bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of interphase zone on the overall elastic properties of nanoparticle-reinforced polymer nanocomposites
Authors: Amraei Jafar , Jam Jafar E , Arab Behrouz , Firouz-Abadi Roohollah D
Published: September 2018

In the current work, the effect of interphase region on the mechanical properties of polymer nanocomposites reinforced with nanoparticles is studied. For this purpose, a closed-form interphase model as a function of radial distance based on finite-size representative volume element is suggested to estimate the mechanical properties of particle-reinforced nanocomposites. The effective Young’s and shear moduli of thermoplastic polycarbonate-based nanocomposites for a wide range of sizes and volume fractions of silicon carbide nanoparticles are investigated using the proposed interphase model and molecular dynamics simulations. In order to investigate the effect of particle size, several unit cells of the same volume fraction, but with different particle radii have been considered. The micromechanics-based homogenization results are in good agreement with the results of molecular dynamics simulations for all models. This study demonstrates that the suggested micromechanical interphase model has the capacity to estimate effective mechanical properties of polymer-based nanocomposites reinforced with spherical inclusions.
Current Medical Research
Authors: Fehring Richard J. , Barron Mary Lee
Published: September 2018

This issue of Current Medical Research (CMR) includes studies that provide evidence that use of natural family planning (NFP) can be helpful for subfertile couples wishing to achieve a pregnancy, the effectiveness of a method of NFP during breastfeeding, and the effects of using NFP on marital relationships. This review also includes evidence on predicting the sex of a baby by timing intercourse, evidence that brain injuries can be reflected in changes in the menstrual cycle, and that women prefer methods of family planning that have no side effects. The issue ends with an in-depth review of new technologies that aid in the use of NFP. Topics covered include subfertile couples, breastfeeding, marriage, predicting the sex of a baby, brain injuries, and new technologies.
The Pivotal Role of the Enemy in Inducing Hope for Peace
Authors: Leshem Oded Adomi
Published: September 2018

Protracted conflicts are also termed “intractable” in part because they are perceived as irresolvable by those mired in the prolonged dispute. The conflict’s perceived irreconcilability leaves little reason for citizens to strive for peace which, in turn, might further exacerbate the conflict. The central question posed in this study is whether hopelessness regarding the possibility for peace can be alleviated among citizens embroiled in protracted conflicts. Results from an experimental study administered in Israel show that hope can be instilled, even among those most skeptical, when an outgroup member claims that peace is possible but not when an ingroup member claims the same. A follow-up study revealed that hope induced by the experimental interventions withstood a period of conflict escalation and elicited active support for peacebuilding. The study demonstrates that hope inducement is a useful tool for carving a pathway out of detrimental structures of intractability.
Clozapine attenuates mitochondrial burdens and abnormal behaviors elicited by phencyclidine in mice via inhibition of p47phox; Possible involvements of phosphoinositide 3-kinase/Akt signaling
Authors: Tran Hai-Quyen , Park Se J , Shin Eun-Joo , Tran The-Vinh , Sharma Naveen , Lee Yu J , Jeong Ji H , Jang Choon-Gon , Kim Dae-Joong , Nabeshima Toshitaka , Kim Hyoung-Chun
Published: September 2018

Background:

Oxidative stress and mitochondrial dysfunction have been implicated in the pathophysiology of schizophrenia.

Aims:

We investigated whether antipsychotic clozapine modulates nicotinamide adenine dinucleotide phosphate oxidase and mitochondrial burdens induced by phencyclidine in mice.

Methods:

We examined the effect of clozapine on nicotinamide adenine dinucleotide phosphate oxidase activation, mitochondrial burdens (i.e. oxidative stress and mitochondrial dysfunction), and activities of enzymatic antioxidant in the prefrontal cortex, and subsequent abnormal behaviors induced by repeated treatment with phencyclidine. p47 phox Knockout mice and LY294002, a phosphoinositide 3-kinase inhibitor, were employed to elucidate the pharmacological mechanism of clozapine.

Results:

Phencyclidine treatment resulted in an early increase nicotinamide adenine dinucleotide phosphate oxidase activity, membrane translocation of p47 phox, interaction between p-Akt and p47 phox, and mitochondrial burdens in wild-type mice. Although these increases returned to near control level four days post-phencyclidine, mitochondrial superoxide dismutase and glutathione peroxidase activities were decreased at that time. Clozapine, LY294002, or p47 phox knockout significantly ameliorated social withdrawal and recognition memory deficits produced by phencyclidine. Importantly, LY294002 did not significantly alter the effects of clozapine against abnormal behaviors and the interaction between p-Akt and p47 phox induced by phencyclidine. Furthermore, neither LY294002 nor clozapine exhibited any additive effects to the protection afforded by p47 phox knockout against phencyclidine insult.

Conclusion:

Our results suggest that p47 phox gene mediates phencyclidine-induced mitochondrial burdens and abnormal behaviors, and that the interactive modulation between p47 phox and phosphoinositide 3-kinase/Akt is important for the understanding on the pharmacological mechanism of clozapine.
Cognitive sex differences in effects of music in Wisconsin Card Sorting Test
Authors: Feizpour Azadeh , Parkington Helena C. , Mansouri Farshad A.
Published: September 2018

Recent studies suggest that females and males show different levels of susceptibility to neuropsychological disorders which might be related to sex differences in executive control of behaviour. Music, as a cognitively salient factor, might influence cognitive functions; however, it is unclear how sex and music interact in influencing executive control of behaviour in a dynamic environment. We tested female and male participants in a computerized analogue of the Wisconsin Card Sorting Test (WCST) while listening to music or in silence. We found that music decreased the percentage of correct trials in both sexes. While music decreased response time in females, it had an opposite effect in males. Response time increased in error trials (error slowing), and music sex-dependently influenced error slowing. Conflict between potential rules adversely influenced performance in the current trial (conflict cost) in both sexes and listening to music increased conflict cost. These findings suggest that music shows both adverse and beneficial effects on various behavioural measures in the WCST, some of which are sex-dependent. Our findings suggest that in using music as an adjunct for rehabilitation of neuropsychological disorders, both adverse and beneficial effects and sex dependency need to be considered.
Predictors of Alcohol Use Disorders Among Baby Boomers Across the Life Course
Authors: Quinn Adam , Mowbray Orion
Published: September 2018

Research suggests that baby boomers entering older adulthood may possess unique alcohol use patterns over time. Using the life course perspective as a guiding framework, this empirical study sought to examine correlates of alcohol use disorders among baby boomers by examining representative data from the National Survey on Drug Use and Health at two points in time, 1998 ( N = 6,213) and 2010 ( N = 5,880). Results from logistic regression analyses suggest that predictors of alcohol use disorders evolve over time as baby boomers continue to age. Risk factors for alcohol use disorders among baby boomers may include concurrent unprescribed pain reliever use, p < .01, while protective factors such as income, p < .01, and social supports, p = .01, may be of increased importance. Based on the findings of this study, practice implications and future research are discussed.
From stigma to the spotlight: A need for patient-centred incontinence care
Authors: Taylor D. Wayne , Cahill Jacqueline J.
Published: September 2018

Incontinence is not a single disorder but a family of related conditions with different etiologies and treatments; it is a chronic disability that carries an enormous stigma. In few disorder/treatment pairings, there is the need to reinvent care more urgent and clear than in the area of incontinence. Patient-centred care has been realized to improve outcomes, quality of care, and patient satisfaction while concurrently reducing healthcare costs. To improve continence care and move it away from “cleaning up accidents” to a patient-centred care model, in which the disorder is managed to best practice guidelines, does not require investigative or developmental prowess but a simple, concentrated effort to diffuse existing knowledge to close the knowledge gaps, both at the clinical language level for clinical nurses and family physicians, as the gatekeepers to specialist care, and in simplified layperson’s language for the healthcare worker, family carer, and person living with incontinence.
Adaptive Heuristics That (Could) Fit: Information Search and Communication Patterns in an Online Forum of Investors Under Market Uncertainty
Authors: Casnici Niccolò , Castellani Marco , Squazzoni Flaminio , Testa Manuela , Dondio Pierpaolo
Published: September 2018

This article examines information-search heuristics and communication patterns in an online forum of investors during a period of market uncertainty. Global connections, real-time communication, and technological sophistication have created an unpredictable market environment. As such, investors try to deal with semantic, strategic, and operational uncertainty by following heuristics that reduce information redundancy. In this study, we have tried to find traces of cognitive communication heuristics in a large-scale data set including 8 years of online posts (2004–2012) for a forum of Italian investors. We identified various market volatility conditions on a daily basis to understand the influence of market uncertainty on cognitive and communication processes. We found that investors communicated more dynamically when the market was unstable, while they were more prone to anchor heuristic when market uncertainty was invariant. Furthermore, abnormal market trends triggered more availability-based communication patterns. We also found that expertise matters. This would suggest that online communities need intelligent, context-specific tools to support partner selection and stimulate nonredundant communication.
Gatekeeping Fake News Discourses on Mainstream Media Versus Social Media
Authors: Al-Rawi Ahmed
Published: September 2018

This study analyzes mainstream media (MSM) coverage of fake news discourse and compares it with social networking sites (SNS) users who reference the term “fakenews” in their tweets. The study employs computational methods by analyzing over 8 million tweets and 1,350 news stories using topic modeling. Building on the theory of (networked) gatekeeping and Herman and Chomsky’s propaganda model, the results show that SNS users follow networked gatekeeping practices by mostly associating fake news references to the alleged bias of MSM. On the other hand, MSM coverage tends to link fake news to SNS’s negative role in spreading misinformation. I argue here that there is a networked flak activity on Twitter which is defined as a collective negative response to MSM in order to discipline it, change its tone and editorial stance, or undermine the public’s trust in it.
Finite element model for predicting the initiation of subsurface damage in railway crossings—A parametric study
Authors: Wiedorn Julian , Daves Werner , Ossberger Uwe , Ossberger Heinz , Pletz Martin
Published: September 2018

In this study, the initiation of subsurface damage due to the impact of new and worn wheels on differently deformed crossing nose geometries is calculated using the Dang-Van criterion. Three crossings with different materials (manganese steel, chromium-bainitic steel, and tool steel) were cyclically loaded in an FE crossing model reported in a previous study to evaluate the run-in state of plastic deformation. The impacts of the wheels on the deformed crossings were then calculated by considering the behaviour of an elastic material. This parametric study showed the effects of different velocities, axle loads, and wheel types on the vertical contact forces, contact pressures, and Dang-Van damage parameters. Additionally, the ability of manganese steel crossings to withstand unfavorable load situations was observed by including plastic material behavior and considering material history, such as residual stresses and hardening.
Inferring Whether Officials Are Corruptible From Looking at Their Faces
Authors: Lin Chujun , Adolphs Ralph , Alvarez R. Michael
Published: September 2018

While inferences of traits from unfamiliar faces prominently reveal stereotypes, some facial inferences also correlate with real-world outcomes. We investigated whether facial inferences are associated with an important real-world outcome closely linked to the face bearer’s behavior: political corruption. In four preregistered studies ( N = 325), participants made trait judgments of unfamiliar government officials on the basis of their photos. Relative to peers with clean records, federal and state officials convicted of political corruption (Study 1) and local officials who violated campaign finance laws (Study 2) were perceived as more corruptible, dishonest, selfish, and aggressive but similarly competent, ambitious, and masculine (Study 3). Mediation analyses and experiments in which the photos were digitally manipulated showed that participants’ judgments of how corruptible an official looked were causally influenced by the face width of the stimuli (Study 4). The findings shed new light on the complex causal mechanisms linking facial appearances with social behavior.
Synthesis and Properties of Amide-containing Bisnadimide Copper Foil Composites
Authors: Chou Shen , Lee Ker-Sen
Published: September 2018

Amide-containing bisnadimide (ACBI) resins were synthesized from nadic anhydride, 4-aminobenzoic acid, 4,4'-oxydianiline, and 4-nitro benzylchloride. The chemical structures were characterized using elemental analysis, FTIR and X-ray, and the thermal properties were determined using TGA. The adhesive properties of copper / ACBI composites were examined by SEM. The peel strength, heat resistance, chemical resistance, dielectric constant, and dissipation factor were measured and fund to be promising.
Problems and Pitfalls in the Evaluation and Design of New Biocides for Plastics Applications*
Authors: Kneale Chris
Published: September 2018

Many factors need to be considered in the design of new biocides for use in plastics applications. In Europe, biocides are now becoming more tightly regulated under the Biocidal Products Directive (BPD), and a significant data package needs to be provided not only for the registration of new actives, but also for existing biocides and biocidal formulations. A novel biocide must be compatible with the polymer matrix and must not adversely affect its physical properties. Once the issue of compatibility has been overcome, the antimicrobial efficacy of the biocide in the substrate should be established. Before selecting a test method to demonstrate such efficacy, it is necessary to consider whether the substrate should be pre-conditioned to simulate end use conditions, e.g. by leaching or artificial weathering. The final use of the product can also dictate the test protocol, e.g. a building membrane for ground contact should be evaluated using a soil burial test. Historically, biocides have been added to plastics to prevent their spoilage by fungal attack. Latterly, plastics with antibacterial effects have aroused much public interest. Advantages and disadvantages of traditional test methods will be discussed, and an alternative method for the evaluation of biocidal performance that is thought to be more representative of end use conditions will be presented.
Gas Sensing Materials from Carbon Black/Poly(Methyl Methacrylate) Composites
Authors: Dong Xian Ming , Fu Ruo Wen , Zhang Ming Qiu , Zhang Bin , Li Jun Rong , Rong Min Zhi
Published: September 2018

In this work, the electrical conductivity of carbon black/poly(methyl methacrylate) composites and its responsiveness to organic solvent vapors were investigated. The carbon black-polymer conducting composites were synthesized by in-situ polymerization. They exhibited a low electrical percolation threshold (~3.3wt% of carbon black). The electric resistance of the composites increased drastically by over 104 times when they were exposed to good solvent vapours such as chloroform, tetrahydrafuran and ethyl acetate, and it recovered when the composites were transferred to air. The effect of temperature on the vapour responsivity of the composites was notable. An elevated temperature accelerated the vapour-induced variation in electrical resistance of the composites. The experimental data also indicate that the composites possessed a good reproducibility of vapour responsivity. These results suggest that they can be regarded as promising gas sensors characterized by easy processability and cost effectiveness.
High-Temperature Adhesives Based on Alder-ene Reaction of Diallyl Bisphenol a Novolac and Bismaleimide: Effect of BMI Structure and Novolac Molar Mass
Authors: Gouri C. , Nair C.P. Reghunadhan , Ramaswamy R.
Published: September 2018

Diallyl bisphenol A formaldehyde novolac (ABPF) resin was cured with four structurally different bismaleimides (BMIs) at high temperatures through an Alder-ene reaction which resulted in thermally stable network polymers. The adhesive characteristics of the different BMI-ABPF systems were evaluated in terms of the lap shear strength (LSS) on aluminium substrates at varying temperatures up to 250°C. The LSS properties were not significantly affected by the structure of the BMI. Although the LSS of BMI-ABPF systems per se were not particularly high due to the brittle nature of the cross-linked structures, all the systems exhibited remarkably good retention of LSS at high temperatures. Replacing ABPF with its monomeric analogue i.e. o,o′- diallyl bisphenol A (DABA) resulted in better adhesion, but in a poorer thermo-adhesive profile. Comparison of DMA and thermo-adhesive profiles implied that in the majority of the cases molecular relaxations at higher temperature are conducive to matrix toughening which results in enhanced adhesion properties.
Phenolic Resins (IV). Thermal Degradation of Crosslinked Resins in Controlled Atmospheres
Authors: Bouajila J. , Raffin G. , Alamercery S. , Waton H. , Sanglar C. , Grenier-Loustalot M. F.
Published: September 2018

The study involved the thermal degradation of phenolic resins in controlled atmospheres (inert and oxidizing). Its aim was to characterize volatile organic compounds (VOC) and inorganic compounds released during heat treatment. The methods used were thermogravimetry coupled with thermodesorption/gas chromatography/mass spectrometry (TG/TCT/GC/MS) and thermogravimetric analysis coupled with infrared (TGA/IR). At the end of the heat cycle, residues were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (solid state 13C NMR (CP/MAS)). The data show that the synthesis conditions of the crosslinked resins, the controlled environment and the temperature of the degradation heat cycle, all affect the composition of volatile compounds and residues at the end of the cycle. The data have enabled us to propose decomposition reaction mechanisms for these resins in oxidizing and inert environments.
Highly Filled Nano-CdS/Polystyrene Nanocomposite Film with Self-Organization Behavior
Authors: Liang Hai Chun , Rong Min Zhi , Zhang Ming Qiu , Zeng Han Min , Xiang Hong , Wang Shu Feng , Gong Qi Huang
Published: September 2018

Highly filled polystyrene (PS) composite film with a nano-CdS loading of 20wt.% can be obtained when a certain mercaptan is applied to the particles' surfaces. Because of a strong electron transfer interaction between the modified CdS nanoparticles and the aliphatic carbons in PS, self-organization of the nanoparticles is perceivable in the composites. As a result, the ultraviolet/visible absorption edge of the treated nano-CdS/PS composites is blue-shifted in addition to the shift caused by quantum size effect. The fluorescence emission peak is accompanied by some fine structures and becomes red-shifted and narrower. Unlike conventional nanocomposites that generally contain low concentrations of nanoparticles (less than 10wt.%), the present approach greatly improves the scope for cooperative behavior of the nanoparticles.
Cylindrical Orthotropic Thermal Conductivity of Spiral Woven Composites Part I: Modelling of a Spiral Woven Structure
Authors: Cheng Chao-Chuan , Chiu Chang-Hsuan
Published: September 2018

This is the first a series of papers on the cylindrical orthotropic thermal conductivity of spiral woven composites. The geometric characteristics of spiral woven composites are modelled in the present study. A single layer of spiral woven fabric is considered as a fundamental structure and used to develop representative models, including round disc and polygon ones. In these representative models, crimps, cross-sections, and radial and circumferential arrangements of yarns are illustrated by cosine and arc yarn shape functions. A trapezoidal unit cell extracted from a polygon model will provide the next project in the series, with basic geometric parameters to develop thermal models for determining the thermal conductivities of spiral woven composites.
Rheology of Highly Filled Polypropylenes Prepared with Surface Treated Fillers
Authors: Ren Z. , Shanks R. A. , Rook T. J.
Published: September 2018

Highly filled polypropylene (PP) composites have been produced by extrusion of polypropylenes with surface treated fillers. The aim is to include the highest proportion of filler that can provide hardness and high density, without undue brittleness. Modification of the filler surface provided significant enhancement of the processing properties that have been studied with parallel plate rheometry. The experimental results indicated that the viscoelastic behavior of melt flow of highly filled polypropylene composites significantly depended on the following properties of the fillers: aspect ratio, specific surface area and particle size in talc, calcium carbonate and barium sulfate filled polypropylene composites. Traditional surface modifiers such as stearic acid are useful, but titanates and in particular small amounts of silicones have provided the greatest rheological modification.
Preform Technology: A Necessary Requirement for Quality Controlled LCM-Processes
Authors: Mitschang P. , Ogale A. , Schlimbach J. , Weyrauch F. , Weimer C.
Published: September 2018

A considerable number of process versions of Liquid Composite Moulding (LCM) technologies have been commercialised during the last few years. Only recently there have been attempts to reduce costs and to implement more complex components by the application of preform technology.

This article indicates the most appropriate application fields for LCM techniques for the manufacture of fibre reinforced polymers. Different LCM methods are described and summarised. The preforming techniques and particularly the sew -and -cut philosophy for developing a tailored reinforcement is explained. Investigations designed to elucidate the influence of sewing parameters and thread properties have led to an understanding of the requirements and preform characteristics needed to operate the quality controlled LCM process. Some concepts related to the control of the resin injection are described, and a realization of a decision-tree-concept is shown. Finally, a comparison of cost effects for different preforming methods shows a need to define a “critical preforming effort” to manufacture quality components as well as economically optimised parts.
Effects of Styrene Evaporation on the Cure Kinetics Behaviour of a Vinylester Resin System Suitable for Composite Pultrusion
Authors: Samaras Z I , Partridge I K
Published: September 2018

The paper describes the effects of styrene evaporation on the curing reactions of a vinylester resin, explored by the use of differential scanning calorimetry. The thermosetting system under study is characterized by the presence of three distinct exothermic peaks, attributed to different cure reaction mechanisms. A chemical cure kinetics model is presented, incorporating effects of diffusion limitations on the later stages of the cure. Whilst the nature of the curing mechanism is unaffected by the loss of styrene, the expected reductions in the overall heat of reaction from the individual reaction components are noted and quantified. The glass to rubber transition temperature, Tg, of fully cured resin is shown to decrease from 124°C in the initial sample to 121°C in samples in which over 20% of the initial styrene content had evaporated.
Linear Temperature Programming Rheometers for the Cure of Rubbers. Effect of the Various Parameters
Authors: Rosca I.D. , Granger R. , Vergnaud J.M.
Published: September 2018

In spite of their drawbacks, rheometers are usually run under isothermal conditions for the cure of rubbers: At least three experiments are needed at different temperatures selected within a narrow temperature window to determine the kinetic parameters of the cure of rubbers, and it takes some time for thermal equilibrium between the sample, initially at room temperature, and the dies to be established. With the rheometer in scanning mode, the dies and the sample are heated from room temperature up to the selected final temperature at a constant rate. The heating rate is crucial in this new method. The rubber used in this study is an ethylene propylene diene monomer vulcanised with 20% sulphur and with a rather high cure enthalpy. The state-of-cure versus temperature curves obtained in scanning mode have been calculated using a numerical model that takes into account the heat transfer by conduction through the rubber, the coefficient of heat transfer at the die-rubber interface, and the kinetics of the heat generated by the cure reaction. The kinetic parameters were determined mathematically from these state-of-cure versus temperature curves, which are similar to torque-temperature curves, by obtaining straight lines from them or using a least squares method. The kinetic parameters calculated in these ways were similar to those introduced by obtaining the state-of-cure versus temperature curves using the numerical model. Whatever the heating rate, ranging from 2 to 10 K/min, and whatever the coefficient of heat transfer at the die-rubber interface which expresses the quality of the contact, the moving die rheometer can be used in scanning mode to determine the kinetics of the cure of rubbers, even when the enthalpy of cure is high.
Amide-containing Bismaleimide Resins and their Copper Foil Composite Materials
Authors: Huang Meng-Shun , Yang Ming-Chien , Chou Shen
Published: September 2018

Amide-containing bismaleimide (ACBI) resins were prepared using four monomeric reactants: 3,4'-oxydianiline (3,4'-ODA), trimellitic anhydride (TMA), maleic anhydride (MA), and 4-aminobenzoic acid. Their chemical structures were characterized using elemental analysis and FTIR. The peel strength, dielectric constant, dissipation factor, heat resistance, and chemical resistance were studied. The experimental results show that the optimal hot-press conditions for ACBI/copper foil laminates was 320 °C and 4.9 MPa. The ACBI laminates treating with 0.2% NZ97 coupling agent had the highest peel strength of 2.097 kN/m. The peel strength was 1.568 kN/m after 24 h at 300 °C. The 1 MHz dielectric constant of ACBI was 3.48, and the dissipation factor was 0.0082. After a hot/wet treatment (steam at 100 °C) for 72h, ACBI laminates maintained 76% of their original peel strength. After treating in 10% H2SO4 solution at 60°C for 30 minutes, ACBI laminates maintained 88% of their original peel strength.
Morphology, Crystalline Structure and Isothermal Crystallization Kinetics of Polybutylene Terephthalate/Montmorillonite Nanocomposites
Authors: Wu Defeng , Zhou Chixing , Fan Xie , Mao Dalian , Bian Zhang
Published: September 2018

The melt intercalation method was employed to prepare poly(butylene terepathalate)/montmorillonite nanocomposites, and their microstructure was characterized by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane such as (010), (111), (100) was smaller than that of pristine PBT, which indicates that the crystallite size of PBT in the nanocomposites could be diminished by adding clay. Moreover, the isothermal crystallization kinetics of PBT and PBT/MMT nanocomposites was investigated by differential scanning calorimetry (DSC). During isothermal crystallization, the development of crystallinity with time was analysed by the Avrami equation. The results show that very small amounts of clay dramatically increased the rate of crystallization and high clay concentrations reduced the rate of crystallization at the low crystallization temperatures.

At low concentrations of clay, the distance between dispersed platelets was large so it was relatively easy for the additional nucleation sites to incorporate surrounding polymer, and the crystal nucleus was formatted easily. However, at high concentrations of clay, the diffusion of polymer chains to the growing crystallites was hindered by large clay particles, despite the formation of additional nucleation sites by the clay layers. At the higher crystallization temperature, the crystallization of the nanocomposites was slower than that of the pure PBT under the experimental conditions, which means that with the increase in chains mobility at the high crystallization temperature, the crystal nuclei are harder to format, and the hindering effect of clay particles on the polymer chains was stronger than the nucleating effect of the layers.

In addition, the activation energies of crystallization for PBT and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBT, while high amounts of clay increased the activation energy of PBT.
Graft Copolymers of Poly(methyl methacrylate) on Cellulose and Their Use as Supports in Metal Ion Sorption
Authors: Chauhan Ghanshyam S. , Kumar Suresh , Verma Monika , Sharma Rajeev
Published: September 2018

In order to develop new polymeric materials for environmental technologies based on cellulose, methyl methacrylate was graft copolymerized using benzoyl peroxide as free radical initiator. Reaction conditions were established for optimum grafting of methyl methacrylate and used to co-graft with it co-monomers such as acrylamide, acrylic acid and acrylonitrile. Graft copolymers were characterized by FT-IR, elemental analysis, and swelling behaviour in water and dimethyl formamide. Attempts were made to evaluate the effect of co-monomer concentration on the grafting behaviour of methyl methacrylate and on the structure of the copolymers. Candidate co-polymers were used as supports for the sorption of metal ions. Results were compared with those obtained using native cellulose, cellulose phosphate and oxycellulose.
Surface Modification of PBO Fibres by Gamma-Ray Irradiation: Effects on Interfacial Properties of their Epoxy Composites
Authors: Zhang C.H. , Huang Y.D. , Liu L.
Published: September 2018

The surfaces of poly [p-phenylene benzobisoxazole] (PBO) fibres were grafted with epichlorohydrin by a gamma (γ)-ray irradiation method. The influence of irrdiation dose on the interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and the fibre wettability were investigated. In addition, the fibre surface composition, and the shear fracture topography of PBO fibre/epoxy resin composites were analysed by X–ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The results indicate that a dose of 30KGy was the optimal condition for PBO fibre surface modification. The oxygen content of the irradiated PBO fibres was 22% higher than that of the untreated ones, and chlorine atoms were introduced onto the surface of the fibres through grafting actions between epichlorohydrin and PBO. The wettability of the epichlorohydrin-grafted PBO fibres was significantly increased, and the values of IFSS and ILSS of its composites were increased by 70% and 135%, respectively.

SEM shows that the improved interfacial adhesion resulted in a change in the failure mode of PBO fibre/epoxy composite from an adhesive-type interfacial failure to a cohesive-like matrix failure.
Effect of Tetradecyl Methyl Acrylate-Maleic Anhydride Copolymer on the Mechanical Properties of Glass Mat Reinforced Polypropylene Composites
Authors: Zhou Shanhua , Xu Zhiyu , Liu Xin , Gao Yan , Dong Qingzhi
Published: September 2018

A new interfacial modifier made of tetradecyl methylacrylate-maleic anhydride copolymer (TMA- co-MAH) was prepared and characterized. The effect of reaction time and monomer ratio on the gross conversion and MAH content in the copolymer was studied. When the glass mat was treated with TMA- co-MAH solutions and compounded with PP, the MAH group of the interfacial modifier formed strong interactions with the glass mat and the long side chain of the interfacial modifier entangled firmly with the polypropylene matrix. In comparison with maleated polyolefins, the higher MAH content of the TMA- co-MAH resulted in better interfacial adhesion between the PP and the glass mat resulting in increased flexural strength and modulus, and the ductility of the TMA- co-MAH introduced a ductile interlayer into the interface of the glass mat reinforced polypropylene composites (GMT-PPs) to achieve higher impact strength. Therefore the mechanical properties of composites treated with TMA- co-MAH were all superior to those of GMT-PPs treated with maleic anhydride grafted polypropylene (PP- g-MAH) solutions when they were used at the same level.

The effects of anhydride content, concentration of copolymer and compounding time on the mechanical property of GMT-PPs were investigated. With the optimal monomer ratio, MAH:TMA = 7:3, a 3% copolymer solution and a compounding time of 5 min, the impact strength, flexural strength and modulus of GMT-PPs treated with the new interfacial modifier were all improved significantly compared with composites treated with 0.3% PP- g-MAH solution.
Self-Reinforcing Composites of Polyacrylic Elastomers and Liquid Crystalline Polymer: Mechanical, Thermal, and Dynamic Mechanical Properties
Authors: Shivakumar E. , Das C.K.
Published: September 2018

In order to study the effect of liquid crystalline polymers (LCP) as reinforcing agents for polyacrylic elastomer (ACM), blends of ACM and a liquid crystalline polymer were prepared. These blends were cured with ammonium benzoate and Diak-4, 4,4'-methylen ebis(cyclohexylamine) carbamate in order to understand the curing behaviour of ACM in presence of LCP. A rheometric study of the blends indicated an improved state of cure in presence of Diak-4, but a deteriorated state of cure in presence of ammonium benzoate. All the blends showed substantial improvement in modulus and tear strength with the increasing amounts of LCP however; this improvement was predominant when Diak-4 was used as a curing agent. The tensile strength of the blends decreased with increasing LCP content, attributed to lack of interfacial adhesion between ACM and LCP, which was confirmed by scanning electron microscopy (SEM). It was found from the X-rd measurements that LCP acts as a nucleating agent by increasing the crystallinity of the blend. The degradation temperatures and heats of degradation deduced from the thermal analysis suggested that ACM had reduced thermal stability when in presence of LCP. A dynamic mechanical analysis (DMA) study revealed the improved storage modulus of the blends with increasing LCP content.
Combined Effect of Nano-clay and Nano-carbon Black on Properties of NR Nanocomposites
Authors: Qing-xiu Jia , You-ping Wu , Ping Xiang , Xin Ye , Yi-qing Wang , Li-qun Zhang
Published: September 2018

Natural rubber (NR)/clay/carbon black nanocomposites, filled with 10 phr, 20 phr, and 30 phr of filler (in total) were obtained by adding carbon black (N330) on a two-roll mill to NR/clay nano-compounds prepared by the emulsion compounding method. X-ray diffraction patterns and transmission electron microscope photographs of the nanocomposites showed that both fillers were dispersed randomly in the NR matrix at nano-scale and that the space between the clay layers was filled with carbon black particles. At the same total filler loadings, the mechanical properties of the naocomposites filled with both clay and carbon black, such as moduli at 100% and 300% elongation, tensile strength and tear strength, were greatly improved compared with those of either NR/clay nanocomposites or NR/carbon black nanocomposites. This indicates that the samples with both fillers possessed excellent mechanical properties.

It was found that the NR/clay/carbon black nanocomposites retained advantages from both fillers, for example, the processability and dynamic properties were close to those of NR/carbon black nanocomposites, and the gas barrier properties were almost as good as those of NR/clay nanocomposites.
The Preparation of Core/Shell Particles with Siloxane in the Shell
Authors: Cao Shunsheng , Deng Xiaobo , Liu Bailing
Published: September 2018

Core-shell microspheres ranging in average diameter from 12.829 to 15.039 μm, with a poly butyl methacrylate (BMA) core, and a poly 3-(methacryloxypropyl)-trimethoxysilane (MATS) shell, were prepared with methanol as the dispersion medium, by a successive seeding method under kinetically controlled conditions. To date, although some of particles (PSi/PA) have been prepared by seeded emulsion polymerisation, only a few core/shell (PA/PSi) microspheres have been reported the literatures.

To prepare core/shell (PA/PSi), the core was first synthesized by dispersion polymerisation and to form seeds; addition of MATS monomer was started after 90~95% conversion of the BMA. The reaction was prolonged for another 12 h to achieve complete consumption of MATS monomer. Microspheres; containing hydrophilic PBMA as the core and hydrophobic PMATS as the shell, were successfully formed through the free radical of surface in the core. The particles morphology and size distribution were examined using a Transmission electron microscope and a Malvern Master Sizer/E particle size analyser, respectively.
Viscoelastic Constitutive Model of Unvulcanized Rubber
Authors: Yong Li , Jing'an Wu , Xingwen Du
Published: September 2018

Based on rheological test results, a new viscoelastic constitutive equation for unvulcanized rubber has been set up, with mathematical justification to describe its mechanical properties in relation to the yield stress and shear-thinning effect. In this model, every term or coefficient has an explicit physical meaning.

The proposed model indicates that the yield stress is one of the main causes for the shear-thinning effect and reveals why some materials possess double-Newtonian regions with the shear viscosity in the first region higher than that in the second region. The yield stress makes the flow index of the power law fluid model vary widely, so that it needs to be eliminated from the power law fluid model. The model can also distinguish the true shear viscosity from the apparent shear viscosity effectively.

The parameters of the equation are determined by the step fitting method, which is the precondition for quantitative analysis.

However, the equation is a one-dimensional model, so further research is needed.
Transport and Flame Properties of Natural Fibre Reinforced Polymers
Authors: Torres F.G. , Flores R. , Dienstmaier J.F. , Quintana O.A.
Published: September 2018

The authors studied the thermal conductivity, water absorption and linear burn rate of natural fibre reinforced polymers (NFRP). High density polyethylene (HDPE) and degradable starch-based polymers were used as matrices. Discrete sisal ( Agave Sisalacea) fibres were used as reinforcement. The effect of fibre content, moisture and void fractions on thermal conductivity was studied. From water absorption tests, it was determined that water diffusion in NFRPs corresponds to a Fickian process only in the early stages of diffusion. Diffusivities were obtained for that case. Linear burn rate experiments showed that sisal reinforced polymers burn twice as fast as unreinforced HDPE specimens, however the reinforced specimens show better structural integrity during burning than the unreinforced ones, probably due to an increase in viscosity and melt strength due to the presence of reinforcing fibres.
Preparation and Properties of Thermoplastic Polyamide-imide and Polyurea-amide-imide/Copper Foil Composites
Authors: Huang Meng-Shun , Yang Ming-Chien , Chou Shen
Published: September 2018

Polyamide-imide (PAI) and polyurea-amide-imide (PUAI) resins were polymerized from five reactants: 4,4'-oxydianiline, 4-nitrobenzoyl chloride, 4,4'-diphenylmethane diisocyanate, 1,2,4,5-benzenetetracarboxylic dianhydride, and 3,3'-4,4'-benzophenone tetracarboxylic dianhydride. Their chemical structures were characterized using elemental analysis, FTIR and 1H NMR spectroscopy.

Their thermal properties, adhesive properties, electrical properties, heat resistance, and chemical resistance were studied. The experimental results show that the glass transition temperatures of PAI and PUAI films occurred respectively at 360 °C and 229 °C, and the 10% weight loss occurred respectively at approximately 481 °C and 420 °C. The optimal hot-press conditions for PAI/copper foil (CU) composite were 380°C and 4.90 MPa, whereas those for PUAI/copper foil (CU) composites were 250 °C and 4.90 MPa.

Values of the peel strength, dielectric constant, and dissipation factor were obtained and the peel strength was re-measured after a thermal stability test. The chemical resistance tests showed that the peel strength retention values of the PAI/CU and PUAI/CU composites were respectively more than 95% and more than 94% after immersing in 10% H2SO4 solution at 70 °C for 1 h.
Poly(2-Hydroxy Ethyl Methacrylate-co-Acrylic Acid) as Novel Biodegradable Macroporous Hydrogel
Authors: Mohapatra Ranjit , Swain Ashok K , Mohapatra Roomky , Rana Pradeep K , Sahoo Prafulla K
Published: September 2018

Hydrogels of macroporous copolymer, 2-hydroxyl ethyl methacrylate with acrylic acid, were prepared in the presence of N,N'-methylene-bis-acrylamide as crosslinker and benzoyl peroxide as initiator. The structure of the copolymer was characterized by FT-IR, H1-NMR and scanning electron microscopy and the thermal stability by thermogravimetric analysis. Its hydrogel character was observed by studying the swelling of the copolymers simply by measuring weight gain and weight loss. The swelling was determined in distilled water, saline solution and buffers of pH, 4 and 9.2, was found to increase with increasing pH, attaining a maximum at pH 9.2.

The biodegradability of the copolymers was studied by introducing microbes to the culture media along with the prepared sample and it was verified by examining the surface morphology by SEM. The rate of biodegradation was monitored by the CO2 release method.
AFM Characterization of Interphase Properties of Silver-Coated Carbon Fibre Reinforced Epoxy Composites
Authors: He J.M. , Huang Y.D.
Published: September 2018

Carbon fibre (CF) surfaces were silver-coated using an electroless deposition technique. Atomic force microscopy (AFM) was used to measure the topography and roughness of the silver-coated carbon fibre surfaces after various deposition times before forming a composite. The height images showed that the surface coverage of silver (Ag) islets after 2 min was the most complete and uniform. AFM in the force modulation mode probed the local mechanical properties within the interphase regions in a CF/epoxy composite system. The results showed that the stiffness of the Ag coating was similar to that of the carbon fibres, and higher than that of the epoxy matrix. The interphase thickness varied from 50 nm to 200 nm, depending on the silver deposition time. The interphase morphology revealed the interaction mechanisms between the silver layers and the carbon fibres. The interfacial adhesion properties were evaluated by microbond testing. The interfacial shear strengths (IFSS) of the microcomposites were improved after Ag plating. Due to the increase in roughness and the small volume of the Ag particles compared with the epoxy resin, the Ag plating layers promoted mechanical interlocking between the carbon fibres and the epoxy resin. At a deposition time of 2 min, the maximum IFSS was 36.2 MPa, 17.9% higher than that of the uncoated specimens.
Dynamic Punch Shear Characterization of Twill Weave Graphite/Epoxy Composites
Authors: Hosur M.V. , Islam S.M. Waliul , Jeelani S.
Published: September 2018

In this study, the high strain rate response of twill weave graphite/epoxy composites under punch shear mode was characterized. 24-layer laminates of twill weave graphite fabrics were fabricated using a relatively inexpensive vacuum assisted resin infusion moulding process (VARIM) with a low viscosity SC-15 resin system. Samples of nominal size 25 by 12.7 by 4 mm were cut from the laminates for high strain rate testing. High strain rate punch shear tests were carried out with a modified Split Hopkinson Pressure Bar setup. Samples were loaded in punch shear mode through the thickness. Varying the breech pressure allowed testing at different strain rates in the range of 1400/s to 3800/s. Samples were tested at room and three elevated temperatures of 52 °C, 79 °C and 107 °C. The samples exhibited increasing peak shear stress with increasing strain rate at all temperatures. However, the peak stress decreased with temperature for a given range of strain rates. Failure modes were characterized with scanning electron microscopy, which revealed the degradation of the fibre-matrix interface with increasing temperatures.
Electrically-Conducting Polyolefin Composites Containing Disperse and Fibre Materials as Conductive Secondary Phases
Authors: Atanasov Atanas , Koleva Dimitrina
Published: September 2018

Polymeric composites based on a combination of polyolefins such as ultra-high-molecular-weight poly(ethylene), high-density poly(ethylene) and poly(propylene) with various disperse and fibre phases, including electrically-conducting polyaniline have been prepared. These composites were characterized by their conductivities as well as by employing optical and electron-scanning microscopy methods.

Composites based on a combination of ultra-high-molecular-weight poly(ethylene) with copper and graphite as secondary phases were found to possess conductivities below 10−7 S/m even at degrees of filling of 20 mass%. Composites containing up to 5 mass% carbon fibres or an equivalent combination with graphite had similar conductivity values. However, when the filler content exceeded the above-mentioned values there was a gradual increase in this parameter. Significantly better results were obtained when the polyaniline complex with dodecylbenzene sulfonic acid was introduced as the electrically conducting component. For example, the antistatic properties of composites based on ultra-high-molecular-weight poly(ethylene) or other polyolefins can be achieved at degrees of filling of 1.5 to 2 mass% with respect to the polyaniline component. Moreover, the conductivity values of the materials obtained in the molten state were, approximately, one to two orders of magnitude lower than those prepared by employing the in situ and wet paste methods. The results obtained from optical and electron-scanning microscopy indicate that, for polyaniline contents of ca. 2 mass%, fine particles of the conducting component were uniformly distributed within the thermoplastic polymer matrix. This contributed to the formation of a more sophisticated polymer network with a higher conductivity.