Bond Quality Research Articles

A Multifunctional Mineral Binder for Plywood Production: The Effect of Manufacturing Parameters on Bonding Quality

Geopolymers show great potential for use as binders in developing and manufacturing multifunctional wood products. The objective of this study was to improve the bonding quality of a geopolymer binder, with wood veneers, using different manufacturing parameters. To this end, we produced five layered plywood panels treated with various lay-up times (1, 5, 10, 15 min), panel compressibility values during hot pressing (5%, 10%, 15%, and 30% compression), veneer roughness values (low, medium, and high roughness), press temperatures (120, 140, and 160 °C), and veneer layouts via changing the middle layer position of plywood relative to the surface layers. The results show that the shear strength and thickness swelling were negatively influenced by increasing the lay-up time of resinated veneers and panel compressibility. Increasing the veneer roughness significantly increased the panels’ properties. Furthermore, the panels produced with a pressing temperature of 140 °C showed the best performances. The veneer layouts also significantly changed the physical and mechanical properties of the plywood panels. Generally speaking, the results obtained in this study show that improving the bonding quality of geopolymer binders with wood can be done through the manipulation of plywood manufacturing parameters.

Thread-by-thread tear mendings in conservation of canvas paintings: a problem of reproducibility in bonding qualities

ABSTRACT The paper introduces the technique of thread-by-thread tear mending in the conservation of canvas paintings and is dedicated to the investigation of difficulties in the reproducibility of bonding qualities. An insight is given into the basics of the bonding technique as well as the requirements on the adhesives. Based on initial test series, the cause of scattering is investigated and examined on the basis of scale effects, thread geometry and general bond qualities. Selected results from uniaxial tensile tests on single thread and canvas strip specimens are presented and discussed. As a result, it can be stated that the scattering is inherent in the material and technology. Therefore, the aim must be to show the range of possible results within further tests to provide reliable data for practical conservation and restoration treatments.

Microstructural evolution and bonding of HVOF sprayed Ni particles on both mild and stainless-steel substrates

In the present study, Ni powder was sprayed onto both mild and stainless-steel substrates using high-velocity oxy-fuel (HVOF) deposition to comparatively analyse the effect of substrate material properties and surface condition on splat formation. A range of microscopy techniques including scanning electron microscopy (SEM), focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX) were employed to characterize both the splat morphologies, including their cross-sectional structure, as well as the nature of the splat-substrate interface. It was shown that the majority of the particles reached the substrate surface in a partially melted form owing to the high velocity typical in the HVOF process. Despite some splat splashing observed on the stainless-steel sample, the diffusion profiles, determined by STEM-EDX line scans, revealed evidence of elemental interdiffusion at the splat-substrate interface, suggesting metallurgical bonding in this sample. It was observed that splat morphologies, their frequency of occurrence and splat-substrate bond quality are all greatly affected by the surface condition of the substrate. These microstructural observations were correlated with the thermo-mechanical characteristics of the substrates to explain the mechanisms driving splat formation. Differences in the degree of plastic deformation of the substrates due to particle impact are also discussed.

The role of siblings in the process of forming life satisfaction among young adults \u2013 moderating function of gender

The main aim of the study was to explore the relationship between life satisfaction and sibling bond quality, with gender playing a moderating role. The sample consisted of 276 young adults with a single biological sibling. The participants completed three questionnaires: a sociodemographic survey, the STQ-Now (quality of the sibling relationship) and the SWLS (level of life satisfaction). No difference was observed between men and women regarding life satisfaction; however, the gender constellation in a sibling dyad was found to be statistically significant. Same-sex pairs scored higher on life satisfaction than cross-sex siblings. A positive relationship with a brother or a sister based on mutuality correlated with high overall satisfaction with life, while criticism, competition and apathy were associated with lower general satisfaction. Additionally, two of these relations (i.e. mutuality and apathy) were moderated by gender. Lastly, representatives of the Supportive type of relationships obtained higher levels of life satisfaction than the Ambivalent or the Reluctant types. The findings suggest that siblings play an essential role in shaping psychological well-being. As early adulthood is a stage characterised by multitasking and various challenges, the formation of positive, adaptive and supportive sibling bond may maintain good life satisfaction. The findings also underline the significance of gender combination in the relationship.

Effects of Selected Parameters on the Bonding Quality and Temperature Evolution Inside Plywood During Pressing.

This research optimizes the process of plywood production to determine its effectiveness in reducing energy and adhesive consumption for more efficient production with the required quality. The influence of selected parameters including veneer treatment (non-densified and densified), plywood structure, temperature, time and pressure of pressing, on the bonding quality and temperature evolution within the veneer stacks during hot pressing was investigated. Rotary-cut, non-densified and densified birch veneers and phenol formaldehyde (PF) adhesive were used to manufacture plywood samples. The effect of pressure and time of pressing on bonding quality of the plywood was determined. Bonding quality was evaluated by determining the shear strength of the plywood samples. The temperature evolution inside the veneer stacks was measured for birch veneers for different pressing temperatures and pressures for different numbers of veneer layers. The heating rate of the veneer stacks increased as the pressing temperature increased and decreased markedly with an increasing number of veneer layers. At a high pressing pressure, the heating rate of the densified veneer stacks was faster than that of non-densified veneers at the same pressure. The use of densified veneers for the production of plywood can lead to a shorter pressing time (17–50% reduction), lower glue consumption (33.3% reduction) and a lower pressing pressure (22.2% reduction) without negatively impacting the bonding strength of the plywood.

Epigenetic differences in inflammation genes of monozygotic twins are related to parent-child emotional availability and health

The inflammatory response is an immune defense engaged immediately after injury or infection. Chronic inflammation can be deleterious for various health outcomes and is characterized by high levels of pro-inflammatory markers such as C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α). A large body of research demonstrates these inflammatory markers are responsive to stress and quality of social relationships throughout the lifespan. For example, the quality of the early parental bond predicts various health outcomes and may be driven by changes in immune function. Epigenetic processes, such as DNA methylation, may be one mechanism by which early social experiences shape immune functioning. The present study used a monozygotic twin difference design to assess if mother-reported emotional availability at 1 year and 2.5 years predicted immune gene methylation at 8 years of age. Further, we assessed if inflammation gene methylation was related to general health problems (e.g. infections, allergies, etc.). We found that mother-reported emotional availability at 1 year, but not 2.5 years, was related to methylation of various immune genes in monozygotic twins. Furthermore, twin pairs discordant in health problems have more difference in immune gene methylation compared to twin pairs concordant for health problems, suggesting that methylation of immune genes may have functional consequences for general health. These results suggest that the emotional component of attachment quality during infancy contributes to immune epigenetic profiles in childhood, which may influence general health.

Ultrasonic Log Response Evaluates Barrier Cells for Cementing Applications

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199578, “Validating Ultrasonic Log Response Against Reference Barrier Cells Simulating Downhole Well Conditions Encountered During Well Construction and Abandonment Operations,” by Amit Govil, SPE, Schlumberger; Dave Gardner, SPE, Norwegian Research Centre; and Guillermo Obando, Schlumberger, et al., prepared for the 2020 IADC/SPE International Drilling Conference, Galveston, Texas, 3–5 March. The paper has not been peer reviewed. Borehole-cement-evaluation logs are used to verify the quality of the cement bond to the casing and formation and identify any defects that could compromise the quality of the annular seal. This study used ultrasonic logging to evaluate reference barrier cells constructed with known defects. The cell concept was developed with an emphasis on low cost and ease of use. Comparison of ultrasonic tool response against reference barrier cells validates the measurements, which are crucial in the decision-making process during well construction and abandonment. Background: Barrier Verification In 2013 and 2014, full-scale experiments were performed to investigate the sealing ability of annulus cement for a plug-and-abandonment design in which the tubing is left in hole (TLIH). The experimental configurations used 9⅝-in. casing with a 7-in. tubing, both with and without control lines clamped to the tubing surface. Experiments were run first using standard Class G cement. In a second phase, Class G cement with an expansion additive was used to compare the quality of the seal achieved. The barrier quality of the cement was evaluated by pressure-testing the casing cement sheath and the tubing plug. The test assemblies subsequently were cut into sections, enabling the cement displacement to be controlled visually. The results showed that good cement placement could be achieved with the tubing left in the well both with and without control lines. The pressure testing showed that the control lines did not have a detrimental effect on the barrier-seal quality compared with the test without control lines. The choice of leaving the tubing in hole when abandoning a well is dependent on an assessment of the quality of the casing cement sheath. The barrier-verification project was initiated to build on the TLIH experiments by investigating the performance of annular-barrier evaluation technologies. Materials and Fabrication The project aim is to construct a barrier-verification reference facility with the objectives of Evaluating technologies for logging through multiple tubulars Investigating the performance of commercial logging technologies Performing experiments with alternative barrier-verification techniques In the first project phase, the TLIH sections were reused as much as possible to enable a starting point with known specifications and quality. The cement plug in the tubing was first removed carefully by hydrojetting. Thereafter, the desired defects, such as long holes of different sizes drilled through the cement immediately adjacent to the 7-in. tubing, were introduced. Reference cells were constructed with the aim of mimicking a range of potential annular-leakage scenarios such as gas channels, mud channels, and micro annuli. A design requirement was to enable the required cells to be coupled easily using quick unions in the configuration required to meet the experimental objectives. The tubing-to-casing annulus was sealed such that both the tubing and annulus could be independently pressurized with the required fluid. The pressure rating for the tubing and annulus is 2,200 psi. Pressure ports machined into the annulus bulkheads allow controlled leakage rates to be applied using water or gas.

System Development for Diffusion Bonding of Multiple Unit Tubes to Produce Long Tubular Tungsten Heavy Alloys

A diffusion bonding system to fabricate long tubular parts by joining of two- or more-unit tubes made of tungsten heavy alloys (THAs) is proposed and characterized in this study. The difficulty of powder processing of THA originates from the weak strength of the green compact and the high weight of the THA powders. The long tubular green compact is difficult to handle due to its weak structural integrity. Furthermore, gravity-induced slumping during liquid phase sintering induces dimensional distortion and degrades the mechanical performances. As a clue for solving these problems, the unit tubes are fabricated. However, the mass of green compacts for unit tubes is not sufficiently great as to cause problematic slumping; tubular unit tubes can be obtained without significant difficulty. Fabricated unit tubes are stacked in a furnace chamber and diffusion-bonded to produce a long tubular part having bond strength substantially equal to that of a monolithic tube. The proposed diffusion bonding system was well characterized and successfully applied to the industrial production line. The feasibility was also confirmed by investigating the bond quality, which can be assessed by metallographic microstructure and mechanical property.

Examining the Relationship Between Student School Burnout and Problematic Internet Use

Student burnout and Internet addiction are two of the serious problems that are common among young people. Both are connected with many negative effects on the mental functioning of adolescents. However, so far only few studies have explored these two phenomena all together. The aim of our study was to test the relationship between student burnout (SB) and internet addiction (IA). Specifically, we explored three problems: (i) sex differences in the level of student burnout and problematic Internet use among Polish late adolescents; (ii) correlations between student school burnout and its sub-dimensions and problematic Internet use indicators; (iii) the prediction power of student burnout indicators, quality of social bonds and school functioning characteristics on the level of Internet addiction and its subdimensions. The study was conducted among 230 high school students. The results of the research showed that there were no significant differences between girls and boys in the level of problematic use of the Internet, except that male students assessed their dishonesty about Internet use as higher compared to females. As expected, a higher level of school burnout indicators was significantly connected with a higher level of problematic Internet use. Additionally, school burnout (especially burnout from studying, loss of interest in school and burnout due to parental pressure) and school performance characteristics such as additional classroom lessons and low quality of classmates relationships, significantly predicted the problematic Internet use, which explained 19% of variances in the total score of internet addiction. Our findings confirmed that preventative and interventional strategies developed to reduce IA should include activities that also reduce school burnout. In reducing IA and SB we should include actions targeted not only on the adolescent’s group, but also on the school environment (teachers and schoolmates) and the family environment (parents and siblings).

Optimization of the Production Factors of Boards Obtained from Arundo donax L. Fibers Without Added Adhesives.

The main objective of this work was to further analyze the optimization of the production factors of Arundo donax L. fiberboards obtained without adhesives. The production of boards derived from Arundo donax L. without added adhesives and with high mechanical performance has already been demonstrated. This present study explored a modification in the production process through a final curing thermal treatment (final heat treatment, FHT). Since pressing time is an influential factor in the production cost, it is expected that curing allows a reduction of this time. This study compared the results obtained by three panel-production alternatives: long pressing time (tp) without curing and long and short tp with FHT. Of the two factors analyzed, pressing pressure (Pp) was the most important production factor in both the modulus of elasticity (MOE) and modulus of rupture (MOR), while curing was the most important factor for the internal bond (IB). The study shows that a FHT facilitates the distribution of lignin and a possible improvement in the quantity and quality of bonds between lignin and cellulosic fibers. As a consequence, it improves the IB, produces boards with more homogeneous physical and mechanical properties and thereby makes them more hydrophobic. The curing thermal treatment allows high performance panels to be obtained in a manner which is more ecological, quicker, and cheaper.

COMPUTATION OF ROUGHNESS AT SUBSTRATE COATING INTERFACE ON DEPOSITION OF ALUMINIUM OVER MEDIUM CARBON STEEL BY FRICTION SURFACING

Friction surfacing is happening to be a solid-state lining process, which proposes a mean of producing perfect coating between alike and unlike materials utilizing mechanical interlocking at the coating interface. During friction surfacing, the low rotational speed with high axial force normally produces good quality bonding; however, poor mechanical interlocking and cavitation at coating substrate interface resulted in an adverse effect on bond quality. In this present work, the substrate plate was preheated at three different temperatures of 100°C, 200°C and 300°C to create a coating of aluminium 6063 over EN8 medium carbon steel using friction surfacing. The mechanical interlocking was recognized from the specimen image of longitudinal cross-sectional slices, received from optical microscopy. Image recognition software (ImageJ) which depicts the substrate coating interface produce the interfacial roughness profile. The deepness of interlocking at coating interfacial region was monitored at different substrate preheating temperatures done by filter profile graph. The degree of interlocking has been calculated by interfacial roughness values of the profile graph by the use of Python programming language. Then this was compared with a bond strength to identify the relationship among them. Further push off and bonding strength caused by the dovetail shaped interlocking have become higher compared to narrow shaped interlocks stated by profile graph.

Mechanical characterization of aged AA2026-AA2026 overcast joints fabricated by squeeze casting

Squeeze overcasting has emerged as an attractive option for casting of Al alloys in terms of mechanical properties. The attainment of the desired magnitude of these properties is challenging in overcasting due to the involvement of a number of process parameters. In this study, the effects of insert preheat temperature (TI) along with pouring temperature (TP), and squeeze pressure (PS) on the mechanical properties of squeeze overcast AA2026-AA2026 joint were investigated. Experimental results revealed that the squeeze pressure is the most prominent factor affecting the ultimate tensile strength (UTS) while micro-hardness (MH) is significantly influenced by the pouring temperature. Maximum values of UTS (315 MPa) and MH (130 HV) were achieved at a PS of 120 MPa, TP of 780 °C, and TI of 250 °C. Energy dispersive X-ray (EDX) analysis witnessed that TI has also a significant role in determining the quality of bond between the substrate and the melt. Scanning electron microscopy (SEM) depicts that the morphology of the fractured surface has a sound influence on both selected responses. Both the strength and hardness are noticed better if the fractured surface possesses the flat-faced morphology. Furthermore, an empirical regression model was developed using response surface methodology (RSM) design and validated through eight confirmatory experiments. RSM integrated multi-objective optimization genetic algorithm (MO-GA) was deployed to optimize the UTS and MH. The comparative results obtained from RSM and MO-GA demonstrated that the deviation in experimental and predicted values is less than 5%.

Position sensing of ultrashort pulsed laser-welded seams in glass by optical coherence tomography

Today's methods for the inspection of the position of weld seams in glass, which has a decisive effect on the strength and thus on the quality of the permanent bond, are costly and often carried out manually in a destructive manner. The present paper proposes the application of optical coherence tomography to determine the position of the weld seam by evaluation of the signals caused by the voids within weld seams. Blind welds of fused silica and alkali-aluminosilicate glass were investigated, and a method for data evaluation is presented. The method is predominantly suitable for glass that exhibits the formation of distinct voids during welding and provides an approach for online monitoring and control of glass welding processes.

Effect of aggregate type on moisture susceptibility of modified cold recycled mix asphalt: evaluation by mechanical tests and Surface Free Energy method

There are deficiencies associated with cold mix asphalts, specifically, cold recycled mix asphalts in comparison with hot mix asphalt or hot recycled mix asphalt such as higher moisture susceptibility. Moisture damage of asphalt mixtures is inversely related to the bond quality between aggregates and binder. In this study, Portland cement (PC) and acryl polymer (AP) additives were employed to improve this bond. The effectiveness of used additives in improving the moisture susceptibility of cold recycled mix asphalt was examined using Surface Free Energy (SFE) method. Indirect Tensile Strength test and Dynamic Modulus test were performed to validate SFE method results. Moreover, scanning electron microscope (SEM) images were obtained for better understanding of mixture's microstructure. Also, effect of using granite, limestone and recycled asphalt pavement (RAP) aggregates was evaluated. The findings showed that cement and acryl polymer additives improved resistance of different studied mixtures, specifically, cold recycled mix asphalt against moisture damage by improving the adhesion between aggregate and asphalt. Considering effect of aggregates on moisture susceptibility, limestone-mixtures had the highest resistance while the RAP-mixtures performed the worst among the three. Finally, it was shown that results of SFE method were compatible with the mechanical tests in predicting moisture damage.

Physical Distance Between Romantic Partners as a Marker for Attachment in Couples: A Proof of Concept Study

Proximity seeking is at the core of attachment theory. Previously proximity has been studied almost exclusively in psychological terms. In clinical practice, however, couple therapists may interpret physical distance between romantic partners as a marker for the quality of the attachment bond. Unfortunately, this concept of physical distance between partners as an expression of attachment has never been tested. This study examines whether physical distance between romantic partners is associated with attachment. In 53 students and 43 clinical couples physical distance was repeatedly measured from video using novel software with excellent reliability. Attachment was measured with the Experiences in Close Relationships questionnaire. It was found that male attachment anxiety about rejection repeatedly showed statistically significant associations with physical interpersonal distance in student and clinical couples. We conclude that attachment may manifest itself not only in terms of psychological intimacy but also in terms of physical distance. Clinical utility and research implications are discussed.

Role of the functional monomer 10-methacryloyloxydecyl dihydrogen phosphate in dentin bond durability of universal adhesives in etch-&-rinse mode.

This study aimed to determine the role of the 10-methacryloyloxydecyl dihydrogen phosphate (MDP) in dentin bond durability of universal adhesive in etch-&-rinse mode through bond strength tests after different degradation conditions. This study used the MDP-containing universal adhesive, Clearfil Universal Bond Quick (CU), and an experimental adhesive (NM) made with the same ingredients as CU, excluding MDP. Shear bond strength (SBS) to dentin were obtained in etch-&-rinse mode with or without MDP. CU in self-etch mode was used as a comparison. The groups were divided into three types: 1) subjected to thermal cycling; 2) subjected to long-term water storage; and 3) stored in water for 24 h, as a baseline. The discrepancies in the mean SBS of the CU and NM groups become prominent with prolonged degradation periods. This study indicates that the MDP in universal adhesive might play a key role in enhancing dentin bond quality even when etch-&-rinse mode is used.

Influence of Moisture Content for Bonding Quality of European Beech and English Oak

This study focused on the comparison of the bonding quality of European beech (Fagus sylvatica L.) and English oak (Quercus robur L.), due to variability of moisture content (MC) in the wood. Hardwood species as a material, often yield a more difficult drying process, which can cause problems between various MC in the process of bonding. Specimens were bonded in two groups of MCs: 10/10% (control) and 6/14%. After reaching the equilibrium MC in standard conditions, specimens were cut into sample dimensions. Afterward the specimens were tested for bonding quality according to the EN 13354. In general, there is increase of the bonding quality for both hardwood species in different MC specimens. Statistically significant increase was notable in oak. With exception of the MUF adhesive, there were statistical difference between control and 6/14% MC group for oak.

Impact of pressing regime and substrate type on bond quality of decorative veneer

The choice of optimal pressing regime for certain types of substrate is of great importance in production of veneered panels. In this paper, the impact of pressing regime on the bonding strength of beech and oak veneers, glued with urea-formaldehyde (UF) adhesive, on medium-density fiberboard (MDF), and moisture-resistant MDF (MR MDF) substrates was examined. The analyses showed a generally higher bond strength with oak veneer compared to beech veneer, which was also the case with regular MDF compared to moisture-resistant MDF. Multivariate analysis of variance (ANOVA) showed that with beech veneer, all of the used regimes produced better results on regular MDF compared to moisture-resistant MDF. In contrast, with oak veneer, the influence of pressing regime had a more noteworthy impact than the type of substrate used. These results indicated that the use of MR MDF as substrate in combination with UF adhesive was inadequate.

On the effect of the curing cycle on the creation of pores in structural adhesive joints by means of X-ray microtomography

ABSTRACT Adhesive bonding is increasingly used in numerous industrial branches (aeronautics, space, etc.) for the many advantages this technique features. The quality of the adhesive bonds depends on diversified factors, and bonding defects within the joints are common. These defects may take the shape of pores, of various sizes, which are a possible threat to the good mechanical strength of the joints. These pores may create unwanted stress concentrations, and they are susceptible to locally weaken the adhesive joints. As they are created during the bonding process, the hypothesis that the bonding and curing conditions should influence their properties is well-founded. In order to validate this assertion, adhesively bonded samples were made, for different adhesives and different curing cycles. In particular, the influence of the peak temperature reached during the curing cycle was studied. The pores in the joints were then observed and studied using X-ray microtomography. The performances of the segmentation technique developed for the data processing were studied beforehand on synthetic data, in order to identify the limitations of the suggested methodology and to quantify the uncertainty on the computed quantities. It was found that a higher curing temperature may induce noticeable pore growth phenomena (mainly dilation and coalescence). In particular, this growth seems to be predominant halfway-through the thickness of the joints, resulting in an observable decrease in the effective section.

Can a traumatic childbirth experience affect maternal psychopathology and postnatal attachment bond?

The aim of the present study was to explore the relationship between the experience of childbirth as a traumatic event and the quality of postnatal attachment to child, analyzing the role of depressive symptomatology on this relationship. A sample of 103 women, aged from 26 to 46 years (M = 35.05, SD = 4.51) filled in questionnaires to assess postpartum stress symptoms related to the childbirth experience, postnatal attachment toward their newborns, and level of depressive symptomatology. A mediation analysis was carried out. The level of postpartum stress symptoms positively affects maternal depressive symptomatology and negatively affects the quality of postnatal attachment. Moreover, the relationship between a traumatic childbirth experience and postnatal attachment is both direct and indirect. In fact, a traumatic childbirth experience also affects the level of postnatal depression that, in turn, negatively affects the quality of postnatal attachment bond. The presence of postpartum distress symptoms affects the well-being of mothers, and these conditions interfere with the ability of women to develop good attachment bonds with their children. These results showed the relevance of paying attention to pregnant women, to help them to live childbirth in a positive and non-stressful way.