bluuebunny/crossref_metadata_2025 huggingface dataset:
Social Engagement and Happiness in Older Adults With and Without Cognitive Impairment
Authors: Morishita-Suzuki Kumi
Published: September 2024

This study investigated the associations between in-person and remote engagement and self-rated happiness in older adults aged 50 years and above in three cognitive function subgroups: Normal Cognition, Cognitive Impairment not Dementia (CIND), and Dementia. Data were obtained from the 2014 Health and Retirement Study. Results showed that remote engagement was significantly associated with higher self-rated happiness, particularly in the CIND group. However, its association with in-person engagement was less consistent. No significant association was observed among individuals with dementia. However, the direction of the relationship between the two types of social engagement and self-rated happiness was positive. Instrumental activities of daily living, depression, and social capital were identified as potential factors influencing the relationship between social engagement and self-rated happiness. These findings emphasize promotion of both in-person and remote social engagement opportunities to enhance the well-being of older adults across different cognitive function subgroups.
Enhancing landfill efficiency to drive greenhouse gas reduction: A comprehensive study on best practices and policy recommendations
Authors: Lair Antoine , Mansuy Michael , Romand Clément , Oberti Odile , Pradels Catherine , Barina Giulia , Denoun Théodore , Venturini Marco , Trommsdorff Corinne
Published: September 2024

This article investigates the pivotal role of non-hazardous waste landfills in achieving greenhouse gas (GHG) reduction objectives within the European Union (EU).1 This study leverages the experience of key stakeholders in the European landfilling, assesses the efficacy of ‘best-in-class’ landfill installations, evaluates their potential impact on GHG reduction, and offers concrete recommendations for operators and policymakers. ‘Best-in-class’ landfills exceed the commonly accepted best practices by implementing all the following practices: (1) an anticipated capture system during the operating phase, (2) prompt installation of the final cover and capture system, with use of an impermeable cover, (3) operated as bioreactor, keeping optimal humidity, (4) adequate maintenance and reporting, (5) recovery of captured gas and (6) treatment of residual methane emissions throughout the waste decomposition process. The main finding is that switching from the actual mix of practices to ‘best in class’ practices would reduce by ~21 MtCO2eq (−36%) the emissions due to the degradation of waste landfilled between 2024 and 2035, compared to the ‘business-as-usual scenario’, while also providing a renewable energy source, bringing potential avoided emissions and energy sovereignty. The findings underscore that in addition to implementing the organics diversion and waste reduction targets of the EU, adopting ‘best-in class’ landfill practices has the potential to bolster energy recovery, mitigate emissions and stimulate biomethane production, thereby advancing the EU environmental goals.
A Call for Afrocentric Decolonial Endogenous Marketing and Public Policy Research and Practice: Toward Sustainable Peace and Well-Being in African Societies
Authors: Francis June N.P. , Mugabo Lama
Published: September 2024

Africa experiences one-third of all conflicts globally, resulting in the diminishment of human, social, and economic well-being; high levels of insecurity; poverty; and disrupted marketing systems. Drawing on the experiences of African countries, the article illuminates the ways in which the slave trade and, later, the colonization of the African continent fomented the social and economic convulsions that continue to erupt into continuing cycles of social conflict. Today these are manifested in the neocolonial influence of public policy on the continent by international organizations, funding bodies, and local and international institutions that control the public policy discourse and resources. The authors argue that if marketing systems are to enhance well-being and reduce social conflict, marketing policy makers need to contest failed “external to Africa” policy frameworks and look to endogenous policies better suited to contemporary African challenges. A case study of Rwanda illuminates how endogenous, “home-grown” decolonial and Afrocentric policy can create enduring peace and improve marketing systems and well-being. The authors call for research at the nexus of public policy and African marketing systems that adopts decolonized, endogenous, and Afrocentric perspectives to address this lacuna in marketing and public policy research and practice.
The Cumulative Impact of Recurrent Experiences of Intimate Partner Violence on Emotion Dysregulation: A Longitudinal Investigation
Authors: Simpson Lauren E. , Kumar Shaina A. , Brockdorf Alexandra N. , Brock Rebecca L. , Messman Terri L. , Gratz Kim L. , DiLillo David
Published: September 2024

Intimate partner violence (IPV) disproportionately affects women and has been linked to a range of negative psychological outcomes, including emotion dysregulation. Although IPV is often recurrent and tends to escalate in severity over time, few studies have examined the potential effects of recurrent experiences of IPV on emotion dysregulation. The current study employed a longitudinal design to examine the cumulative impact of recurrent experiences of IPV on emotion dysregulation. Participants were 491 young adult community women ( Mage = 21.74; 61.3% White, 35% African American/Black) who completed self-report measures of IPV and emotion dysregulation every 4 months for 28 months. Multilevel structural equation modeling techniques revealed that, at the within-person level, increases in cumulative IPV were associated with increases in global emotion dysregulation across the 28 months. In particular, the accumulation of IPV experiences over time was associated with increases in difficulties controlling impulsive behaviors when distressed and accessing effective emotion regulation strategies. At the between-person level, greater average cumulative IPV was associated with greater mean levels of global emotion dysregulation, as well as four specific dimensions of emotion dysregulation, including difficulties accepting emotional responses, accessing effective emotion regulation strategies, and both engaging in goal-directed behaviors and controlling impulsive behaviors when distressed. These findings suggest the potential cumulative impact of IPV on both global and more specific dimensions of emotion dysregulation. Results also highlight emotion dysregulation as a potentially important construct to assess and target in interventions for women experiencing recurrent IPV.
Optimization of graphene oxide/conducting polymer nanocomposites as electrodes for nonenzymatic glucose sensing. Part I: Preparation, characterization and surface morphology
Authors: Saleh Basma K , Yacout Sara F , Soliman Moataz , Ebrahim Shaker , Awad Anhar , Abou-Kandil Ahmed I
Published: September 2024

In this study, we Prepared a new composite of graphene oxide (GO), polyaniline (PANI) and poly(3,4-ethylenedioxythiophene) that can be used for non-enzymatic glucose sensing. Graphene oxide was prepared using modified Hammer’s method and PANI was prepared using Chemical oxidative method. PANI:PSS/GO and PANI:PSS/GO/PEDOT:PSS nanocomposites were synthesized by physical mixing at room temperature. Characterization was carried out using several analytical techniques to ensure the correct preparation and study the structure of the prepared nanocomposites and its individual components. Raman spectroscopy showed successful preparation of (GO) with high D:G ratio. XRD spectroscopy confirmed the interlayer spacing of graphene oxide increased by 26.9% and 34.6% respectively for both composites allowing the polymer to diffuse in-between the graphene layers and enhance its conductivity. EDX illustrated the chemical composition of nanocomposites with the atomic percentage. The surface morphology was also investigated using SEM and HRTEM proved the formation of homogenous surface due of the nanocomposites. Atomic force microscopy (AFM) proved the reduction in surface roughness by 17.5% and 20.7% of PANI:PSS/GO and PANI:PSS/GO/PEDOT:PSS nanocomposite respectively.
On 3D printed polyvinylidene fluoride composite-based diaphragmatic hernia sensors
Authors: Barwar Abhishek , Kala Prateek , Singh Rupinder
Published: September 2024

Diaphragmatic hernia (DH) recurrence is a commonly reported disorder among bovines. Recently, studies have been reported using wireless devices (like ultrasonic and radio-frequency (RF) based pressure sensors) to detect DH. But hitherto, little has been reported on using polyvinylidene fluoride (PVDF)-based sensors mounted on the diaphragm of bovine to detect the recurrence of the DH post-surgery. In this work, the PVDF-hydroxyapatite (HAP)- chitosan (CS) composite in the proportion of 90-8-2 (wt.%) was used as a substrate for sensor fabrication based on microstrip patch antenna (MPA). Based on the results, the parts of the sensor, that is, substrate, patch, and the ground plane, were designed in the high-frequency structural simulation (HFSS) software assigned with the material properties of PVDF-HAP-CS (as substrate) and 17-4 precipitated hardened (PH) stainless steel (SS) alloy (as patch or ground plane). Upon simulation, it was observed that some deviation in resonance frequency occurred with/ without the natural bovine diaphragm, which was verified based on experimental analysis. The parts were 3D printed for validation through material extrusion (MEX) and direct metal laser sintering (DMLS) processes. Upon testing using a vector network analyzer (VNA), it was observed that the sensor without the diaphragm resonated at 3036.57 MHz with a return loss (S11) of −12.81 dB, whereas the sensor with the diaphragm resonated at 2019.35 MHz with an S11 of −21.06 dB. This shift in frequency with/without the diaphragm is measurable in the industrial, scientific, and medical (ISM) frequency band on a Bluetooth device to detect the reoccurrence of DH.
An enhanced continuous contact force model for deployable structures with clearance joints: Validation, simulation, and dynamic characteristics
Authors: Yao Huaibo , Liang Lei , Ma Wenlai , Zhang Huibo , Zhao Yang , Cui Hutao
Published: September 2024

Joint clearance is inevitable and affects the dynamic characteristics of deployable structures in orbit. An accurate contact force model can improve the dynamic modeling accuracy of deployable structures. This work proposes and validates an enhanced contact force model for modeling deployable structures with clearance joints. First, an enhanced continuous contact force model is presented based on a hybrid theoretical and numerical static cylindrical contact force model with a modified hysteresis damping factor obtained by reassessing energy and momentum transduction during the impact process. Subsequently, the proposed model’s validity is established through comparisons with results from the finite element method. Finally, dynamic simulations for planar deployable structures demonstrate the applicability of the proposed model. The dynamic characteristics of the structures with clearance joints are studied. Results indicate that the proposed model is a reasonable approach for evaluating contact forces during the impact process of clearance joints, which undeniably influence the dynamic characteristics of deployable structures. External loads further affect the dynamic characteristics, and the clearance joints exhibit distinct contact modes, warranting further investigation. This work is vital for designing and analyzing high-precision space deployable structures in orbit.
Enhancing biocompatibility and antibacterial activity of Mg/HA (magnesium-hydroxyapatite) composites with silver nanoparticles for orthopedic implant applications
Authors: Chowdeswarihalli Narayanappa Chandrahasa , Nagappan Beemkumar , Vignesh Packkirisamy , Thirugnanasambandam Arunkumar
Published: September 2024

Recent medical research is focusing on biodegradable and biocompatible magnesium-based alloy materials and composites for repairing damaged bone structures. Their rapid deterioration and poor antimicrobial properties prevent them from being used as implant materials. Hence, this study aims to develop novel nanocomposites (Mg/5% HA and Mg/5% HA/1% Agnp) by innovative ultrasonic-aided squeeze-rheo casting to enhance the mechanical, corrosion, and biological properties of Mg-based composites, demonstrating their potential as biodegradable implants with a low implant/tissue infection risk. Herein, the fabrication process involved the application of 2 kW power and 20 kHz acoustic waves during ultrasonic treatment of the molten magnesium alloy to achieve uniform dispersion of HA and Agnp, followed by squeeze pressure to solidify the composite materials. The morphological and phase analysis reveals minimal Agnp aggregation, surface defects, and presence of primary Mg, HA, and Ag phases without intermetallic phase formation. Furthermore, potentiodynamic polarization study reveals that Agnp-reinforced nanocomposites have lower corrosion rate (0.82 mm/y) than pure Mg (1.15 mm/y) and Mg/HA (2.55 mm/y) composites in a simulated body fluid (SBF). Likewise, the contact angle testing and MTT assay demonstrated improved cell adhesion and proliferation properties of the nanocomposite. Also, the release of Ag+ ions during degradation inhibited colony-forming units of E. coli bacteria and disrupted its cell membrane, proving its bactericidal properties. Altogether, these novel nanocomposites (Mg/5% HA/1% Agnp) may be suitable for biodegradable implants with a low implant/tissue infection risk.
Optimization of wire electrical discharge machining process parameters on Inconel 690 superalloy via Taguchi technique
Authors: Manoj Mariadhas
Published: September 2024

The research work deals with the improvement of wire electrical discharge machining process parameters for Inconel 690 super alloy. The goal of optimization is to achieve a maximum material removal rate (MRR) and a minimum surface roughness (SR). Brass wire is employed as the electrode, and Pulse on time (PON), Pulse off time (POF), Wire tension (Wt) and Wire feed (Wf) were selected as the process variables. The investigations were modelled based on Taguchi L16 orthogonal array. The results revealed that maximum MRR was obtained when PON=12 µs, POF=57 µs, Wf=6 m/min, Wt=9 g, and a minimum SR was obtained when PON=12 µs, POF=60 µs, Wf= 9 m/min and Wt=7 g. The optimum condition for machining by grey relational grade and its rank order method are found to be PON=12 µs, POF=59 µs, Wf=7 m/min and Wt=10 g. Whereas on using grey-Taguchi technique, the optimum parameters are found to be PON=12 µs, POF=58 µs, Wf=6 m/min and Wt=10 g. Analysis of variance was utilized to determine the input parameter's influence on the performance parameter and it was found that PON has high significance in maximizing the MRR and minimizing the SR.
Analysis of laser power/scan speed combinations on constant energy density: Correlation of roughness-density and structure-property of additively manufactured Ti-6Al-4 V alloy
Authors: Kumar D. Praveen , Jebaraj A. Vinoth
Published: September 2024

The present work mainly addresses the influence of laser power (LP) and scan speed (SS) variations within constant energy density (CED) on Titanium alloy (Ti-6Al-4V) fabricated through laser powder bed fusion (L-PBF) process. The samples were fabricated with five different combinations of LP and SS with variations from 150 to 370 W and 475 to 1170 mm/s respectively within CED of 44 J/mm3. Strong inter-relationship observed between the outer surface topography and the interior part density showed that a sample with minimum roughness parameters (Ra = 0.88 µm) exhibiting higher relative density (99.15% ± 0.12). Decrease in the roughness parameters such as 47.61% of Ra, 53.01% of Rq, 63.56% of Rz and 74.76% of Rt was seen from the samples S1 to S4 as the LP and SS gradually increased within CED beyond which it again increased. Decrease in the melt track width was seen with simultaneous increase in LP and SS, and revealing a narrow melt track of range between 235.8 and 241.4 μm with high LP (370 W) and high SS (1170 mm/s) combination. Conversely, at low LP (150 W) and low SS (475 mm/s), the moving heat source provided enough time for melting resulted in a wider scan track of range between 307.9 and 311.5 µm. XRD pattern showed identical peaks in all the samples with noticeable peak shift despite the change in LP and SS at CED. EBSD analysis revealed more than 97% of martensite (α′) phases and also strong texture along the <0001 > direction. The presence of more amount of needle shaped martensitic structure led to higher ultimate tensile strength (UTS) of more than 1145 MPa in all the samples. However, notable uncertainty was observed between the samples in the percentage of elongation due to the presence of porosity.
Incidence of non-alcoholic fatty liver disease in antiretroviral therapy-naïve people with human immunodeficiency virus who start DTG/ABC/3TC compared to BIC/FTC/TAF at 48-week follow-up
Authors: Cano Díaz Ana Luz , Triana González Salma , Salinas Velázquez Gloria Elizabeth , Mata Marín José Antonio , Gaytán Martínez Jesús Enrique , Mauss Stefan
Published: September 2024

Purpose

To determine the incidence of non-alcoholic fatty liver disease (NAFLD) by non-invasive methods in people living with HIV (PLWH).

Methods

Prospective cohort, in PLWH naïve to antiretroviral therapy, starting bictegravir (BIC) or dolutegravir (DTG) at the Hospital de Infectología “La Raza”, in Mexico City, from February 2021 to August 2023. We measured at baseline and 48 weeks triglycerides and glucose index (TyG), fatty liver index (FLI), hepatic steatosis index (HSI) and liver ultrasonography; relative risk (RR) for developing NAFLD was determined.

Results

At 48 weeks, TyG index in BIC-group 4.54 (IQR 4.36–4.75), in DTG-group 4.66 (IQR 4.49–4.80), p = .080; HSI in BIC-group 30.30 (IQR 28.12–33.70), in DTG-group 30.85 (IQR 28.02–34.50), p = .650; FLI in BIC-group 14.88 (IQR 7.91–31.80), in DTG-group 19.49 (IQR 8.49–32.28), p = .729; NAFLD was detected by US in 6 [10.3% (95%CI 4.8%–20.7%)] in BIC-group and, 7 [10.9% (95%CI 6.4%–20.9%)] in DTG-group, p = .916. Risk factors for NAFLD development were baseline BMI ≥25 kg/m2, baseline HDL-c <40 mg/dL, and FIB-4 >1.3 at 48 weeks.

Conclusion

There is a high incidence of NAFLD in PLWH who start a second generation INSTI at 48 weeks; baseline overweight, low HDL-cholesterol and FIB-4 >1.3 at 48 weeks of treatment were independent risk factors for NAFLD development.
Servant of three masters? Comparing competing demands of representation, integration and solidarity – Dutch vis-à-vis German works councils
Authors: Behrens Martin , Brehmer Wolfram , Grift Yolanda , Sapulete Saraï , van den Berg Annette , van Witteloostuijn Arjen
Published: September 2024

Comparing the Netherlands and Germany, and building on different theoretical perspectives on cooperation, we analyse whether works councils are able to accommodate and reconcile the competing demands of representation (relationship to the workforce), integration (relationship to management) and solidarity (relations to the union), or whether varying geometries of interest lead works councils to prefer one of those three demands. The analysis of an online-survey of 1,776 works councillors reveals differences and similarities between the two countries. Despite very similar institutional settings, multivariate statistical analysis shows that works councils differ in the priorities they set when choosing a preferred partner. German worker representatives feel close to the unions and workforce alike, while their Dutch counterparts maintain comparatively close relations to management. Nevertheless, we see many similarities as well. So, despite different historical trajectories and differences in regulatory detail, works councils have much in common in both countries, which suggests that they have a systematic impact on how employee voice materialises on the ground.
Developments in Hindered Amine Chemistry Promote Polyolefin Growth Opportunities
Authors: Solera Peter , Capocci Gerald
Published: September 2024

Over the past four decades, advances in polyolefin stabilization have helped manufacturers expand their material choices to capture economic and performance benefits. In the ’60s and 70s, antioxidants and UV absorbers provided baseline levels of protection against thermal and UV degradation. During the 1980’s hindered amine light stabilizers substantially extended the service life of polyolefins for a multitude of film, fibre and moulded articles. In the last ten years, breakthroughs in hindered amine chemistry have pushed the performance boundaries of polyolefins to even greater heights.

Now, in the ’90s, the elimination of undesirable aspects of hindered amine stabilization, such as amine deactivation in flame retardant systems and reduced colour yield in pigmented plastics, is allowing material substitution in markets traditionally earmarked for engineering polymers, glass and metal. This paper focuses on advances in hindered amine chemistry designed to address these shortcomings. Examples of applications where new hindered amines provide enhanced value are demonstrated. Performance data are presented for polypropylene fibre, thermoplastic olefins for automotive parts and construction applications, polyethylene agricultural film and flame retardant systems. The advantage of using hindered amines as thermal stabilizers is also discussed.
Formulating Rigid PVC to Optimise Flame Retardancy and Smoke Suppression
Authors: Thomas Noreen L. , Harvey R.J.
Published: September 2024

Fire performance tests have been carried out on a number of inorganic flame retardants and fillers in rigid PVC formulations. The results have been used to find a way of maximising fire retardancy and minimising smoke evolution without affecting the physical and mechanical properties of the material.
New Performance Additives from DSM
Authors: Bruens C. , Nieland R. , Stanssens Dirk
Published: September 2024

Over the last few years, DSM New Business Development has been active in the field of performance additives with flame retardants based on melamine and with ultra thin UHMWPW films. Now, DSM NBD has started the commercialisation of three new developments:-

A carrier material for the production of polyolefin concentrates with liquid or low melting additives and reactants. Products based on a new technology to coat fine particles with a conductive polymeric layer. Products (based on hyperbranched polymers), which can be considered as multifunctional nano-carriers. Dependent on the nature and the quantity of the different substituents brought onto this core molecule, tailor-made additives can be produced.
A Textile Design System for Engineering Preforms
Authors: Hill B.T. , Soden T.A. , McIlhagger R. , Miller L.
Published: September 2024

A system is reported which automates the methodology needed to design complex 3D woven composite reinforcements. The system generates the design code enabling automatic preform manufacture on a conventional loom and provides specific data for composite modelling and analysis. This is a fundamental design tool and facility that amalgamates the collective interests of a multi-disciplinary group researching the many facets of textile composites. The cross-sectional program (XS program) has to facilitate the design rationale and methodology necessary for the production of a diverse range of flat and complex shaped reinforcements in a variety of weave architectures. Program outputs, for use within the textile modelling and analysis software and for fabric analysis data ofthe different architectures, are provided in a compatible format. The program and data generated has evolved into the foundation for a knowledge based system for fibre reinforced composites. This paper outlines the specification and attributes of the program, verifying its capabilities by designing and manufacturing complex fabric architectures in the form of a lower limb prosthesis and T-section reinforcement. The paper also indicates some other areas of on-going research to provide basic information for the program database.
Effect of Thermal and Mechanical Processes on the Molecular Orientation of Polyester Fibres
Authors: Fouda I. M. , Shabana H. M.
Published: September 2024

This study uses the optical results obtained by a double-beam interference polarized microscope connected to a mechanical device to measure the molecular orientation produced in polyester (PET) fibres. The samples were boiled for various periods oftime and stretched at room temperature. The changes in the molecular orientation were evaluated to obtain the values ofthree orientation functions. The results of the extension were used to calculate some mechanical factors and the shrinkage stress. In addition, the crystalline and amorphous orientation functions, the dielectric constant, the dielectric susceptibility and the number of moles of network chains per unit volume were among the calculated parameters. The present work throws light on how the thermal treatment and the applied stress affect the molecular orientation factors and the calculated structural parameters. Relationships among the calculated parameters and both the draw ratios and the boiling time are given. for illustration.
Polyurethane-Bound Stabilisers
Authors: Munteanu Dan , Bolcu Constantin , Ostafe Vasile
Published: September 2024

Addition of antioxidants and light stabilisers into the polyol component before its reaction with the isocyanate com ponent is common practice for polyurethane stabilisation. The stabilisers usually contain single OH and NH groups, which are involved in the mechanisms of stabilisation and the additives may then be regarded as monofunctional stabilisers. The OH and NH groups are very reactive towards the -N=C=O (isocyanate) groups so that a reaction between the stabiliser and the isocyanate groups during the synthesis of the polyurethane may occur to some extent. The stabiliser will become part of the polymer chain but the resulting structure will lose its active groups and consequently will not demonstrate the stabilisation effect. Some stabilisers have an additional OH group, not engaged in the stabilisation mechanisms. Having no constraints, these groups are more reactive towards the isocyanate groups. For these bifunctional stabilisers the resulting structure will bear the unreacted stabilising group, still effective, and a polyurethane-bound stabiliser will be obtained. The reaction of various commercial monofunctional and bifunctional stabilisers with isocyanates has been studied, as well as t heir use for the stahi lisation of polyurethanes, under conditions typical of practical applications. Whereas the reaction yields of the isocyanates with the monofunctional stahi lisers were very low (less than 15%). the reaction yields exceeded 90% for the hifunctional stahilisers. Therefore. commercial products with hi fu nctional structures may he regarded as reactive stabilisers, which yield polyurethan e-bound stabilisers.
Effect of Surface Treatment of Glass Fibres on Adhesion to Polypropylene Resin
Authors: Chou Shen , Lin Ling-Shiou , Yeh Jen-Taut
Published: September 2024

This study concerns the treatment of glass fibres to improve their adhesion to polypropylene resin (PP). The glass fibres were treated with four types of coupling agents and then with maleic anhydride grafted polypropylene (MAPP) emulsion. The surface characteristics and bond strength were analyzed by scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS), and a microbonding pull-out test. The mechanical properties of the composites were tested.

Because the two ends of the coupling agent molecules reacted with the glass fibre surface and the MAPP emulsion respectively to form chemical bonds, and the MAPP emulsion possesses good compatibility with polypropylene, an interphase was formed while melt blending, which improved the glass fibre/polypropylene bonding. This could be proved by using a microbonding pull-out test. The composites of glass fibre and PP were fabricated by means of a twin screw extruder and an injection moulding machine. The tensile strength and flexural strength were measured and the fracture surfaces were observed by SEM to assess the contribution of the surface treatment.

The test results demonstrate that the tensile strength of those composites reinforced by glass fibres treated with coupling agent and MAPP emulsion was 38% higher than that of the composites reinforced by untreated glass fibres, and 21% higher than that of composites that used the coupling agent alone. As for the flexural strength, the coupling agent/MAPP emulsion treatment was 44% better than having no treatment and 25% better than using the coupling agent alone.
Effects of Moulding Pressure on the Mechanical and Friction Properties of a Semi-metallic Friction Material
Authors: Dong Feng , Blum Frank D. , Dharani L.R.
Published: September 2024

The effects of compression moulding pressure on the mechanical and frictional properties of a semi-metallic friction material has been studied via flexural, wear, fade, and recovery tests. The moulding pressure was varied from 5.5 MPa (800 psi) to 16.6 MPa (2400 psi), a typical range used by friction material manufacturers. Flexural strength and modulus increased generally as the moulding pressure increased. The friction coefficient of this material was approximately 0.3 and remained approximately constant with changes in the moulding pressure. The coefficient of friction obtained is reasonable for the application. The volumetric wear at different moulding pressures for the material decreased as the moulding pressure increased.
Shrinkability of Poly(ethylene vinyl acetate) - Epichlorohydrin Blends and their Characterisation
Authors: Chowdhury S. Ray , Das C.K.
Published: September 2024

The heat shrinkability of polymers is utilised in various applications -mainly in the field of encapsulation. Elastic memory is introduced into the system by means of an elastomeric phase. Here, blends of ethylene vinyl acetate (EVA) and epichlorohydrin were studied with reference to their shrinkability, by introducing crosslin king in the elastomer phase. It was found that an increase in elastomer content and cure time caused the shrinkage to increase. High temperature (H-T) stretched samples showed higher shrinkage than room tern perature (R-T) stretched ones. Generally the crystallinity of high temperature (H-T) stretched samples was higher than that of low temperature stretched ones which was again higher than that of the original unstretched samples. From high temperature DSC it was found that with increase in epichlorohydrin content, stability towards oxygen was decreased and for high temperature stretched samples, the stability was increased compared to the original unstretched and high temperature shrunk samples. But for H-T shrunk samples the first and second decomposition temperatures were lower and the rate of degradation was enhanced compared to unstretched samples and H-T stretched ones. SEM showed that H-T stretched samples were more elongated than R-T stretched ones.
Pressure Rise Inside a Cylindrical Pultrusion Die for Graphite/Epoxy Composites
Authors: Gadam S.U.K. , Roux J.A. , McCarty T.A. , Vaughan J.G.
Published: September 2024

The pultrusion die, a fundamental component of the pultrusion process, is basically a cavity ofthe desired product cross-section and a means by which the composite material can be cured through the application of heat and pressure. In the pultrusion process, the pressure rise inside the die inlet can significantly affect the quality of the fabricated composite. The pressure rise in the die inlet helps in enhancing the fibre wet-out and suppressing void formation during manufacturing. A three-dimensional, axisymmetric model based on Darcy's law for resin flow through a porous fibre bed in cylindrical coordinates, which employs the finite volume solution method, was developed to predict the pressure rise in a pultrusion die for graphite/epoxy composites. A varia?le viscosity was employed, and an anisotropic permeability model was used for calculatmg the permeability values in the axial and radial directions. Various process control parameters including preform plate cavity to die cavity area ratio (compaction ratio), resin viscosity, pull speed, die heating profile, and fibre volume fraction were varied to investigate their impact on the die inlet pressure rise in the pultrusion manufacturing of graphitel epoxy com posites.
Fractal Surfaces of 8-(hydroxyquinoline)zinc and their Relation to Electroluminescence Behaviour
Authors: Jin Hong-Wei , Jin Chang-Qing
Published: September 2024

A method has been developed for analysing the fractal surface behaviour of 8- (hydroxyquinoline)zinc (Znq2) using small-angle X-ray scattering (SAXS). The measurements indicated that the surface of Znq2 can be described by fractal and powerlaw decay of the scattering intensity I for values of the scattering vector q between 0.8 nm-1 and 5 nm-1 where I(q) ~ qα. The exponent is smaller than the four values given by Porod's law. The surface fractal dimension Ds was found to be 2.96 in agreement with surface fractals. We also report the fractal surface characteristics of 8- (hydroxyquinoline)aluminum (Alq3) and make a comparison between the fractal surface behaviours of Znq2 and Alq3. We believe that SAXS is the most appropriate technique for the determination of the fractal dimension and that it can be used to study the relations between the surface and electro-optical properties of organic materials.
Effect of Plasma Polymerisation of Monomers on Glass Fibre Surfaces on Adhesion to Polypropylene
Authors: Chou Shen , Chen Shuh-Heng
Published: September 2024

Plasma polymerisation was used to treat glass fibres to improve their interfacial bond to polypropylene. After the glass fibres were treated with a coupling agent, four different monomers were polymerised onto the fibre surfaces with a plasma. The plasma polymers changed the surface morphology and surface free energy of the fibres. The experimental results indicate that a particle-like surface induces a transcrystalline layer to form on the fibre surface and improves the polypropylene/glass fibre interfacial shear strengthrelative to glass fibres treated with coupling agent only. Glass fibres treated with coupling agent and then with acrylonitrile and styrene showed an increase in the interfacial bond strength between polypropylene and glass fibres of 65% and 81% respectively. Those glass fibre surfaces treated with particle-like organosilicon, plasma polymerised tetramethylsilane (PP/TMS) and hexamethyldisiloxane (PP/HMDSO), induced a transcrystalline layer to form and there was an increase in the interfacial shear strength of 196% and 160% respectively, i.e. it was 70% and 49% higher than that for samples treated with coupling agent only.
Effect of Filler Blend Composition on the Electrical and Mechanical Properties of Conductive EVA Composites
Authors: Das N.C. , Chaki T.K. , Khastgir D. , Chakraborty A.
Published: September 2024

The electrical conductivity and mechanical properties of ethylene vinyl acetate based polymeric composites filled with short carbon fibres (SCF) and conductive carbon black has been investigated. While carbon fibres provide charge transport over large distances, carbon black improves inter fibre contact and mechanical properties by reinforcing the polymer matrix. The resistivity of the composites decreases with increasing SCF concentration in the filler blend, but the mechanical properties decrease. The change in volume resistivity during heating and cooling does not follow the same path, leading to the phenomena of electrical hysteresis and electrical set. These composites show both NCT (negative coefficient of temperature) and PCT (positive coefficient of temperature) depending upon the filler blend ratio in the polymer matrix. This observation of temperature dependence is explained by both the differential thermal expansion of polymer and Filler, and electron emission theory.
Thermal Simulation of Electrically Heated Tools for Composite Manufacturing
Authors: Liu X.L. , Lam Y.C. , Chiu W.K.
Published: September 2024

This paper describes a finite element procedure for the simulation of the thermal response of integrally and electrically heated tools for composite manufacturing. In particular, a methodology is developed to simulate temperature control of the electrical heating. Applications of the procedure were demonstrated through simulation of the thermal responses of two electrically heated tools using different temperature control strategies. The predicted responses were found to be in good agreement with the experimental measurements.
Cure Characteristics of a Vinyl Ester Resin as Assessed by FTIR and DSC Techniques
Authors: Mousa A. , Karger-Kocsis J.
Published: September 2024

Thecuring kinetics of a vinyl ester (VE) resin has been investigated as a functionof curing temperature by using Fourier Transform infrared spectroscopy (FTIR)and differential scanning calorimetry (DSC). The curing reaction was monitoredby the decrease in double bond intensities for both VE and styrene (St). Thisallowed us to estimate the fractional conversion (degree of cure) by differentmethods. DSC was used to determine the overall degree of cure at differenttemperatures as well as the rate of the curing reaction. A good correlationbetween the degree of cure obtained by the two above techniques was observed inhigh temperature isothermal curing, in particular at 120°C. No complete curewas recorded by either FTIR or DSC. This was traced to the vitrificationphenomenon making the curing reaction diffusion controlled.
Progressive Crush Behaviour in 3-D Braided Composite Square Thbes with Various Braiding Parameters
Authors: Chiu C.H. , Cheng C.C.
Published: September 2024

This paper systematically investigates the effects of various braidingparameters, pitch- length, axial yarn contents, number of braiding layers andfibre types, on the crushing failure modes and specific energy absorption capabilityof three-dimensional (3-D) braiding composite square tubes. Quasi-static axialcompressive crush tests were carried out in this study. The results show thatthe crushing failure modes and energy-absorption capabilities weresignificantly dependent upon the braiding parameters. There were four differentcrush failure modes observed in this work. They were splaying, folding, spiky-folding and splaying-curling. The specific energy absorption capabilityincreased with decreasing braiding pitch-length. The larger numbers of braidinglayers led to higher energy absorption capability. Based on the crush failuremechanism, the axial yarns were the main sources of energy absorption and thebraiding yarns were the controllers for crush failure modes. Tubes made withcarbon fibre axial yarns displayed higher energy absorption capability, whereasthe tubes made of Kevlar braiding yarns exhibited better post-crush integrity. The tubes with carbon axial yarns and Kevlar braiding yarns not only had higherenergy absorption capability but also exhibited better post-crush integrity.
Effect of Silicone Oil on the Mechanical Properties of Highly Filled HDPE Composites
Authors: Zhang Yong , Yang Jinhai , Peng Zonglin , Wang Yanli , Zhu Song , Zhang Yinxi
Published: September 2024

The effects of aluminium and magnesium hydroxide filler, surfacemodifications of the fillers, and silicone oil on the mechanical properties ofhigh density polyethylene (HDPE) composites were studied. The surface modificationsof magnesium hydroxide (Mg(OH)2) and aluminium hydroxide (Al(OH)3)with coupling agents such as silanes and organotitanate increase the tensilestrength to some extent, and have little effect on elongation at break andnotched Izod impact strength of HDPE composites containing 140 phr fillers. Silicone oil was found to be an effective additive for toughening highly filledHDPE composites, and this, together with an appropriate surface modification ofthe fillers, is an important factor in realizing the change in the highlyfilled HDPE composites from brittle to tough fracture under tensile and impactstress. The plastic deformation of the fracture surfaces of HDPE compositesobserved by scanning electron microscopy is associated with the presence ofsilicone oil.
Vitamin E: An Effective Biological Antioxidant for Polymer Stabilisation
Authors: AI-Malaika S.
Published: September 2024

The bio-active form of vitamin E, α-tocopherol, has been shown to be an extremely effective antioxidant for plastics and rubbers, e.g. under melt processing conditions in polyolefins, under long term storage conditions in polybutadiene, PBD, and under fatiguing conditions in natural rubber, NR. The concentration of tocopherol needed to stabilise polymers, and in particular plastics, is very small and a concentration as low as 100-300 ppm would be sufficient to impart an excellent melt stabilisation to polyethylene, PE, and polypropylene, PP, at a level lower than is required by some of the best synthetic hindered phenol antioxidants traditionally used for this purpose. The colour stability of polyolefins, e.g. PP, processed in the presence of α-tocopherol is as good as that of Irganox 1010 when the former is used at low concentrations, though higher concentrations of the former impart greater discoloration to the polymer. The incorporation of a phosphite antioxidant drastically reduces polymer discolouration concomitant with higher levels of retention of the tocopherol in the polymer. Examination of the nature and distribution of oxidative transformation products formed from α-tocopherol during melt processing of polyolefins has confirmed that polymer discoloration is, at least in part, due to the formation of coloured products from tocopherol.
New Metal Hydroxides with Improved Performance for Flame Retardancy in Plastics
Authors: Herbiet Reńe
Published: September 2024

Magnesium and aluminium hydroxide have become very important additions for plastics. The paper gives an overview of the latest developments in metal hydroxide technology taking into account the actual market requirements for flame retardancy in plastics, as well as smoke suppression.
Effect of mechanical activation of natural filler on the properties of elastomeric composites
Authors: Bobrova Valeria , Kasperovich Andrei , Efremov Sergey , Nechipurenko Sergey , Lezhnev Sergey , Panin Evgeniy
Published: September 2024

In this paper, the structure and surface properties of a mechanically activated filler based on rice processing products were studied. The particles of the natural filler were mechanically activated on a vibrating and planetary ball mill with different impact times and abrasion forces. The particles of the filler were characterized by laser diffraction, scanning electron microscopy and X-ray phase analysis. To study the possibility of using rice production waste in rubber products, model elastomeric compositions were made on laboratory rollers according to a standardized method with a complete replacement of industrial low-strength carbon black. It was determined that the mechanical activation of a natural filler in a planetary mill leads to an improvement in the physical-chemical parameters of the particle surface (the average size of the aggregates decreases by 2.2 times, the specific external surface increases by 3.1 times), increases the interfacial interaction of the filler with rubber (up to 33.9%), increases the Mooney viscosity values of rubber mixtures, increases resistance rubber to premature vulcanization (by 23.1%–61.5%) and leads to the production of vulcanizates with higher elastic strength indicators.
“Moral spaces”: A feasibility study to build nurses’ ethical confidence and competence
Authors: Morley Georgina , Copley Dianna Jo , Bena James F , Morrison Shannon L , Field Rosemary B , Gorecki Julia , Horsburgh Cristie Cole , Albert Nancy M
Published: September 2024

Background: Pre-licensure ethics nursing education does not adequately prepare and instill confidence in nurses to address ethical issues, and yet ethics education provides nurses with greater confidence to take moral action, which can mitigate the negative effects of moral distress. Objectives: To assess the feasibility and acceptability of a nursing ethics education program that included simulated case-based ethics competencies as a form of evaluation. The program aimed at building nurses’ ethical knowledge and confidence to respond to ethical challenges in practice. Research design: A prospective, longitudinal, correlational, single-cohort feasibility study using an investigator-developed survey and intervention field data. Participants and research context: Registered nurses were recruited from an academic quaternary-care medical center and 9 small- to mid-sized regional hospitals within one health system in the Midwest United States. Ethical considerations: IRB approval was obtained. Participants could complete the educational program regardless of research process participation. Findings: Of 20 participants, 19 (95%) provided post-program surveys and 18 completed competencies. Median (IQR) scores with quartiles for scheduling, timing, and length of sessions were all 10.0 [9.0, 10.0], and participants perceived that the content was interesting, increased knowledge and confidence in ethics, increased skills in providing ethical care, and would recommend the program to colleagues. Of factors, an increase in ethics knowledge had the highest “always agree” (17, 89.5%) response. Most participants reported that ethics competencies were appropriate 9.0 [9.0, 10.0] and sufficiently challenging 10.0 [9.0, 10.0]. Discussion: The education program developed nurses’ ethics knowledge and confidence. The single-cohort feasibility design provided early-stage intervention outcomes; however, a larger randomized controlled trial would substantiate program value. Conclusion: This novel ethics education program was highly feasible and acceptable to hospital-based nurses who reported increased knowledge and confidence in providing ethical care. Simulated case-based ethics competencies were an appropriate evaluation method.
The Role of MSMEs in Enhancing Income and Economic Well-being of Owners/Managers in Assam, India
Authors: Sanu Md Sahnewaz , Anjum Shabana
Published: September 2024

The aim of this study is to investigate the contribution of micro, small and medium enterprises (MSMEs) to the economic well-being and earnings of their owners/managers with reference to the Cachar district of Assam. A standardised questionnaire is utilised to collect data from 200 randomly chosen MSMEs operating in the Cachar district of Assam, a developing region of India, to accomplish the aim of the study. Descriptive statistics are used to analyse the collected data. Additionally, the study employs Wilcoxon signed-rank test to examine the statistical difference between the income of MSME owners/managers before and after joining MSMEs. The results demonstrate that MSMEs enhance the monthly income of 74 per cent of owners/managers. The results of the Wilcoxon signed-rank test indicate that the median income of MSME owners/managers has significantly increased after their involvement in MSMEs. The study also indicates that almost 9 out of every 10 MSMEs generate earnings of the owner-managers above the poverty line, whereas 83.9 per cent of MSMEs generate household income of owners/managers above the defined poverty line. MSMEs significantly improve the households’ material well-being by enhancing the spending ability of their owners/managers and increasing asset holding.