Mechanical Properties of High-Density Polyethylene/Chlorinated Polyethylene Blends

Results of experimental investigation of mechanical properties of high-density polyethylene (HDPE)/chlorinated polyethylene (CPE) blends in tension are reported. The specimens of pure HDPE, CPE, and nine types of HDPE/CPE blends, with different component ratios at 10 wt.% intervals, are examined. The features of the stress-strain curves obtained are discussed. Data on the influence of blend composition on the elastic modulus, yield stress, breaking stress, and ultimate elongation are obtained. The results of investigations into the creep behavior are also presented. It is found that the creep compliance obeys the power law of creep with coefficients depending on blend composition.     

Mechanical Properties of Polyethylene and Poly(Ethylene Terephthalate) Blends

The results of experimental investigation of mechanical properties in tension of polyethylene (PE) and poly(ethylene terephthalate) (PET) blends are reported. Seven types of specimens with PE/PET weight ratios of 100/0, 90/10, 70/30, 50/50, 30/70, 10/90, and 0/100 were examined. The data on the influence of blend composition on the yield stress, breaking stress, yield strain, and ultimate elongation are obtained. The features of the effect of PE/PET ratio on the elastic properties of the blends are discussed.     

Creep of Poly(Vinyl Chloride)/ Chlorinated Polyethylene Blends

The results of experimental investigations of the creep behavior of blends of poly(vinyl chloride) (PVC) with chlorinated polyethylene (CPE) are presented. Eight types of specimens with the PVC/CPE weight ratios of 100/0, 90/10, 80/20, 60/40, 40/60, 20/80, 10/90, and 0/100 are examined. The creep tests were continued for 1000 h. It is discussed how the blend composition affects the elastic and inelastic behavior of the material. The elastic compliance of the blend can be determined from the properties of its components by using the Kerner and Budiansky equations for heterogeneous systems with a phase structure of statistic-dispersion type. The creep compliance (the total current compliance minus the elastic compliance) obeys the power law of creep with coefficients depending on the blend composition.     

Cross-Linked Thermoplastic Blends of Polyethylene with an Elastomer 2. Some Structural Characteristics and Their Relationship with Mechanical Properties

Results of an experimental investigation into the changes of some structural characteristics of binary blends of high-density polyethylene and low-density polyethylene with an elastomer (ethylene-propylene-dicyclopentadiene terpolymer, EPDM) in the course of γ-radiation and chemical cross-linking are reported for a wide range of component ratios. The data on changes in the crystallinity, density of the blends, content of the cross-linked part, as well the correlation of these characteristics with some mechanical properties, are discussed. Suggestions are put forward about the possibility of formation of a combined amorphous PE-EPDM phase with a higher structural arrangement than that in the individual components.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 545–562, July–August, 2005.     

Thermal Deformation of Blends of Poly(Vinyl Chloride) with Chlorinated Polyethylene

The results of experimental and theoretical investigation of thermal deformation (expansion or contraction) of poly(vinyl chloride) (PVC) and chlorinated polyethylene (CPE) blends are presented. Eight types of specimens with PVC/CPE weight ratios of 100/0, 90/10, 80/20, 60/40, 40/60, 20/80, 10/90, and 0/100 were tested. The experimental curves of thermal deformation in the longitudinal direction of the specimens are presented. The primary attention is paid to the mathematical prediction of the effective coefficients of thermal expansion for the blends based on the composition and properties of the components. The blends are regarded as heterogeneous two-phase systems where the inversion changes of morphology occur gradually over a rather wide range of intermediate compositions. It is found that the thermal expansion coefficients of PVC/CPE blends can be predicted, with an adequate accuracy over the whole range of blend compositions, by the Levin and Budiansky equations for a two-component medium with randomly arranged component particles.     

Elastic and Thermophysical Properties of Poly(Vinyl Chloride) and Chlorinated Polyethylene Blends

The results of experimental and theoretical investigations of elastic and thermophysical properties of poly(vinyl chloride) (PVC) and chlorinated polyethylene (CPE) blends are presented. Eight types of specimens with different ratios of weight contents of PVC and CPE (PVC/CPE = 100/0, 90/10, 80/20, 60/40, 40/60, 20/80, 10/90, and 0/100) were tested. The effect of blend composition on the elastic constants (tensile and shear modulus) is discussed. The data on the thermal conductivity, thermal diffusivity, and heat capacity of the blends investigated are also presented.     

Cross-Linked Thermoplastic Blends of Polyethylene with an Elastomer. 1. Deformation and Strength Characteristics

Results of an experimental investigation into changes of some mechanical characteristics of binary blends of high- and low-density polyethylenes with an elastomer (ethylene-propylene-dicyclopentadiene terpolymer) in the course of -radiation and chemical cross-linking are reported for a wide range of component ratios. Data on changes in the tensile strength and total, residual, and reversible strains at break, as well the microhardness and other characteristics are obtained. The effect of component ratio and cross-linking on these characteristics is discussed.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. -, March–April, 2005.     

Correlation between the Mechanical Properties and the Amount of Desorbed Water for Composites Based on Low-Density Polyethylene and Linen Yarn Production Waste

The effect of the amount of desorbed water on the mechanical properties of composites based on low-density polyethylene and linen yarn production waste (LW) is analyzed by statistical methods. It is shown that the amount of absorbed water decreases during the desorption process at room temperature both for specimens modified and unmodified with diphenylmethane diisocyanate (DIC.) The most sensitive to the action of water is the elastic modulus, which decreases considerably under the effect of water and is fully restored in the desorption process. The tensile strain also increases with the amount of absorbed water. It is found that the elastic modulus of the unmodified composite correlates linearly with the amount of desorbed water. Between the amount of desorbed water and the tensile strain, as well the specific work of deformation, a negative linear correlation is revealed. After water desorption, all strength and deformation characteristics of both the modified and unmodified composites are fully recovered.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 4, pp. 515–524, July–August, 2005.     

Cross-Linked Thermoplastic Blends of Polyethylene with an Elastomer 3. Rheological Charcteristics of Melts

Results of an experimental investigation into the changes of viscosity and the flow character of binary blends of high-density polyethylene with an elastomer (ethylene-propylene-dicyclopentadiene terpolymer) during the γ-radiation and chemical cross-linking are reported. The type of functions of the effective viscosity of temperature (activation energy of flow) and shear rate (flow-behavior index) in relation to the structure of melts of the blends is discussed for a wide range of component ratios and various extents of cross-linking. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 819–830, November–December, 2005.     

Effect of Water on the Physicomechanical Properties of Composites Containing Low-Density Polyethylene and Linen Yarn Production Waste

The effect of the amount of absorbed water on the physicomechanical indices (tensile modulus and tensile strength) of composites based on low-density polyethylene (LDPE) and linen yarn production waste (LW), both with and without coupling agents (stearic acid - SA and diphenylmetane diisocyanate - DIC), is studied. It is shown that the strength properties depend considerably on the time of water sorption and on the blend composition. The tensile strength decreases with increased amount of absorbed water (with increased time of exposure to distilled water) and with increased content of LW in the composite. Somewhat different results are obtained for systems containing SA and DIC modifiers. The modifiers, intensifying the interfacial interaction, retard the process of water sorption, therefore the drop in the strength indices is not so significant. Of special interest is the behavior of systems with DIC. In some cases, a slight increase in strength (after a two to five day exposure to water) is observed, which is probably caused by cross-linking of the free diisocyanate in the system under the action of moisture.     

Evaluation of Deformation and Strength Characteristics of Composites Based on Low-Density Polyethylene and Linen Yarn Production Waste by the Methods of Mathematical Statistics

The possibilities of using various methods of mathematical statistics for processing and analyzing the results of deformation and strength tests on composites made from a low-density polyethylene and linen yarn production waste are evaluated. The hypothesis that the experimental strength data agree with the Gaussian distribution is examined by the Shapiro–Wilk test (W-test.) It is shown that the Gaussian distribution, both for systems unmodified and modified with diphenylmethane diisocyanate (DIC), is valid only for two parameters: the maximum tensile strength _max and the elastic modulus E _t. For the other parameters (the relative elongation _max corresponding to _max, the specific total work of failure A _b), and the specific work of failure to the tensile strength A _max), a non-Gaussian distribution is observed. An analysis of measurements for different specimens by the Bartlett test shows that the E _t data have equal variances for both systems (with and without DIC), but for the system containing DIC, the _max data have different variances. A two-factor ANOVA analysis reveals that DIC considerably affects the tensile strength and modulus of composites, but the influence of test conditions is a statistically significant factor only for the modulus. The coefficient of variation is considerably lower for _max than for E _t and can be used as a quantitative measure for the degree of heterogeneity of the composites investigated.     

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.     

Optimization of Multilayered Composite Structures with Randomly Distributed Mechanical Properties

The variability of mechanical properties commonly encountered in composite structures should be taken into account in the optimal design. The present paper discusses such a possibility by using the fuzzy-set and antioptimization approaches. The main attention is focused on the formulation of optimization problems. The formulation and methods proposed are successfully implemented in the buckling analysis of multilayered composite plates. The problem of optimum stacking sequence for plates is also solved. __________ Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 753–760, November–December, 2005.     

低密度奇偶校验码的构造

低密度奇偶校验码(LDPC)最早是由Gallager于1962年提出.它们是线性分组码,其比特错误率极大地接近香农界.1995年Mackay和Neal发掘了LDPC码的新应用后,LDPC码引起了人们的广泛关注.本文利用组合结构给出一些新的LDPC码:利用可分组设计构造一类Tanner图中不含四长圈的正则LDPC码.     

A Study of the Relation between the Mechanical Properties and the Adhesion Level in a Laminated Packaging Material

The mechanical properties of a laminate consisting of aluminum-foil, adhesive, and polymer layers were studied in relation to the adhesion level. A special application for liquid-food packaging materials was considered. In experiments, laminates with and without adhesive layers were tested. Tensile tests were first run for every layer of the laminate, and the data obtained were then used in analyzing the results of tensile tests on the entire laminate, as well as in theoretical and finite-element calculations. Relations between different mechanical properties (such as Young's modulus, the peak stress, and the strain at the peak stress) and the adhesion level were analyzed. It was found that the tensile strength and the strain at the peak stress increased with adhesion level. Only slight differences in Young's modulus were observed at different adhesion levels.     

不同应变率下PC,ABS和PC/ABS合金拉伸变形行为研究

采用实验方法研究了PC(聚碳酸酯)、ABS(丙烯腈-丁二烯-苯乙烯)和PC/ABS合金(PC与ABS共混率为80∶20,60∶40,50∶50和40∶60),在不同应变率条件下的拉伸变形行为.采用MTS-810万能材料试验机和分离式Hopkinson拉杆实验系统分别进行了PC,ABS和PC/ABS合金室温条件下的准静态和冲击拉伸实验,得到了上述材料在不同应变率条件下的真应力-真应变曲线;通过对其变形特点的详细分析,讨论了应变率和ABS含量对拉伸变形的影响,并且给出了10-4s-1～103s-1应变率范围内屈服应力与应变率的线性关系式.     

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.     

Environmental Effects on the Mechanical Properties of Glass-FRP and Aramid-FRP Rebars

In the paper, the experimental results on the effect of temperature and moisture on the mechanical properties of FRP (Fiber-Reinforced Polymer) reinforcements are presented. FRP rebars made from glass and aramid fibers were subjected to cyclic thermal actions at temperatures ranging between 20 and 70°C, typical of natural hot-climate environments. Tensile tests were also carried out on FRP rebars. The effect of moisture was investigated by cyclic wetting and drying the FRP rebars under laboratory conditions before their testing in tension. Finally, the elastic modulus and tensile strength of the FRP rebars exposed to these cyclic actions were compared with those obtained for unexposed ones, in order to evaluate the mechanical damage caused by environmental conditions.     

Correlation between the mechanical properties and the amount of desorbed water for composites based on a recycled low-density polyethylene and linen yarn production waste

The effect of the amount of sorbed water on the mechanical properties (tensile modulus, tensile strength, unit work of fracture, and characteristic strains) of composites based on a recycled low-density polyethylene, both unmodified and modified with diphenylmethane diisocyanate (DIC), is an a lyzed by statistical methods. The results of tensile tests are found to depend on the amount of sorbed water considerably. The elastic modulus, the unit work of fracture, and the characteristic strains correlate linearly with the amount of water. It is found that the elastic modulus drops after the sorption of water, but then, during the desorption process, it is restored gradually and reaches its initial value after a 30-day drying. This is explained by the plasticizing effect of water on composite materials containing hydrophilic natural fibers. DIC improves the interfacial interaction of the fiber-matrix interface and slows down the desorption of water. The investigations of the main deformational and strength characteristics of the unmodified and modified systems showed that the ad verse effect of water completely disappeared after a 30-day drying. The same conclusion, with a 95% probability, can be drawn from the results of an analysis of variance (ANOVA). __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 5, pp. 626–638, September–October, 2007.     

The influence of water sorption-desorption cycles on the mechanical properties of composites based on recycled polyolefine and linen yarn production waste

The effect of water on the mechanical properties (tensile modulus, ultimate tensile strength, tensile strain, and specific work at break) of both chemically treated and untreated composites based on a recycled low-density polyethylene and linen yarn production waste is analyzed. It is found that three water sorption-desorption cycles change the tensile properties of both the materials irreversibly. This effect is considered as the result of partial fracture of the fiber-matrix interface. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 43, No. 6, pp. 839–848, November–December, 2007.