bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of binge-eating disorder and food addiction
Authors: Ratković Dragana , Knežević Vladimir , Dickov Aleksandra , Fedrigolli Elsa , Čomić Maša
Published: April 2023

In the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, binge-eating disorder (BED) is classified as episodes of binge eating while not being hungry, eating too fast until feeling uncomfortably full, or eating in solitude with feelings of shame and disgust after eating, without compensatory mechanisms. The controversial disorder food addiction (FA) is characterized by overconsumption, cravings, failure to cut down on amounts of food, and withdrawal and tolerance to overeating. In this narrative review, we aimed to comprehensively characterize and compare BED and FA. We searched PubMed using the keywords “binge-eating disorder” and “food addiction.” We finally included 51 publications according to topic specificity, credibility, the authors’ reputation, and non-bias criteria. BED is characterized by concerns about dietary issues, body shape, and weight as well as depressive symptoms and brooding rumination. FA can be divided into substance addiction and behavioral addiction, which can be differentiated using a list of criteria including hunger, taste, pleasure, function of food, loss of social connections, weight concerns, and awareness about the disorder. Further research is needed to further characterize and distinguish BED and FA.
Make a good impression: Recommend different products for self-presentation
Authors: Wang Lili , Chen Hanyu (Yuki) , Zhang Xuan
Published: April 2023

Word-of-mouth (WOM) has become one of the most important ways consumers obtain and deliver self-image. However, little research has investigated how product type influences consumers’ WOM intention through self-presentation motivation. Across six studies, this research explores how, why, when, and for whom the product type matters in self-presentation and WOM. Specifically, Study 1A and Study 1B demonstrate that consumers are more likely to engage in WOM for experiential (vs material products) regardless of the type of WOM. Study 2 investigates whether this effect is mediated by promotion-oriented rather than prevention-oriented self-presentation. Finally, three moderator studies, including self-affirmation (Study 3), materialism (Study 4), and need for uniqueness (Study 5), illustrate when and whose WOM intention is more likely to be influenced. This research contributes to theory and practice in impression management and the growing literature on WOM intention.

JEL Classification:

M310 Marketing and M370 Advertising
Balanced Mix Design Production Analysis of Asphalt Mixtures in Vermont
Authors: Nener-Plante Derek , Schwartz Aaron , Veeraragavan Ram Kumar , Tran Nam , Myers Leslie
Published: April 2023

Performance testing has been recognized by state highway agencies and the asphalt paving industry as an important tool to complement volumetric properties for improving asphalt pavement performance. Thus, the Vermont Agency of Transportation (VTrans) began evaluating the Hamburg wheel-tracking test in 2015, Illinois flexibility index test in 2018, and indirect tensile cracking test in 2020 as steps toward balanced mix design (BMD) implementation. These tests were conducted on reheated common plant-produced asphalt mixtures for multiple shadow projects, and the results were analyzed to determine the typical production variability observed in the performance testing results. Production variability is important to assess potential specifications in field production, especially for statistical quality acceptance procedures, such as percent within limits. Based on the percent within limit analysis, most of the modified Type IVS (i.e., 9.5 mm) mixtures would be acceptable based on the proposed performance requirements, while those found not acceptable were close to meeting the performance requirements and would need minimal adjustments. The lot data was further examined to generate typical lot production variability values for potential use in specification development. The information from this research effort will help VTrans achieve its goal to move beyond solely volumetric properties for asphalt mixture design and acceptance and serve as an example for other agencies exploring the implementation of BMD for improving asphalt pavement performance.
Cancer Decedents’ Hospital End-of-Life Care Documentation: A Retrospective Review of Patient Records
Authors: Russell L. , Howard R. , Street M. , Johnson C. E. , Berry D. , Flemming-Judge E. , Brean S. , William L. , Considine J.
Published: April 2023

Objective: International standards of end-of-life care (EOLC) intend to guide the delivery of safe and high-quality EOLC. Adequately documented care is conducive to higher quality of care, but the extent to which EOLC standards are documented in hospital medical records is unknown. Assessing which EOLC standards are documented in patients’ medical records can help identify areas that are performed well and areas where improvements are needed. This study assessed cancer decedents’ EOLC documentation in hospital settings. Methods: Medical records of 240 cancer decedents were retrospectively evaluated. Data were collected across six Australian hospitals between 1/01/2019 and 31/12/2019. EOLC documentation related to Advance Care Planning (ACP), resuscitation planning, care of the dying person, and grief and bereavement care was reviewed. Chi-square tests assessed associations between EOLC documentation and patient characteristics, and hospital settings (specialist palliative care unit, sub-acute/rehabilitation care settings, acute care wards, and intensive care units). Results: Decedents’ mean age was 75.3 years (SD 11.8), 52.0% (n = 125) were female, and 73.7% lived with other adults or carers. All patients (n = 240; 100%) had documentation for resuscitation planning, 97.6% (n = 235) for Care for the Dying Person, 40.0% for grief and bereavement care (n = 96), and 30.4% (n = 73) for ACP. Patients living with other adults or carers were less likely to have a documented ACP than those living alone or with dependents (OR 0.48; 95% CI 0.26-0.89). EOLC documentation was significantly greater in specialist palliative care settings than that in other hospital settings ( P < .001). Conclusion: The process of dying is well documented among inpatients diagnosed with cancer. ACP and grief and bereavement support are not documented enough. Organizational endorsement of a clear practice framework and increased training could improve documentation of these aspects of EOLC.
An Examination of the Non-linear Relationship Between Cognition and Total Hemoglobin Among the Cognitively Normal Older Adults by Gender
Authors: Min Se Hee , Schnall Rebecca , Lee Chiyoung , Topaz Maxim
Published: April 2023

Objectives: This exploratory study aimed to identify the potential non-linear relationship between hemoglobin (Hgb) and cognition among cognitively normal older adults and how this relationship differs in terms of gender in generalized additive models (GAM). Methods: This is a secondary data analysis using Wave II (2010–2011) data from the National Social Life, Health, and Aging Project. A generalized additive model was used to understand the non-linear relationship between Hgb and cognition, and to identify critical Hgb point related to cognition. Results: While both genders had a non-linear association between Hgb and cognition, the degree of non-linearity was more pronounced in male older adults with EDF value close to 2. The inflection point of 15.10 g/dL for male older adults and inflection point of 11.72 g/dL for female older adults were obtained. Conclusion: Further studies are needed to validate these results and develop precision medicine approaches to integrate these results into clinical practice.
Evaluation of residual strength in fiber reinforced composites subjected to impact using acoustic emission test
Authors: Souri-Solut Reza , Farahani Mohammadreza , Meshkizadeh Pouria , Ghani Mohammad Sadegh
Published: April 2023

This paper investigates the relation between acoustic emission events and the corresponding behavior of the specimens after damage under tensile loading. Tensile strengths of carbon/glass fiber epoxy composites subjected to impact damage were evaluated experimentally. The variations of amplitude, energy, and dominant frequencies of the AE events were studied to investigate the post-impact behavior of specimens. Different layers (6, 12-ply) and fiber materials were assessed, and their effects were considered. Waveform patterns and frequency domain analyses were also utilized to evaluate the damage severity. This practical method can be used as an advanced and straightforward approach to estimate either the value of the damage or residual strength subsequent to impact in laminated composites. It was proved that the impact damage led to dropping residual strength, especially in carbon/epoxy specimens, since they are sensitive to impact.
A global view on digital legal deposit: what could be learned?
Authors: Neshat Narges , Ghasemi Rahim
Published: April 2023

Aim

Procedures for legal deposit of the print material are well established and widely practiced. Such procedures, however, are not necessarily applicable to the digital environment, mainly because bibliographic specifications of print material do not match those of digital objects and digital environment. The history of legal deposit of publications in Iran goes back to 1906. Since then, the press, publishers, public and private institutions are required to deposit one or more copies of their published material to the National Library of Iran (NLIR). However, reports have always indicated incomplete deposit or lack of coherent and comprehensive policies, especially with regard to digital resources. The present study aims to propose a framework for NLIR by comparing several national libraries.

Methodology

This research examined the policies and practices of 10 large national libraries that according to the World atlas (2018) have been ranked the highest in terms of the number and variety of resources. They were the Library of Congress, the British Library, National Library and Archives of Canada (LAC), and national libraries of France, Germany, Denmark, Spain, Australia, Japan, and China. The data related to digital legal deposit implementation was collected from various sources including directories; official publications of international organizations, national legal deposit laws and regulations.

Findings

A global trend towards legal deposit to cover digital publications and preservation of comprehensive national archives is developing. In Iran, there was no mechanisms for identification, selection and deposit of digital materials either do not exist or are inappropriate for some types of publications.

Conclusion

National libraries and other libraries are at the forefront of research and development in the field of legal deposit. In this research, an effort was made to design and propose a framework for depositing digital material at NLIR drawing on the policies and practices of the top 10 national libraries. The proposed framework has two parts. The first includes elements such as introduction, general principles, resources comprehensiveness, legal deposit method, the origin of publications, collaboration and partnership, and legal considerations. In the second part -the plan-areas addressed in the first part are discussed in detail.
A detailed investigation of enhancement in heat transfer using Al2O3 nanofluid as coolant
Authors: Swain B , Pati AR , Mohapatra SS
Published: April 2023

In the current research, enhancement in the film and transition boiling regime is tried to obtain using Al2O3 nanofluid as coolant. The coolant properties such as physical, thermal and interfacial and the droplet dynamics during evaporation are the prime controlling factors for defining the effectiveness of dropwise evaporative cooling. In the current study, aluminium oxide nanoparticle with water is considered as coolant. The quality of the aluminium oxide nanoparticle has been confirmed by performing various characterizations such as X-ray diffraction analysis, scanning electron microscope with energy dispersive spectroscopy and transmission electron microscope. Using aluminium oxide + water as the coolant, the augmentation was obtained by altering the thermo-physical properties of the coolant in the favourable direction of heat transfer. The thermal analysis and the comparative study ensures step up in heat transfer. With the increase in the concentration of nanoparticles from 0.1%–0.2% in the base fluid, the evaporation rate increases significantly due to the decrease in the residence time, increase in the maximum spreading diameter and minimisation or elimination in blasting characteristics.
Settler colonial counterinsurgency: Indigenous resistance and the more-than-state policing of #NoDAPL
Authors: Seraphin Bruno
Published: April 2023

In 2016, the US-based private military contractor TigerSwan was denied a license to operate in North Dakota. Nonetheless, it coordinated a counterinsurgency (COIN) campaign employing war-on-terror tactics, brutalizing Indigenous and allied water protectors associated with the Indigenous-led movement to stop the Dakota Access Pipeline (#NoDAPL) on Standing Rock Lakota territory. This article takes COIN as an analytic to show that US settler colonialism is a multilateral, internally conflicted, and anxious mode of power. The settler state both depends upon and disavows anti-Indigenous and anti-Black violence enacted by rogue civilian individuals and organizations, a phenomenon here termed ‘more-than-state policing’. The repression of #NoDAPL was not solely a boomerang by-product of the global war on terror but rather exposes an established infrastructure of settler colonial COIN intrinsic to US normal politics, in which Indigenous resistance and sovereignty are constructed as metastasizing, viral threats to settler colonial legitimacy. As modern COIN warfare has evolved from four centuries of North American settler colonial invasion and governance, settler colonial studies are key to grasping 21st-century topics of war, imperialism, securitization, resource extraction, and climate justice.
Substitution Group Effects on Gas Sorption and Diffusion into Polyimides
Authors: Toi Keio , Suzuki Hirotaka , Ito Tomoyasu , Ikemoto Isao , Kasai Tetsuo
Published: April 2023

The sorption and diffusion of carbon dioxide below 1 atm were measured for seven polyimide films by a volumetric sorption method and a permeation method. The diffusivities of carbon dioxide were correlated with packing density (reciprocal of specific free volume) for ail except two polyimides. When the packing density of the polymer was increased, the diffusivities decreased. But, as the packing density was increased further, the diffusivities increased. The substituent sulphone = SO 2 promotes hydrogen bonding and causes the polymer main chain to pack densely. Consequently the gas diffusion of this polymer is rather low. The packing density of these two polymers may not be successfully calculated by Bondi's method. However, all die diffusion coefficients decrease linearly with an increase in the cohesive energy density (CED) which is calculated by the group contribution method of van Krevelen. These results suggest that the gas diffusions of polyimides correlate with CED more than with the packing density.
Observations on New Proposals for Assessing how well Unsaturated Polyester Glass Laminates Withstand Petrochemical Environments
Authors: Ghotra Joginder S. , Pike Stephen
Published: April 2023

The chemical resistance of glass fibre laminates to petrochemical environments has to be evaluated before they can be adopted for use in petroleum storage tank applications. In this paper, the behaviour of isophthalic polyester glass laminates in the revised CEN test liquid, proposed in the draft CEN Standard, is compared with the corresponding behaviour in unleaded petrol, super unleaded petrol, diesel, and EEC Mixture (composition B). The chopped strand mat (CSM) laminates were tested under single-sided contact conditions with these liquids and with their vapours for 1000 hours at (50±1)°C, using the apparatus and procedure specified in the draft CEN Standard. Changes in the surface profile and percentage retention of flexural properties after exposure are reported.
Effects of Fibre Permeability on Moisture Diffusion Coefficients of Polymeric Composites
Authors: Aditya P.K. , Sinha P.K.
Published: April 2023

A single fibre composite model reinforced with a permeable fibre is used to evaluate the moisture diffusion coefficient analytically. Due to the fibre permeability, absorption of moisture takes place through both the fibre and the matrix. The diffusion paths around the fibre, due to their curved nature, are generated using the cubic spline theory. The diffusion paths through the permeable fibre are assumed to be a set of parallel lines. Diffusivities of such single fibre composites are computed at different values of relative fibre diffusivities. The relative fibre diffusivities corresponding to kevlar and jute fibres are considered separately to evaluate composite diffusivities. The diffusivities obtained for kevlar-epoxy and jute-epoxy single fibre models are found to be in good agreement with those available in the existing literature.
Fracture Characteristics of Discontinuous Carbon Fibre-Reinforced PPS and PES-C Composites
Authors: Zhang Mingqiu , Zeng Hanmin , Zhang Li , Lin Guangmin , Li Robert K.Y.
Published: April 2023

Tensile strength, σ b, Young's modulus, E, and critical stress intensity factor, K IC, of two types of short carbon fibre (CF) reinforced high performance brittle thermoplastics (CF/PPS and CF/PES-C) have been measured for different volume fraction, V f, of CF. Young's modulus increases linearly with increasing of V f with a Krenchel's efficiency factor of 0.05, whereas σ b and K 1C initially rise and then level up at V f of 25 vol. %. With the help of load-deflection curves and fractography, the experimental results have been analysed in the light of fibre-matrix adhesion characteristics. By using crack pinning model, the effective crack tensions, T, were calculated for both composites and they are 26 KJ/m (for CF/PPS) and 2.1 KJ/m (for CF/PES-C) respectively. The localized plastic deformation near fibre-matrix interface provides the major contribution to fracture toughness.
Effect of Polyetheretherketone Oligomer on the Mechanical Properties of Polyetheretherketone with Aromatic Liquid Crystalline Copolyester Blends
Authors: Yazaki Fumihiko , Suzuki Kiyotaka , Yosomiya Ryutoku , Zheng Yubin
Published: April 2023

The mechanical properties of blends of polyetheretherketone (PEEK) with an all aromatic liquid crystalline copolyester (LCP) have been investigated. Additionally, PEEK oligomers were added as a third component to the above blends in order to improve the mechanical properties. The flexural modulus and tensile strength decreased except for the blends with low LCP. In contrast, the addition of the PEEK oligomers has little effect on modulus, but flexural and tensile strength were clearly improved and the ESCA absorption caused by carbonyl group was also reduced by addition of PEEK oligomer to PEEK/LCP blend. The improvement of the mechanical properties of the blend may be due to the formation of a crosslinked product which behaves as a good compatibilising agent for PEEK with LCP during the blending process.
Epoxy Resin Compositions Cured with Dianhydrides of Tetracarboxylic Acids
Authors: Rokicki Gabriel , Adamczyk Leszek
Published: April 2023

Curing of epoxy resin compositions with tetracarboxylic dianhydrides in the presence of BF 3 aromatic amines as initiators is presented. The presence of boron trifluoride amine complexes enables to crosslink the epoxy resin at room temperature. It was shown that the reactivity of the complex may be controlled by the nature of the amine. The influence of the initiator concentration and curing conditions on the mechanical and thermal properties of the epoxy resin is also presented. The epoxy resins cured at room temperature exhibit good mechanical properties and high thermal resistance. The deflection temperature of the composition was higher than 180°C and after postcuring heating the deflection temperature exceeded 220°C.
Solvent Absorption by Carbon Fibre Reinforced PEEK Laminates
Authors: Pritchard Geoffrey , Randies Steven J.
Published: April 2023

The absorption of organic liquids by polyaryl ether-etherketone (PEEK) was investigated. Experiments with carbon fibre reinforced PEEK immersed in liquids of linear and cyclic molecules at 23°±2°C show that three important parameters (molecular size, shape, and polarity) have important effects on the diffusion rate. For the purposes of this study, using fibrous laminates rather than unreinforced polymers ensured matrix samples which were well-characterised and representative of practical materials with respect to crystallinity.

Special attention was directed to alkanes and alcohols. Three dimensional plots of weight absorption against hydrogen bonding capacity and the product of molar volume and solubility parameter mismatch are presented.

Implications for solvent resistance are suggested.
Styrene Crosslinked Vinylesters I: Correlation between the Theoretical Structure and Some Thermophysical Properties
Authors: Bellenger V. , Verdu J. , Ganem M. , Mortaigne B.
Published: April 2023

Six di or tetramethacrylates based on respectively bisphenol A diepoxides or phenol-epoxynovolacs were crosslinked by styrene in optimized conditions. Density, glass transition temperature, propagation rates of ultrasonic waves, tensile properties and rubbery modulus were then experimentally determined. A constitutive repeat unit of the network was written, on the basis of the hypothesis that the conversion of the styrene-methacrylate copolymerization was complete and that the resulting network was homogeneous. The relationships between the corresponding (theoretical) structure and the physical properties were then studied. Generally, the property values are in good agreement with theoretical predictions, except perhaps for tensile ultimate properties which appear lower than expected. It can be concluded that the true network structure is probably close to the ideal structure as assumed here.
Silica nano-composites of Allyl Diglycol Carbonate Resin
Authors: Frounchi M. , Burford R.P. , Chaplin R.P.
Published: April 2023

Composites of poly allyldiglycolcarbonate (ADC) and nano-sized silica particles were investigated in search of an alternative method to improve the fracture toughness of ADC resin. Transmission electron microscope studies revealed relatively uniform dispersion of silica particles in the resin. Dynamic mechanical analysis measurements indicated that an increase in the glass transition temperature of ADC resin was also accompanied by a higher flexure modulus. A small but significant increase in the fracture toughness of the composites was also observed. The fracture surfaces studied by scanning electron microscopy did not reveal silica particles even at very high magnification and appeared to be featureless smooth surfaces.
Prediction of Fatigue Damage Development in Undirectional Long fibre Composites
Authors: Plumtree A. , Shen G.
Published: April 2023

Cyclic damage development in polymer matrix composites reinforced with long fibres may be modelled by a two stage process. The first stage involves transverse and shear cracking of the matrix which is particularly significant in cross-ply laminates. Its development may be described using a two-parameter Weibull model. The damage rate continuously decreases until saturation is reached. This stage also occurs in unidirectional glass’ polyester rods pultruded under industrial conditions. The second stage exhibits an increasing rate of damage development resulting from longitudinal splitting, delamination, fibre pull-out and fracture. This may be described by applying continuum damage mechanics. The summation of the two expressions results in a comprehensive description of the fatigue damage evolution process. Using this approach it is possible to predict complete damage accumulation in undirectional long fibre composites.
Fibre Orientation Behaviour of Different Types of Glass Mat Reinforced Thermoplastics (GMT)
Authors: Meij A. , Munder O. , Neitzel M.
Published: April 2023

The mechanical characteristics of GMT strong depend on processing parameters. Processing simulation codes give satisfactory results on mould-filling, but not yet on fibre orientation and mechanical performance. This paper describes a method for quantifying fibre orientation in compression-moulded plates. Needled- and paper type-GMT blanks were moulded between parallel platens, inducing one- and two- dimensional flow fields. The fibre orientation was measured and compared to theories based on Jeffery's equation. Matching results were obtained for paper-type-GMT. Due to the different and complex orientation mechanism of needled-GMT, new mathematical models describing the orientation of this type of GMT need to be developed.
A Design Procedure for Elastomer-coated Rolls in Two-Roll Systems
Authors: Idelberger H. , Flade D. , Michael D. , Görke U.-J.
Published: April 2023

The preliminary calculation of the mechanical behaviour of two-roll systems and the influences on their performance derived from this are important for the efficient development and design of these kind of systems. This article describes the stages in a procedure which may be used to design the roll system taking into account the geometrical and physical non-linearities which occur and to determine the parameters which are important for the performance of this system, e.g. the nip width or the pressure distribution in the contact surface. The design procedure is explained using the example of a specific roll pairing. The numerical and analytical results are verified by experiments.
High-Performance Aromatic Polyimide Fibres. 4. A Copolymer Fibre Containing BPDA-OTOL-PPD (100/70/30)
Authors: Shen Dexing , Wu Zongquan , Liu Jiang , Wang Lixiao , Lee Sangkug , Harris Frank W. , Cheng Stephen Z.D. , Blackwell John , Wu Tzongming , Chvalun Sergei
Published: April 2023

A copolyimide has been synthesized from 3,3',4,4′-tetracarboxybiphenyl dianhydride (BPDA), 3,3′-dimethyl-4,4′-diaminobiphenyl (OTOL) and p-phenylene diamine (PPD) in a mole ratio of 100/70/30 through a one-step polymerization at elevated temperature. It has been spun as fibres by dry-jet wet spinning. The tensile modulus of the fibres reaches 120 GPa, with a tensile strength of 3.2 GPa. Such high tensile properties are the result of the high draw ratio (up to x8) while annealing at 400°C. The homopolyimide (BPDA-OTOL) is found to adopt a triclinic crystal lattice, based on wide angle X-ray and electron diffraction experiments. In the copolyimide, it's crystal lattice is disturbed by the introduction of the PPD comonomer. As the draw ratio of the copolymer fibre is increased, the crystallinity, overall orientation and the apparent axial crystallite sizes also increased, as evidenced by wide angle X-ray diffraction, optical birefringence and density measurements. These structural developments critically affect the tensile properties of the fibres. The glass transition temperature of the copolyimide is 308°C, based on thermal mechanical measurements. Dimensional stability is retained up to about 300°C. At around 100–250°C, a subglass transition is observed in dynamic mechanical measurements, and is assigned as a β relaxation. The activation energy of this relaxation is 140 hJ/mol, based on its frequency dependence. The α relaxation corresponds to the glass transition. As the crystallinity increases with drawing, this relaxation is suppressed due to the restriction of molecular segmental motion.
Effects of Compatibilisers on the Properties of Polyvinyl Chloride/Nonpolar Rubbers Blends
Authors: Zhang Yinxi , Zhang Yong , Han Shuyu , Zhang Xiangfu , Yang Changqing
Published: April 2023

The effects of some commercial polymers used as a third component on the properties of the PVC blends with nonpolar rubbers, such as BR, SBR, EPDM, NR and reclaimed rubber, were studied. It was found that NBR-18 was a very efficient compatibiliser for PVC/nonpolar rubbers blends in a wide range of blend composition, and the mechanical properties of these blends were significantly improved even when the NBR-18 content was as low as 2%. The presence of NBR-18 in PVC/nonpolar rubbers blends promoted better dispersion of PVC particles in rubber matrix, and the interfacial adhesion between PVC and the rubber phases was significantly improved by the co-vulcanisation of NBR-18 and nonpolar rubbers as well as the same compatibility of PVC with NBR-18. The PVC/NBR-l8lnonpolar rubbers ternary blends have not only good mechanical properties but also good oil and low-temperature resistance and excellent electrical insulation property.
Experimental Verification on Simulating Shrinkage and Warpage of Thin Compression Moulded SMC Parts
Authors: Osswald Tim A. , Sun Esther M. , Tseng Shi-Chang
Published: April 2023

One of the important issues in designing plastic parts, especially those that are fibre reinforced, is to predict shrinkage and warpage of the moulded parts. Shrinkage and warpage result from material inhomogeneities caused by flow induced fibre orientation, curing, poor thermal mould lay-out, and processing conditions. Shrinkage and warpage are directly related to residual stresses which result from locally varying strain fields that occur during the curing or solidification stage of a manufacturing process. This paper presents research conducted in numerical simulation and experimental investigation of the shrinkage and warpage of compression moulded fibre reinforced composite parts. A coupled temperature and stress simulation program with a three-noded shell element formulation was developed to calculate the residual stress build-up during curing and solidification stages of a compression moulding process. The numerical model also included the spring forward effect present in curved parts. Correlation between experimentally measured and simulated shrinkage and warpage of the moulded composites is presented for various geometries and processing conditions.

The simulated results have shown excellent agreement with the experimental data. The results indicated that fibre orientation distributions which vary with different charge locations have a significant effect on the final warpage. Shrinkage and warpage can be substantially reduced by using lower shrinkage polyester matrix or by increasing the fibre content within the charge. Unsymmetric curing caused by uneven mould temperatures leads to a thermal moment which could increase or possibly even reduce warpage of a finished part. Preheating or increasing the fibre content of the charge could also help reduce the final warpage. The spring forward effect was found to be significant in large-curved parts.
Use of Fractional Factorial Design in the Development of a Method to Measure the Delamination of Unsaturated Polyester Resin Laminates
Authors: Skrifvars Mikael , Keinänen Kari , Blomqvist Tuula , Koivisto Vesa , Antell Siv , Skagerberg Bert
Published: April 2023

The development of a method for the measurement of delamination in unsaturated polyester resin laminates is described. A laminate is wedge-opened in a tensile testing machine, and the load at break is taken as a measurement for delamination. The results are compared with the delamination measured by the degree of fibre pull-out on the surface of laminates opened by hand. By testing a large sample series with both methods it could be shown by statistical analysis that wedge-opening in a tensile testing machine is more sensitive towards differences in laminate properties, and therefore gives more reliable results.
Studies on the Synthesis of Polyarylates with Allylic Side Groups. Part 1. Polyarylates from 2,2-bis (3-allyl-4-hydroxyphenyl)propane and Isophthaloyl Chloride
Authors: Brzozowski Z.K. , Zadrozna I. , Lato E.
Published: April 2023

Conditions of synthesis of diallyl derivatives of bisphenol-A via a Claisen rearrangement reaction and the preparation of polyarylates from these derivatives via interfacial polycondensation with isophthaloyl chloride were established. The structure of polymers was confirmed by the methods of 1H-NMR, IR, and UV/Vis spectroscopy and elementary analysis. The results of intrinsic viscosity determinations and thermal analysis revealed the high molecular weight and considerable thermal resistance of these polyarylates.
Studies on Self-Crosslinking Blend System Based on Polychloroprene and Polyacrylamide: Cure Characteristics, Physical Properties and Degradation
Authors: Kole S. , Tripathy D.K. , De P.P.
Published: April 2023

Polychloroprene and polyacrylamide form a self-crosslinking blend during mixing and moulding in the temperature range 140 to 190°C and mis inter-crosslinking is revealed by a torque rise in the rheometric studies. The nature of the stress-strain curves of the blend indicates the generation of a bonded structure where one soft matrix is bonded with a rigid phase and the bonding fails after a critical loading. The results of hysteresis measurements are in agreement with a bonded structure. The SEM study shows that the majority of the polyacrylamide particles are covered with a layer of rubber matrix. It also shows the distribution of particles and the extent of breakdown of the particles in various blends. The SEM observations are also in line with interfacial bonding and help in understanding the physical properties of various blends based on the extent of inter-crosslinking reaction.

Thermogravimetric analysis of aqueous solutions, cast film, and dry powdered of polyacrylamide confirms the role of moisture in polyacrylamide degradation. It also confirms that although polychloroprene imparts some water resistance to the polyacrylamide component, it still remains degradable by water.
Biocompatibility Testing of Thermoplastic Elastomers for Use in Hard Tissue Replacements
Authors: Helsen J.A. , Jaecques S. , Simon J.-P. , Mattheeuws D.
Published: April 2023

The resistance of two types of thermoplastic elastomers to the near-realistic combined action of compressive and shear fatigue was assessed as part of an overall study of the biocompatibility of this class of elastomers. After fatigue the SEM of the low temperature fractured surface, the kinetics of swelling in a 3% acetic add solution, the dynamic mechanical properties (DMTA), the change in crystallinity (by FT-IR and WAXS) and the change in size of the voids (SANS) revealed subtle but small fatigue damage after cyclic loading between 150 and 1500 kPa over about 107 cycles. It may be concluded tentatively that the elastomers studied are potential candidate materials for endoprosthetic use.
Phase Equilibria in Polymer/Solvent Systems. Part HI. Similarity between the Swelling of Polyurethane Gels in Water and the Water Absorption of Wood around the Ice Point
Authors: Hladik B. , Frahn S. , Borchard W.
Published: April 2023

Some aspects of the thermodynamics of swelling of polyurethane gels in the solvent water around 0°C are discussed. It is shown that the results obtained are very similar to the water sorption behaviour of plant cells or tissue in the same temperature range in a few cases.
The Control of Pore Size in Polypropylene/Paraffin Mixtures Using Intercalated Guest SiO2 Particles
Authors: Sakami Hiroshi
Published: April 2023

This paper discusses the control of fine layer-like pores in high crystallinity polypropylene (PP) films from a mixture of liquid paraffin and silica particles (SiO2) by rolled compression. Mixtures with various ratios were hot rolled, and then paraffin was extracted in organic solvents. The fine structure of these films was investigated by measuring the apparent specific volume, the surface area using the after nitrogen gas adsorption-desorption method, and small angle X-ray scattering (SAXS). Polythene films with mixing ratios with paraffin from 0.10 to 0.50 w/w showed layer-like pores using rolling ratios of 10 to 30 at 115°C. A wide surface area of 160 m2/g was achieved by rolling the films with mixing ratios 0.17 to 0.10 at rolling ratios of 20 to 30. The SiO2 guest was randomly dispersed in paraffin. It was suggested that a regularly spaced structure of polypropylene layers (host) and layer-like pores of 9 nm and 10.5 nm thick, respectively, is formed at rolling ratios of 25 to 30. The SiO2 plays an important role of intercalation through the polypropylene thin layers, oriented by rolled compression.
Effect of Cooling Rate on the Energy Absorption Capability of Carbon Fibre/PEEK Composite Tubes
Authors: Hamada H. , Ramakrishna S. , Maekawa Z. , Sato H.
Published: April 2023

The primary objective of this work was to identify the effect of cooling rate on the energy absorption capabilities of carbon fibre/PEEK tubes. Thermoplastic composite tubes were fabricated using a thermally expandable PTFE mandrel technique. Three cooling rates were used: rapid-cooling (95.5°C/min.), gradual-cooling (8.2°C/min.) and slow-cooling (0.7°C/min.). The energy absorption characteristics were evaluated by axial compression of tube specimens between flat platens. All the composite tubes, independent of cooling rate, crushed progressively in splaying mode. The specific energy absorption capability of rapidly cooled tubes was 15% higher than that of gradually-cooled and slowly-cooled tubes. Efforts have been made to identify the factors which resulted in the superior energy absorption capability of rapidly cooled tubes.
The Role of Rate Effects of Adhesives and Graphite/epoxy in Structural Design
Authors: Chiu W.K. , Jones R.
Published: April 2023

This paper discusses the significance of the non-linear mechanical behaviour of a thermoset adhesive, FM73, in the design and analysis of bonded joints. This adhesive is widely used in the bonded repair of metallic aircraft structures. The results presented in this paper include test data conducted at room temperature and at an elevated temperature. The time dependent properties of this film adhesive are shown to be significant even at room temperature. There was considerable stress relaxation observed during strain hold experiments and the adhesive was also found to demonstrate significant creep characteristics during creep tests. The monotonic shear stress/strain behaviour and time dependent characteristics can be adequately described using a unified theory of plasticity. This paper also presents results from a finite element analysis of a adhesively bonded joint. These results show that significant error in the analysis may result during monotonic loading if the rate dependency of the adhesive is not taken into account. This has significant implications in the design and analysis of bonded joints.
Effects of Structure and Microcracks on Fatigue Properties of Three-Dimensional Composites
Authors: Chou Shen , Chen Hong-En
Published: April 2023

Three-dimensional carbon fibre/epoxy resin composites were prepared, which had either three-axis or five-axis carbon fabrics (3D-3A and 3D-5A) in four weave gauges, and were embedded with PTFE film in the fabric structures to initiate various types of microcracks. The flexural fatigue properties of these 3-D composites were studied. The results show that the flexural properties and fatigue life of 3D-3A are higher than those of 3D-5A. Enlarging the weave gauge of 3D-3A and 3D-5A enhances the flexural properties, fatigue life and resistance to fatigue crack growth. The 3D-3A with a weave gauge of less than 5 mm or the 3D-5A with a fatigue stress lower than 140 MPa has a considerably higher ability to resist fatigue in presence of PTFE film. Under 120 MPa stress, both 3D-3A and 3D-5A retain more than 70% residual flexural breaking strength. However, with PTFE film embedding, their stiffness reduces significantly. A crack in 3D-3A grows along the Z-axial bundle, whereas a crack in 3D-5A grows in the X-Y plane. The 45°-axial bundle shows a pull-out phenomenon.
Novel Bismaleimide - Epoxy Resin System: III
Authors: Patel Hasmukh S. , Patel Nilesh P.
Published: April 2023

Novel diamines, namely N,N′-bis[1-(4-aminophenyl) ethanonyl]-4,4′-(1,1′-biphenyl)diamine (DA1), N,N′-bis[1-(4-aminophenyl) ethanonyl]-4,4′-(1,1′-biphenyl methane) diamine (DA2) and N,N;-bis[1-(4-aminophenyl) ethanonyl]-4,4′-(oxybisphenyl)diamine (DA3) have been prepared and reacted with various bismaleimides (BM) at a BM: diamine ratio of 1:2. The resulting oligoimides have been characterized by elemental analysis, IR spectral studies, and thermogravimetry. Their number average molecular weights ([Formula: see text]n) were estimated by nonaqueous conductometric titration. All of the oligoimides have been used as curing agents for epoxy resins based on the diglycidyl ether of bisphenol-A, and studied by differential scanning calorimetry (DSC). Glass and carbon fibre reinforced composites have also been prepared and characterized by mechanical properties.
NDT of Composite Materials - Problems and Solutions 1. NDT as a Source of Information
Authors: Matiss I.
Published: April 2023

This introductory paper is devoted to highlighting distinctive features of the non-destructive testing (NDT) techniques used in the study of polymers and composite materials. More than 30 years experience at the Institute of Polymer Mechanics has shown that success in the application of NDT to advanced materials depends crucially on the optimal choice of the technique and on the skill of the operator. The reason for a special approach to testing of these materials is that a number of specific features characterise composite structures. Analysis of these features, recommendations to increase the reliability and the accuracy of the NDT methods and a search for new testing techniques are the major areas of research carried out in the Institute. The following topics will be covered:

1. Non-destructive testing as a source of information.

2. Relaxation spectrometry for the structural study of polymers and polymer composites.

3. Modelling of dielectric relaxation phenomena.
NDT of Composite Materials - Problems and Solutions 2. Relaxation Spectrometry for the Structural Study of Polymers and Polymer Composites
Authors: Matiss I.
Published: April 2023

The use of mechanical and dielectric spectrometry for macrostructural studies (cure, ageing, moisture absorption, etc.) of polymers and composite materials is described. Dynamic relaxation parameters including the most probable relaxation time, and the width and symmetry of the spectrum are proposed for the quantitative evaluation of the structure. The analogy between mechanical and dielectric relaxation phenomena is discussed.
NDT of Composite Materials - Problems and Solutions 3. Modelling of Dielectric Relaxation Phenomena
Authors: Matiss I.
Published: April 2023

This paper discusses the modelling of frequency dependent dielectric relaxation as a support for designing transducers, the optimisation of testing conditions, identification of the internal structure of heterogeneous media, evaluation of errors and development of software for expert systems, etc. Basic principles, and the main models for relaxation behaviour are described. In this way it is possible to calculate the frequency dependence of the complex dielectric permittivity of various two- and three-component structures if the frequency dependence of the components is known.
Molecular Transport of Organic Esters into Copolymeric and Terpolymeric Membranes
Authors: Aminabhavi Tejraj M. , Harlapur Sujata F. , Ortego J. Dale
Published: April 2023

Solvent uptake into thin fluoropolymer membranes (FC-2179 and FLS-2650) has been measured as a function of temperature using a sorption gravimetric method. Diffusion coefficients, percent mass uptake, and apparent activation energies for the process of diffusion and permeation have been obtained. Both polymers exhibit anomalous diffusion behaviour and this is due to specific interactions between polymer chain segments and esters. Molecular migration of esters into the dense membrane materials showed a dependence on polymer morphology and/or their chemical structures. The liquid concentration profiles have been calculated at different depths of the membranes for different time intervals. A numerical mediod based on a finite difference approach was also employed to predict concentration profiles of liquids into the membrane materials.
The Development and Appraisal of 3D Interlinked Woven Structures for Textile Reinforced Composites
Authors: Hill B.J. , McIlhagger R.
Published: April 2023

A method, based on simple geometry, is devised to predict the percentages of fibre in the three mutually perpendicular directions for 3D woven interlinked structures. This provides an opportunity to design fabrics for specific applications which have known amounts of fibre in the principal stress direction.
Synthesis and Properties of Block Copolymers of Poly(ether sulphone)s with Liquid Crystalline Polyester Units
Authors: Shibata Mitsuhiro , Yosomiya Ryutoku , Wang Junzuo , Chen Chunhai , Bai Guohong , Wu Zhongwen , Wang Shanger , Mo Zhishen
Published: April 2023

Block copolymers of poly(ethersulphone) (PES) oligomers with liquid crystalline polyester units were synthesized by the reaction of dihydroxy-terminated poly(ether sulphone) oligomers (number-average molecular weights: 704, 1,158 and 2570) and terephthaloyl bis(4-oxybenzoyl chloride), and their properties were investigated. The results indicated that the copolymer with PES segments of molecular weight of 704 possessed birefringent features when annealed at 360°C, while the copolymer with PES segments of molecular weight of 2,570 became isotropic. Also, the block copolymers had a better chemical resistance and high-temperature stability than PES.
Photo-ageing of Poly(Butylene Terephthalate) and Poly(Butylene Terephthalate)-Fibre Glass Systems
Authors: Gardette Jean-Luc
Published: April 2023

The photolysis and photo-oxidation mechanisms of poly(butylene terephthalate) (PBT) and poly(butylene terephthalate)-fibre glass (PBT-FG) irradiated under polychromatic light (λ ≥ 2300 nm) were studied. Derivatisation reactions coupled to FTIR analysis of the exposed samples permitted the identification of the various photo-products and the proposal of mechanisms. It was found that the same photo-products were formed in PBT and PBT-FG. Micro-FTIR analysis of the irradiated samples showed that the photochemical reactions were limited to a depth of 50 urn from the exposed surface, both in PBT and PBT-FG.
Effects of Processing Variables on the Powder Impregnation Technique for Continuous Fibre Composite Materials
Authors: Wei C.Y. , Miller A. , Gibson A.G.
Published: April 2023

Prepregs of continuous glass fibre reinforced thermoplastics were produced, applying different processing variables of the powder impregnation process. The investigation was concerned with the effects of tow tension, line speed and temperature. A recently developed process model was employed to interpret the effects of temperature and fibre volume fraction on void content. An equation was derived to calculate fibre volume fraction according to the width of a spread fibre tow. Experimental results demonstrate that the process variables greatly affect the fibre content and the void content of the prepregs. The unidirectional prepregs of polyphenylene sulphide were laminated by hot-pressing. The flexural and shear strengths of the laminates are disproportionate to the void content of the prepregs, and the laminates.