Correlation between adhesion of aqueous solutions of nonionic and anionic surfactant mixture with short-chain alcohols to polymer surface and their adsorption at interfaces. I. Adhesion tension and adsorption

Contact angle measurements of aqueous solutions of a p-(1,1,3,3-tetramethylbutyl) phenoxypoly(ethylene glycol) (Triton X-100)/sodium dodecylsulfate (SDDS) mixture with a short-chain alcohol (methanol, ethanol or propanol) on polytetrafluoroethylene (PTFE) and nylon-6 surfaces were made. Complete spreading of the studied solutions was observed only in the case of nylon-6. Contact angle isotherms were considered with regard to alcohol activity as well as the adsorption of the surfactant mixture and alcohol at the polymer-solution interface. For this analysis solid-liquid interfacial tension and changes of adhesion tension as a function of the surface tension of the solution were taken into account. It appeared that in the range of alcohol concentration in which it is present in the monomeric form in the bulk phase, the Gibbs surface excess concentration of the surfactant mixture and alcohol at the PTFE-solution interface is close to that at the solution-air interface. However, alcohol activity at these interfaces differ from each other. The adsorption of the surface active agents at the nylon-6-solution interface is much lower than at the solution-air interface.     

Adhesion of resin cements to contaminated zirconia resin cements on zirconia: effect saliva-contamination and surface conditioning

This study evaluated the adhesion of resin cements to zirconia after saliva contamination using resin cements with different chemistries. Zirconia discs (N?=?240, n?=?10 per group) were randomly divided into three groups: (a) C: No contamination (Control), (b) S: Contamination with saliva, (c) S?+?AA: Contamination with saliva followed by air-abrasion (CoJet). While half of the specimens were not conditioned, the other half were conditioned with 37.5% H₃PO₄ for 60?s. After rinsing, all specimen surfaces were silanized (Monobond Plus). Resin cements based on either methacrylate (Variolink II–VL) or MDP monomer (Panavia 21-PN) were polymerized on the substrates. The specimens were randomly divided into two further groups to be tested either after (a) 24?h dry storage at 37?°C or (b) thermocycling (×5000, 5–55?°C). Microshear bond (MSB) tests were conducted in a Universal Testing Machine and failure types were analyzed. Data were analyzed using Univariate analysis and Tukey’s tests (alpha = 0.05). While saliva contamination, 37.5% H₃PO₄ application (p?<?.001) and aging (p?<?.05) significantly affected the bond results, cement type did not show significant difference after aging (p?>?.05). Adhesive strength of PN (1.2–4.4?MPa) on saliva contaminated and etched zirconia was more stable than that of VL (0–2.8?MPa). After aging, bond strength results decreased the most with VL (3–100%) compared to PN (32–71%) but the decrease was less in the air-abraded groups after aging (VL: 3%; PN: 32%). Exclusively adhesive failures were experienced in all groups.     

Adhesion of photocurable acrylates to solid polymer substrates

The adhesion of a hydrophilic (surface tension γ ≈ 40 mj/m²) and a hydrophobic (γ ≈ 30 mj/m²) photopolymerized acrylate lacuer a low-density polyethylene, polystyrene, polycarbonate, polymide-6-6, polyvinylchloride, polyethyleneterephthalate, poly-(1,1)-difluoroethylene, and polymethylmetacrylate has been investigated. A primary condition to obtain sufficient adhesion, as probed by the Scotch tape test, is that the surface tension of the lecquer has to be lower than the critical surface tension of the lacquer. There is no obvious correlation with possible doner/acceptor interactions between lacquer and substrate. Even when spreading occurs, other factors may cause insufficient adhesion. On polyamide, residual moisture on the surface is vary detrimental to adhesion. Extending the lag-time between application and curin reduced adhesion, in particular to polymers containing aromatic groups. This appears to be due to inhibition of the polymerization reaction by radiation-adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choicd of initiator and radiation-adsorbing aromatic groups in the swollen interphase. The effect can be avoided by proper choice of initiator and radiation source. Curing of the lacquers in a nitrogen atmosphere generally results in poor adhesion because the rate of polymerization/curing becomes very high compared with rats of relaxation of stresses in the lacquer.     

Adhesion of solid particles to gas bubbles. Part 2: Experimental

In slurry bubble columns, the adhesion of solid catalyst particles to bubbles may significantly affect the G-L mass transfer and bubble size distribution. This feature may be exploited in design by modifying the hydrophilic or hydrophobic nature of the particles used. Previously we have proposed a generalised model, describing the adhesion of particles to G-L interface under stagnant conditions. In this work, we studied the adhesion of particles characterised by different degree of hydrophobicity and porosity: non-porous polystyrene and glass beads, unmodified and hydrophobised mesoporous silica, and activated carbon particles. Images recorded at high optical magnification show the particles adhering to gas bubbles individually or as aggregates. In aqueous media, higher liquid surface tension and particle surface hydrophobicity increase the adhesion strength and the tendency of particles to agglomerate, in agreement with the model. The adhesion of non-porous rough-surface particles to gas bubbles can be characterised by the receding contact angle. The advancing contact angle represents better the adhesion of the same particles to liquid droplets. We found that the “effective” contact angle of porous particles is much lower than an “intrinsic” contact angle calculated from the heat of immersion in water, or measured by sessile drop method. An equivalent contact angle derived from the Cassie rule explains the wetting behaviour of particles having the pores filled with liquid.     

Adhesion of orthodontic brackets to indirect laboratory-processed resin composite as a function of surface conditioning methods and artificial aging

This study compared the shear bond strength of orthodontic brackets to laboratory-processed indirect resin composites (IRC) after different surface conditioning methods and aging. Specimens made of IRC (Gradia Indirect, GC) (thickness: 2 mm; diameter: 10 mm) (N = 80) were randomly assigned to one of the following surface conditioning methods: C – Control: no treatment; AA – Air-abrasion (50 μm Al₂O₃ particles); DB – Diamond bur and HF – Etching with hydrofluoric acid (9.6%). After adhesive primer application (Transbond XT), orthodontic brackets were bonded to the conditioned IRC specimens using adhesive resin (Transbond XT). Following storage in artificial saliva for 24 h at 37 °C, the specimens were thermocycled (×1000, 5–55 °C). The IRC–bracket interface was loaded under shear in a Universal Testing Machine (0.5 mm/min). Failure types were classified using modified adhesive remnant index criteria. Data were analyzed using two-way ANOVA and Tukey`s HSD (α = 0.05). Surface conditioning method did not significantly affect the bond strength results (p = 0.2020), but aging significantly decreased the results (p = 0.04). Interaction terms were not significant (p = 0.775). In both non-aged and aged conditions, non-conditioned C group presented the lowest bond strength results (MPa) (p < 0.05). In non-aged conditions, surface conditioning with DB (8.03 ± 0.77) and HF (7.87 ± 0.64) showed significantly higher bond strength results compared to those of other groups (p < 0.05). Thermocycling significantly decreased the mean bond strength in all groups (2.24 ± 0.36–6.21 ± 0.59) (p < 0.05). The incidence of Score 5 (all adhesive resin remaining on the specimen) was the highest in HF group without (80%) and with aging (80%) followed by DB (40, 70%, respectively). C groups without and with aging showed exclusively Score 1 type (no adhesive resin on the specimen) of failures indicating the least reliable type of adhesion.     

高聚物溶液在固体炸药表面上的湿润性

通过测试接触角，从湿润热力学和动力学2方面研究了丙烯腈苯乙烯共聚物(AS)溶液在不同粒径的三氨基三硝基苯(TATB)炸药表面湿润性，并结合紫外光谱法探讨了湿润性与吸附量之间的关系。研究结果表明，随着聚合物溶液浓度的增加，AS溶液在TATB表面上的湿润性变差．湿润速度减小。溶剂种类和该炸药粒径不同，其湿润性也不同；若聚合物溶液在固体炸药表面湿润性好．则其在炸药表面上的吸附量大。     

Adhesion of microorganisms to polymer membranes: a photobactericidal effect of surface treatment with TiO2

The adhesion of Escherichia coli, Pseudomonas putida and Acinetobacter calcoaceticus cells to Microdyn-Nadir ultrafiltration membranes of various chemical nature: PS100 (polysulfone), P005 (polyethersulfone), C100 (regenerated cellulose) was studied. It was shown that an adhesiveness of the microorganisms to the membranes essentially depends on hydrophobic/hydrophilic properties of both the cells and membranes. In particular, it was found that the adhesion of relatively hydrophilic E. coli to membrane surfaces is essentially lower comparing with the adhesion of more hydrophobic P. putida, or A. calcoaceticus cells. In a turn the microorganisms attachment to more hydrophobic polyethersulfone and polysulfone membranes is higher than to hydrophilic cellulose one. It was shown that the volume fluxes of membranes with adhesive microorganisms dropped while samples were kept in contact with natural surface water due to increasing of cell number on membrane surface. In attempts to reduce membrane biofouling, TiO₂ particles were deposited on membrane surface with following ultraviolet (UV) irradiation at 365 nm. It was shown that due to photobactericidal effect the fluxes of surface modified membranes were 1.7–2.3 times higher comparing with those for control membrane samples (without TiO₂ deposition and UV treatment).     

Adhesion potential of relining materials to polyamide and PMMA-based denture base materials: effect of surface conditioning methods

This study evaluated the bond strength of relining materials to different denture base materials polyamide and polymethylmethacrylate denture base materials after various surface conditioning methods. Denture base resin specimens (N?=?128; n?=?8 per group) (10?×?10?×?2.5?mm³) were fabricated out of injection-moulded thermoplastic polyamide resin (POL) (Deflex) and heat-polymerized polymethylmethacrylate (PMMA, Dura Dent) (HC). The specimens were randomly divided into 4 main groups according to different surface conditioning methods: (a) No conditioning, control (C), (b) grinding with green stone (G), (c) application of primer (V), (d) silica coating with Al₂O₃ particles coated with SiO₂ (Rocatec) (R). Half of the specimens in each group received auto-polymerized hard relining resin (GC, GC Reline Hard) and the other half PMMA based relining resin (SC, Dura Dent). After thermocycling (×5000), the bonded specimens were tested under tensile forces (0.5?mm/min). Data (MPa) were analyzed using Mann–Whitney U and Kruskal–Wallis tests (alpha = 0.05). Bond strength of relining resins were significantly higher to PMMA than to POL, regardless of the conditioning method (p?<?0.05). While R positively affected the bond strength results (p?<?0.05) (4.99?±?1.65–3.27?±?1.31), application V or G did not show significant effect to POL-relining resin adhesion. After R conditioning, bond strength values were significantly higher in HC-GC group (7.48?±?2.32) than POL-GC group (3.27?±?1.31) (p?<?0.05). Adhesion of auto-polymerized relining materials to thermoplastic polyamide or polymethylmethacrylate denture resins could be improved after surface conditioning with silica-coating.     

Simulation of a flexible polymer tethered to a flat adsorbing surface

A lattice self‐avoiding polymer chain with one end attached to an adsorbing flat surface is simulated using Monte Carlo method. The chain model has z = 26 bond vectors with bond length being 1, , and on the simple cubic lattice. The dependence of the number of surface contacts M on temperature T in the unit E/k_B with E the interacting energy and k_B the Boltzmann constant and chain length N is investigated by a finite‐size scaling law M = N^?(a₀ + a₁(T ? T_c)N^1/δ + O((T ? T_c)²N^2/δ)) near the critical adsorption point T_c. It was estimated that T_c = 1.625 and the exponents ? = 0.52 and δ = 1.63. It was observed that both mean square end‐to‐end distance 〈R²〉 and mean square radius of gyration 〈R〉 reach minimum at T_c. And we discover that the asphericity parameter 〈A〉 is independent of chain length at T_c. A simple relationship is discovered between T_c and bond vector number n_b for lattice chain models, and which can be extended to nonlattice chain models by introducing an attraction range fraction f. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adhesion at copper- polyamide 11- copper and aluminum-poly amide 11-aluminum laminate interfaces: influence of metal surface oxidation

Adhesion at copper-polyamide 11-copper and at aluminum-polyamide 11-aluminum laminate interfaces was studied. Metal-polymer-metal laminates were prepared by compression molding using processing conditions similar to the normal melt processing of polyamide 11. The results show that the time of contact at the molding temperature required to reach a constant level of adhesion is significant. Mild oxidation of the metal prior to molding improves the adhesion of polyamide 11 to aluminum; with copper, a monotonic slow decrease in adhesion with the oxidation time is observed. The presence of a metal surface affects the crystallization behavior of polyamide. With a cooling rate of 40-50°C/min, an approximately 15 μm transcrystalline polymer layer is formed with a degree of crystallinity that is almost 10% higher than the material away from the interface. The metal substrate surface oxidation prior to molding does not change the crystallinity profile of the polymer in the bulk. The polymer surface crystallinity is also a function of the time of contact with the metal substrate. The cooling rate and the metal substrate structure and its nucleating activity are responsible for the surface/bulk crystallinity ratio. Although the highly-crystalline polymer surface layer improves the adhesion to some extent, the formation of active species on the polymer surface which are able to react with the metal surface is mostly responsible for the increase of adhesion with time and its ultimate strength.     

Elastica bend testing of the effective interfacial shear strength and critical deformation strains of brittle coatings on ductile substrates

An elastica bend test is described that provides a rapid, convenient, and reproducible means for examining the interfacial delamination of brittle coatings on ductile substrates. By bending a coated strip into a half-loop and examining the microscopic cracking that is observed on the sample surface as the loop size decreases, information is obtained about the characteristic initial, mean, and final strains _i, _m and _f that describe the distribution in strength of the coating. By measuring the distance between the cracks at high strains, we obtain an estimate of the interfacial shear strength τ.     

Synthesis and behavior of the polymer covering on a solid surface. II. Effect of the adsorbent particle size on adsorption

Adsorption of poly(5-tert-butylperoxy-5-methyl-1-hexen-3-yne-co-maleic anhydride) and poly(styrene-co-maleic anhydride) on the various ultrafine powders (TiO₂, ZnO, Al₂O₃, CaCO₃, aerosil, and quartz powder) was studied. Plateau adsorption amount per unit surface of adsorbent (a^s) decreased with the decreasing of particle size of the adsorbent. The a^s-molecular mass relationship was different for copolymers of low and high molecular mass. The fractal dimension D = 2.5 of adsorbent surface was determined if the particle radius was less than 2.5 μm. Fractal behavior was explained by aggregation of particles. Due to the aggregation the interparticle space (pore) in the area of contact of neighboring particles is inaccessible for the polymer and accessible for the solvent. The experimental isotherm with maximum was employed for estimation of the volume of inaccessible pores 2.4 cm³/g for suspension of aerosil. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 299–305, 1998     

Adhesion of resin cement to contemporary hybrid ceramic and polymeric CAD/CAM materials: effect of conditioning methods and ageing

This study assessed the effect of different surface conditioning methods and ageing protocols on adhesion of resin cement to hybrid ceramic and polymeric CAD/CAM materials. CAD/CAM materials (n?=?360, n?=?30 per group), namely (a) Lithium disilicate (IPS e.max CAD-LIS), (b) Zirconia (IPS e.max ZirCAD-ZIR), (c) Polymer (Lava Ultimate-LAV), (d) Polymer infiltrated ceramic network (Enamic-ENA), (e) Polymer infiltrated ceramic (Experimental-1-CS1), (f) Polymer infiltrated ceramic (Experimental-2-CS2), (g) Lithium disilicate reinforced alumina (n!ce-NIC) were cut into slices (3?×?6 × 8?mm³) and conditioned: (a) Method 1: 5% hydrofluoric acid etching (H)+silane and (b) Method 2: Silica coating (CoJet (A)+silane). Group LIS was conditioned with only Method 1 and Group ZIR only with Method 2 (control). Resin cement (Variolink Esthetic II) was bonded onto the conditioned specimens and photopolymerized. One-half of the specimens was subjected to ageing (thermocycling 5–55°, 5000 cycles) and the other half was stored in distilled water (37?°C, 24?h). The resin-substrate interface was loaded under shear forces in a Universal Testing Machine (1?mm/min). Data (MPa) were analyzed using two-way ANOVA and Tukey`s tests (α?=?0.05). Substrate type, conditioning method and ageing had a significant effect on adhesion values (p?<?.05). In aged conditions, ENA-H, ENA-A, LAV-H, LAV-A, CS2-A (15?±?4 – 11.6?±?5) showed no significant difference (p?>?.05), with the CS2-A (15?±?4) showing the least reduction (5.5%) compared to all other groups (5.8–62.6%). CS1-A (100%) followed by ENA-H, ENA-A (93%), CS2-A (80%) presented the highest incidence of cohesive failures after ageing.     

XPS法研究表面活性剂、碱和聚合物在固体颗粒表面吸附的协同效应

利用光电子能谱法(XPS)研究了表面活性剂、碱和聚合物在固体颗粒表面上的吸附量及相互之间的协同效应。表面活性剂和碱在S iO2固体颗粒上的最大吸附量随着浓度的增大而增加,分别在1 200,5 000 mg/L达到最大吸附量1.15 mg/g和1.65 mg/g,吸附量达到最大值后趋于稳定;聚合物的平衡吸附曲线随着浓度的增大吸附量先增加后减少,600 mg/L达到最大吸附量1.30 mg/g,后减小至0.40 mg/g基本不变;在表面活性剂、碱和聚合物复合吸附体系中,碱的存在大大降低了表面活性剂在固体表面上的吸附量,在一定程度上增加了聚合物在固体表面上的吸附量,聚合物和表面活性剂在共存竞争吸附影响下S iO2表面上的吸附量都有了较大的减少;在表面活性剂、碱和聚合物复合体系中,聚合物与碱协同吸附的固体表面吸附层比其它情况下厚。     

Measurement of the Adhesion of a Viscoelastic Sphere to a Flat Non-Compliant Substrate

The adhesion between a single polystyrene bead (radius, 27 μm) and a flat silica surface has been measured with an atomic force microscope as a function of two variables: (a) The maximum applied load and, (b) the loading time at a constant maximum applied load. Analysis of the results indicates significant plastic deformation of the bead under the action of the load forces. There is also evidence for time-dependent viscoelastic effects as a load is exerted on the bead. The contact zone of the polystyrene bead used for these experiments was examined using Scanning Electron Microscopy. The microscope images revealed a surface covered in small polymer beads with a radius of only 115 nm. In the contact zone these beads had undergone substantial and permanent deformation as a function of the applied load. Basic geometric analysis reveals that the large sphere is not contacting the flat surface under any load. The results presented here indicate the value of being able to measure adhesion using an atomic force microscope. The importance of being able to characterise the contact zone accurately is also highlighted.     

Measurement of the Adhesion of a Viscoelastic Sphere to a Flat Non-Compliant Substrate

The adhesion between a single polystyrene bead (radius, 27 μm) and a flat silica surface has been measured with an atomic force microscope as a function of two variables: (a) The maximum applied load and, (b) the loading time at a constant maximum applied load. Analysis of the results indicates significant plastic deformation of the bead under the action of the load forces. There is also evidence for time-dependent viscoelastic effects as a load is exerted on the bead. The contact zone of the polystyrene bead used for these experiments was examined using Scanning Electron Microscopy. The microscope images revealed a surface covered in small polymer beads with a radius of only 115 nm. In the contact zone these beads had undergone substantial and permanent deformation as a function of the applied load. Basic geometric analysis reveals that the large sphere is not contacting the flat surface under any load. The results presented here indicate the value of being able to measure adhesion using an atomic force microscope. The importance of being able to characterise the contact zone accurately is also highlighted.     

Imaging in evaluation of polymer coatings adhesion to glass at high humidity

Adhesion reduction occurring after polymer coated glass was immersed in water was studied in a variety of UV-cured urethane acrylate coatings containing alkyloxysilane adhesion promoting additives. It was observed that water accumulated under the coating surface in drops and formed ‘blisters’ in the glass-polymer interface. A non-destructive imaging technique was developed to measure the average size of the water blisters. The size of the water blisters within the interface was correlated with the wet adhesion force measured by coating resistance to 180° peel. The force of coating resistance to 180° peel off glass surface decreased non-linearly with the increase of the average size of the water blisters. It was concluded that the decrease in adhesion between the coating and glass was a result of stretching and breaking of the silane bridging bonds and polymer fibrils by water condensing on the glass surface within the polymer-glass interface. The mathematical model relating coating wet peel resistance force with the size of the debonding produced by water accumulation was presented.     

Polymer-Polymer Adhesion in the Presence of Compatibilizer

The influence of compatibilizers in three types of joints-natural rubber (NR)-polyethylene (PE), silicone rubber (Si)-ethylene propylene diene rubber (EPDM) and hydrogenated nitrile rubber (HNBR)-nylon has been demonstrated. The compatibilizers increase the peel strength in every case. The results are explained with the help of new approaches based on (1) strain energy density, (2) reptation scaling theory. It is observed that the diameter of the strained tip for NR-PE and Si-EPDM systems increases in the presence of compatibilizers. Also, the peel strength of the HNBR-nylon joint has a first power dependence on the interfacial thickness.     

A Method for Measuring the Adhesion Strength of Powder Coatings

A method for testing and quantifying the adhesion strength of particulate coatings was developed. A gas impingement test was developed to measure adhesion forces of electrophoretically-deposited layers of phosphor particles for use as information display screens. A high pressure jet of nitrogen gas is directed perpendicularly to a particulate deposit. The particles are removed from the substrate in a ring pattern which can be correlated to the skin friction on the substrate, giving a measurement of adhesion strength in the range of 100 to 450 Pa.