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A decrease in the electrical durability, which is defined as an amount of time required for dielectric breakdown at a constant electric field strength, of polyethylene and Lavsan (polyethylene terephthalate) films under tensile loading is registered in a temperature range from 100 to 300 K. It is established that the pulling apart of the axes of neighbor chain molecules in consequence of tensile loading gives rise to a decrease in the energy level of the intermolecular electron traps. In the amorphous region of a polymer, this accelerates the release of electrons from the traps through over-barrier transitions at higher temperatures ranging from about 230 to 350 K and quantum tunneling transitions at lower temperatures in the range from about 80 to 200 K. As a result, the time required for the formation of a critical space charge, i.e., the waiting period of dielectric breakdown, decreases, which means a reduction in the electrical durability of polymers.

The kinetics of electrical damage (breakdown) of polymer films 20–50 μm thick in a constant-sign field of 0.5–0.6 GV/m at 77–300 K has been studied. At elevated temperatures (250–300 K), the exponential temperature dependence of the durability and the above-barrier thermal-fluctuation mechanism of electron emission from traps, i.e., space charge accumulation leading to breakdown, take place. At low temperatures (77–200 K), there are separate local decreases in the durability (minima) at the athermal durability level. The identity of the temperatures of durability minima and measured thermoluminescence maxima of polymers was found. A conclusion is made about the mechanism of thermally stimulated tunneling (subbarrier emission) of electrons from traps.

In polymer crystals (in particular, polyethylene), changes in the axial and contour lengths of skeletal interatomic bonds in chain molecules under mechanical loading (stretching) and heat treatment (heating) were measured using X-ray diffractometry and Raman spectrometry. The performed analysis of the measured force and temperature dependences gave theoretical descriptions of the deformation of a polymer crystal (the confirmation of the data available in the literature for mechanical loading and an original development for heating). The components of the potential energy of a deformed polymer crystal were determined both for stretching of skeletal bonds and for bending of chain molecules. It was found that there is a significant difference in the ratios of these components for a deformed polymer crystal under mechanical loading and during heating.

Structural changes in polymer crystals (polyethylene, polyimide, and others) have been studied using the X-ray diffraction and Raman spectroscopy methods under different influences: tensile loading along the chain molecule axis and heating from 90 to 350 K. An increase in the molecule axial length under loading and a decrease in the molecule axial length upon heating have been identified and measured using X-ray diffraction. A decrease in the skeletal vibration frequency during loading and heating has been identified and measured using Raman spectroscopy, which indicates an increase in the molecule contour length in both cases. A technique for determining the change in the polyethylene molecule contour length in the crystal from the measured change in the skeletal vibration frequency has been justified. The contributions of two components, namely, skeletal (carbon–carbon) bond stretching and the change (an increase during stretching and a decrease during heating) in the angle between skeletal bonds, to the longitudinal deformation of polyethylene crystals, have been quantitatively estimated. It has been shown that the negative thermal expansion (contraction) of the polymer crystal is caused by the dominant contribution of the decrease in the bond angle.

Experimental data on two known effects arising in response to an adiabatic elastic loading of solid bodies are presented. These are the thermoelastic effect, which consist in a change in temperature upon loading, and the frequency-elastic effect, which consists in a change in the frequency of vibrations of atoms upon loading. Similar and dissimilar features of these two effects are indicated. The mechanisms of the effects are discussed, and the degree of their interplay is revealed. The frequency-elastic effect is found to play a leading role. The temperature effect appears to be a quantum consequence of the change in the frequency of vibrations of atoms because of the anharmonicity of atom-atom interaction. Energy features of both effects are discussed.

A decrease in the frequency of skeletal vibrations (frequency-elastic effect) has been measured using Raman spectroscopy, and the stretching of backbone interatomic bonds in polyethylene molecules under elastic tensile loading of oriented polyethylene fibers has been measured using X-ray diffraction. It has been found that there are differences in the sign and magnitude of the changes in the zero-point energy and the work of the external force. The energy of the frequency-elastic effect has been explained in terms of the influence exerted by the initial (before loading) anharmonic stretching of backbone bonds and the force of anharmonic pressure, with the separation of the anharmonic (potential) component of the zero-point energy of the solid. A change in the frequency of vibrations corresponds to a change in the harmonic component of the zero-point energy. The loading with an external force causes a redistribution of the zero-point energy components. An energy analysis of the loaded quantum anharmonic oscillator has confirmed the conclusion regarding the mechanism of energy transfer and revealed that, under loading, there is a redistribution of the average values of the kinetic and potential components of the internal energy of the oscillator.

This paper reports on the results of measurements of changes in the temperature of a solid under the adiabatic elastic loading (thermoelastic effect), the coefficient of thermal expansion, and the Young’s modulus of a rigid-chain vitrified polymer, namely, polyimide. It has been found that there are differences in the sign and magnitude of the changes in the energy of thermal origin in samples and the work of the external force. The energy of the thermoelastic effect has been explained in terms of the influence exerted by the anharmonic expansion of a solid, with the separation of the quasi-static potential and dynamic components of the thermal energy of the solid. The loading with an external force causes a redistribution of the thermal energy. A change in the temperature of the solid corresponds to a change in the dynamic component. An energy analysis of the adiabatically loaded anharmonic oscillator has confirmed the conclusion regarding the mechanism of energy transfer and revealed that, under loading, there is a redistribution of the kinetic and potential components of the internal energy of the oscillator.

Dielectric losses in poly(vinyl acetate) and poly(ethyleneterephthalate) polar polymers are measured in wide ranges of frequencies and temperatures. The temperature dependences of the frequency of activation transitions of two types, small-scale and conformational, are derived. For conformational transitions, it is revealed that the temperature dependence of their frequency exhibits nonlinear behavior (in Arrhenius coordinates); it determines the temperature dependence of barriers to transitions and the defreezing temperature of conformational dynamics (∼300 K for poly(vinyl acetate) and ∼370 K for poly(ethyleneterephthalate)). This temperature is found to be close to the temperatures of the quantum defreezing of the molecular dynamics of poly(vinyl acetate) and poly(ethyleneterephthalate) (∼300 and 400 K) according to IR spectroscopy data. It is assumed that a decrease in the barrier to the conformational transitions that provide defreezing of the conformational dynamics is caused by a decrease that occurs in the rigidity of polymer molecules owing to quantum defreezing of the vibrational molecular dynamics of the polymers.

The kinetics of electrical breakdown of thin (15–70 μm) layers of polymers and ceramics in a constant-sign field at 77–480 K has been investigated. The temperature dependences of the longevity (breakdown waiting time) of both dielectrics have been found to be similar to each other. At elevated temperatures, the longevity of the dielectrics varies exponentially with increasing temperature, and at reduced temperatures, it is temperature-independent (there is an athermal plateau). The mechanisms of elementary events controlling the process of preparation of the dielectrics for breakdown at elevated and reduced temperatures are the thermal-fluctuation over-barrier electron transition from trap to trap and the tunneling (under-barrier) transition, respectively. The hopping electron transport in the field direction gives rise to critical space charges causing breakdown of the dielectrics. The transition barrier heights (trap depths) have been determined. The low-temperature longevities of the polymer and the ceramic have been found to be similar, whereas the transition barrier for the ceramic is much higher than that for the polymer and the applied field in the former case is significantly (by a factor of tens) lower than that in the latter case. Electron traps in the polymer are adequately described by the Coulomb center model, whereas this is not the case for the ceramic.

The change in temperature under adiabatic elastic deformation of solids (thermoelastic effect) at low and high temperatures has been calculated taking into account the quantum properties of thermal dynamics. In the high-temperature range, a quantum-mechanical correction to the classical Kelvin formula has been found. In the low-temperature range, a new formula for the description of the thermoelastic effect has been derived.

The kinetics of indentation of a solid (viz., the dependence of the indenter intrusion depth on the time, force, and temperature), is analyzed theoretically taking into account quantum effects in the atomic dynamics of solids. The experimental study of the temperature dependence of the boron microhardness reveals qualitative and quantitative agreement with calculated dependences. A possible manifestation of quantum (tunnel) effects in the boron microindentation kinetics is predicted.

An elementary event in the kinetics of fracture of polymers, i.e., breaking of a stressed skeletal bond in a chain molecule, has been simulated by the decay of a loaded quantum anharmonic oscillator. The probability and the average time of expectation of the escape of a particle from the potential well in the Morse potential under the action of a tensile force have been calculated over a wide range of temperatures. It has been demonstrated that the escape of the particle occurs predominantly through the tunneling mechanism at low and medium temperatures and through a combination of the tunneling (under-barrier) and over-barrier (thermal-fluctuation) mechanisms with comparable contributions at high temperatures. The calculations have revealed that the participation of the tunneling mechanism in the kinetics of fracture of polymers manifests itself in a low-temperature athermal plateau in the temperature dependence of the breaking strength. A comparison between the calculated and experimental temperature dependences of the breaking strength for the oriented polymer polycaproamide has shown that the calculated and experimental results are in qualitative and quantitative agreement, which allows the conclusion that the tunneling mechanism can contribute to the fracture of polymers.

Analysis of the energy distribution in an ensemble of quantum anharmonic oscillators loaded by an external force in a wide temperature range (from T = 0) is carried out using a general approach based on the virial theorem. At T = 0, anharmonic effects are observed: a linear variation of zero-point energy of an oscillator under loading (energy decrease during extension and increase under compression) and a linear variation of the average kinetic and potential energy components. At high temperatures, at which the dynamics of the oscillators becomes classical, the anharmonic effects are manifested in a linear variation in the vibrational energy and a linear variation in the average kinetic and potential energy components upon an increase in force. Mutually compensating variation in the average kinetic and potential energy components of the internal dynamic energy of an oscillator (energy redistribution upon loading) takes place both at low and high temperatures.

A quantum anharmonic oscillator in the ground state has been considered under the conditions of loading with an external force. The wave functions have been calculated for different forces, and the eigenvalues of the energy of the system have been determined as a function of the load. It has been established that the zero-point energy of the oscillator varies linearly with a variation in the force (decreases under tension and increases under compression) and that the average kinetic and potential components of the energy are also characterized by linear variations.

The ballistic strength and hardness have been measured for a series of SiC ceramic samples with variable (from 1 to 20%) porosity. It is shown that interpore bridges are stress concentrators, and the dependence of the factor of stress concentration on porosity is determined. The conclusions based on the experimental results are confirmed by the finite-element calculations of stress fields in porous systems.

The dielectric and mechanical losses in the amorphous polar polymer poly(vinyl acetate) (PVA) are measured over wide ranges of frequencies and temperatures. It is established that the temperature dependence of the frequency of conformational transitions exhibits a nonlinear behavior (in the Arrhenius coordinates). This temperature dependence is used to determine the defreezing temperature of the conformational dynamics of PVA (∼300 K). The defreezing temperature appears to be close to the temperature of the quantum defreezing of one of the modes of the molecular dynamics of PVA (according to the Raman spectroscopic data). It is assumed that the revealed decrease in the barrier to conformational transitions with an increase in the temperature is associated with the weakening of the intermolecular interaction and the increase in freedom of adjustment of neighboring units in the vicinity of the conformational transitions due to the excitation of the molecular dynamics.

The temperature dependences of the dynamic tensile stresses on the chemical bonds of the skeleton of chain molecules and the bonds between molecules in poly(ethylene) and polyamide 6 crystals are measured using X-ray diffraction and Raman spectroscopy in the temperature range 5–500 K. The relations of the dynamic stresses to the quantum characteristics of the vibrational dynamics of polymer molecules are derived. The contributions from the zero-point and thermal vibrations of molecules to the stresses are determined. It is revealed that the dynamic tensile stresses on the intermolecular bonds at the melting temperatures of the crystals approach the tensile strength of these bonds.

Samples of silicon carbide ceramics with variable microporosity and hardness are studied. By measuring the hardness of the ceramics as a function of the integral porosity, it is established that the hardness is proportional to the mean length of bridges connecting pores. Microporosity is found to influence the hardness via stress concentration at the bridges, as a result of which they break up. Indentation causes extensive breakup of the bridges. The mean stress coefficient as a function of the integral porosity of the ceramics is estimated. It is shown that the micromechanisms of quasi-static indentation and high-speed indentation (penetration of a striking bar) are in many ways similar to each other.

The decrease in the electrical lifetime (time of expectation of a breakdown in an electric field of constant polarity) under tensile loading of disoriented polyethylene, Teflon, and lavsan films in the range of 100–300 K is studied. It is found that tensile loading decreases the depth of intermolecular electron traps due to an increase in the spacing of chain molecules in amorphous regions of polymers. This accelerates the hopping (from one trap to another) transport of electrons, leading to the formation of critical (breakdown) volume charges.

A series of silicon carbide ceramic samples with variable characteristics of the microporosity and strength, such as the ballistic strength σB and the static strength σS, are investigated. The dependences of the strength on the integral porosity for ceramic materials are determined. It is established that the strength (both σB and σS) is directly proportional to the average length of the bridges between micropores. The mechanism of the influence of microporosity on the strength of the ceramic materials is elucidated. According to this mechanism, interpore bridges are concentrators of stresses and, hence, are broken when a load is applied to the ceramic material. Numerous breakings of bridges bring about the failure of the ceramic body. The average stress concentration coefficient is estimated as a function of the integral porosity of the ceramic material. It is demonstrated that the static strength of the ceramic material is determined by the presence of large micropores (50–100 μm).

Magnetic and structural properties of an amorphous alloy based on iron are investigated. The properties and state of the alloy are changed under hydrostatic pressure of up to 1.3 GPa. An increase in the pressure leads to a linear increase in the maximum magnetic induction and a linear decrease in the remanence. Two nanopore fractions with average sizes of ∼20 and 150 nm are revealed in the alloy with the use of small-angle x-ray diffraction. The application of the pressure decreases the size of nanopores and increases the average distance between their boundaries, i.e., increases the average sizes of continuity regions in the alloy. It is established that the relative change in the magnetic characteristics is linearly related to the change in the size of the continuity regions in the alloy. Upon extrapolation to zero nanoporosity, the remanence reduces to zero. The inference is made that the nanopores play a dominant role (as compared to other structural defects) in the magnetic properties of the alloy.

The kinetics of electric failure (breakdown) of PET and PP films 10–20 μm in thickness in a dc electric field at 77–340 K was studied. Two temperature intervals ∼340–200 K and ∼200–77 K were revealed. The durability and the breakdown field strength strongly depend on temperature at ∼340–200 K but not at ∼200–77 K. The mechanisms of elementary events that determine the process prerequisite to the breakdown of polymers are discussed; these are the thermofluctuation mechanism (electron hopping from trap to trap over the barrier) at elevated temperatures and the tunneling transit of electrons at low temperatures. The barrier heights (trap depths) of 1–1.5 eV and the elementary transit length of ∼1 nm were determined. The hopping transport of electrons in a field leads to the formation of critical space charges, which cause the breakdown of the polymer film.

The main characteristics of elementary acts in the mechanical fracture kinetics of oriented polymers, namely, the initial potential barrier U 0 and the activation volume V A , are determined. The values of U 0 And V A are obtained from analyzing the temperature and force dependences of the life of polymers with allowance for the actual stresses (overstresses) applied to chain molecules, which are found by IR spectroscopy. The values obtained (U 0 ≈ 4 eV, V A ≈ 0.03 nm3) agree satisfactorily with the dissociation energy and activation volume of the fluctuation breaking of covalent skeleton bonds in polymer molecules.

The supermolecular structure of oriented crystalline polymers and the submicrocracks created in them under mechanical loading were studied by small-angle x-ray diffraction. Most of these polymers consist of fibril-like formations disposed along the polymer orientation axis, and ranging in thickness from tens to hundreds of angstroms. Crystalline and amorphous regions alternate along the fibrils with periods of hundreds of angstroms. Amorphous regions are mechanically weak. The weakest amorphous regions are torn under loading along the axis of orientation, and submicrocracks are formed. Interlayer rupture occurs by a chain mechanism of successive decomposition of stressed molecules. This process is initiated by free radicals formed at primary thermofluctuation ruptures of macromolecules and is terminated on the amorphous interlayer boundaries. Submicrocracks have the form of disks with transverse dimensions which practically coincide with the fibril thickness. Thus the specific morphology of an oriented crystalline polymer determines the course of development of the fracture from the initial stage.

For large polyethylene crystallites (100 × 60 × 60 nm), the width of the Raman band at 1129 cm−1 and the angular position of the x-ray equatorial 110 reflection were measured as a function of temperature over the range 5–300 K. It is found that the Raman bandwidth has an athermic (zero-point) component at low temperatures. This component is used to estimate the zero-point energies of torsional and bending vibrations of polyethylene molecules. These energies are close to those obtained from analyzing the x-ray diffraction data. It is concluded that the characteristics of zero-point dynamics can be determined directly from measuring the zero-point width of a Raman band.

The structure and magnetic properties of this amorphous alloy are studied. The structure was varied by applying a hydrostatic pressure of 10 kbar. By means of small-angle x-ray diffraction analysis, two fractions of nanopores (30 and 140 nm in size) are revealed. The pressure decreases the size of nanopores and raises their mean spacing. As a result of pressure application, the maximal magnetic induction grows, in contrast to the remanent induction. A correlation between the magnetic properties and nanoporosity of the alloy is discussed.

The kinetics of electrical failure of poly(ethylene terephthalate) under different experimental conditions is studied. Process variables are the film thickness, electrode configuration and material, presence of partial discharges, and field application conditions. It is found that the potential barrier for elementary events, which controls the failure kinetics, is nearly the same irrespective of the process, 1.1–1.3 eV. The control process is discussed.

An excited anharmonic oscillator is considered under conditions of adiabatic (i.e., slow, as compared to the oscillation period) loading with an external force tending to a constant value at long times. The energy characteristics of the adiabatically loaded anharmonic oscillator, such as the instantaneous energy of the oscillator, the maximum kinetic (oscillation) energy, and the kinetic and potential energies averaged over the period, are analytically calculated as a function of the steady-state force. The analytical results are confirmed by the data of numerical calculations. It is established that the external force gives rise to a redistribution of the average kinetic and potential components of the initial energy of the anharmonic oscillator and that the transferred energy portions at a small external force considerably exceed the average work done by the external force.

Experimental studies of the fracture kinetics of polycrystalline metals have led to the problem of the barrier and activation volume of elementary fracture acts. A model is proposed where the field binding one atom to its environment in a metal is represented by equivalent bonds directed along three orthogonal axes. These bonds are described using the Morse potential, whose parameters are found from the values of the Young’s modulus and the linear thermal expansion coefficient for metals. The validity of the model is checked by comparing the results obtained with metal sublimation data. The values of the barrier and activation volume of elementary fracture acts are determined for 15 polycrystalline metals. The levels of local overstresses are estimated. The theoretical breaking strengths of the metals are calculated.

The dependences of the coefficients of reversible thermal expansion on the tensile stress and the temperature dependences of the elastic modulus are measured for solids with different structures, such as a metal, rigid-chain oriented polymers, and a flexible-chain oriented polymer-poly(ethylene) in the devitrified state. For these materials, the elastic moduli differ by several orders of magnitude, whereas the thermal expansion coefficients can differ not only in magnitude but also in sign. It is found that, for a solid, the derivative of the thermal expansion coefficient with respect to the stress is close to the derivative of the reciprocal of the elastic modulus with respect to the temperature. The inference is made that these parameters do not depend on the specific features of the solids under investigation. Calculations are performed for several mechanisms of thermal and stress deformations of solids with different structures. The results of these calculations are in reasonable agreement with experimental data.

The kinetics of penetration of deformable striking rods into SiC ceramics with different void content is studied. The penetration may be viewed as a two-stage process. At the first stage, the penetration rate is minimal and the rate of contraction of the rod is maximal. At this stage, the penetration resistance of the ceramic is the highest. At the second (quasi-steady-state) stage, the penetration kinetics is similar to the kinetics of penetration into a zero-strength medium and resistance to penetration is largely inertial. At the first stage, the penetration resistance is shown to correlate with the hardness of the ceramic and depend strongly on the void content.

Rupture strength of the amorphous alloy based on nickel (Ni >80 ) has been measured in the temperature region 293–650 K under loading with a rate of 25 MPa/s. The samples in the form of 60–70 μm bands were prepared by spinning and were stabilized by temperature and force treatments, the amorphous state being preserved. The observed linear decrease in the rupture strength with increasing test temperature was analyzed in the framework of the kinetic thermal fluctuation theory of fracture. The initial barrier for elementary events of fracture of the alloy (activation energy), coefficients of local overstresses in the samples, and the theoretical strength of the alloy has been found.

Temperature variations of oriented polyethylene (PE) with a draw ratio of ∼ 450% were measured in longitudinal adiabatic tension and compression (along the orientation axis) and transverse compression. Stress-strain curves (for tension and compression) were recorded. Linear thermal expansion coefficients in the longitudinal and transverse direction were measured. Thermoelastic characteristics and also thermal properties of oriented PE were quantitatively analyzed. It has been concluded that conformational dynamics has a dominating influence on these characteristics.

The expansion of the carbon skeleton of molecules in crystallites and the longitudinal contraction of the crystallite lattice in poly(ethylene) (PE) and poly(caproamide) (PCA) with an increase in the temperature are measured using IR and Raman spectroscopy and x-ray diffraction. The thermal expansion of the carbon skeleton due to transverse vibrations is theoretically calculated within the atomic chain model. The theoretical and experimental data on the thermal expansion of the carbon skeleton are in good agreement.

The temperature dependence of the thermal expansion of polymers subjected to small harmonic temperature oscillations about certain base temperatures near the glass transition range is considered. The conformational component of the expansion as a function of temperature is calculated in terms of the conformational transition kinetics. The temperature dependences of the expansion and the expansion vs. oscillation phase shift are analyzed with allowance for the vibrationally anharmonic component. The thermal expansion of polyvinylacetate at base temperatures of 295–320 K, oscillation frequencies of 0.3 and 0.1 Hz, and an oscillation amplitude of 0.8 K are studied experimentally. The measured and calculated data for the expansion and expansion vs. temperature phase shift are shown to be in good agreement.

The temperature dependences of the transverse expansion ɛ⊥(T) and the longitudinal contraction ɛ‖(T) (with respect to the axes of chain molecules) in large-sized poly(ethylene) (PE) crystal grains (100×60×60 nm) are measured using x-ray diffraction in the temperature range 5–380 K. The temperature dependence of the elongation of the molecular skeleton ɛC(T) is obtained by Raman spectroscopy. It is found that the dependences ɛ⊥(T), ɛ‖(T), and ɛC(T) exhibit a similar specific nonlinear behavior. Analysis of these dependences indicates that the nonlinearity is associated with the quantum statistics of transverse vibrations. The energies and amplitudes of zero-point (at T=0) transverse (torsional and bending) vibrations and the relevant zero-point components ɛ‖(0) and ɛC(0) are estimated. It is revealed that the zero-point components make a considerable contribution to the dynamics of the PE crystal up to the melting temperature (∼400 K).