bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient analysis for offset-elliptical journal bearings under misalignment and dynamic loading
Authors: Wang Kai , Yang Lihua , Wang Haoze , Ji Xilong , Zhu Kaidi
Published: March 2023

Although the offset-elliptical journal bearings (OEJBs) are widely used in industry, there are few researches on the OEJBs, especially under the conditions of journal misalignment and sudden load. To overcome such deficiency, the dynamic response of misaligned OEJBs subjected to the dynamic load has been studied in this paper. Based on the Reynolds equation, Euler equation, and kinetic equations, a hydrodynamic model is developed and validated to conduct the transient analysis for the OEJBs. Moreover, the modified film thickness of the misaligned OEJB is given. The partial derivative method and the finite difference method are adopted to solve the lubrication equations. The correlations of bearing characteristics such as the minimum film thickness, maximum film pressure, journal orbits, and time-varying dynamic coefficients with the misalignment and dynamic load are studied. In addition, the effects of the misalignment, rotating speed, and clearance ratio on the transient performance of OEJBs under the dynamic load are discussed in detail. The results indicate that the journal misalignment and dynamic load have a significant impact on the transient performance of OEJBs. The decrease of the film thickness caused by the journal misalignment can be aggravated by the suddenly applied load. The proposed model can provide theoretical fundament in the design and monitoring of the dynamically loaded bearing-rotor system.
Legislating softly: The effect of preference heterogeneity on the share of EU soft-law instruments over time
Authors: Zhelyazkova Asya , Haverland Markus , Joosen Rik
Published: March 2023

This study analyses how preference heterogeneity across EU member states affects the adoption of soft-law acts over time. On the one hand, high diversity in policy preferences is expected to increase the proportion of soft-law instruments because governments are less likely to agree to binding measures. Conversely, preference heterogeneity could also decrease soft law due to the perceived threat of compliance problems. We test these competing arguments using a dataset on all EU soft-law and hard-law instruments adopted between 1967 and 2019. The results show that preference heterogeneity increases the share of soft EU instruments. However, more past heterogeneity prompts EU legislators to decrease the proportion of softer measures in areas that experience high levels of past non-compliance.
Towards an index of linguistic justice
Authors: Gazzola Michele , Wickström Bengt-Arne , Fettes Mark
Published: March 2023

As a step towards a systematic comparative evaluation of the fairness of different language policies, a rationale is presented for the design of an index of linguistic justice based on public policy analysis. The approach taken is to define a ‘minimum threshold of linguistic justice’ with respect to government language policy in three domains: law and order, public administration, and essential services. A hypothetical situation of pure equality and freedom in the choice of language used by all members of society in communicating with the state is used as a theoretical benchmark to study the distributive effects of policy alternatives. Departures from this standard incur lower scores. Indicators are chosen to assess effective access to three kinds of language rights: toleration (the lack of state interference in private language choices), accommodation (accessibility of public services in different languages), and compensation (symbolic and practical recognition of languages outside the dominant one). In order to take account of the cost-benefit trade-offs involved in providing language-related goods to language groups of varying sizes, a method is adopted for weighting scores with respect to compensation rights so that lack of recognition for larger groups incurs greater penalties, while factoring in the particular characteristics of each language-related good. A trial set of ten indicators illustrates the compromises entailed in balancing theoretical rigour with empirical feasibility.
Emotions and attentional engagement in the attention-based view of the firm
Authors: Vuori Timo O
Published: March 2023

This essay integrates emotions into the attention-based view of the firm to enhance the theory’s explanatory power and open a generative path for future research. Organizational structures and communicative practices shape organization leaders’ and members’ emotions. These emotions influence their attentional engagement. Structures and communicative practices shape emotions via two main paths: (1) perceived issue or initiative characteristics, which influence organization leaders’ and members’ specific emotions toward the issue and initiative, and (2) the socially constructed context for interaction about the issue or initiative, which influences the emotional energy leaders and members associate with the issue or initiative. The resulting emotions influence attentional engagement over three time horizons: immediately in the triggering situation, recurringly after the triggering situation, and through the creation of additional structures and practices that influence attentional engagement.
In-Line Quality Monitoring of Pultruded Profiles using Dielectric Measurements
Authors: Methven J.M. , Katramados Y.
Published: March 2023

A cylindrical microwave cavity operating in the TM010 mode at 2450MHz has been incorporated in a Microwave Assisted Pultrusion (MAP) line to monitor continuously the quality of a cylindrical 6.0mm diameter solid rod for use as a tension member in optical cables. The cavity is coupled to a HP 8753C vector network analyser and measures in realtime the quality factor and shift in resonant frequency of the cavity as the profile passes through it en route to the haul-off. The measurements are used to calculate the dielectric constant and loss tangent of the profile. The results can be associated with degree of cure of the profile and may be used to prescribe a process window where quality is related directly to line speed, power input, etc. The technique could be used as the basis of a feedback control system in pultrusion.
Mechanical Properties of Non-Woven Glass Fibre Composites
Authors: Kang Tae Jin , Lee Sung Ho
Published: March 2023

The mechanical and impact resistant properties of needle punched non-woven glass fibre composites have been studied. The non-woven composites showed an improvement in mechanical properties with increasing fibre entanglements caused by needle punching. At the same time fibre damage during the needle punching process caused an impairment of performance. Tensile, bending, impact, compression after impact and mode-I tests were performed to investigate the effect of punching density on the mechanical properties. The tensile strength increased with punching density, but the tensile modulus, absorbed impact energy and bending properties decreased. The non-woven composites showed more isotropic mechanical properties with increasing punching density. The energy absorption capability under repeated impact showed a maximum at the low range punching density. The higher the punching density the smaller was the reduction in compression strength after impact. The mode-I interlaminar fracture toughness (GIc) increased with punching density due to the through-the-thickness reinforcing fibres. It was three times as tough as the woven laminate composites. At the optimum punching densities, non-woven composites showed profoundly improved mechanical and impact properties compared with woven laminate composites.
Polymeric Coupling Agents as Properly Enhancers in Highly Filled Polymer Systems
Authors: Hausmann K. , Flaris V.
Published: March 2023

Unfilled polymers do not fulfill in many cases the specific end use requirements in terms of cost, stiffness, flame retardancy or other properties. Maleic anhydride grafted polymers have been evaluated as coupling agents in various polyolefm-filler systems such as ATH (Alumina trihydrate), calcium carbonate, glass and mica. Substantial increases in the elongation and impact strength properties can be achieved in highly filled blends using coupling agents.
Preparation and Characterisation of Polyacrylic Acid Leucaena Gum as a Thickener in Reactive Dye Printing Pastes
Authors: Kantouch F. , Ragheb A.
Published: March 2023

Polyacrylic acid-leucaena gum was prepared by the polymerisation of acrylic acid on leucaena gum using potassium persulphate as initiator. The rheological properties of the gums and their utilisation as thickening agents in printing cotton fabrics with reactive dyes were investigated.

It was found that polyacrylic acid-leucaena gum pastes are characterised by a non-Newtonian pseudoplastic behaviour. The apparent viscosity depends on the amount of acrylic acid. Cotton fabric samples printed with cibacron blue 3R acquire soft handle and colour fastness properties nearly identical with those printed using sodium alginate paste; the highest colour strength was obtained using a mixture of polyacrylic acid/leucaena gum with sodium alginate at a ratio of 1:3 w/w.
Effect of Reactive Compatibilisers on the Impact Properties of Polypropylene/ Poly(butylene terephthalate) Blends
Authors: Xiaochuan Zhu , Shibata Mitsuhiro , Yosomiya Ryutoku
Published: March 2023

Improvement of the impact strength for blends of polypropylene and poly(butylene terephthalate), with a polypropylene content of not less than 70 wt.% was investigated by the addition of reactive compatibilisers. Izod impact strength of the blends considerably increased with the addition of both maleic anhydride-modified polypropylene (MAH-PP) and a bisphenol A type epoxy resin with epoxy equivalent of 488 g/eq. From the SEM micrographs, it appeared that the interfacial adhesion increased on addition of the two compatibilisers.
Experimental Methods for Estimation of Stabiliser Efficiency
Authors: Gurvich Ya. A. , Arzamanova I.G. , Zaikov G.E.
Published: March 2023

An extensive review of (mainly Russian) research in stabilisers for important commercial organic high polymers is presented. Model systems for estimating the efficiency of stabilisers are discussed. Two kinds can be recognised: (a) polymer-based, (b) others. The review also considers examples of the many techniques used in these model reaction experiments and discusses structure-activity relationships.
Effects of Mixing Regimes on the Fracture Toughness of Polyurethane Rubber-Toughened Unsaturated Polyester Resins
Authors: Miller N.A. , Langford V.S.M. , Howell O.T. , Finch G.R.
Published: March 2023

The effects of different mixing regimes on the fracture toughness of polyurethane rubber-toughened polyester resins has been investigated. Variables studied included stirring action, temperature of mixing and rubber content. Two polyurethane rubbers, one hydroxyl terminated and one isocyanate terminated, were studied. It was found that mixing at 60°C and stirring with a laboratory mixer gave the most consistent results in terms of improvement in fracture toughness of the base resin. The optimum rubber content for the hydroxyl terminated rubber was found to be 2.5% w/w while for the isocyanate terminated rubber the optimum rubber content lay between 5% and 7.5%. Both rubber additions produced a decrease in flexural modulus and tensile strength of the base resin, with the hydroxyl terminated rubber giving the greatest decrease.
In-Situ Observation of Thermal Residual Strains in Carbon/Thermoplastic Microcomposites Using Raman Spectroscopy
Authors: Nielsen Anders S. , Pyrz Ryszard
Published: March 2023

Thermal residual strains in carbon/thermoplastic microcomposites have been measured in-situ using micro Raman spectroscopy. This experimental method provides quantitative information of the relation between the level of residual strains and the temperature history. Two different microcomposites have been investigated; carbon fibre/ polycarbonate and carbon fibre/polypropylene. The observed strain-temperature profile exhibits two characteristic nonlinear zones for both composite systems. It is shown that the linear thermoelastic solution strongly overestimates residual thermal strains. In order to overcome this deficiency the thermorheologically simple model is applied to predict residual strains. The results indicate that the model correctly estimates the level of residual strains in thermoplastic microcomposites, but fails to describe the two nonlinear characteristic zones. This leads to the conclusion that a more complex constitutive model of the matrix phase must be considered.
Techniques for Pressure-Density-Temperature Measurements in Polymer Melts
Authors: Sombatsompop N. , Liolios K. , Jamel M.H. Mohd , Wood A.K.
Published: March 2023

The development and use of a novel design of apparatus for the evaluation of pressure-density-temperature relationships for molten polymers are presented in this paper. The experimental method allows the determination of the pressure-density-temperature characteristics at high pressure (up to 1000 Bar) and temperature (up to 250°C) as appropriate. The data generated are compared with direct measurements made on an injection moulding machine. Three-dimensional relationship plots between pressure, density and temperature of the molten polyethylene can be constructed.
Mechanical and Impact Properties of Composite Laminates Reinforced with Kevlar Multiaxial Warp Knit Fabrics
Authors: Kang Tae Jin , Kim Cheol
Published: March 2023

The mechanical and impact properties of multiaxial warp knit fabric reinforced composite laminates have been studied. Kevlar® fibre was used to fabricate the multiaxial warp knit structure for unidirectional reinforcing as well as stitching yarns. Tensile, flexural, short beam shear, and impact properties have been compared with those of woven laminated composites.

The results showed that increased interlaminar shear strength is the main characteristic feature of the multiaxial warp knit composite compared with plain woven laminates. The interlaminar shear strength of multiaxial warp knit composites showed up to 52% increase compared with that of woven laminates composites. Also the delamination was retarded due to the increase in interlaminar shear strength of the multiaxial warp knit composites. It is shown that the through-the-thickness reinforcing loops resist any delamination. The tensile strength of the multiaxial warp knit composites increased by about 5–12% compared with the theoretical values computed from classical lamination theory.

It is generally accepted that impact induced delamination area increases with the increase in the total absorbed impact energy in collisions with foreign objects. But the multiaxial warp knit composites showed that the total absorbed impact energy decreased with the increase in through-the-thickness reinforcement fibres. The multiaxial warp knit composites showed reduced vertical deformations compared with woven laminates, as the reinforcing loop density increased.
Thermoplastic Composites Based on Jute Fibre Treated with Cardanol-Formaldehyde
Authors: Tan Ton That Minh
Published: March 2023

The effect of surface treatment of jute fibre by aqueous NaOH solution and cardanol formaldehyde (CF) was evaluated by Diffuse Reflectance Fourier Transform infrared spectroscopy (DRIFT) and Carbon-13 nuclear magnetic resonance spectroscopy (C13-NMR) and the fibre tensile properties and the fibre water absorption were measured. Composites based on untreated and treated fibres and common thermoplastic films (LDPE, HDPE and PP) were also prepared by hot press moulding. Treatment of jute fibre with CF reduced the water absorption of composites and improved the tensile and flexural strength, especially when the samples were immersed in water.
Average Deviations in Electrical Conductivity of Poly aniline-Poly (ethylene- co-Vinyl Acetate) Composites as a Novel Characterisation Method
Authors: Tsanov Tihomir , Mokreva Pavlina , Terlemezyan Levon
Published: March 2023

It is well known that a slight deviation of experimental conditions during preparation and during conductivity measurements of films, such as conditions of drying, temperature, moisture, etc., may affect the fundamental property of both conducting polymers and their composites, namely their conductivity, resulting in approximate conductivity values and variations in conductivity. In this paper the problem of variations of the conductivity of poly(aniline) - poly(ethylene-co-vinyl acetate) (PANI-EVA) composites was investigated. Three average conductivities (σ̅1, σ̅2, σ̅t) were determined and various average deviations (Δ̅σ1, Δ̅σ2, Δ̅σ1,2, Δ̅σt, G) were also estimated. Changes during the storage of PANI-EVA composites were studied by using both the average conductivities and the average deviations from conductivity. As a result of structural changes in the composites the electrical conductivity of the films increased, i.e. the conductive pathways became more exact, after four months storage of the composites. It was clearly shown that the existence of variations in conductivity is a characteristic feature of PANI- EVA composites studied and describes their evolution. The new method can be helpful and applicable to the structural characterization of other conductive polymer composites as well.
Polymer Moulding Manufacturing Using Rapid Tooling
Authors: Smith G.F. , Tromans G.
Published: March 2023

An important factor in the design cycle of polymer moulded components is the ability to produce representative components for test. Rapid modelling and tooling has become an essential part of this programme, particularly since it enables significant design time compression. The computer modelled rapid prototype has provided design confidence by allowing it to be fitted, tested for functionality and analysed. Possibly more important, rapid tooling is established by using the models as patterns; this allows the production of a prototype in the correct shape and material. Rapid tooling methods for injection moulding enable manufacture in days rather than months.
Compatibilized Polyamide/Ultra High Molecular Weight Polyethylene Blends
Authors: Qiu Chun-Hai , Komppa Veikko , Sivola Arto
Published: March 2023

A study of the compatibilization of polyamide (PA)/ultra high molecular weight polyethylene (UHMWPE) blends by reactive processing has been initiated. Attention has been focused on the effect of compatibilization on the morphology and the mechanical and thermal behaviour of the resulting blend systems. A triblock copolymer, functionalized with maleic anhydride, has been found to have a profound effect on the properties of the blends. Compatibilized PA/UHMWPE blends combining the desirable properties of the two basic polymers will offer considerable development potential.
Opto-Thermal Properties of Fibres. Part 2: Investigation of Optical Parameter Changes in Annealed and Quenched Nylon 6-6
Authors: Fouda I.M. , Kabeel M.A. , El-Sharkawy F.M.
Published: March 2023

The changes in refractive indices and birefringence of nylon 6-6 fibres with different annealing conditions were” studied by interferometry. The polarizing interference microscope was used to determine the mean refractive indices and mean birefringence of these fibres. Also, an acoustic method has been used to measure densities. The results are used to calculate some structural parameters such as the form birefringence, virtual refractive index, harmonic mean polarisability of the dielectric, and the specific refractivity of the isotropic dielectric. Also, the number of monomer units per unit volume and the refractive indices of fully oriented fibre, when using monochromatic light vibrating parallel and perpendicular to the fibre axis, were calculated and found to be 1.5543 and 1.4723. The generalized Lorentz-Lorenz equation given by de Vries was used to determine nylon 6-6 fibre structural parameters. Comparisons between Herman's optical orientation function formula and the corrected formula by de Vries are given.
Stearate Coatings on Particulate Fillers - the Effects on Resulting Compound Properties
Authors: Gilbert Marianne , Petiraksakul Pinsupha
Published: March 2023

Conditions have been established for coating particulate fillers (magnesium hydroxide and calcium carbonate) with metal stearates. The coating process was followed using a quantitative DRIFT (Diffuse Reflectance Fourier Transform Infra Red Spectroscopy) technique. Polyethylene compounds containing 40 weight % filler were produced. Compounds containing stearate coated fillers were found to possess better impact properties than those containing uncoated fillers, or fillers coated with an equivalent level of stearic acid. For the magnesium hydroxide filler, optimum impact properties were obtained with a monolayer stearate coating. When stearate type was varied, property changes in calcium carbonate filled samples were small, but optimum performance was obtained with calcium stearate for magnesium hydroxide-containing compounds. Of the three stearates studied, this was the only one which did not react with the filler to produce stearic acid. Polyethylene crystallinity was increased by stearate coatings, but did not appear to be a major factor controlling properties.
Hydrogenated NBR (HNBR) in Power Steering Hose
Authors: Sandland Nick , Harris Stuart , Nakajima Kazu
Published: March 2023

This paper considers the relative performance of HNBR, NBR, CSM and CM Elastomers in a power steering environment. Also discussed are the effects of oxidised fluids and additive packages on the elastomer compound. The paper highlights recent changes in requirements for hoses in power steering applications and describes how HNBR can help hose manufacturers meet these requirements.
Tensile Properties of Poly(vinyl Chloride) Filled with Precipitated Calcium Carbonate
Authors: Nakamura Yoshinobu , Azuma Fumie , Iida Takeo
Published: March 2023

The tensile properties of poly(vinyl chloride) filled with precipitated calcium carbonate particles having two different mean sizes were studied. The particles were porous agglomerates of spherical primary particles. For this purpose, 10–50 parts of the particles were mixed with 100 parts of poly(vinyl chloride) and 3 parts of lead stearate using a mixing roll. The particle size decreased during the mixing process. The measured mean sizes in the resin were about 0.6 and 1.2 μm at filler contents of 10 phr. The tensile tests were carried out using dumbbell specimens. The yield stress decreased only slightly with filler content in the small particle-filled system, whereas it decreased considerably with an increase in filler content in the large particle-filled system. From a scanning electron microscopic observation of the specimen surfaces after test, the larger particles used in this study seemed to be more brittle, therefore, the particles tended to fracture when a stress was applied, and voids formed around them. These observations appear to explain the decrease in yield stress in the large particle-filled system, because the voids made the ductile polymer matrix yield around the particles.
New Evidence Supporting the Interfacial Model of Electrically Conductive Polymer Composites. 2. Indication of Phase Separation during Ageing of Polyaniline-Poly(ethylene-co-vinylacetate) Composites
Authors: Tsanov Tihomir , Terlemezyan Levon
Published: March 2023

Phase separation in conductive polyaniline-poly(ethylene-co-vinyl acetate) (PANI-EVA) composite films, resulting in formation of PANI enriched (lower side) and PANI deficient (upper side) layers was found during storage of these composites. A distinct difference in the conductivity of the two sides of the films reaching a half order of magnitude was detected. It was shown that phase separation and conductive pathways formation resulted from flocculation of PANI particles during ageing of the films. Subsequently, the total electrical conductivity of the composites of lower PANI content (up to 2.5 wt. %) was substantially enhanced (ca. five orders of magnitude).

The observed conductivity jump and phase separation phenomena have been discussed using mathematical terms. Moreover, for the first time a mathematical interpretation of the evolution in percolation behaviour of PANI-EVA composites over time is presented. Coefficients of correlation (rxy) between average conductivity, σ, (y) and PANI content (x) in the composites were calculated to be ca. 0.85 - 0.99. Besides, the shape of percolation curves (σ vs. PANI content) was found to change during storage of the films. The unstable conducting properties (both conductivity jump and phase separation phenomena) of PANI-EVA composites over time revealed their dissipative nature, and have to be regarded as evidence supporting the dynamic interfacial model of conductive polymer composites.
Damping of Patched Structures Subjected to Acoustic Fatigue: A Numerical Study
Authors: Chiu W.K. , Galea S.C. , Callinan R.
Published: March 2023

This numerical study seeks to evaluate a set of reinforcement/damping treatment options to alleviate the acoustic fatigue damage of the nacelle panel of the F/A-18 aircraft. This study focuses on the use of constrained layer damping to increase the structural loss factor in the nacelle region in a bid to reduce the incidence of acoustic fatigue. The findings of this report show that where add-on damping material is to be implemented on a repair/reinforcement, orthotropic material, (e.g. boron/epoxy), is a more appropriate material to use as a repair/reinforcement material than isotropic material, e.g. aluminium. In addition, the results presented in this paper revealed that boron/epoxy laminate can be used as an alternative constraining layer for the damping treatment in regions of intense acoustic excitation.
Centrifugal Casting of Polyamide 6 I. Influence of Thermal Treatment
Authors: Rusu M. , Ibanescu Constanta , Murariu M. , Bordeianu Alexandrina , Balint S. , Andrei Elena
Published: March 2023

Centrifugal casting combined with anionic polymerisation of ε-caprolactam was used to obtain polyamide 6 tubes. These tubes were thermally treated (7 - 8 hours at 170°C) to improve their properties.

Comparative analysis of thermally treated and untreated products allows the conclusion that the thermal treatments improved the polymers’ crystallinity and the products became more suitable for certain specific applications (such as slide bearings).
Chemical Modification of Starch-Poly (Vinyl Acetate) Materials
Authors: Waly A. , Abdel-Mohdy F.A. , Hebeish A.
Published: March 2023

Starch-poly (vinyl acetate) materials were prepared through polymerization of vinyl acetate with starch using a ferrous ammonium sulphate-hydrogen peroxide redox system. Carboxymethylation through reaction with monochloroacetic acid in presence of alkali and graft polymerization with acrylamide and acrylonitrile of a material having 23% graft and 43% homopolymer were studied. Carboxymethylation occurs during the saponification process of starch-poly (vinyl acetate) in the alkaline medium of sodium monochloroacetate through reaction of the latter with the hydroxyl groups of starch and PVA. On the other hand, grafting seems to proceed via starch macroradicals which are created through the attack of the decomposition products of the redox system on the starch hydroxyl. Carboxymethylation of starch-poly (vinyl acetate) gives polyblended materials which exhibit 100% solubility at 100°C. The same holds true with starch-poly (vinyl acetate) grafted with acrylamide after saponification. Replacement of acrylamide with acrylonitrile results in polyblended material, the solubility of which never exceeds 20% after saponification.
Study of Polymer Materials by Dielectric and Thermal NDT Methods
Authors: Matiss I. , Muschik H.
Published: March 2023

The application of Non-Destructive Testing (NDT) techniques (dielectric spectroscopy, thermal conductivity and thermal activity) to different polymers, including fibre reinforced materials with and without voids is described. The NDT results are shown to correlate well with the structural parameters of the polymers.
Improvements in the Properties of Mechanically Recycled Thermoplastics
Authors: Tall Stefan , Karlsson Sigbritt , Albertsson Ann-Christine
Published: March 2023

It is difficult, costly and in many cases also impossible to acquire a material with a purity comparable to that of a virgin material when plastic waste is being recovered by mechanical recycling. Processing and reprocessing initiate degradation of the plastic, which severely reduces the life-time of recycled plastics. This article summarizes recent advances in studies of the compatibility of mechanically recycled polymeric materials. Two grades (amorphous and crystalline) of EPDM were evaluated as impact modifiers in order to upgrade recycled HDPE. The EPDM elastomers improved the tensile impact strength and elongation at yield. The reduced impact strength and elongation caused by up to 10% PS or PET could be compensated for by adding an amount of amorphous EPDM equal to half the weight of HDPE containing low levels of other polymer. The mechanical compatibility between the most common polymer types, such as ABS, polypropylene, polyethylene and polystyrene is reviewed and complemented by new, previously unpublished results. The mineral-filled PP yields at lower elongations and stress-levels when contaminated with ABS, but the ultimate properties are not severely affected. Some contamination by ABS in polypropylene is tolerable whereas ABS shifts from ductile to brittle failure modes when contaminated with only 6% polypropylene. A computer program for response surface methodology (RSM) is presented and the mechanical compatibility of polyethylene and propylene have been evaluated.
Influence of Block Molecular Weight on the Dielectric Properties of Segmented Polyamides
Authors: Ghosh Subiman , Khastgir D. , Bhowmick Anil K.
Published: March 2023

Dielectric measurements of segmented polyamides consisting of polyether and polyamide structural units have been carried out over a wide range of temperatures and frequencies. The polymers exhibit different peaks - α, β and γ in the log (tan 8) temperature curves. With decreasing hard block molecular weight, the α and β transitions shift to lower temperatures, but the γ transition remains unaltered. The a transition becomes weaker, while the γ transition shifts to higher temperatures when the soft segment molecular weight is increased. The dielectric constant at 100°C at a frequency of 1000 Hz decreases with decreasing hard segment molecular weight. However, the variation of dielectric constant with soft segment molecular weight is irregular. The results of dielectric studies are explained with the help of the segmented structure of the polyether-ester-amides.
Kinetics of Formation of Heterocyclic Polymer Networks. 3. Catalyst Effect
Authors: Privalko V.P. , Kramarenko V.Yu. , Sokol V.L. , Karateev A.M.
Published: March 2023

Non-isothermal trimerization kinetics of 1,6-hexamethylene diisocyanate (HMDI) in the reaction mixture with epoxy resin (ER) at a fixed ratio HMDI/ER = 85/15 (mass) catalyzed by differential concentrations of triethylene amine (TEA) was studied by differential calorimetry at four heating rates. In contrast to the simple single-step models, the isoconversional approach proved to describe quantitatively the reaction kinetics over the entire range of conversions, The apparent activation energies of the curing process and the corresponding pre-exponential factors tended to decrease smoothly, the higher the conversion, whereas a definite excess of the amine component turned out to be necessary to arrive at the maximum reaction rate.
PA-6/PET Interpolymers: Their Mechanochemical Synthesis and its Effect on Properties of Polyblends
Authors: Kuleznev V.N. , Ushakova O.B. , Turiachumura B. , Berestneva G.L.
Published: March 2023

Interpolymers of PA-6 and PET were synthesized in the presence of oligocarbodiimides having a degree of polymerisation of 5 and 20. The synthesis was carried out by blending PA-6 with PET in the melt at 280°C. IR-spectroscopy and selective extraction experiments demonstrated the main features of the chemical structure of the reaction products, which can be considered as interpolymer concentrates. A significant increase in Charpy impact strength occurred when at least 2 parts per hundred by weight of interpolymer concentrate was introduced into a PA-6/PET polyblend.
Transport Behaviour of Aliphatic Hydrocarbons through Dynamically Crosslinked Natural Rubber/Polystyrene Blends
Authors: Asaletha R. , Kumaran M.G. , Thomas Sabu
Published: March 2023

The transport behaviour of aliphatic hydrocarbon liquids through crosslinked natural rubber/polystyrene blends has been studied in the temperature range of 28–58°C. Natural rubber/polystyrene blends were dynamically crosslinked using different vulcanising systems, i.e., sulphur, peroxide and a mixed system consisting of peroxide and sulphur. The sorption behaviour of the above systems was analysed in three different solvents viz., mineral turpentine, diesel and petrol. The effects of various vulcanising systems, temperature, blend composition and solvents on different sorption parameters were studied. The mechanism of transport showed anomalous behaviour in all the systems. The sorption data have been used to estimate the activation energy, the enthalpy and entropy of sorption, diffusion coefficient and polymer-solvent interaction parameter. Arrhenius activation parameters for diffusion, permeation and sorption have been estimated. The first and second order kinetic equations were used to study the sorption kinetics. Finally, the experimental results were compared with theoretical models.
Polytetrafluoroethylene-Blended Polyphenylenesulphide Coatings for Mitigating Corrosion of Steel in Geothermal Environments
Authors: Sugama T.
Published: March 2023

To improve the ability of polyphenylenesulphide (PPS) coatings to protect cold-rolled steel against corrosion in a low pH, hypersaline brine geothermal environment at 200°C, polytetrafluoroethylene (PTFE) was blended into the PPS. Not only does PTFE inhibit hot brine-induced oxidation of PPS surfaces, it provides a less susceptible surface to moisture because of its hydrophobic characteristics, reducing the rate of infiltration of corrosive ionic species through the coating film. However, blending an excessive amount of PTFE into PPS creates two undesirable features, causing the failure of the coatings as corrosion-preventingbarriers. One is the development of porous microstructure in the coating layer; the other is the formation of a weak boundary region at the interphase between the blended topcoating and the zinc phosphate precoating. The reason for the latter is the phase separation of PTFE from PPS.
Effects of Non-Uniform Particle Distributions on Damage Evolution in Pre-Cracked, Particulate Composite Specimens
Authors: Kwon Y.W. , Liu C.T.
Published: March 2023

Particle distribution in a particulate composite, in general, cannot be controlled so that a composite specimen can have a non-uniform particle distribution. This study examines the effects of non-uniform particle distributions in particulate composite specimens made of hard particles embedded in a soft rubbery binder on the crack tip behaviour, using a numerical technique called a micro/macro-approach. This technique couples the micro-level and macro-level analyses. The micro-level analysis uses a three-dimensional unit-cell model and a continuum damage theory at the constituent material level (the particles and the binder) while the macro-level analysis utilizes the finite element method at the smeared composite specimen level. Both analyses are conducted in tandem as damage evolves in the specimens.

The study investigates the damage evolution around the crack tip, the resulting stress variation near the crack tip, and the crack opening displacement for several specimens with different particle distributions. All the specimens have the same average particle volume fraction so that all of them have the same average effective elastic modulus. Every specimen has multiple zones, each of which has a uniform particle distribution. A crack is located in a single zone. The numerical results indicate a possible wide variation of crack tip behaviours, for example, with respect to fracture strength from specimen to specimen, depending on the state of particle volume distribution and the location of the crack.
A Study of Blends of Poly(ethylene naphthalate) with a Liquid Crystalline Polyester
Authors: Shibata Mitsuhiro , Zhu Xiaochuan , Yosomiya Ryutoku
Published: March 2023

Blends of poly(ethylene naphthalate) (PEN) and a liquid crystalline copolymer based on p-hydroxybenzoate and ethylene terephthalate, known as Novaccurate E310 (E310), were studied. The effect of compatibilizers on the mechanical properties and morphologies has been investigated. The mechanical properties of the PEN/E310 (weight ratio 80/20) blend were considerably improved on the addition of 4,4′-dihydroxy-3,3',5,5′-tetramethyldiphenyl ether (TM-DPE), in agreement with the improvement in compatibility shown by the SEM analysis. The gel permeation chromatography analysis showed that most of the TM-DPE in the PEN/E310/TM-DPE blend does not react. The IR spectral analysis suggested that the hydrogen bonding between the hydroxyl group of TM-DPE and the ester group of PEN and/or E310 acts beneficially for compatibilization.
Experimental Investigation of Design Rules for Resin Gating and Venting Using the Vacuum Injection Technique
Authors: Abraham D. , McIlhagger R.
Published: March 2023

Various resin gating methods commonly used for the Resin Transfer Moulding (RTM) method of composite manufacture are discussed, with their associated advantages and disadvantages. Peripheral gating combined with vacuum impregnation was identified from previous studies as being particularly beneficial in achieving complete wet-out and fast injection times. Reported design rules for gating and venting arrangements are also discussed. This investigation has attempted to assess the capabilities of peripheral gating, initially for simple geometrical shapes which then increased in complexity. Existing design guidelines were confirmed and new concepts proposed. RTM processing of the final shape to be considered was finally assessed by comparison of peripheral with rectilinear gating. This process also identified the importance of component design for manufacture and the benefits of peripheral gating. It is hoped that this experimental investigation will not only be useful to RTM mould designers but also to those involved in resin flow modelling of such processes for composite components
Effect of Climatic and Radiation Ageing on Properties of Glass Fibre Reinforced Epoxy Laminates
Authors: Startsev O.V. , Krotov A.S. , Golub P.D.
Published: March 2023

The effect of radiation on the properties of glass fibre reinforced epoxies was investigated. Radiation treatment with a maximum dose of 30 MGy was performed for virgin samples and after 0.5, 1, 2, and 5 years of exposure in cold, moderate and warm damp climates. Evaluation of climatic and radiation resistance was by the change in bending strength, interlaminar shear strength, and Young's modulus. Dynamic mechanical analysis and linear dilatometry were employed to investigate the epoxy matrix during ageing. It has been established that radiation treatment of both virgin and climatically aged samples causes the destruction of the interfacial bond. The large increase in mechanical properties observed is explained by the competing effects of two processes. There is little indication of the occurrence of additional crosslinking of the epoxy binder during irradiation. It is shown that ageing in the reverse order (radiation treatment with subsequent exposure to the climate) is more severe, and intensifies the changes in the properties of the material.
Changes in Opto-Thermal Properties of PET Fibres during Annealing
Authors: Fouda I.M.
Published: March 2023

The changes in refractive indices and the birefringence of polyester (Egyptian PET) fibres with different annealing conditions were studied by interferometry. The polarizing interference microscope was used to determine the mean refractive indices and mean birefringence of these fibres. An acoustic method has been used to measure densities. The results are used to calculate structural parameters such as the form birefringence, virtual refractive index, harmonic mean polarizability of the dielectric, the number of molecules per unit volume, and the specific refractivity of the isotropic dielectric. Also, the number of monomer units per unit volume and the refractive indices of the fully oriented fibre, when using monochromatic light vibrating parallel and perpendicular to the fibre axis, were calculated and found to be 1.803 and 1.562. The effect of the annealing conditions on the refractive index was studied. The generalized Lorentz-Lorenz equation given by de Vries was used to determine PET fibre structural parameters. Comparisons between the Hermans optical orientation function formula and the corrected formula by de Vries are given.
Comparative Study of the Fire Behaviour of Glass-Fibre Reinforced Unsaturated Polyesters Using a Cone Calorimeter
Authors: Le Bras Michel , Bourbigot Serge , Mortaigne Bruno , Cordellier Guillaume
Published: March 2023

This work deals with the fire behaviour of unsaturated polyester resin-based composites and with the influence of glass-fibre level on limiting oxygen index and oxygen consumption (in particular the rate of heat release). The combustion products are identified. 65 wt.% reinforcement allows reasonable FR properties using a first generation type resin.
Synthesis of Polyarylates with Allylic Side Groups. Part 4. Polyarylates Based on Chalcones
Authors: Zadrozna I. , Wyszomierska A.
Published: March 2023

Several UV sensitive polyarylates based on chalcones with allylic groups side chains for potential use as photosensitive polymers were obtained by interfacial polycondensation. The structure of the UV-sensitive monomers and polymers obtained has been confirmed using IR, 1H NMR and UV spectroscopies. Their physical, chemical and mechanical properties have also been determined.

The investigations show that some of the new polymers bearing allylic groups as photosensitive side chains conjugated with benzylideno-acetophenone groups exhibit different behaviour under UV light exposure from the polyarylates based only on bisbenzylideneketone bisphenols, presented in our previous work.
Comment on: “Case-to-Factor Ratios and Model Specification in Qualitative Comparative Analysis (QCA)”
Authors: Dușa Adrian , Marx Axel
Published: March 2023

The article by Thiem and Mkrtchyan appears in a context of rising interest about the number of cases needed to perform a QCA analysis. They question the benchmark tables proposed by Marx and Dușa (2011) and conclude the ratios from those tables are “misplaced.” We believe this conclusion deviates from the scientific method and focus on two essential aspects: (1) their approach to the case to factor ratios and (2) omitted variable bias. We conclude our tables hold until a better alternative is proposed and encourage QCA researchers to continue using them.
Novel Self-Expanding Interwoven Nitinol Stent for Treating Femoropopliteal Artery Disease: 12-Month Results of Single-Center First-in-Man Study
Authors: Yang Shuofei , Ni Qihong , Wang Weilun , Chen Jiaquan , Guo Xiangjiang , Ye Meng , Zhang Lan , Xue Guanhua
Published: March 2023

Purpose:

To evaluate the safety and efficacy of Innospring® stent, a novel self-expanding interwoven nitinol stent, in treating femoropopliteal atherosclerotic lesions.

Methods:

A prospective, single-center, single-arm, first-in-human study enrolled 15 patients (mean age 73.1 years; 13 men) to evaluate the safety and efficacy of the Innospring® stent monitored by core laboratories. The inclusion criteria were claudication or ischemic rest pain, de novo lesions or nonstented restenosis, >70% stenosis, lesion length <20 cm, and a reference vessel diameter of 4–7 mm. The primary safety endpoint was 30-day major adverse events. The primary efficacy end point was stent patency at 12 months. Follow-up evaluations were conducted at 30 days, 6 months, and 12 months.

Results:

The lesion length was 6.1 ± 3.5 mm. Fourteen (93.3%) patients had lesions of the superficial femoral artery and 3 (20.0%) patients had lesions of the popliteal artery. Nine (60.0%) patients had moderate-to-severe calcified lesion. Technical and procedural success was 100%. No patients experienced major adverse events in the first 30 days. The Rutherford category showed significant and sustained improvement at 6 and 12 months. The 12-month follow-up radiographs obtained in 13 patients confirmed the absence of stent fractures in 100% of examinations. The cumulative primary stent patency rate at 6 and 12 months were 93.3% and 84.6%, respectively.

Conclusion:

Stenting of the superficial femoral and popliteal arteries using the Innospring® stent is safe and effective. This competing interwoven nitinol stent may provide superior stent integrity and fracture-resistance as well as serve areas under extreme mechanical stress.

Clinical Impact

Endovascular recanalization is a widely accepted and recommended treatment for symptomatic peripheral artery diseases. The Innospring® stent is a novel self-expanding interwoven stent containing eight nitinol wires with additional radial force, fracture-resistance, and visibility under fluoroscopy. This first-in-human study using the Innospring® stent in patients with femoropopliteal occlusive disease reported that stenting of the superficial femoral and popliteal arteries using the Innospring® stent is safe and effective. This competing interwoven nitinol stent may provide an impressive stent integrity and fracture-resistance as well as serve areas under extreme mechanical stress.
Rethinking Remakes: Value and Culture in Video Game Temporalization
Authors: Brown Logan
Published: March 2023

As previous generations of players have aged and new generations with new tastes and expectations have emerged, the game industry has increasingly turned to high-profile remasters and remakes to re-valorize old software for new market conditions. To date, scholars and journalists have viewed this development almost entirely through an authenticity-focused lens inherited from preservation discourses, which has led many to dismiss rerelease efforts as simultaneously derivative and ahistorical. But this focus on authenticity has obscured the complex cultural and economic processes which give rise to rereleased games and the heterogeneity of the adaptive strategies that the industry has produced to appeal to varied consumer groups. This paper argues that we should instead view remastering and remaking as sub-practices of what I call temporalization, which, like the more familiar practice of localization, should be viewed as a creatively challenging and politically underdetermined cultural force which demands analysis on its own terms.
Optimizing Recruitment for Qualitative Research: A Comparison of Social Media, Emails, and Offline Methods
Authors: Sledzieski Nana , Gallicano Tiffany D. , Shaikh Samira , Levens Sara
Published: March 2023

Participant recruitment through social media platforms has been suggested as an effective method for sampling from specific populations; however, recent online recruitment attempts have been met with varying levels of success. In the current study, we targeted a specific social media population: those who advocate for the Black Lives Matter movement, delineating between those with high and with low follower counts on Twitter. We compared the outcomes of our recruitment methods, which include Facebook ads; unpaid, personalized tweets; emails to groups involved in community advocacy; and offline methods. Included in our analysis is the amount of effort involved in each recruitment method, as well as advertising costs. Based on our comparison, Facebook advertising was the most effective form of social media recruitment for our study. In contrast, unpaid, personalized tweets were time consuming and ineffective.