Effect of filler surface state on the properties of polyethylene composites

Treatment of the filler surface may either strengthen or weaken the forces of adhesion between the filler and the polyethylene matrix, thereby affecting the coefficient of linear expansion. Reduction of the adhesion by the creation of a polyalkylsiloxane (antiadhesive) film on the surface of silicate fillers leads to an increase in the coefficient of linear expansion (up to 80%) as compared with an annealed or paraffined surface. Radiation-induced crosslinking of the polysiloxane film and the polyethylene reduced the expansion coefficient. Surface treatment of the filler will reduce the wear of the composite, especially one filled with fine metal powder, the coefficient of fraction remaining unchanged.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1038–1045, November–December, 1969.     

Cross-linked thermoplastic blends of polyethylene with an elastomer 4. Thermorelaxation and adhesion characteristics

The results of an experimental investigation of changes in the thermorelaxation and thermoshrinkage stresses and the strength of adhesion joints with steel of binary blends of high-density polyethylene with an elastomer (ethylene-propylene-dicyclopentadiene terpolymer) in the course of γ-radiation and chemical cross-linking are reported. The interconnection/relationship between the highest values of the stresses, as well as the characteristics of formation processes of the joints, and certain structural characteristics of the blends (content of their cross-linked part, the degree of crystallinity, etc.) is discussed. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 2, pp. 265–278, March–April, 2006.     

Adhesion bond and temperature stresses at the polymer - filler interface in polyethylene composites

The temperature stresses in polyethylene composites with fibrous fillers have been estimated. It is shown that they do not represent a threat to the adhesion bond or the cohesion strength of the components of the systems investigated. Model experiments have revealed the presence of an adhesion interaction between the filler and the matrix in the composite itself and have made it possible to estimate the actual threat posed by the temperature stresses. The mechanism of action of the filler particles on the thermal expansion of the composite is explained.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 1049–1056, November–December, 1970.     

Effect of the conditions of bond formation and destruction on the adhesion of polymers to synthetic fibers

It is shown that the adhesion of linear polymers can be measured by shearing a monofilament relative to a microblock of adhesive [1]. Experiments have been performed on polypropylene, polyethylene terephthaliate, polycaprolactam, polyvinyl alcohol, and glass fibers. Broad variation of the diameter, structure, and physicomechanical properties of the various kinds of oriented fibers had practically no effect on the adhesion. The physicochemical properties of the adhesive solutions at the moment of application to the fiber likewise do not affect the adhesion which, other things being equal, is determined by the nature and supermolecular structure of the polymers in the contact zone.Belorussian Lenin State University, Minsk. Branch of the Karpov Scientific-Research Physicochemical Institute, Obninsk. Translated from Mekhanika Polimerov, No. 6, pp. 1042–1048, November–December, 1970.     

Allowance for boundary dislocations in the theory of adhesion of polyethylene to alkali halide crystals

The correction to the energy of adhesion of polyethylene on three alkali halide crystals, due to boundary dislocations resulting from the difference in lattice constant, is calculated. It is found that, in the examples considered, the dislocation energy is only 4 to 6% of the adhesion energyA. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 3, pp. 533–536, May–June, 1976.     

Adhesion of filled polyethylene compositions to steel

The adhesion to steel of polyethylene filled with a number of inorganic fillers has been investigated. Adhesion is shown to be affected by the filler content, the condition of the steel surface, and the bonding conditions.Mekhanika Polimerov, Vol. 2, No. 2, pp. 245–252, 1966     

“Fundamental” and “practical” adhesion in polymer-fiber systems

The relationship between adhesion and bond strength in thin fiber-polymer matrix systems was studied. Adhesive interaction in composite materials was analyzed within the scope of thermodynamic and molecular-kinetic theories of adhesion. Methods based on wetting are shown to give poor estimation of the work of adhesion in fiber-polymer systems, which is due to their low sensibility to donor-acceptor interactions taking place at the interface. Important information about the acidity and basicity of contacting surfaces can be obtained by using inverse gas chromatography to investigate the thermodynamics of adsorption. The calculation of the work of adhesion including acid-base interactions shows the best agreement with the bond strength in the same systems. The local (ultimate) interfacial shear strength is proposed to characterize the quality of fiber-matrix bonding. Analysis of the relationship between the work of adhesion and adhesive pressure for various systems allowed us to differentiate the dispersive and acid-base components of the local bond strength as well as to estimate distances characteristic of these twoTypes of interaction. For dispersive forces, our estimation gives 7–8Å, i.e., of an order of magnitude of the center-to-center distance for van der Waals interactions. At the same time, the acid-baseInteractions have a characteristic range of 4–5Å and can be attributed to hydrogen bonding. The agreement between the calculated distances and literature data is evidence for the applicability of the proposed method to the analysis of the adhesive interaction in fibrous polymer composites.Presented at the 10th International Conference on the Mechanics of Composite Materials (Riga, April 20–23, 1998).Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 4, pp. 431–446, July–August, 1998.     

Characterization of ZnO: Al films deposited by r.f. magnetron-sputtering at low temperature

Transparent conducting ZnO: Al thin films with good adhesion and low resistivity have been prepared on organic substrates and Corning 7059 glass substrates by r.f. magnetron-sputtering technique at low substrate temperature (25–210°C). Structural and photoelectric properties of the deposited films are investigated. The deposited films are polycrystalline with hexagonal structure and a preferred orientation with the c-axis perpendicular to the substrate. Only the (002) peak is observed. High quality films with resistivity as low as 1.0 x 10^-3Ω·cm and 8.4 x 10^-4Ω·cm, the average transmittance over 74% and 85% in the wavelength range of the visible spectrum have been obtained on different substrates.     

Estimation of the quality of adhesion of a metallic coating to a polymer film using the scratch method

A method of determining the quality of adhesion of a metallic coating to a polymer film at coating thicknesses of 1000–3000 Å and film thicknesses of 10–100 µ using the scratch method is described. The results of testing various aluminized polyethylene terephthalate and polyethylene film specimens, differing with respect to the treatment of the polymer surface before deposition of the metal, are presented. The aluminization vacuum was 5 · 10^?4 or 9 · 10^?3 mm Hg.     

Formation of the adhesion bond between polyethylene and solids

When a coating of low-density polyethylene on steel or aluminum is heat-treated, the adhesion strength increases linearly from zero to values exceeding the strength of the film. This is caused by the metal-catalyzed oxidation of the polymer in the contact zone by oxygen diffusing through the film.Ural Scientific-Research Chemical Institute, Sverdlovsk. Translated from Mekhanika Polimerov, No. 5, pp. 932–934, September–October, 1970.     

The use of polyolefins-based hot melts for wood bonding

The shear strength of three-layer birch veneer/polyolefin/birch veneer lap joints has been investigated. It was found that the optimum technological parameters for producing three-layer laminated systems (plywood) at 180°C were a pressure time of 1-3 min (plus 3-min preheating) and pressure of 5-10 MPa. All the systems investigated exhibited relatively high values of shear strength, which were higher than those of the industrially produced plywood based on phenol-formaldehyde glues (3.5-5 MPa). It is shown that the use of interfacial modifiers can increase the shear strength by 50% compared with its initial values. The high shear resistance is explained by the high mechanical adhesion between the hot melts and the wood substrate. After a prolonged moisture influence (70 days at relative air humidity of 80%), all the systems investigated showed a considerable (up to 25%) increase in the shear strength. This can be explained by swelling of birch veneer, which gives rise to additional resistance forces between the hot melt and the substrate.     

Residual stresses in glass-reinforced polyethylene

The variation of the axial and radial components of the residual stresses in fiber-reinforced polyethylene with distance from the fiber has been investigated. It is shown that, irrespective of the agent employed, coupling leads to an increase in stresses. The values obtained for the residual stresses are compared with the adhesion strength determined by the shearing method. The effect of a structure-forming agent on the residual stresses is investigated.Mendeleev Moscow Chemical Engineering Institute. Translated from Mekhanika Polimerov, No. 4, pp. 722–724, July–August, 1971.     

Effect of the substrate on the strength of adhesive-bonded joints

The possibility of the adhesion failure of adhesives is discussed. It is shown that the properties of the adhesive film depend on the physicomechanical characteristics of the substrate as a result of the action of molecular forces.V. I. Lenin All-Union Electrotechnical Institute. Translated from Mekhanika Polimerov, No. 2, pp. 295–300, March–April, 1972.     

Effect of temperature and strain rate on the adhesion of polyvinyl butyral to glass

The shear strength of silicate glass bonded with polyvinyl butyral has been investigated over a broad temperature interval together with the effect of plasticization of the polymer on the strength of the bond. The _adh ^–t curves have intervals corresponding to adhesion failure, cohesion failure of the substrate, and cohesion failure of the adhesive, respectively. The dependence of adhesion on strain rate has been investigated and a maximum observed at 20 mm/min.Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1104–1107, November–December, 1970.     

Temperature-time dependence of the adhesion strength for polymer — Polymer systems

The temperature — time dependence of the adhesion strength has been studied for polymer systems differing in the thermodynamic compatibility of the substrate and adhesive and in the rate of polymerization of the latter. The fracture-activation energies of these systems have been calculated. It is shown that the temperature — time dependence of the adhesion strength varies depending on whether chemical intermolecular forces are responsible for the strength of the joint.Perm Scientific-Research Institute of Polymer Materials. A. M. Gor'kii Ural State University. Translated from Mekhanika Polimerov, Vol. 4, No. 4, pp. 665–671, July–August, 1968.     

The Effect of Adhesion Interaction on the Mechanical Properties of Thermoplastic Basalt Plastics

The effect of temperature, adhesion time, and surface treatment of a reinforcing filler on the mechanical properties of thermoplastic basalt plastics based on a high-density polyethylene and a copolymer of 1,3,5-trioxane with 1,3-dioxolan is investigated. An extreme dependence for the adhesive strength in a thermoplastic-basalt fiber system is established and its effect on the mechanical properties of basalt plastics and the influence of the adhesion contact time on the adhesive strength in the system are clarified. The surface modification of basalt fibers in acidic and alkaline media intensifies the adhesion of thermoplastics to them owing to a more developed surface of the reinforcing fibers after etching. It is found that the treatment in the acidic medium is more efficient and considerably improves the mechanical properties of basalt plastics.     

A study of glass reinforced polyethylene

The effect of dressing a fiber on the wetting of it by a polyethylene melt is studied. The interconnection between the value of the adhesive strength and the residual stresses at the boundary between the glass fiber and polymer is analyzed. The role of the residual stresses during use of the glass-reinforced material and the part played by the chemical interaction between the polyethylene and the fiber in the water-resistant composition obtained in this way is analyzed.D. I. Mendeleev Moscow Chemicotechnical Institute. Translated from Mekhanika Polimerov, No. 6, pp. 1048–1052, November–December, 1972.     

Two-dimensional adhesion mechanics of a graded coated substrate under a rigid cylindrical punch based on a PWEML model

The paper aims at the contact mechanics of functionally graded coated substrate by taking into the adhesion effect. The coating-substrate structure is indented by a cylindrical punch to form a contact region where the adhesion forces are described by using the Maugis adhesion model. A piece-wise exponential multi-layered (PWEML) model is used to simulate the functionally graded materials with arbitrary spatial variation of material properties. This model divided the functionally graded coating into several sub-layers in which the elastic parameter varies as exponential form. Using the Fourier transform technique and the Transfer matrix method, the boundary value problem for adhesive contact of graded coated substrate is reduced to the singular integral equation. Some numerical results are presented to analyze the influence of gradient index on the pull-out force, contact stresses and adhesion region. The results can be applied to improve the performance of the coating by adjusting the gradient index.     

Transportation of dry fine powders by coordinated friction manipulation

The transportation of dry fine powders is an emerging technologic task, as in biotechnology, pharmaceutical or coatings industry particle sizes of processed powders are getting smaller and smaller. Fine powders are primarily defined by the fact that adhesive and cohesive forces outweigh the weight forces. This leads to mostly unwanted agglomeration (clumping) and adhesion to surfaces, what makes it more difficult to use conventional conveyor systems (e. g. pneumatic or vibratory conveyors) for transport. A rather new method for transporting these fine powders is based on ultrasonic vibrations, which are used to reduce friction and adhesion between powder and the substrate. One very effective set-up consists of a pipe, which vibrates harmoniously in axial direction at low frequency combined with a pulsed radial high frequency vibration. The high frequency vibration accelerates the particles perpendicular to the surface of the pipe, which in average leads to lower normal and thereby smaller friction force. With coordinated friction manipulation the powder acceleration can be varied so that the powder may be greatly accelerated and only slightly decelerated in each excitation period of the low frequency axial vibration of the pipe. The amount of powder flow is adjustable by vibration amplitudes, frequencies, and pulse rate, which makes the device versatile for comparable high volume and fine dosing using one setup. Within this contribution an experimental set-up consisting of a pipe, a solenoid actuator for axial vibration and a piezoelectric actuator for the radial high frequency vibration is described. An analytical model is shown, that simulates the powder velocity. Finally, simulation results are validated by experimental data for different driving parameters such as amplitude of low frequency vibration, pipe material and inclination angle. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A polymer film hardening effect

It is shown that a polyester film incapable of forced high-elastic deformation can be subjected to such deformation by stretching a film-substrate system. The resulting oriented structure is stable and on being measured from the substrate, the film exhibits a hardening effect. In this case contact with and adhesion to the substrate are a necessary condition for the development of the latent potential of the film.Lenin All-Union Electrical Engineering Institute, Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 731–733, July–August, 1971.