bluuebunny/crossref_metadata_2025 huggingface dataset:
Diurnal Evolution of Submesoscale Front and Filament Circulations
Authors: Dauhajre Daniel P. , McWilliams James C.
Published: September 2018

The local circulation of submesoscale fronts and filaments can be partly understood through a horizontal momentum balance of Coriolis, a horizontal pressure gradient, and vertical diffusivity in a turbulent boundary layer, known as the turbulent thermal wind balance (TTW or T2W). T2W often reproduces the instantaneous relative vorticity and divergence of submesoscale circulations in open-ocean and shelf settings. However, a diurnal cycle in submesoscale vorticity and divergence is characterized by a non-T2W phasing: a maximum in divergence magnitude lags the maximum in vertical diffusivity (with vorticity lagging divergence). Here, an idealized model is used to solve the transient turbulent thermal wind (T3W) equations and to investigate the diurnal evolution of front and filament circulation in a 2D plane. Relative to a steady-state circulation, transient evolution can cause both instantaneous strengthening and a weaker diurnal average of the secondary circulation. The primary mechanisms controlling the diurnal variability exist in a 1D Ekman layer that imprints onto the 2D circulation. In midlatitudes, acceleration during separate phases of the diurnal cycle (from night to day and from day to night) is dominated by distinct inertial oscillation and vertically diffusive mechanisms, respectively. However, the manifestation of these dual accelerations is sensitive to latitude, boundary layer depth, and the strength of the forcing. A simple 1D model predicts the diurnal phasing of submesoscale divergence and vorticity in realistic primitive equation simulations of the southwestern Pacific and coastal California.
Statistical Inversion of Surface Ocean Kinematics from Sea Surface Temperature Observations
Authors: Nummelin Aleksi , Jeffress Stephen , Haine Thomas
Published: September 2018

The sea surface temperature (SST) record provides a unique view of the surface ocean at high spatiotemporal resolution and holds useful information on the kinematics underlying the SST variability. To access this information, we develop a new local matrix inversion method that allows us to quantify the evolution of a given SST perturbation with a response function and to estimate velocity, diffusivity, and decay fields associated with it. The matrix inversion makes use of the stochastic climate model paradigm—we assume that SST variations are governed by a linear transport operator and a forcing that has a relatively short autocorrelation time scale compared to that of SST. We show that under these assumptions, the transport operator can be inverted from the covariance matrices of the underlying SST data. The accuracy of the results depends on the length of the time series, and in general the inverted properties depend on the spatial and time resolution of the SST data. Future studies could use the methodology to explore the interannual variability of SST anomalies; to estimate the scale dependency of ocean mixing; and to estimate anomaly propagation, both at the surface and in the interior. The methodology can be easily used with any gridded observations or model output with adequate time and spatial resolution, and it is not restricted to SST. The inversion code is written in Python and distributed as a MicroInverse package through GitHub and the Python Package Index.
Inconvenience versus Rationality: Reflections on Different Faces of Climate Contrarianism in Poland and Norway
Authors: Ceglarz Andrzej , Benestad Rasmus E. , Kundzewicz Zbigniew W.
Published: September 2018

There has been increasing scientific evidence related to climate change and its attribution, impacts, and possibilities of mitigation. Yet, climate contrarianism still persists. This paper concentrates on Poland and Norway—two fossil fuel giants that represent essential differences on climate contrarianism. In Norway there is a broad social and political consensus about the attribution and importance of climate change and a motivation to undertake climate change mitigation measures, whereas in Poland the inconvenient truth on anthropogenic climate change remains particularly inconvenient. By taking a qualitative approach, this paper discusses different drivers of climate contrarianism in both countries; provides examples of contrarian attitudes present in society, media, politics, and research; and compares their role in Polish and Norwegian contexts. The findings show the difficulties in defining universal factors determining contrarian attitudes, because their understanding and weight can be different among countries and a more nuanced analysis is needed to scrutinize different national contexts. The conclusion calls for more comparative research, which would combine quantitative and qualitative approaches investigating climate contrarianism.
Does School Band Kill Creativity? Embracing New Traditions in Instrumental Music
Authors: Wall Michael Patrick
Published: September 2018

In schools, band is often seen as a class where students and teachers can be creative. But is this true? Many schools use a traditional band model, which may not allow space for creative activities. This article, inspired by the Music Educators Journal March 2017 special focus on teaching for musical creativity, examines and critiques the traditional model of school band with respect to the space offered for creative music experiences and offers ideas for band directors of how to structure their programs to help foster more creative musical activities.
Music Education in the Era of School Choice
Authors: Martin Lisa
Published: September 2018

School choice has become an increasingly available option for families in the United States. Given the current political climate, music educators must better understand the various dimensions of the school choice movement and how it may affect the music classroom. Following a brief history of school choice, this article offers a look at the movement’s influence on the music teacher workforce, music curricula, and funding for music education. Recommendations surrounding the equity of school music opportunities are explored.
Bi-stretch auxetic woven fabrics based on foldable geometry
Authors: Cao Haijian , Zulifqar Adeel , Hua Tao , Hu Hong
Published: September 2018

The fabrication of auxetic fabrics by using conventional yarns and machinery has gained extraordinary interest from researchers in recent years. However, to date this approach has only been adopted to fabricate auxetic knitted fabrics and uni-stretch auxetic woven fabrics. This paper reports a study that aimed to develop a new class of bi-stretch woven fabrics with auxetic behavior using conventional elastic and non-elastic yarns, and available weaving machinery. Bi-stretch auxetic woven fabrics were firstly designed based on a foldable geometry possessing negative Poisson’s ratio by consideration of different design parameters, including the yarn float length, the placement of tight and loose weaves, and the arrangement of elastic and non-elastic yarns in the weft direction, and then fabricated on a dobby weaving machine equipped with multiple weft supplies and a separately controlled second beam assembly attachment. The fabricated fabrics were finally tested on a tensile machine to assess their auxetic behavior in both the warp and weft directions. The results showed that the bi-stretch woven fabrics developed exhibit negative Poisson's ratio up to −0.36 and −0.27 when stretched along the warp and weft directions, respectively, and could be applied for clothing applications that require enhanced shape fit and comfort.
New Frontiers: Approaches to Understand the Mechanistic Basis of Renal Toxicity
Authors: Nabity Mary B. , Polli Joseph W. , Vaidya Vishal , Krolewski Andrzej , Glaab Warren E.
Published: September 2018

A scientific session entitled “New Frontiers: Approaches to Understand the Mechanistic Basis of Renal Toxicity” focused on novel biomarkers to monitor kidney injury both preclinically and clinically, as well as providing mechanistic insight of the induced injury. Further, the role and impact of kidney membrane transporters in drug-induced kidney toxicity provided additional considerations when understanding kidney injury and the complex role of drug transporters in either sensitivity or resistance to drug-induced injury. The onset of nephropathy in diabetic patients was also presented, focusing on the quest to discover novel biomarkers that would differentiate diabetic populations more susceptible to nephropathy and renal failure. The session highlighted exciting new research areas and novel biomarkers that will enhance our understanding of kidney injury and provide tools for ensuring patient safety clinically.
A Mold Surface Treatment for Improving Surface Finish of Injection Molded Microcellular Parts
Authors: Yoon Jae D. , Hong Soon K. , Kim Ji H. , Cha Sung W.
Published: September 2018

Micro-cellular foaming technology draws attention due to the enhancement of mechanical strength, which has been considered as a weak point of current plastic foaming technology. Foam materials produced by this technology offer improved consistency and homogeneity of cell structure, which can result in products with superior properties and uniformity(1). Thus it is widely used for commercial purposes and its market is now growing significantly. However, since the foamed injection parts have swirl marks on its surface, this technology has limited uses such as interior products, in spite of its diverse merits. In this paper, we propose surface treatment of the mold as a way to remove the swirl mark. We injected simple shape specimens with PP and PC/ABS materials and measured the surface quality values such as roughness and gloss. Also we researched the foaming characteristics of both treated and untreated surface using SEM analysis.
Characterisation of Plastic Foams used as Backer Rod in the Construction Industry
Authors: Iglauer S. , Hutchinson A.R. , Lee T.C.P.
Published: September 2018

Six polyethylene (PE) and two polyurethane (PU) commercially available foams typically used in the construction industry were investigated in terms of their mechanical, morphological and surface chemistry properties. Both PU foams were open cell foams, while all PE foams had closed cells; this led to a significantly lower hardness and compressive strength, but to a higher water absorption in the open cell foams. It was found that a higher density leads to a smaller cell size, which resulted in lower water absorption. Optical microscopic pictures were taken and they revealed a broad distribution of cell size and cell shape; skin cells were generally smaller than bulk cells. A new concept, the “theoretical solid foam surface”, is introduced with which an estimation of the contact area between foam and sealant (or any other solid/highly viscous material) is possible. XPS and IR experiments showed that all PE foams had an oxidised surface, and several PE foams also contained oxygen in their bulk phase. The PU foams contained silicon at a high concentration; some of the PE foams also had silicon incorporated though to a lesser extent. Nitrogen was found in some PE foams. The silicon and nitrogen contamination was assumed to arise from additives such as release agents. These impurities probably led to the high surface free energies found on PE foam. In particular, the skins with larger amounts of contamination had higher surface free energies. The measurement of the surface free energy of foams with the VCA method proved to be difficult because a large distribution of distorted contact angles was measured, caused by the roughnesses of the foam surfaces. Recommendations are made for the practical application of the research in the context of construction.
Extrusion and Injection Moulded Microcellular Wood Fibre Reinforced Polypropylene Composites
Authors: Bledzki Andrzej K. , Faruk Omar
Published: September 2018

Microcellular processing techniques have been applied at an experimental level to both extrusion and injection moulding plastics processing, using wood fibre as reinforcing filler. The focus of the current research is the investigations of these processes using chemical foaming agents and comparative studies of physico-mechanical properties of materials. Results of using different chemical foaming agents (endothermic and exothermic), the variation of their content for producing wood fibre-polypropylene microfoamed composites and the effect of a coupling agent on the composites are presented. Microcells morphology, cell size, shape and distribution were investigated using scanning electron micrographs.
Analysing the effect of Mold Temperature on Foam Density and Foam Surface Texture
Authors: Abdul-Rani A.M. , Hopkinson N. , Dickens P. M.
Published: September 2018

Polyurethane (PU) foam is molded into preheated tools and expands to fill the mold cavity. Foam parts frequently have defects such as varying density and flaws in surface texture. Although there are many possible causes uneven mold temperatures are suspected to be a leading cause of defects(1,2). Much of the work previously undertaken to reduce flexible foam molding scrap and improved quality has focused on chemical compositions, chemical reactions and materials development. This research is to investigate the effects of mold temperature on high-resilience cold-cure polyurethane foam molded parts. A specially designed airtight mold capable of holding tight temperature tolerance was used to produce standard size foam specimens at varying temperatures ranging from 30 °C to 80 °C. The specimens were kept in a controlled temperature and humidity environment for a stipulated time before analysis. The effect of mold temperature on the average foam density, density gradients and surface texture were measured.

The foam specimens were weighed and measured for the overall density while Computerized Tomography was used to examine the density gradients throughout each foam specimen. 3D topographical analysis of the foam surface structure was conducted using a non-contact laser triangulation gauge. The results show that the mold temperature has an effect on the foam density and foam surface texture with specimens produced at 50 °C having the ideal texture.
Low-Density Phenolic Syntactic Foams: Processing and Properties
Authors: John Bibin , Reghunadhan Nair C.P. , Ninan K.N.
Published: September 2018

Low-density phenolic syntactic foams with different volume percentages of microballoons were processed and their mechanical performance has been evaluated in terms of tensile, flexural, compressive and the corresponding specific properties. Tensile and flexural strength increased with volume fraction of microballoon and optimized at 72–74 percentage by volume of microballoon. Both the properties decreased with further addition of microballoon. The corresponding specific properties also manifested a similar order. Compressive and specific compressive strength decreased with increase in microballoon volume percentage. The flexural and compressive modulus values followed the same trend as the strength values. The properties of phenolic syntactic foams were compared with syntactic foams based on an addition cure phenolic resin, Propargyl Ether Novolac resin (PN). The mechanical properties of the latter were inferior to those of phenolic syntactic foams. The morphology of the failed samples as examined by SEM showed that failure occurred by a combination of matrix and microballoon failure at low microballoon loading whereas it occurred by microballoon cracking and resin to microballoon debonding at high concentration of filler. The dynamic mechanical analysis of phenolic and PN resin syntactic foams showed a higher use temperature for PN system in comparison to phenolic.
Using thermochromism to simulate blood oxygenation in extracorporeal membrane oxygenation
Authors: Al Disi Mohammed , Alsalemi Abdullah , Alhomsi Yahya , Bensaali Fayçal , Amira Abbes , Alinier Guillaume
Published: September 2018

Introduction:

Extracorporeal membrane oxygenation (ECMO) training programs employ real ECMO components, causing them to be extremely expensive while offering little realism in terms of blood oxygenation and pressure. To overcome those limitations, we are developing a standalone modular ECMO simulator that reproduces ECMO’s visual, audio and haptic cues using affordable mechanisms. We present a central component of this simulator, capable of visually reproducing blood oxygenation color change using thermochromism.

Methods:

Our simulated ECMO circuit consists of two physically distant modules, responsible for adding and withdrawing heat from a thermochromic fluid. This manipulation of heat creates a temperature difference between the fluid in the drainage line and the fluid in the return line of the circuit and, hence, a color difference.

Results:

Thermochromic ink mixed with concentrated dyes was used to create a recipe for a realistic and affordable blood-colored fluid. The implemented “ECMO circuit” reproduced blood’s oxygenation and deoxygenation color difference or lack thereof. The heat control circuit costs 300 USD to build and the thermochromic fluid costs 40 USD/L. During a ten-hour in situ demonstration, nineteen ECMO specialists rated the fidelity of the oxygenated and deoxygenated “blood” and the color contrast between them as highly realistic.

Conclusions:

Using low-cost yet high-fidelity simulation mechanisms, we implemented the central subsystem of our modular ECMO simulator, which creates the look and feel of an ECMO circuit without using an actual one.
Enhanced Model for Continuous Dielectric-Based Asphalt Compaction Evaluation
Authors: Hoegh Kyle , Dai Shongtao , Steiner Trevor , Khazanovich Lev
Published: September 2018

The compaction of asphalt concrete significantly affects long-term pavement performance. Although coring provides a relatively accurate way of assessing in-place density at specific locations, the coverage of the assessment is limited, especially at longitudinal joint locations. This can be particularly problematic because it is difficult to identify problematic locations that are likely to fail prematurely using current compaction assessment methods. Ground penetrating radar (GPR) provides an attractive nondestructive testing alternative for evaluation of compaction quality, especially with recent significant improvements in the GPR technology for this specific application. However, assessment of the air void content of the asphalt mix from the GPR-measured dielectric constant of the surface requires conversion of dielectric variation to air void content variation, which is the subject of this paper. An alternative to the commonly used model is proposed, leading to more justifiable predictions for low values of dielectric constants. The proposed model was used to interpret data from a 7-mi long asphalt overlay construction project. The results of the interpretation as compared with the results obtained with the conventional model show an improvement on the stability of the prediction at low air void contents, especially when core calibration data are limited and uncertainty is considered. These results are promising in the direction of reducing field cores necessary to have a stable model providing continuous compaction assessment of new asphalt pavement construction.
Le marché entre violence symbolique et émancipation : le cas des Hardcore gameuses
Authors: Tiercelin Alexandre , Remy Eric
Published: September 2018

Cet article cherche à appréhender la construction identitaire via le marché en prenant appui sur des récits de vie de Hardcore gameuses. Un double cadre théorique est mobilisé : la construction identitaire par la consommation et le genre via la violence symbolique. L’analyse du sens donné aux pratiques de consommation et aux logiques identitaires sous-jacentes face à une norme masculine de marché, montre (1) le rapport des Hardcore gameuses à la norme genrée du marché des jeux à destination des hypers-joueurs (2) les modalités d’appropriation de la norme en question (3) parcours-type des joueuses en question sont alors présentés. Ces résultats permettent de discuter de la notion de violence symbolique portée par le marché, le genre y devenant une ressource identitaire manipulable dans le cadre de pratiques de consommation qui peuvent amener une certaine émancipation en fonction notamment de la détention de capitaux.
Impact of Critical Care Transesophageal Echocardiography in Medical–Surgical ICU Patients: Characteristics and Results From 274 Consecutive Examinations
Authors: Arntfield Robert , Lau Vincent , Landry Yves , Priestap Fran , Ball Ian
Published: September 2018

Objective:

Critical care echocardiography has become an integral tool in the assessment and management of critically ill patients. Critical care transesophageal echocardiography (TEE) offers diagnostic reliability, superior image quality, and an expanded diagnostic scope to transthoracic echocardiography. Despite its favorable attributes, TEE use in North American intensive care units (ICUs) remains relatively undescribed. In this article, we seek to characterize the feasibility, indications, and clinical impact of a critical care TEE program.

Design:

Retrospective, observational study.

Setting:

Tertiary care, academic critical care program consisting of 2 hospitals in Ontario, Canada.

Participants:

Consecutive critical care TEE examinations on ICU patients performed between December 2012 and December 2016

Interventions:

None.

Measurements and Main Results:

Consecutive critical care TEE studies on ICU patients from December 1, 2012, to December 31, 2016, were reviewed. The TEEs performed on cardiac surgery patients and those without reports were excluded. Examination details, including indications, complications, examination complexity (number of views, Doppler techniques), and clinical recommendations were aggregated and analyzed. Two hundred seventy-four TEE studies were performed by 38 operators. Common indications for TEE studies were hemodynamic instability (45.2%), assessment for infective endocarditis (22.2%), and cardiac arrest (20.1%). A change in patient management was proposed following 79.5% of TEE studies. Thirty-eight percent of TEE studies were performed during evening hours or on weekends. There were no mechanical complications.

Conclusions:

Our observational data support intensivist-performed TEE as being safe and therapeutically influential across a broad range of indications. Our program’s demonstrated feasibility and impact may act as a model for TEE adoption in other North American ICUs.
Terminal Withdrawal of Mechanical Ventilation: A Hospice Perspective for the Intensivist
Authors: Bodnar John
Published: September 2018

The intensive care unit (ICU) and hospice inpatient unit (IPU) environments differ in many ways. Although both endeavor to provide the best care possible for their patients, the day-to-day goals of these environments are almost antithetical. Similarly, the experiences and expertise of the staff differ. When performing a similar clinical task, it may be addressed in different ways because each group is engrained in their primary day-to-day focus. Terminal withdrawal of mechanical ventilation is a procedure that is performed in both ICUs and some hospice IPUs. Previous examinations of this subject have been based largely upon the correlative background, practices, and perceptions of the ICU prescriber. The purpose of this review is to examine how the manner in which this procedure is performed in the hospice environment may differ in ways that the intensivist can incorporate into their own plan of care, or better appreciate when making the decision to remove mechanical ventilation in the critical care unit or transfer the patient to a hospice environment for the procedure to be completed.
A Comparison of Adjusted Versus Unadjusted Doses of Polymyxin B Based on Renal Function and Incidence of Acute Kidney Injury
Authors: Peyko Vincent , Cohen Henry
Published: September 2018

Purpose:

To determine whether or not polymyxin B needs dose adjustments based on renal function by comparing the incidence of acute kidney injury (AKI) in patients whose polymyxin B doses were adjusted versus not adjusted according to renal function.

Methods:

This was a single-center, prospective study with a retrospective cohort taking place in an acute care community hospital. Forty-two patients treated with polymyxin B were evaluated between April 2012 and December 2015. The primary outcome was incidence of AKI at day 7 after initiation of polymyxin B therapy with secondary outcomes including microbiological cure, clinical cure, and 30-day mortality.

Results:

There was no difference in the incidence of AKI at day 7 in patients with polymyxin B doses adjusted according to renal function versus patients without polymyxin B dose adjustment (20.0% vs 18.2%; P = .882). There were no differences between groups in occurrence of microbiological cure, clinical cure, or 30-day mortality (27.8% vs 57.1%; P = .065, 70.0% vs 72.7%; P = .845, 40.0% vs 31.8%; P = .581, respectively).

Conclusion:

The results from this study support the use of polymyxin B without any dose adjustment in the setting of renal impairment.
Durability prediction of an ultra-large mining truck tire using an enhanced finite element method
Authors: Nyaaba Wedam , Bolarinwa Emmanuel O , Frimpong Samuel
Published: September 2018

Ultra-class mining trucks used for material haulage in rugged surface mining terrains experience premature tire fatigue failure in operation. Typical failures include belt edge separation, ply turn-up separation, and tread base and sidewall cracking. The use of reinforcing fillers and processing aids in tire compounds result in the formation of microstructural in-homogeneities in the compounds. This article presents an application of the critical plane analysis technique for predicting the fatigue life of the belt package of an ultra-large mining truck (CAT 795F) tire of size 56/80R63 in a surface coal mine. Experimental data obtained from extracted specimens (sidewall, tread, and belt edge region) of the tire are used to characterize the stress–strain and fatigue behavior of the modeled tire. The tire’s duty cycle stresses and strains were obtained from finite element analysis of the rolling tire in Abaqus. Fatigue life calculations were performed in the rubber fatigue solver Endurica CL. Effects of inflation pressure, tire speed, and axle load on the fatigue life of the belt package under strain-crystallizing and non-crystallizing conditions of the belt compound are discussed. Specifically, the results show the belt edges to be critical regarding crack nucleation.
Effects of Atbn Rubber Additions on the Fracture Toughness of Unsaturated Polyester Resin
Authors: Miller N.A. , Stirling C.D.
Published: September 2018

Improvement to the fracture toughness of an unsaturated polyester resin and composites by the addition of amine terminated butadiene-acrylonitrile (ATBN) rubber has been investigated. Addition of 6pph ATBN rubber gave a modest gain in fracture toughness of the resin. Electron microscopy studies showed that large agglomerates of a mixture of the rubber and the base resin were formed rather than discrete droplets of the rubber, and this is considered to be the reason for the modest gain in fracture toughness. Unidirectional glass fibre reinforced composites, made with ATBN toughened resin, showed significant gains in inter-laminar fracture toughness. The increased inter-laminar fracture toughness of the rubber modified resin is considered to be due to a combination of localised bonding between rubber/resin agglomerates and the glass fibres, and the lower tensile strength and flexural modulus of the rubber modified resin.
Transport of Water through Polyamide-Nitrile Rubber Blends and its Influence on Mechanical Properties
Authors: Kumar C. Radhesh , Francis Bejoy , Thomas Sabu , George K. E.
Published: September 2018

Polyamide-nitrile rubber blends of high polyamide content (100/0, 70/30, 50/50) were prepared by melt mixing in a Haake Rheocord. The diffusion of water through the blends was investigated at various temperatures; 28, 45, 65 and 75°C. The temperature dependence of the diffusion characteristics indicates that the transport mechanism varied with blend composition, morphology and temperature. The weight gain curves for pure polyamide and blends rich in polyamide showed a maximum followed by a decrease (overshoot effect). The enthalpy and entropy of sorption have been computed from the sorption data. Transport was found to follow the Fickian type mechanism. The effects of water uptake on the mechanical behaviour of the blends have also been analysed. The mechanical properties were found to decrease considerably as a result of water absorption.
Metallic Methacrylate as a Reactive Filler to Reinforce Ethylene-Propylene-Diene Rubber
Authors: Peng Zonglin , Zhang Yong , Liang Xun , Zhang Yinxi
Published: September 2018

The reinforcement of non-polar ethylene-propylene-diene rubber (EPDM) by the polar metal salts of methacrylic acid was achieved by directly mixing the salt into EPDM at a high level and curing with peroxide. Mechanical properties and crosslink density of the vulcanizates were investigated. Wide-angle X-ray diffraction (WAXD) and Fourier transform-infrared spectroscopy (FTIR) were employed to analyze the reactivity of zinc dimethacrylate (ZDMA) in EPDM compounds before and after vulcanization. It was observed that the commercial ZDMA or magnesium dimethacrylate (MDMA) can greatly improve the hardness and tensile strength of the EPDM vulcanizates, while retaining a high elongation at break. WAXD and FTIR revealed that ZDMA is a reactive filler in the EPDM matrix during peroxide curing. The crosslink density of the vulcanizates was determined by equilibrium swelling. Covalent crosslinks and ionic crosslinks were distinguished by an acidolysis treatment. Ionic crosslinks were greatly improved by increasing the amount of zinc dimethacrylate or dicumyl peroxide, and the relationship between mechanical properties and crosslink density indicates that the tensile strength of the vulcanizate was principally dependent on ionic crosslink density.
Nanostructured Silver/Polystyrene Composite Film: Preparation and Ultrafast Third-Order Optical Nonlinearity
Authors: Zeng Rong , Wang Shu Feng , Liang Hai Chun , Rong Min Zhi , Zhang Ming Qiu , Zeng Han Min , Gong Qi Huang
Published: September 2018

Surface-modified silver nanoparticles with various sizes, synthesized by water-in-oil micro-emulsion, were incorporated into polystyrene (PS) to form transparent nanocomposite films through solution-mixing and static-casting. It was found that the Ag nanoparticles could be re-dispersed well in the polymer matrix by using chloroform as a solvent due to a strong interaction between Ag and chloroform. XPS analysis suggested that there is no obvious interaction between nanosilver and the polystyrene matrix. The third-order nonlinear optical susceptibility of Ag/PS nanocomposite films is around 10-esu and increases with increasing particle size, as measured by the time-resolved femtosecond optical Kerr effect experiment at a wavelength of 830nm. The results demonstrate that the present fabrication approach can effectively tailor the structure and properties of the nanocomposites.
Silane Modified Fillers for Reinforcing Polymers
Authors: Domka Ludwik , Krysztafkiewicz Andrzej , Kozak Maciej
Published: September 2018

Some white natural fillers (kaolin and talc) and synthetic mineral ones (precipitated silica, sodium-aluminium silicate, zinc silicate, calcium silicate) together with waste materials (cement dusts and post-fluor silicas) were subjected to surface modification and characterised. Various types of silane coupling agents (amino-, mercapto-, methacryloxy- and ureidosilanes) were used for surface modification. The modified fillers were mixed with butadiene-styrene rubber, polyurethane and PVC. Good physico-mechanical properties were obtained for PVC containing talcs and kaolins modified with methacryloxy– and ureidosilanes. The strength of polyurethanes was increased most by modification of the fillers with mercapto- and aminosilanes.
A Critical Review of Polymer-based Composite Automotive Bumper Systems
Authors: Sapuan S.M. , Suddin N. , Maleque M. A.
Published: September 2018

An automobile bumper is a structural component, which contributes to vehicle crashworthiness or occupant protection during front or rear collisions. The bumper systems also protect the hood, trunk, fuel, exhaust and cooling system as well as safety related equipments. A brief description of bumper components and a critical review of polymer-based bumper systems with specific methodology are provided. This article advocates proper bumper design and material selection. The authors also discuss bumper components from the standpoint of the materials and their manufacturing processes.
Rheological Behaviour of PP/PET and Modified PP/PET Blends. II. Dynamic Viscoelastic Properties
Authors: Zdrazilova Natalie , Hausnerova Berenika , Kitano Takeshi , Saha Petr
Published: September 2018

The increasing amount of post-consumer waste leads to a search for effective recycling methods. Compatibilisation of immiscible blends of polypropylene (PP) and polyethylene terephthalate (PET) represents one such novel approach that allows recycling of significant scrap materials without any need for separation steps. The intention of this paper is to investigate the dynamic viscoelastic properties of unmodified and modified PP/PET blends. To study the effect of the matrix, three polypropylenes differing in flow properties were chosen. The compatibilisation was carried out by both one- or two-step reactive in situ techniques. In the former case, the addition of 1 wt.% of maleic anhydride, and in the latter, polypropylene supplied already modified by the producer were employed. The measurements were performed by using a rotational cone and plate rheometer at temperatures of 265 °C and 245 °C. Since PET is not melted at the lower temperature, completely different behaviour is observed in the two cases. The rheological functions generally decrease with PET content at 265 °C (conventional blend behaviour), while they increase at 245 °C, in a manner reminiscent particle-filled systems (including the yield behaviour). The positive effect of compatibilisation can be deduced not only from the results of the morphological study (dispersed phase size reduction, strengthened interfacial adhesion), but also through increased values of the viscous and elastic characteristics, which suggests enhanced interactions between the blend components. Comparing steady shear and dynamic viscoelastic properties, the extent of deformation applied during both types of measurements leading to different material responses should be considered.
Thermal and Dynamic Mechanical Properties of Low Density Polyethylene-Silica Nanocomposites: Effect of Zinc-Ion Coating on Nanosilica
Authors: Reddy C.S. , Das C.K.
Published: September 2018

Low-density polyethylene (LDPE)/silica nanocomposites were developed by conventional melt blending in a sigma internal mixer. Two types of composite, each with 2.5 wt% filler, were produced. The first was obtained by melt blending nano-silica with LDPE in a co-rotating sigma internal mixer. The second was obtained by melt blending the same LDPE, with zinc-ion coated nano-silica. In the case of zinc-ion coated nano-silica- filled LDPE, wide-angle X-ray diffraction (WAXD) showed a decrease in the interplanar distance and an increase in lamellar crystal size when compared to nano-silica filled LDPE. DSC and TGA results showed the zinc-ion coated nano-silica filled LDPE has higher thermal stability, heat of fusion, melting temperature and crystallinity than LDPE filled with nano-silica. AFM surface topography images showed a uniform surface and lower roughness in the case of zinc-ion coated nano-silica filled LDPE than nano-silica filled LDPE. Furthermore, the zinc-ion coating over nano-silica showed improvements in storage modulus E’, static modulus and thermal properties - a 26% increase in static elastic modulus and a rise in degradation onset temperature from 337 °C to 355 °C, in comparison to the nano-silica.
Preparation and Characterization of EVA/MMT Nanocomposites
Authors: Ran Qianping , Hua Hongyan , Tian Yan , Wu Shishan , Shen Jian
Published: September 2018

Nanocomposites composed of poly(ethylene-co-vinyl acetate) (EVA) and montmorillonite (MMT) were prepared by melt intercalation. Their structure and properties were studied by FT-IR, XRD, TGA, the Molau test, and tensile and tear strength measurements. The results showed that those silicate layers of MMT treated with the swelling agent hexadecyl trimethylammonium bromide (CTAB) were dispersed in the EVA matrix on a nanometer scale and an intercalated EVA/MMT nanocomposite was obtained. The interfacial interaction, tensile strength and tear strength of those EVA/MMT samples treated with CTAB (denoted by MMT-CTAB) nanocomposites were noticeably improved. Whether treated or not, the composites underwent two thermal degradation steps. In the first step, the thermal stability of EVA/CTAB-MMT nanocomposites was lower than that of EVA/ MMT ones because of the degradation of the swelling agent, whereas in the second step EVA/CTAB-MMT nanocomposites exhibited higher thermal stability.
Optical Transparency Change Method for Cure Monitoring of GFRPs
Authors: Todoroki Akira , Hana Norihiko
Published: September 2018

The resin transfer moulding (RTM) process is becoming popular for low-cost fabrication of complicated commercial products made from glass-fibre-reinforced plastics (GFRPs). As regards the RTM process for complicated components, the optimal fabrication process is found by repeated trial and error. This process is time consuming and one of the reasons for the high cost of composite products. To overcome this problem, it is useful to monitor the degree of cure of target GFRP products. In this study, the luminance change method is used for cure monitoring of polyester-based composites. Polyester resin is normally used as the matrix resin for low-cost GFRP products. Polyester resin usually changes its optical transparency during the curing process. This enables us to monitor the degree of cure by measuring the luminance change of light or reflected light. In this study, we present a system that measures reflected light. The sensing system employs an LED as the light source and a photodiode as a light power sensor. This low-cost cure monitoring system is applied to the monitoring of the degree of cure in GFRPs and is achieved using commercially available dielectric sensors. Results are compared with the results of luminance change. The effectiveness of this method has been confirmed experimentally.
Processing and Performance Evaluation of Nanoclay Infused EPON 828
Authors: Hosur Mahesh V. , Gebremedhin Orion , Jeelani Shaik
Published: September 2018

The field of polymer-clay nanocomposites has attracted considerable attention as a method of enhancing polymer properties and extending their utility. In this research, different nanocomposites were manufactured by modifying the EPON828 resin system through the infusion of 0.5%, 1%, 1.5% and 2% by weight of clay (Nanocor(r) I.30ZE) nanoparticles. Mechanical properties such as flexural, compressive, tensile and high strain rate strengths and moduli of the polymer matrix were improved in nano-structured materials, owing to their unique phase morphology and improved interfacial interactions. A dynamic mechanical analysis was performed to monitor changes in the thermal properties of the nanocomposite. Nanoclay reinforced epoxy showed consistent improvement in all the mechanical as well as thermomechanical properties. High strain rate compressive modulus showed a progressive improvement over the neat values for all the strain rates used. SEM micrographs of the fracture surfaces for both tensile and flexural samples showed regular and continuous patterns of failure for the neat samples. The nanophased samples on the other hand showed multiple irregular failure surfaces which increased in number with nanoclay loading.
Effective Surface Deformation Height and Bond Rigidity of GFRP Reinforcing Bars with Ribs
Authors: Moon Do Young , Ebead Usama A. , Benmokrane Brahim
Published: September 2018

This study focuses on the evaluation of the surface deformation height of ribbed type of GFRP rebars. The bond behaviour of ribbed type of GFRP rebar is investigated in terms of the effective deformation height and bond rigidity, both experimentally and numerically. Pullout tests on ribbed type GFRP rebars embedded in concrete have been conducted to obtain an accurate bond stress-slip law and also to closely observe the state of the surface of pulled-out rebars at failure, in order to categorise accurately the mode of failure. In the pullout tests, the high temperature regime is particularly considered. In addition, finite element (FE) simulations of the specimens subjected to pullout tests are developed. From the FE analyses and the experiments, the effective surface deformation height and bond rigidity of the GFRP rebar with ribs was determined. The numerical results were substantiated by the experimental findings and good agreement was observed. Moreover, adding milled glass fibres in the surface deformations could not increase the effective surface deformation height and bond rigidity of the rebar; however, it seems to improve the bond strength because increasing the proportion of milled glass fibres improves the connections between the core and rib section.
Synthesis and Characterisation of Polyaniline/Montmorillonite Nanocomposites
Authors: Shakoor Abdul , Rizvi Tasneem Zahra , Foot Peter J.S.
Published: September 2018

A series of polyaniline / montmorillonite clay (PANI-MMT) composites has been synthesised by solution polymerisation in the presence of hydrochloric acid and a substoichiometric amount of ammonium persulfate (APS). For a preferred molar ratio of monomer to oxidant of 2:1, the aniline was polymerised and largely incorporated into the MMT. The PANI-MMT composites were characterised and compared by Fourier-transform infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction and scanning electron microscopy (SEM). The effect of loading with the conducting polymer on the nanocomposites’ DC electrical conductivity was studied, and the maximum conductivity (pressed powder compact) was found to be 4.73 × 10 1 S.cm-1, comparable with that of pure polyaniline in the same form. The conductivity followed quite well the temperature-dependence relationship □(T) = □0.exp[-To/T)1/2], characteristic of one-dimensional variable-range hopping (1-D VRH).
Effect of Intertube Adhesion on Mechanical Properties of Tubular Cell Polypropylene Honeycombs
Authors: Rahimi H. , Khalili V. , Ghoreishy M.H.R. , Rezadoust A.M. , Esfandeh M.
Published: September 2018

An experimental study was carried out to evaluate the effect of adhesion level between polypropylene tubes on mechanical properties of tubular cell polypropylene honeycomb sandwich panels. The honeycomb core adhesion level was varied by altering the duration of corona surface treatment on the polypropylene tubes. In order to assess the effect of polypropylene surface treatment, contact angle measurements were carried out to measure the surface energy values of substrates. Core delamination, compressive and flexural tests were also conducted on the honeycomb samples. The test results revealed that the mechanical properties of honeycomb samples improved with increasing adhesion strength between PP tubes. In general, the test samples with strong core adhesion exhibited a more ductile behaviour and possessed higher energy absorption capacity.
Preparation of Linear Low Density Polyethylene/Poly(Ethylene-Co-Vinyl Acetate) Blend Films with Various Transparencies
Authors: Kwak Kun Young , Lee Young Jae , Oh Kyeong Il , Song Du Hyun , Shin Eun Joo , Jeon Han Yong , Gal Yeong Soon , Oh Tae Hwan , Han Sung Soo , Choi Han Gon , Lee Yong Rok , Noh Seok Kyun , Lyoo Won Seok
Published: September 2018

Linear low density polyethylene (LLDPE)/poly(ethylene-co-vinyl acetate) (EVAc) blend films having various vinyl acetate (VAc) contents (12, 18, and 25 wt.%) with various degrees of transparency were prepared using a hot plate press. Effects of VAc contents in EVAc and ratio of EVAc in LLDPE/EVAc blend films on the structure and properties of these films were investigated through a series of instrumental analyses. The transparencies of films were classified into three types: non-transparent (1–75 T(%)), semi-transparent (76–85 T(%)), and transparent (86–100 T(%)). With increasing the contents of VAc in EVAc and the ratio of EVAc in blend films, the transparencies of films were increased. The differential scanning calorimeter curves of blend films show that there are two obvious endothermic peaks at around 125 and 75–85 °C, which corresponded to the melting of the LLDPE and EVAc crystals, respectively. The intensity of crystalline peaks of LLDPE decreased as the ratio of EVAc in blend films was increased. The thermal stability of blend film decreased with increasing degree of transparency. This might be due to the fact that transparent film can contain higher amount of amorphous regions, which were degraded at lower temperature than that of non-transparent films having high contents of crystalline regions. The storage modulus of non-transparent films was higher than that of semi-transparent films due to a higher crystallinity.
Effect of Alumina Trihydrate and Borax on Fire Retardancy and Mechanical Properties of High Density Polyethylene (Hdpe) Compounds
Authors: Faghihi Jalal , Morshedian Jalil , Ahmadi Shervin
Published: September 2018

The influence of the inorganic flame retardants, including alumina trihydrate (ATH) and borax (Na2B4O7-10H2O, hydrated sodium tetraborate), on the mechanical properties and flammability of high density polyethylene has been studied. Results showed that an increase in the amount of flame retardant compounds caused a decrease in tensile strength, ultimate strain and impact resistance. Using of ethylene vinyl acetate (EVA) caused an increase in impact resistance compared to other compositions without EVA. Flammability test results showed an improvement in flame retardancy due to using alumina trihydrate and borax. Composite containing EVA and borax showed better flammability properties compared with composite containing EVA and ATH because, EVA as a compatibiliser can increase the stability of the borate component and form a glassy layer on the char, which results in an enhancement in the flammability properties. Furthermore a synergistic effect was observed when alumina trihydrate and borax were incorporated together. The charred layers provided a good thermal and flame barrier. Morphological, rheological and thermal gravimetric analyses studies supported the idea that the improvement in the flame retardancy was due to charred layers formed by the ignition of inorganic flame retardant and polymeric matrix.
Study on a High Performance Packaging Material of HDPE/LLDPE/OMMT Nanocomposites
Authors: Zhou Lianzhong , Li Peiyao , Song Guojun , Gu Zheng , Wang Li , Gao Zhenbin
Published: September 2018

New types of HDPE/LLDPE/OMMT nanocomposites, which were used as packaging materials, were prepared by direct injection moulding without any compatibiliser. This method was similar to the film forming technology. TEM observation revealed that the OMMT layers were homogeneously dispersed throughout the matrix at the nano-scale. The results of mechanical properties measurement showed that the tensile strength, tensile modulus, flexural strength and flexural modulus were improved remarkably with small amounts of OMMT, whose contents were below 6.0 wt.%. For example, the yield strength of the nanocomposite with 4.0 wt.% OMMT was 32.8 MPa, which increased 27.6% compared with that of the neat sample. Meanwhile, the heat deflection temperature values and TGA results showed that the thermal stability also improved.