Elasticity of the crystal lattice of polyethylene terephthalate

The elasticity of the crystal lattice of polyethylene terephthalate was studied along and across the axes of the polymer molecules. The elastic modulus across the chains depended on the degree of crystallinity and the interplane distances in the directions of thea and b parameters of the unit cell. The nature of the elastic deformation in the crystal lattice was analyzed, and its elastic modulus along and across the axes of the chains was calculated. On loading biaxially oriented amorphous-crystalline polymers with a tensile stress applied in the direction of one of the orientation axes of the polymer, the stresses in the crystallites oriented along and across the external applied force and the amorphous regions in series with them were equal to the stress in the sample averaged over the cross section.Deceased.Translated from Mekhanika Polimerov, No. 6, pp. 982–986, November–December, 1972.     

Two-dimensional extension of polyethylene and polypropylene film

The two-dimensional extension of polyethylene and polypropylene film has been investigated by optical microscopy. It has been established that there is no two-dimensional plastic flow (two-dimensional necking) and that failure is quasi-brittle in character. In a small region near the cracks that develop, uniaxial orientation of the polymer associated with stress concentrations near the crack tip is observed. Measurements show that the ultimate stress in two-dimensional extension is close to the necking stress in uniaxial tension.Mekhanika Polimerov, Vol. 3, No. 1, pp. 41–45, 1967     

Effect of γ radiation on the long-term strength of polyethylene terephthalate

By analyzing the results of a study of the long-term strength and isometric heating diagrams of polyethylene terephthalate exposed to radiation it has been established that irradiation leads to a decrease in the short-time and long-term strength of the polymer and to the misorientation of its structural elements. The coefficient in the long-term strength equation increases with the radiation dose, while U₀ varies along a curve with a maximum at small doses.Lenin Tadzhik State University. Translated from Mekhanika Polimerov, No. 2, pp. 239–243, March–April, 1973.     

Study of the supermolecular transitions associated with the reorientation of high-pressure polyethylene film

Small-angle optical and X-ray diffraction techniques have been used in a comparative study of the processes of orientation and reorientation of high-pressure polyethylene film. It is shown that at large stretch ratios both processes are governed by the same laws. In these supermolecular transitions it is possible to observe spherulite-macrofibril conversions during orientation and macrofibril-macrofibril conversions during reorientation, a direct genetic relationship being preserved between the dimensions of the starting spherulites or macrofibrils and the dimensions of the macrofibrils formed by stretching. However, the major period of the oriented film, the basic element of the microfibrils forming the macrofibril, is independent of the major period of the starting film and depends only on the temperature at which stretching is carried out.Institute of High-Molecular Compounds, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 5, pp. 771–777, September–October, 1969.     

Experimental investigation of low cycle fatigue of metallized polyethylene terephthalate films

Conclusion The destruction of the coating of a loaded metallized film is a process that includes the stages of formation of point defects, formation and development of a network of cracks. In proportion to the increase of the load or of the number of load cycles the density of the network of cracks increases. When an element of the network has attained the critical dimension, crumbling ceases. Measurement of the light transmission is an effective method of investigating the damage to metallized films, even if they are opaque in the undamaged state.Translated from Mekhanika Kompozitnykh Materialov, No. 6, pp. 787–795, November, 1992.     

Effect of annealing temperature on the mechanical properties of polyethylene terephthalate fiber

The mechanical properties of polyethylene terephthalate fibers stretched at 45 and 110° C have been investigated in relation to annealing temperature. It is shown that for fibers with the maximum degree of stretch the annealing temperature has no effect on mechanical strength. Reduction in the stretch of the fibers leads to an increase in strength upon annealing, and this may be associated with densification of the amorphous zones due to the formation of a large number of intermolecular bonds between the links of the polymer chains.Mekhanika Polimerov, Vol. 3, No. 3, pp. 503–506, 1967     

Creep of polyethylene terephthalate with variable stresses under conditions of uniaxial extension

The results from experimental and theoretical investigation of the creep of polyethylene terephthalate film during stepwise varying stresses under conditions of uniaxial extension are given.Izhevsk Mechanical Institute. Translated from Mekhanika Polimerov, No. 5, pp. 929–933, September–October, 1972.     

Scattering of an incident acoustic wave by an elastic sphere in a shallow water

The scattering of acoustic waves by an elastic sphere in a shallow ocean wave guide is investigated taking into account the shear waves which can exist in addition to compressional waves in scatterers of solid material. Expressions for the scattered waves are given. Numerical values for a quantity called the farfield form function for various depth are presented in graphical forms.      

The factorization method for inverse acoustic scattering by a penetrable anisotropic obstacle

This paper is devoted to studying the factorization method applied to the inverse problem of reconstructing a penetrable anisotropic obstacle from far field patterns. We proved the validity of the factorization method. Copyright © 2013 John Wiley & Sons, Ltd.     

Some characteristics of the failure of heat-sealed polyethylene film

It is shown that weld failure most often occurs in the inner weld zone. The mode of failure and deformation of the weld in uniaxial tension depends on the welding conditions. For severe welding conditions the _t-T curve has a certain maximum.Institute of Physicotechnical Problems of Power Engineering, Academy of Sciences of the Lithuanian SSR, Kaunas, Kaunas Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 537–538, May–June, 1971.     

Scattering of an incident acoustic wave by an infinite elastic cylinder in a shallow sea

The scattering of sound waves by an isotropic elastic circular cylinder of infinite extent in a water of finite depth is investigated taking into account the shear waves that can exist in addition to compressional waves in scatterers of solid material. The axis of the cylinder is parallel to the water level. The reflected and transmitted energies are plotted for the various values of the radius of the cylinder, and the farfield scattered pressure is obtained for various depth and presented in a graphical form. Copyright © 2008 John Wiley & Sons, Ltd.     

A perturbative method for the spectral analysis of an acoustic multistratified strip

We consider the acoustic propagator A=−∇·c²∇ in the strip Ω={(x, z)∈ℝ²∣0<z<H} with finite width H>0. The celerity c depends for large ∣x∣ only on the variable z and describes the stratification of Ω: it is assumed to be in L^∞(Ω), bounded from below by c_min>0, such that there exists M>0 with c(x, z)=c₁(z) if x< −M and c(x, z)=c₂(z) if x>M. We look at the propagator A as a ‘perturbation’ of the free propagators A_j in Ω associated to the velocities c_j, j=1, 2, and implement a ‘perturbative’ method, adapting ideas of Majda and Vainberg. The spectrum of A is defined in section 2, a limiting absorption principle is proved in section 3 outside of a countable set Γ(A). The points of Γ(A) can only accumulate at the left of the thresholds of the free propagators. The needed material about A_j, j=1, 2, and some technical estimates for A are given in Appendix. © 1998 B. G. Teubner Stuttgart—John Wiley & Sons, Ltd.     

Analysis of extraordinary optical transmission trough a conducting film by the discrete sources method

The discrete sources method is used to analyze the transformation of evanescent waves by a nanometric structure. The extraordinary transmission of light through a nanohole in a conducting film is shown to arise in other inhomogeneities. The mechanism of this phenomenon is established using simulation results.     

Axisymmetric interaction of an acoustic wave with a thin elastic spherical shell stiffened by an elastic rib

In nonstationary formulation in the context of the classical theories of shells and curvilinear rods we solve the axisymmetric problem of scattering of sound on a spherical shell stiffened by a rib. We analyze the effect of the rib on the spectral density of the echo-signal. We give the results of computing the reflected pulse and classify the sequence of pulses of peripheral waves in the echo-signal. Translated fromMatematichni Metodi ta Fiziko-Mekhanichni Polya, Vol. 40, No. 2, 1997, pp. 142–147.