Effect of aging on the lifetime of industrial polyimide film

Results are given of a study of the thermomechanical properties of industrial polyimide film at constant mechanical-stress values and on nonlinear change in temperature with time. The effect of thermal aging and of irradiation with neutrons on polyimide (PM) film is examined. From the experimental data obtained, the possibility is presented of predicting the "service life" of material over a wide range of mechanical loads and temperatures.S. M. Kirov Polytechnic Institute, Tomsk. Translated from Mekhanika Polimerov, No. 6, pp. 1046–1049, November–December, 1974.     

Investigation of the structure and physicomechanical properties of polypropylene film

The authors have investigated the effect of the dynamic degree of crystallinity, stereoisomeric composition, intrinsic viscosity, and other factors on the nature of the structure formed when polypropylene is made into film and on the physicomechanical properties of the film.Mekhanika Polimerov, Vol. 3, No. 6, pp. 970–976, 1967     

Deformation of elastic polyurethanes with a bimodal cellular structure

This article examines the cellular structure and mechanical properties of elastic foamed polyurethanes with a bimodal cellular structure (BFPUs). It is shown that the sizes of the oval cells (3–12 mm) in the elastic foamed polyurethenes that are studied are a tenth of an order greater than the sizes of the polyhedral cells (0.1–0.6 mm). Conversely, for rigid foamed polyurethanes, the polyhedral cells are more than a tenth of an order larger than the oval cells (microcells). The equations of the compression curve of BFFUs are found, and it is established that the deformation of BFPUs is determined by the deformation function of the cellular structure and the viscoelastic properties of the polymer matrix. The deformation functions of the cellular structure and the relaxation properties of BFPUs are determined. It is shown that choosing BFPUs with a cellular structure improves the comfort properties of the foamed material: the softness coefficient increased by 8–19% in the investigated case, while the support coefficient increased by 15–35%.Paper presented at the IX International Conference on the Mechanics of Composite Materials (Riga, 1995).Translated from Mekhanika Kompozitnykh Materialov, Vol. 32, No. 3, pp. 330–339, May–June, 1996.     

Effect of structural changes in amorphous polymer films on the mechanical properties of coatings

The effect of structure formation on the mechanical properties of amorphous paint films has been investigated. It is shown that the organization of the supermolecular formations affects the internal stresses and adhesion of the film and, moreover, their tensile and impact strengths over a broad temperature interval. Fibrillar and "reticulate" structures give the best mechanical properties.State Scientific-Research and Planning Institute of the Paint Industry, Moscow. L. Ya. Karpov Physicochemical Institute, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 5, pp. 771–775, September–October, 1968.     

Two-stage biaxial orientation of polypropylene film

The microstructure of polypropylene film at various points of the two-stage orientation process is described. It is shown that the supermolecular structures and film properties vary with the method of orientation. A proposed mechanism of two-stage biaxial film orientation is based on the experimental results.Moscow M. V. Lomonosov Institute of Fine Chemical Technology. Translated from Mekhanika Polimerov, No. 4, pp. 735–737, July–August, 1969.     

Effect of small additives of oligomer on the viscoelastic properties of carbon fiber plastics

The viscoelastic properties of carbon fiber composites whose phenol-formaldehyde matrix is modified by thermodynamically incompatible isocyanate derivatives have been investigated. Data are given on fiber wetting (Table 11), internal stress (Table 2), viscoelastic properties (Fig. 1), and tensile strength (Fig. 2). The modified composites are strengthened by the addition of 0.5–4% oligomer additive. This process involves the formation of a two-phase structure, in which the additive phase microparticles act as a polymer filler. Due to selective interactions, the intermediate layer formed at the fiber-binder interface leads to changes in the viscoelastic properties and tensile strength of the matrix and improved maintenance characteristics for the material as a whole.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 4, pp. 440–445, July–August, 1993.     

Physicomechanical properties of composites from recycled polyethylene and linen yarn production wastes

The possibilities of utilizing wastes of linen thread production (chaffs, spinning and roving losses) in recycled polyolefin composites have been investigated. The wastes were mixed with recycled polyethylenes (produced from domestic and industrial film production wastes). The physicomechanical properties (tensile strength, bending and tensile moduli, and water resistance) and the fluidity (melt flow-behavior index) for systems with a different filler content are estimated. Almost all the composite materials obtained have satisfactory fluidity (melt flow-behavior index is not lower than 0.07–0.15 dg/min). For all types of the composites, a slight increase in tensile strength and a considerable increase (3–7 times) in bending and tensile moduli were observed. The water resistance of the composites decreased with an increase in the filler content. The modification of filled systems with diisocyanates (diphenylmethane diisocyanate) improved the useful properties and water resistance of all the composites investigated.Translated from Mekhanika Kompozitnykh Materialov, Vol. 35, No. 2, pp. 199–210, March–April, 1999.     

Strength properties of polymer films subjected to continuous tearing

Using the principle of tearing at a constant velocity and applying this to samples with longitudinal notches, a method of recording the tearing strength as a continuous function of temperature, crystallization time, and other factors which continuously vary the state of a (polymer) film material is developed. The characteristic points of the temperature transitions are determined for a number of polymer films in relation to their mechanical (strength) properties. The crystallization kinetics of polyethylene terephthalate films are analyzed.Scientific-Research Institute of Plastics, Moscow. Translated from Mekhanika Polimerov, No. 2, pp. 257–261, March–April, 1972.     

Effect of quartz concentration and dispersity on the physico-mechanical properties of perchlorovinyl film

The structure of perchlorovinyl film is not affected by the addition of finely ground quartz. The modulus of elasticity and coefficient of thermal expansion of the film change additively with increase in filler concentration and do not depend on filler dispersity. The filler reduces the strength of the film and the elongation at break.Institute of Physical Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 6, pp. 1023–1027, November–December, 1969.     

Study of the effect of various factors on the low-temperature strength of polyethylene with graft polyacrylonitrile

Low-density polyethylene film has been subjected to graft polymerization with acrylonitrile. The effect of the graft polymerization conditions and subsequent treatment on the strength of the grafted film has been investigated. The strength was measured at -196°C. The grafted film behaves like a heterogeneous material in which the unoriented polyacrylonitrile macrostructures play the part of filler particles. The strength of the grafted film is additively composed of the strengths of the polyethylene and the polyacrylonitrile and the change in strength after stretching, heating, and other treatments is determined by the changes in the degree of orientation of the polyethylene.V. I. Lenin Belorussian State University, Minsk. Translated from Mekhanika Polimerov, No. 4, pp. 589–593, July–August, 1973.     

Influence of technological factors on the supramolecular structure and frictional properties of the surface layers of thermoplastics

X-ray and optical diffraction methods have been used to study the changes in supramolecular structure, degree of orientation, and drawratio of the material in the 0–650-µm range for polypropylene samples obtained by molding. Using a microtribometric technique, the influence of these factors on the frictional properties of the polymer have been elucidated.Institute of Mechanics of Metal-Polymer Systems, Academy of Sciences of the Belorussian SSR, Gomel'. Translated from Mekhanika Polimerov, No. 2, pp. 202–206, March–April, 1976.     

Study of a polyethylene terephthalate film by an acoustic method

The effect of orientation on the acoustic properties of a polyethylene terephthalate film is examined. In a crystallized, uniaxially oriented film the velocity of ultrasound measured along the orientation axis is lower than in an amorphous oriented film, while the velocity of ultrasound measured at angles of over 35° to the direction of orientation rises after crystallization. Evidently the supramolecular organization of the polyethylene terephthalate film before and after heat treatment is quite different.Scientific-Research Institute of Plastics, Moscow. Voronezh Branch of the Experimental Design Office of Automation. Translated from Mekhanika Polimerov, No. 4, pp. 759–761, July–August, 1972.     

Effect of polymetaphenylene isophthalamide (phenylon) structure on the properties of an antifriction material

The relationship between phenylon structure and the friction properties of a phenylon-based material is established using the data of friction tests, x-ray analysis, and electron microscopy. It is shown that amorphization of the binder structure leads to a change in the coefficient of friction and to a displacement of the zone of maximum operating temperatures in the direction of higher values.Institute of Hetero-Organic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 5, No. 2, pp. 201–206, March–April, 1969.     

The problem of strengthening of plastics in polymer solvents medium

It was found that short-term treatment of unstressed acrylate AST-T samples with n-amyl alcohol and butyl acetate leads to a marked improvement in their mechanical properties. The influence of temperature, holding time, and the nature of the solvent on the strength of acrylate AST-T has been studied. The increase in the strength indexes is the result of the thermal effect of the medium on the molecular structure of the surface layers and healing of the surface defects of the material. The great importance of the state of the surface on the physicomechanical properties compared with the temporary plasticizing action of the solvents has been shown.V. I. Lenin Kharkov Polytechnic Institute. Translated from Mekhanika Polimerov, No. 5, pp. 913–915, September–October, 1972.     

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.     

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.     

Modern trends in the development of fibrous composites

The two main trends in the development of high-modulus composites are considered. Improved methods of calculation sensitive to the effects associated with the weak shear and transverse characteristics are reviewed. It is shown that the disadvantages of composites with a traditional arrangement of the reinforcement can be overcome. The properties of boron- and carbon-reinforced plastics with a traditional reinforcement structure are described and compared with those of three-dimensionally structured materials with two- or three-strand reinforcing. Whiskerized fiber reinforcement is also considered. A program of further research on high-modulus composites is outlined.Presented at the 2nd All-Union Conference on Polymer Mechanics, Riga, November 10–12, 1971.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 541–552, May–June, 1972.     

Theory of filled polymers and the problem of modifying the structure and properties of polymers with fillers

An attempt is made to explain the effect of fillers on the structure and properties of polymers. The effect of fillers on the state of thermodynamic equilibrium and the stability of polymer structure and properties is also considered.Kiev Shevchenko State University. Translated from Mekhanika Polimerov, No. 6, pp. 1031–1041, November–December, 1970.     

Deformation and stress distribution in a layered plastic

The stress distribution over the unidirectionally reinforced layers is investigated in relation to the layer thickness ratio and the direction of loading of a two-way reinforced plastic. An expression is obtained for the modulus of elasticity of the layered plastic in an arbitrary direction relative to the directions of reinforcement. The effect of the geometry of the structure of the layered material on its deformation properties is experimentally illustrated.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 3, pp. 563–570, May–June, 1972.     

Some special features of the structural changes of epoxy resins under the action of magnetic fields

Conclusions 1. The action of a magnetic field leads to a change in the structure of an epoxy resin both at the molecular and at the supramolecular levels.2. A homogeneous magnetic field acting on the hardening process of an epoxy resin, due to the presence of the orientating moment, is able to produce ordered formations.3. A nonhomogeneous magnetic field results in a distribution of anisotropic morphological formations along the field gradient, promoting a change in the physicomechanical properties of the material.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 583–587, July–August, 1978.