scholarly journals Alkyl-Chitosan-Based Adhesive: Water Resistance Improvement

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1987 ◽  
Author(s):  
Narimane Mati-Baouche ◽  
Cédric Delattre ◽  
Hélène de Baynast ◽  
Michel Grédiac ◽  
Jean-Denis Mathias ◽  
...  
Keyword(s):  
Shear Stress ◽  
Bond Strength ◽  
Chemical Modification ◽  
Chemical Structure ◽  
Water Resistance ◽  
Flow Properties ◽  
Adhesive Properties ◽  
Alkyl Chains ◽  
Modified Polymers ◽  
Resistance Improvement

A chemical modification by grafting alkyl chains using an octanal (C8) on chitosan was conducted with the aim to improve its water resistance for bonding applications. The chemical structure of the modified polymers was determined by NMR analyses revealing two alkylation degrees (10 and 15%). In this study, the flow properties of alkyl-chitosans were also evaluated. An increase in the viscosity was observed in alkyl-chitosan solutions compared with solutions of the same concentration based on native chitosan. Moreover, the evaluation of the adhesive strength (bond strength and shear stress) of both native and alkyl-chitosans was performed on two different double-lap adherends (aluminum and wood). Alkyl-chitosans (10 and 15%) maintain sufficient adhesive properties on wood and exhibit better water resistance compared to native chitosan.

scholarly journals AFM TESTING OF NANOSTRUCTURE OF RESILIENCE ORTHODONTIC BONDING SOLUTIONS ORTHODONTIC ADHESIVE

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Vladan Mirjanić ◽  
Đorđe Mirjanić
Keyword(s):  
Composite Material ◽  
Bond Strength ◽  
Chemical Structure ◽  
The Other ◽  
Roughness Parameters ◽  
Adhesive Properties ◽  
Arithmetic Means ◽  
Strength Based ◽  
Orthodontic Bonding

Nanostructure of Resilience Orthodontic bonding solutions, an orthodontic adhesive that is mostly used nowadays in the orthodontic practice, is analyzed in the paper. After determining the adhesive properties, a correlation was established between the nanostructure of tested adhesive and the tooth bracket bond strength. Based on AFM images of the analyzed adhesive, by way of correlations of arithmetic means of debonding force (I) and average adhesive roughnesses (Ra, Rq, Rzijs, Rz) we come to a conclusion that by increasing the average adhesive roughnesses, increases the debonding force too (I). After that we compared the obtained results with the other adhesives that are also most commonly used. It was observed that with all the roughness parameters (Ra, Rz, Rzijs and Rq) the strongest bond was achieved with Resilience Orthodontic bonding solutions, followed by Heliosit, Orthodontic (Ivoclar, Vivadent), GC Fuji Ortho LC, while the weakest bond was with ConTec LC − Dentarum. Higher roughness of Resilience Orthodontic bonding solutions at the nano level is most probably due to a bigger number of thorns which penetrate into micro cavities developed under the action of acids. Higher roughness is a consequence of the chemical structure itself of the composite material.

scholarly journals Chitosan-Based Adhesive: Optimization of Tensile Shear Strength in Dry and Wet Conditions

2021 ◽  
Vol 2 (1) ◽  
pp. 110-120
Author(s):  
Maisa Abdelmoula ◽  
Hajer Ben Hlima ◽  
Frédéric Michalet ◽  
Gérard Bourduche ◽  
Jean-Yves Chavant ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Shear Strength ◽  
Bond Strength ◽  
Water Resistance ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Spread Rate ◽  
Assembly Time ◽  
Deacetylation Degree ◽  
Dry And Wet Conditions

Commercial adhesives present a high bond strength and water resistance, but they are considered non-healthier products. Chitosan can be considered as an interesting biosourced and biodegradable alternative, despite its low water resistance. Here, its wood bonding implementation and its tensile shear strength in dry and wet conditions were investigated depending on its structural characteristics. Firstly, the spread rate, open assembly time, drying pressure, drying temperature, and drying time have been determined for two chitosans of European pine double lap specimens. An adhesive solution spread rate of 1000 g·m−2, an open assembly time of 10 min, and a pressure temperature of 55 °C for 105 min led to a bond strength of 2.82 MPa. Secondly, a comparison between a high molecular weight/low deacetylation degree chitosan and a lower molecular weight/higher deacetylation degree chitosan was conducted. Tests were conducted with beech simple lap specimens in accordance with the implementation conditions and the conditioning treatments in wet and dry environments required for thermoplastic wood adhesive standards used in non-structural applications (EN 204 and EN 205). The results clearly revealed the dependence of adhesive properties and water resistance on the structural features of chitosans (molecular weight and deacetylation degree), explaining the heterogeneity of results published notably in this field.

Enhancement of Thermo-Oxidative Stability of Vegetable Oil Based Lubricant via Chemical Modification Techniques

2015 ◽  
Vol 813-814 ◽  
pp. 695-699
Author(s):  
S. Arumugam ◽  
G. Sriram ◽  
A. Hemanth Sai Kumar Chowdary ◽  
Janga Subramanya Sai
Keyword(s):  
Chemical Modification ◽  
Oxidative Stability ◽  
Vegetable Oils ◽  
Rapeseed Oil ◽  
Chemical Structure ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Thermo Gravimetric ◽  
Transesterification Method ◽  
Unique Chemical

The rising demand for environmentally acceptable lubricant has led researchers to look to vegetable oils as an alternative to petroleum based lubricants. Vegetable oils have radically distinctive properties owing to their unique chemical structure which have greater ability to lubricate and have higher biodegradability. In spite of advantages, they are limited to inadequate thermo-oxidative stability and poor low-temperature properties which hinder their utilization. In the present study in order to produce a bio lubricant with good thermo-oxidative stability, rapeseed oil was subjected to two different chemical modification techniques viz., epoxidation method and successive transesterification method. The thermo-oxidative stability of formulated oil was analysed using Thermo Gravimetric Analysis (TGA). TGA analysis divulges that the thermo-oxidative stability of rapeseed oil was greatly improved with the epoxidation method in comparison with the successive transesterification method.

scholarly journals Influence of the chemical structure of cation surfactants on the wetting process of rock-forming minerals

2019 ◽  
Vol 55 (2) ◽  
pp. 142-148
Author(s):  
O. N. Opanasenko ◽  
N. P. Krutko ◽  
O. L. Zhigalova ◽  
O. V. Luksha
Keyword(s):  
Cationic Surfactants ◽  
Chemical Structure ◽  
Polyhydric Alcohol ◽  
Amino Groups ◽  
Interfacial Interactions ◽  
Alkyl Chains ◽  
Chemical Structures ◽  
Adsorption Interaction ◽  
Wetting Process ◽  
Steric Hindrances

Interfacial interactions of cationic surfactants of various chemical structures at the solution / finely dispersed mineral material (quartz and dolomite) interface were studied. It is established that the modification of the surfaces of quartz and dolomite with cationic surfactants leads to a change in the structure and radius of the capillaries due to the formation of adsorption-solvate shells. The hydrophobic ability of cationic surfactants is determined by the structure of the hydrophilic part of their molecules – the balance of amino groups in the alkyl chains and the absence of steric hindrances during adsorption interaction with the surface of mineral materials. The mixture of surfactants containing six amino groups and a polyhydric alcohol glycerin has an effective hydrophobic ability from both aqueous and highly mineralized solutions.

Superhydrophobic, highly adhesive arrays of copper hollow spheres produced by electro-colloidal lithography

Soft Matter ◽  
2017 ◽  
Vol 13 (33) ◽  
pp. 5500-5505 ◽  
Author(s):  
Damien Bazin ◽  
Chrystel Faure
Keyword(s):  
Chemical Modification ◽  
Electric Fields ◽  
Hollow Spheres ◽  
Hollow Microspheres ◽  
Colloidal Lithography ◽  
Adhesive Properties

Arrays of copper hollow microspheres produced under electric fields display anti-wetting and super-adhesive properties without resorting to any chemical modification.

Fracture Behavior and Tensile Adhesive Properties of HA Coatings

1997 ◽  
Author(s):  
K.A. Khor ◽  
P. Cheang
Keyword(s):  
Bond Strength ◽  
Fracture Behavior ◽  
Size Range ◽  
Deposition Process ◽  
Adhesive Properties ◽  
Particle Size Range ◽  
Powder Morphology ◽  
Bioactive Properties ◽  
Accurate Comparison ◽  
Plasma Sprayed

Abstract The attractive bioactive properties of HA are significantly reduced upon plasma spraying because of the phase transformation that accompanied the deposition process. One major factor that influence the extent to which the transformation occur appears to be the morphology and physical states of the HA raw powders. This paper reports the study on the influence of powder morphology and property on the fracture behaviour and tensile adhesive strength of plasma sprayed HA coatings. Three types of powders were used in the study; calcined HA (CHA), spray dried HA (SDHA) and flame spheroidised HA (SHA). The particle size range of 53 - 75 μm was employed for all 3 types of powders to effect an accurate comparison of the powders. Results show that the cohesive bond strength of the SHA coating was the highest because of the denser microstructure created by well-formed lamella splats. A correspondingly lower bond strength was recorded with less coherent coatings generated by agglomerated CHA and SDHA powders.

Influence of the Chemical Structure of Functional Monomers on Their Adhesive Performance

2008 ◽  
Vol 87 (8) ◽  
pp. 757-761 ◽  
Author(s):  
K.L. Van Landuyt ◽  
Y. Yoshida ◽  
I. Hirata ◽  
J. Snauwaert ◽  
J. De Munck ◽  
...  
Keyword(s):  
Bond Strength ◽  
Dissolution Rate ◽  
Chemical Bonding ◽  
Chemical Structure ◽  
Calcium Salt ◽  
Atomic Absorption Spectrophotometry ◽  
Functional Monomer ◽  
Functional Monomers ◽  
Chemical Structures ◽  
Adhesive Performance

Functional monomers in adhesive systems can improve bonding by enhancing wetting and demineralization, and by chemical bonding to calcium. This study tested the hypothesis that small changes in the chemical structure of functional monomers may improve their bonding effectiveness. Three experimental phosphonate monomers (HAEPA, EAEPA, and MAEPA), with slightly different chemical structures, and 10-MDP (control) were evaluated. Adhesive performance was determined in terms of microtensile bond strength of 4 cements that differed only for the functional monomer. Based on the Adhesion-Decalcification concept, the chemical bonding potential was assessed by atomic absorption spectrophotometry of the dissolution rate of the calcium salt of the functional monomers. High bond strength of the adhesive cement corresponded to low dissolution rate of the calcium salt of the respective functional monomer. The latter is according to the Adhesion-Decalcification concept, suggestive of a high chemical bonding capacity. We conclude that the adhesive performance of an adhesive material depends on the chemical structure of the functional monomer.

scholarly journals Derivation of Ice Sliding Properties from The Numerical Modelling of Surging Ice Masses

1979 ◽  
Vol 23 (89) ◽  
pp. 420-421 ◽  
Author(s):  
W. F. Budd ◽  
B. J. McInnes ◽  
I. Smith
Keyword(s):  
Shear Stress ◽  
Numerical Modelling ◽  
Sliding Friction ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Flow Properties ◽  
Two Dimensional Model ◽  
Two Parameters ◽  
Basal Shear ◽  
Best Fit

Abstract It is difficult to deduce sliding properties from the numerical modelling of ordinary glaciers because the flow law of ice is still not known well enough to clearly differentiate sliding from internal deformation of the ice. For glaciers undergoing high-speed surges it appears that the majority of the total speed is due to sliding. Furthermore the average basal shear stress of the ice mass is lowered during the surge. This suggests that surging glaciers can be modelled by incorporating a sliding friction law which has the effective friction coefficient decreasing for high velocities. A relation of this type has been found for ice sliding on granite at −0.5°C by Barnes and others (1971) and has also been obtained for rough slabs with ice at the pressure-melting point by Budd and others (1979). A simple two-dimensional model was developed by Budd and McInnes (1974) and Budd (1975), which was found to exhibit the typical periodic surge-like characteristics of real ice masses. Since the sliding-stress relation for the low velocities and stresses was not known, and was not so important for the surges, it was decided to use the condition of gross equilibrium (i.e. that the ice mass as a whole does not accelerate) together with a single-parameter relation for the way in which the friction decreases with stress and velocity to prescribe the basal shear-stress distribution. The low-stress-velocity relation can thus be obtained as a result. This two-dimensional model has now been parameterized to take account of the three-dimensional aspects of real ice masses. A number of ice masses have since been closely matched by the model including three well-known surging ice masses: Lednik Medvezhiy, Variegated Glacier, and Bruarjökull. Since the flow properties of ice are so poorly known—especially for longitudinal stress and strain-rates—the model has been run with two unknown parameters: one a flow-law parameter (η) and the other a sliding parameter (ø). The model is run over a wide range of these two parameters to see if a good match can be made to the real ice masses and if so what the values of the parameters η and ø are for best fit. The matching of the three above ice masses gave very similar values for each of the two parameters η and ø, the value of η being within the range of values expected for the flow properties of temperate ice as determined by laboratory experiments. Using the same values of η and ø it is found that the ordinary glaciers modelled so far do not develop surging but that they could do if the value of ø were increased or if the mass-balance input were sufficiently increased. For Lednik Medvezhiy a detailed analysis of the friction coefficient with velocity was carried out and it was found that the values required for best fit showed a very close agreement to the sliding friction curve of Barnes and others (1971) at −0.5°C. It is concluded that this type of sliding relation can account for the major features of glacier surge phenomena. Finally it is apparent that the numerical modelling technique can be used very effectively to test any large-scale bulk sliding relation by the analysis of real surges of ice masses and in addition can provide further insight into the sliding relation in association with other stresses in the ice mass.

scholarly journals Evaluating the Toxicity of Ionic Liquids on Shewanella sp. for Designing Sustainable Bioprocesses

2020 ◽  
Vol 7 ◽  
Author(s):  
Hakima Kebaili ◽  
Antonia Pérez de los Ríos ◽  
María José Salar-García ◽  
Víctor Manuel Ortiz-Martínez ◽  
Mostefa Kameche ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Chemical Structure ◽  
Marine Bacterium ◽  
Diffusion Test ◽  
Disk Diffusion Test ◽  
Alkyl Chains ◽  
Key Factor ◽  
Wide Group ◽  
Separation Media ◽  
The Relationship

Ionic liquids (ILs) are widely used as reaction and separation media in many technologies due to their unique and advantageous physicochemical properties. Thus, further studies approaching the study of the toxicity of these materials are required. Moreover, they are utilized in devices in which microorganisms such as Shewanella sp. act as biocatalysts. Thus, in this work, the toxicity of 69 ILs on the marine bacterium Shewanella sp. was tested. Specifically, the ILs analyzed were based on the cations imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, oxazolinium, phosphonium, ammonium, and sulfonium, in combination with different anions. The toxicities of this wide group of ILs on Shewanella sp. were determined using two methods: 1) the agar disk-diffusion test and 2) the growth inhibition test in liquid media. The relationship between toxicity and IL chemical structure was elucidated. A decrease in the hydrophobicity of the alkyl chain length was found to be a key factor to reduce IL toxicity. On the other hand, phosphonium-based ILs containing long alkyl chains were shown to be largely incompatible with Shewanella sp.

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