Bond Strength Parameters Research Articles

Adsorption of CO, NO and SO on Fe2-10 clusters: A computational investigation on the metal catalysed activation of atmospheric pollutants

The adsorption and activation of CO, NO and SO gas molecules on the surface of Fe2-10 clusters were investigated. The calculated adsorption energies of –81 to –376 kJ mol−1 confirmed the chemisorption of the gases on the metal clusters. The chemical activations of the gas molecules were verified by analyzing the strength of the inter-nuclear bond by using various bond strength parameters. The metal-to-ligand charge transfers were investigated to understand the role of metals in the bond activation process. The current investigation is highly relevant to design efficient catalysts for the capture and recycling of gaseous pollutants.

The stability and reactivity of neutral and charged aluminium doped carbon clusters (Al1,2C2-70,±)

The stability and reactivity of Al-doped linear and quasi-linear carbon chains (Al1,2C2-70,±) were computationally investigated using various reaction and binding energy parameters. The dissociation of the clusters was studied via the elimination of Al, C from the neutral species, Al0,+, C0,+ the cationic species, and Al0,-, C0,- from the anionic species. The stability was further examined based on electron elimination reactions, such as electron detachment from Al1,2C2-7- and ionization of Al1,2C2-7. The study proceeded by formulating a novel relative energy parameter, which was generated from the binding energy values. The lowest energy dissociation channels of Al1,2C1-70,± were the Al and Al+ elimination from the neutral/anionic and cationic clusters, respectively. Under the dissociation conditions, the even-carbon species (m = 2,4,6) AlCm (doublet), AlCm+ (triplet), AlCm- (singlet), Al2Cm (singlet), Al2Cm+ (doublet) were found to be more stable than that of the odd-carbon clusters (m = 3,5,7), irrespective of the spin states. In the case of Al2Cm-, the odd carbon clusters were found to be more stable. The stability orders based on the widely used highly endothermic C-elimination reaction were found to be significantly different. We have systematically addressed the above disparities and have commented on how to accurately predict the abundance of the species under extreme experimental conditions. The reactivity of Al1,2-doped clusters was found to be higher than the bare carbon chains. Based on the bond-strength parameters calculated using AIM analysis, the Al1,2-doping led to an activated Al-C bond rather than the carbon chains, eventually resulting in reactive meal-carbon clusters. The Al-C bonding was discussed using electron density at the Al-C bond critical points (ρAl-C), the vibrational frequency of the Al-C bond (νAl-C), bond length (rAl-C), the NBO charge on the Al atoms (qAl) and with the molecular orbital diagrams. The results of the current investigations can be highly relevant to astrochemistry, spectroscopy, material, and organometallic chemistry communities.

Composite-veneering of polyether-ether-ketone (PEEK): evaluating the effects of different surface modification methods on surface roughness, wettability, and bond strength.

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.

INTERFACIAL BOND STRENGTH BETWEEN MICRO-SYNTHETIC FIBER-REINFORCED PATCH REPAIR MORTAR AND CONCRETE SUBSTRATE BASED ON PUSH-OFF TEST

A micro synthetic fiber-reinforced mortar has been developed as a patch repair material. The bond strength of this material is a crucial parameter for successful repair applications. The state of stress occurring at the interfacial plane between the repair material and the concrete substrate influences the bond strength requirements of patch repair material. Therefore, bond strength envelope criteria should be established using, among others, the interfacial adhesion and friction coefficient parameters. This research aims to determine the composite’s interfacial bond strength parameters (adhesion and friction coefficient) between micro-synthetic fiber-reinforced patch repair mortar (MSFRPRM) and concrete substrate by push-off tests. At this stage, the smooth joint texture limits the investigation. The fiber volume fraction and age of repair are considered. The tests were conducted at the age of 1, 3, 7, and 28 days. In addition to the laboratory experiment, this research used ATENA Science GiD to numerically simulate the push-off test and study the influence of the fiber volume on the adhesion and friction coefficient. The results show that at a fiber volume of 0.06%, the adhesion and friction coefficients increase from 1.15 to 2.33 MPa and 0.74 to 0.85, respectively, corresponding to age. Numerical simulation indicates that the maximum adhesion and friction coefficient occurs at the fiber volume fraction of 0.06%. Thus, the overall simulation results can be used in the future as a parameter to establish MSFRPRM and concrete substrate bond strength envelopes that will be useful for evaluating the suitability of MSFRPRM as repair materials under various states of stress. Keywords: Bond Strength, Concrete Patch Repair, Concrete Substrate, Micro-Synthetic Fiber-Reinforced Repair Mortar, Push-Off Test DOI： https://doi.org/10.35741/issn.0258-2724.58.1.20

Comparative Evaluation of Surface Science Approach with Indirect Tensile Strength and Binder Bond Strength Tests to Determine Aggregate-Bitumen Bond

Abstract The present study investigated the efficacy of moisture sensitivity parameters obtained from the surface free energy (SFE) approach, namely the energy ratio (ER) and physiochemical parameters, by comparing the tensile strength ratio (TSR) and bond strength ratio (BSR) parameters, obtained from indirect tensile strength and binder bond strength tests, respectively. The bond strength against the moisture damage of basalt aggregates collected from two different sources with three different binder types, namely, unmodified (VG30), crumb rubber–modified (CRMB60), and polymer-modified (PMB40) binders, was evaluated. Results showed that both the ER parameter, which evaluates stripping potential of bitumen, and physiochemical parameters, which relate the compatibility of water with aggregate and bitumen, evaluated different rankings of an aggregate-bitumen system against moisture damage. However, the comparative study showed that physiochemical parameters evaluated similar rankings of aggregate and bitumen as obtained using TSR and BSR parameters in determining the aggregate-bitumen bond. Thus, it indicates that stripping of a binder may not always be the primary reason for moisture damage in bituminous mixes. It was observed that B2-CRMB60 with the highest ER of 0.71 was the least favorable combination in terms of resistance to moisture damage because of its lowest value of standard TSR and BSR parameters (i.e., 0.72 and 0.74, respectively) compared with five other combinations of aggregate-bitumen systems. Therefore, it is advised to carefully select the bond strength parameters to identify compatible aggregate-bitumen combinations while using the SFE approach. Further, it was found that the SFE approach is capable of addressing the complex moisture damage mechanisms in bituminous mixes; hence, it can be used for forensic investigations related to moisture damage in the field.

Correlation between bond strength and surface free energy parameters of asphalt binder-aggregate system

The bonding potential is one of the imperative parameters of the asphalt binder-aggregate compositions and significantly affects the resistance of the asphalt mixtures against moisture damages. The properties of asphalt binder and aggregate have considerable effects on the moisture sensitivity and bond strength of the asphalt binder-aggregate composition. In the present study, the effects of the aging and stiffness of the asphalt binder, aggregate type, and their interactions on the bond strength and moisture susceptibility of the asphalt binder-aggregate systems were evaluated. The binder bond strength (BBS) test with a new approach of analyzing the failure pattern and the surface free energy (SFE) method were carried out to characterize the bond strength and bond energy parameters. The relationship between the bond strength, failure pattern in the BBS test, and SFE properties were presented. The results indicated strong and meaningful correlations between the SFE properties, failure patterns, and bond strength under dry and wet conditions. The meaningful and good correlations between the failure patterns and bond energies under dry and wet conditions demonstrate that the changes in the adhesive and cohesive failures in the asphalt binder-aggregate compositions highly depend on the SFE properties. Besides, according to SFE results and the failure patterns under dry and wet conditions, new energy parameters were introduced to evaluate the bond strength and moisture sensitivity.

Effect of Pb/B ion replacement in B2O3.PbO.Fe2O3.Na2O glasses: Optical, magnetic, and fluorescence properties

Abstract Glasses of the formula (70-x) %B2O3. x%PbO.10%Fe2O3.20%Na2O are prepared by the melt quenching technique. Complete amorphous structure is confirmed for the XRD checked glasses. Molar polarizability, optical basicity and refractive index are found to decrease with increasing the mol% of PbO in the glasses. Single bond strength and interaction parameters suggest the transfer from covalent to ionic nature with the increase of the mol% of PbO in the glasses. The increase of the polarizability values of the studied glasses leads to a high optical nonlinear properties of the glasses. Metallization criterion is found to increase from 0.37 to 0.53 with increasing the mol% of PbO. Continuous addition of PbO is found to control the paramagnetic character of the glasses. The absorption and emission characteristics are studied. The system band gap and absorption intensity are found to be tunable. Also, it is found that the glass system under investigation experiences fluorescence characteristics with green color.

Non-Deterministic Assessment of Surface Roughness as Bond Strength Parameters between Concrete Layers Cast at Different Ages.

The importance of surface roughness and its non-destructive examination has often been emphasised in structural rehabilitation. The presented innovative procedure enables the estimation of concrete-to-concrete strength based on a combination of low-cost, area-limited tests and geostatistical methods. The new method removes the shortcomings of the existing one, i.e., it is neither qualitative nor subjective. The interface strength factors, cohesion and friction, can be estimated accurately based on the collected data on a surface texture. The data acquisition needed to create digital models of the concrete surface can be performed by terrestrial close-range photogrammetry or other methods. In the presented procedure, limitations to the availability of concrete surfaces are overcome by the generation of subsequential Gaussian random fields (via height profiles) based on the semivariograms fitted to the digital surface models. In this way, the randomness of the surface texture is reproduced. The selected roughness parameters, such as mean valley depth and, most importantly, the geostatistical semivariogram parameter sill, were transformed into contact bond strength parameters based on the available strength tests. The proposed procedure estimates the interface bond strength based on the geostatistical methods applied to the numerical surface model and can be used in practical and theoretical applications.

Effects of mechanical properties of adhesive and CFRP on the bond behavior in CFRP-strengthened steel structures

The bond between carbon fiber-reinforced polymer (CFRP) composites and steel is a key issue in CFRP-strengthened steel structures. The determination of key parameters in the bond strength model remains debatable. We studied the bond behavior between CFRP and steel, focusing on the effects of different types of epoxy adhesive and CFRP on the failure modes, bond–slip relationships, and bond strength parameters. The results show that due to the use of various materials, some specimens fail in interface debonding characterized by brittle failure, whereas others have cohesive failure or CFRP delamination characterized by ductile failure. The bond–slip models showed gentle-slope descending branches for interfaces with ductile failure, which is missing in brittle failure. The bond–slip relationships of most specimens can be simplified as bilinear models. However, trilinear models should be used for the specimens failing in the delamination and tearing of CFRP. As for the modes of interface debonding and CFRP superficial delamination, the maximum shear stresses in the interface linearly correlate with the elastic moduli of adhesive. The nonlinear mechanical behavior of interfaces can be well simulated by a cohesive zone model.

Effect of silica-palm shell carbon composite additive in enhancing the strength of the concrete in the oil-well cementing job

This study provides an analysis of composite additive effect to concrete’s strength in the oil-well cementing job. The composite additive is originated from the nano-sized form of silica and charcoal from palm shell waste. The quality of the concrete will be determined from its porosity, compressive strength, and shear bond strength parameters. Those parameters must be reliable base on the most respectable standards in oil and gas industry, in this study we use the standard from American Petroleum Institute (API). Six concrete samples with different concentration will be tested to obtain these parameters. The result from the test shown a decrement trend of the porosity while the concentration is increased. In contrast, the highest values of compressive strength and shear bond strength are obtained from the sample with higher additive concentration. The optimum strength was obtained in sample with 0.02% The results become clearly proven through verification by scanning electron image where the additive has successfully fill the voids in the concrete’s sample, resulting in strength enhancement of the sample.

Determination of Bond Strengths in Non-woven Fabrics: a Combined Experimental and Computational Approach

Interfiber bonds are important structural components in non-woven fabrics. Bond fracture greatly affects the strength and damage progression in a fiber network structure. Here, we present a novel combined experimental and computational approach to extract bond strengths in non-wovens. In this method, a small specimen is imaged and the obtained 3D geometry of the network is directly modeled in a finite element framework. Bond properties are determined by matching finite element simulation predicted mechanical response to the experimental data. This method is demonstrated by applying it to six specimens of a commercial polypropylene non-woven. A four parameter bi-linear interface law is used with normal stiffness k, shear stiffness βk, separation at the start of damage d 1, and separation at total loss of bond stiffness d 2. The determined normal strength (kd 1)and shear strength (βkd 1) are (1.3 ± 0.3) × 102 MPa and (1.0 ± 0.2) × 102 MPa, respectively. To show that the obtained bond parameters can be applied to a new specimen, a cross validation is conducted whereby parameters are fit from five specimens and then evaluated on the sixth. Additional validation of the obtained bond strength parameters was conducted with larger size artificial network simulations and peel tests. The proposed method in this work carries the dual advantages of characterizing actual bonds in a non-woven and characterizing hundreds of bonds simultaneously. The method can be applied to a variety of non-woven fabrics that are bonded at fiber-fiber intersections.

The Influence of Impressed Current on Residual Bond Strength of Corroded Structure

An experimental work was carried out to study the influence of impressed current on residual bond strength of corroded specimens. In accelerated corrosion process, two different current densities 0.08 mA/cm2 and 0.4 mA/cm2 were used which identified as ‘slow’ and ‘fast’ current. Beam end type bond specimens reinforced with 10 mm and 16 mm bar diameter were prepared for the bond test. Stirrups were provided along the main bar. Corrosion level of the main reinforcement was limited to 8% theoretical section loss. Other parameter such as the location of the test bar (corner and centre location) was also considered. The results indicate a significant influence of impressed current on the crack width with the ‘fast’ current tended to have wider crack than the ‘slow’ current. The influence on bond strength and other related parameters are being discussed.

Residents' journal review

Residents' journal review

Effect of atmospheric pressure plasma pre-treatment and aging conditions on the surface of thermoplastics

The application of atmospheric pressure plasma is a popular pre-treatment method in the field of joining technology. Its purpose is the improvement of adhesion between different materials, e.g., for adhesive bonding, painting, or injection molding. Especially, while bonding parts with lower surface energies, efficient surface activation can be achieved via this treatment method. The surface is specifically modified in its chemical, physical, and topographical properties. However, after surface treatment, it is possible that these new surfaces progressively change by aging and compensation processes. Knowing the time-variant surface state after pre-treatment is extremely important for interpreting the entire process chain. Additionally, the effect of the pre-treatment on other properties—such as the bonding strength of an adhesive bond—must be known. The aging behavior of an atmospheric pressure plasma-treated plastic surface has been demonstrated in several studies based on the surface properties (chemical composition, surface energy, etc.). Whether these property changes also significantly affect the bond strength of structural adhesive joints is to be clarified in the present analysis. In this study, the aging behavior of three typical thermoplastics (polyethylene, polypropylene, and polystyrene) is examined after a treatment with an atmospheric plasma jet. The aging is taken into account by two factors: ambient temperature and time. Kinematic parameters (distance and velocity) of the pre-treatment are integrated in the experimental design to include the effects of the pre-treatment method in the investigation. The dependence of these influencing effects on bond strength and surface energy is analyzed with the help of central composite experimental designs. The results show a change in surface properties over time and ambient temperature. An increase of temperature and time leads to a reduction of surface energy. Furthermore, the kinematic factors of the plasma treatment determine aging. However, a mathematical correlation between bond strength and aging parameters could not be detected in this study. The bond strength is time-invariant but significantly dependent on the parameters distance and speed. Additionally, a dimensional analysis was conducted in order to describe the dependency of surface energy and load factor on the investigated parameters. Therefore, several dimensionless parameters were developed. Regarding the load factor, it was possible to describe the ongoing processes based on the correlations discovered by dimensional analysis. This allows the prediction of the load factor based on process and storage parameters. A relationship between the investigated Π-numbers could not be detected for the surface energy, which means a functional relationship to describe the surface energy could not be found.

Computational Studies on Azaphosphiridines, or How to Effect Ring‐Opening Processes through Selective Bond Activation

The relative energies of azaphosphiridine and its isomers, the ring stability towards valence isomerization, and the ring strain, as well as the kinetics and thermodynamics of possible ring-opening reactions of P(III) derivatives (1-5) and P(V) chalcogenides (6-9; O to Te), were studied at high levels of theory (up to CCSD(T)). The barrier to inversion at the nitrogen atom in the trimethyl-substituted P(III) derivative 5 increases from 12.11 to 15.25 kcal mol(-1) in the P-oxide derivative 6 (P(V)); the relatively high barrier to inversion at the phosphorus in 5 (75.38 kcal mol(-1)) points to a configurationally stable center (MP2/def2-TZVPP//BP86/def2-TZVP). The ring strain for azaphosphiridine 5 (av. 22.6 kcal mol(-1)) was found to increase upon P-oxidation (6) (30.8 kcal mol(-1); same level of theory). Various ring-bond-activation processes were studied: N-protonation of P(III) (5) and P(V) (6, 7) derivatives leads to highly activated species that readily undergo P-N bond cleavage. In contrast, metal chlorides such as LiCl, CuCl, CuCl(2), BeCl(2), BCl(3), AlCl(3), TiCl(3), and TiCl(4) show little P-N bond activation in 5 and 7. Remarkably, TiCl(3) selectively activates the C-N bond, and induces stronger bond activation for P(V) (6, 7) than for P(III) azaphosphiridines (5). The ring-expanding rearrangement of P(V) azaphosphiridines 6-9 to yield P(III) 1,3,2-chalcogena-azaphosphetidines 32 a-d is predicted to be preferred for the heavier chalcogenides 7-9, but not for the P-oxide 6. The first comparative analysis of three bond strength parameters is presented: 1) the electron density at bond critical points, 2) Wiberg's bond index, and 3) the relaxed force constant. This reveals the usefulness of these parameters in assessing the degree of ring bond activation.

The effect of formation of second hydrogen bond in adjacent two-ring resonance-assisted hydrogen bonds – Ab initio and QTAIM studies

Two-ring intramolecular resonance-assisted hydrogen bonds (RAHBs) existing in 1,5-dihydroxy-1,4-diene-3-pentanone and some its symmetrically substituted derivatives have been studied at the MP2/6-311++G∗∗ level of theory. The influence of the coexistence of two intramolecular hydrogen bonded rings in these molecular systems on the structure, intramolecular hydrogen bonding and π-electron delocalization was investigated. The results of calculations show that such coexistence increases the π-electron delocalization but it leads also to the weakening of hydrogen bonding. The Quantum Theory of ‘‘Atoms in Molecules’’ (QTAIM) of Bader was also applied here to get more details about the nature of hydrogen bonds. Correlations between the hydrogen bond strength and different parameters were also analyzed. It was found that topological characteristics of critical points (bond critical points and ring critical points) are also useful to estimate the strength of intramolecular hydrogen bonds in two-ring RAHB systems.

Polyolefin Macroradical Properties: A Semiempirical Quantum Chemistry Study

AbstractSummary: Semiempirical quantum chemistry simulations have been used to estimate the properties of mid‐chain alkyl radicals of ethylene, propylene and styrene oligomers depending on the chain length. The values of spin density and charge on the radical site proved to be almost unchanged for oligomer radicals having from 2 to 11 repeated units. Bond strength parameters of bonds neighboring the radical site demonstrate stable values starting from pentamers. The reliable inference is that the electron structure of polyethylene, poly(propylene) and polystyrene (PS) macroradicals may be simulated by means of relatively short oligomers. The obtained data indicate clearly that the polystyrene tertiary alkyl radical has noticeably decreased values of both spin and charge onto the radical site as well as very decreased strength of β‐bonds. For that reason the PS tert‐alkyl radical is estimated as that having decreased activity and increased susceptibility to chain scission. The most probable cause is delocalization of the free electron onto the neighboring aromatic ring.Spin density distribution in tertiary radical of polystyrene.magnified imageSpin density distribution in tertiary radical of polystyrene.

Correlation between bond strength parameters in molten materials exhibiting semiconductor-semiconductor melting behavior

Experimental data on the thermal expansion of molten semiconductors are used to evaluate the Debye characteristic temperature of the melt, the m>Θ2value (characterizing the energetics of the short-range-order structure), and the root-mean-square dynamic displacement of atoms from their equilibrium positions. These bond strength parameters are shown to be correlated with one another. Comparison with earlier data for crystalline materials demonstrates that melting notably reduces the bond strength and changes the vibrational spectrum of the material.

Stability of protein-bound glycyl radical: a density functional theory study

Density functional theory is used to study different models of the glycyl radical in proteins. The radical is characterized by means of the C α–H bond strength, geometry, spin distribution, and hyperfine parameters. It is shown that, due to substituent effects from the peptide bond, the protein-bound glycyl radical is less stable than the nonprotein-bound one. This effect is of great importance for the biological function of the glycyl radical. The capto-dative resonance stabilization is confirmed, and new resonances are suggested to arise due to the peptide bond, resulting in further delocalization of the unpaired spin.

Further evidence for Tl 3+ in Tl-based superconductors from improved bond strength parameters involving new structural data of cubic Tl 2O 3

We report on refined structural parameters for cubic Tl 2O 3 (avicennite, space group Ia3, a=10.5344 (3) A ̊ ) using Guinier powder diffraction data. The final reliability factor of the structure analysis was R( F)=0.015. Empirical bond valence sums of the two different Tl 3+ ions in the structure were calculated from bond lengths. These values deviate negatively from the actual 3+ valence by the same amount that has been frequently observed for Tl-based superconductors. Therefore, a least squares fit of the Tl 3+ bond strengths s on the bond lengths d according to s=( d d 0 ) -N has been performed giving improved parameters d 0=2.04 (1) A ̊ , N=6.4(2) and as result persuasive evidence forthe 3+ valence Tl in high- T c superconductors, even though the Tl site is occupied to some extent by Cu 1+.