Thermal expansion of a composite with a hybrid granular-fibrous filler

Conclusion The thermal deformation of LDPE with a granular-fibrous filler was studied experimentally within a broad temperature range. We analyzed the effect of fillers on characteristics of relaxational transitions in LDPE as determined from dilatometric tests. A method was proposed for calculating the effective CLE of a composite with allowance for aggregation of a powdered filler and the statistical distributions of the length and orientation of the anisotropic fibers. The method was substantiated experimentally. Results were also presented of a theoretical analysis of the effect of the parameters of the fiber distributions f(l.) and (, ) and the relative volume contents of granular and fibrous fillers on _ij for the composite. It was established that aggregation of the granular filler may produce a hybrid effect consisting of maximum suppression of thermal expansion of the binder by the combination filler relative to a two-component composite.Translated from Mekhanika Kompozitnykh Materialov, No. 2, pp. 237–246, March–April, 1989.     

Thermal expansion of a polymer composite with an aggregating disperse filler

Conclusion The thermal deformation of HDPE with an aggregating disperse filler was experimentally studied in a wide range of temperatures. The effect of the filler on the characteristics of relaxation transitions in HDPE, determined from dilatometric tests, was analyzed. A method of calculating the effective thermal expansion coefficient of a composite with an aggregating filler was proposed. Satisfactory agreement between the calculated and experimental data was obtained. It was shown that the effect of aggregation results in a significant decrease in the thermal expansion coefficient of the composite.Translated from Mekhanika Kompozitnykh Materialov, No. 1, pp. 70–77, January–February, 1989.     

Effect of disperse mineral fillers on the strain-strength properties and crack resistance of cured polyesters

Conclusion The tendency of disperse mineral fillers toward aggregation, with the formation of a continuous framework of particles, when filler content is greater than the SCC is manifest in a sharp increase in the difference between the relative viscosity of polyester binder-pastes in the uncured state and the relative elastic modulus in the cured state. It is also manifest in an increase in the relative modulus and a reduction in crack growth energy in cured composites. In this case, there is an especially large increase in the size of the characteristic defect, which ultimately determines the reduction in the breaking stress. The modification of binder-pastes with surfactants increases filler dispersion and makes it possible to increase the strength of cured composites.Presented at the Sixth All-Union Conference on the Mechanics of Polymer and Composite Materials (Riga, November, 1986).Translated from Mekhanika Kompozitnykh Materialov, No. 5, pp. 819–824, September–October, 1987.     

Prediction of the deformation properties of a polymeric composite with a granular-fibrous filler

Conclusion A variant of calculation of the characteristics of the deformation properties of a hybrid composite containing a complex disperse filler in the form of granular particles and short fibers was proposed. The effect of aggregation of the granular filler, the statistical distributions of the fibers by lengths and orientation in the material, and the anisotropy of the fibers are taken into consideration in the calculation. The statistical distribution of the orientation of the fibers is given by a function proportional to the distance from the center to the surface of a triaxial ellipsoid in the corresponding direction. The uniform random distribution of the fibers in bulk and in the plane is a special case of this distribution. The results of the analysis of the effect of the parameters of the statistical distributions of the length and orientation of short fibers on the elasticity characteristics of a composite are reported. The dependence of the creep of the composite on the ratio of the concentration of the components of the complex filler was determined, and the efficiency of partial replacement of a granular filler by a short-fiber filler to inhibit creep of the composite was demonstrated. The possibilities of predicting the long-term creep were experimentally confirmed on the example of LDPE filled with ground limestone and short glass fibers.Presented at the Sixth All-Union Conference on the Mechanics of Polymer and Composite Materials (Riga, November, 1986).Translated from Mekhanika Kompozitnykh Materialov, No. 5, pp. 898–909, September–October, 1987.     

On stability of linear hybrid mechanical systems with distributed components

We present a new approach to the solution of problems of stability of hybrid systems based on the constructive determination of elements of a matrix-valued functional. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, No. 2, pp. 204–216, February, 2008.     

The effect of fullerene fillers on the mechanical properties of polymer nanocomposites

The effect of fullerene and carbon fillers on the mechanical properties of polymer nanocomposites based on thermoreactive (epoxy resin) and thermoplastic (polyamide-12) matrices was investigated. It was found that the introduction of these fillers did not affect the properties of the thermoreactive blends, but Young’s modulus and the tensile strength of the thermoplastic ones increased by about 30-40% upon addition of 0.02-0.08 wt.% fullerene materials. The best results were obtained for a mixture of C ₆₀/C ₇₀.     

Reinforcement of epoxy compounds with fillers

The mechanical and physicochemical properties of epoxy compounds containing different amounts of a series of fillers have been investigated. The strength characteristics of compounds with reinforcing fillers improve, starting from very low concentrations, pass through a maximum, and then fall at large concentrations. In the case of nonreinforcing fillers, the strength falls, slowly at first, and then, beyond a certain critical concentration, much more rapidly. Electron microscope studies have shown that reinforcement of the resin is associated with deep-seated changes in supramolecular structure, which passes from globular to partially fibrillar when the resin is cured in the presence of fillers. On the basis of the studied concentration laws a method is proposed for characterizing the reinforcing effect of fillers with respect to the particular property tested and a given production technology.Mekhanika Polimerov, Vol. 3, No. 6, pp. 1060–1065, 1967     

Dynamic diagnostics of mechanical manufacturing systems

We consider an approach to the computation of the dynamic parameters of a kinematic system based on the Chebyshev approximation of the trajectory of the process. We give recursion relations for estimating the approximation error. Translated fromDinamicheskie Sistemy, Vol. 11, 1992.     

Dynamic mechanical properties of multicomponent polymeric compositions

The mechanical relaxation processes in rubber-polymer compositions have been investigated by the forced nonresonance vibration method. A method of evaluating black-filled polymer mixtures with advantages over microscopic methods is proposed.Scientific-Research Institute of the Tire Industry, Moscow. V. I. Lenin Moscow State Pedagogical Institute, Laboratory of Problems in Polymer Physics. Translated from Mekhanika Polimerov, No. 1, pp. 138–141, January–February, 1970.     

Effect of powdered mineral fillers on the crosslinking of phenol-formaldehyde oligomers and the mechanical properties of the molding materials

By investigating the effect of various powdered oxides on network formation in phenolformaldehyde oligomers, it has been established that nonionogenic oxides increase the number of network defects in proportion to the surface energy of the powder. Small amounts of ionogenic oxides with a divalent cation cause the formation of new ionic or ionic-coordination linkages in the polymer network. The effect of mineral powders on polymer network formation is correlated with the mechanical properties of molding materials based on phenol-formaldehyde polymers with different network densities.Moscow Aviation Technological Institute. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1033–1042, November–December, 1968.     

Properties of fillers and reinforcing fibers

Fillers have always played an important role in the plastics industry. Filled polymers form a specific class of composites, which are tending to replace many traditional materials. Various kinds of organic fillers are used. The experimental study of such nonconventional organic and inorganic fillers obtained from agricultural waste is presented to modify the properties of thermoplastics, such as pVC, HDPE, LDPE, and ABS. The properties obtained by using these fillers alone and in combinations show very interesting results, which are tabulated. The use of organic fillers should help lower the cost of many plastic products required in the building and agricultural industries.Presented at the 10th International Conference on the Mechanics of Composite Materials (Riga, April 20–23, 1998).Maharashtra Institute of Technology, Pune, India. Published in Mekhanika Kompozitnykh Materialov, Vol. 34, No. 5, pp. 651–663, September–October, 1998.     

Dynamic mechanical properties of a heavily filled rubber

The acoustico-mechanical properties of a heavily filled rubber (70% by vol. NaCl) are investigated over a broad frequency-temperature interval. It is shown that there are various qualitative differences as compared with unfilled polymers. The effects of tensile strain and hydrostatic pressure on the dynamic properties of a heavily filled rubber are also determined.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 4, 688–692, July–August, 1968.