of dependence at 46%. Factor analysis of AUDIT-D yielded a one - or three-factor solution, distinct from the AUDIT-M factor structure. Cronbach alpha coefficients for the total AUDIT-D was 0.83. Significant Spearman’s correlations existed between AUDIT-D and AUDIT-M scores (Spearman’s rho=0.999, p<.001). AUDIT-D and AUDIT-M were both significantly correlated with M.I.N.I. alcohol dependence subscales (rho=0.624 and 0.617 respectively, with p<0.0001). Both were not significantly correlated with CAGE. Conclusion: The AUDIT-D questionnaire has acceptable psychometric properties, properties and demonstrates similar factor structures to other areas with high alcohol dependence prevalence. It is suitable for the assessment and identification of alcohol use disorders in the unique Sabahan Borneo cultural landscape.Uvod: Test identifikacije poremećaja uzrokovanih alkoholom (AUDIT eng. The Alcohol Use Disorder Identification Test) kojeg je razvila Svjetska zdravstvena organizacija (WHO), od iznimne je koristi u identifikaciji pojedinaca koji boluju od poremećaja ponašanja uzrokovanih alkoholom. Doduše, ne postoji kulturološki primjerena verzija testa na Dusun jeziku u saveznoj državi Sabah na otoku Borneu, Malezija. Cilj ovog istraživanja je razviti i potvrditi verziju AUDIT test na Dusun jeziku. Metode: AUDIT test je preveden na Dusun jezik, zatim s Dusun jezika na engleski i malezijski. Prva verzija je bila pilot test koji je uključio 20 ispitanika, te je bio usklađen. Usklađena verzija testa je provedena na 50 ispitanika čiji je prvi jezik bio Dusun, te su također bili tečni u malezijskom jeziku, a bili su žitelji ruralnih sela Sabaha. Ispitanici su ispunili socio-demografske upitnike, Dusun (AUDIT-D) i Bahasa malezijske (AUDIT-M) verzije testa, usklađene verzije M.I.N.I. testa alkoholne ovisnosti na Bahasa malezijskom jeziku, te CAGE upitnik. Rezultati: ROC krivulje izračunale su graničnu ovisnost AUDIT-D od 9 i više, s prevalencijom ovisnosti od 46%. Faktorska analiza AUDIT-D dala je jedno- ili trofaktorsko rješenje, za razliku od strukture faktora u AUDIT-M testu. Cronbach alfa koeficijenti za ukupni AUDIT-D bili su 0,83. Značajne Spearmanove korelacije postojale su između AUDIT-D i AUDIT-M rezultata (Spearmanov rho = 0,999, p <0,001). AUDIT-D i AUDIT-M bili su značajno povezani s M.I.N.I. podskupinama za ovisnosti o alkoholu (rho = 0,624 i 0,617, s p <0,0001). Oba nisu pokazala značajnu povezanost s CAGE upitnikom. Zaključak: AUDIT-D upitnik ima prihvatljiva psihometrijska svojstva i pokazuje slične faktorske strukture u odnosu na druga područja s visokom prevalencijom ovisnosti o alkoholu. Prikladan je za procjenu i utvrđivanje poremećaja ponašanja uzrokovanih konzumacijom alkohola u jedinstvenom kulturnom krajoliku Sabaha

Materials, Manufacturing and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite of is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded

Impact Behavior of Composite Fan Blade Leading Edge Subcomponent with Thermoplastic Polyurethane Interleave

Impact damage tolerance and damage resistance is a critical metric for application of polymer matrix composites where failure caused by impact damage could compromise structural performance and safety. As a result, several materials and/or design approaches to improve impact damage tolerance have been investigated over the past several decades. Many composite toughening methodologies impart a trade-off between increased fracture toughness and compromised in-plane strength and modulus. In large part, mechanical tests to evaluate composite damage tolerance include static methods such as Mode I, Mode II, and mixed mode failures. However, ballistic impact damage resistance does not always correlate with static properties. The intent of this paper is to evaluate the influence of a thermoplastic polyurethane veil interleave on the static and dynamic performance of composite test articles. Static coupon tests included tension, compression, double cantilever beam, and end notch flexure. Measurement of the resistance to ballistic impact damage were made to evaluate the composites response to high speed impact. The interlayer material showed a decrease of in-plane performance with only a moderate improvement to Mode I and Mode II fracture toughness. However, significant benefit to impact damage tolerance was observed through ballistic tests