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1.
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. 相似文献
2.
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. 相似文献
3.
Maksimov R. D. Merii Meri R. Kalnin M. Zicans J. 《Mechanics of Composite Materials》2003,39(3):189-196
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. 相似文献
4.
The results of experimental investigation into the mechanical properties of blends of low-density polyethylene (LDPE) with chlorinated polyethylene (CPE) in tension are presented. The specimens of pure LDPE, CPE, and nine types of LDPE/CPE blends, with different content of components at 10 wt.% intervals, were examined. Data on the influence of blend composition on the tensile stress-strain diagram, elastic modulus, yield stress, breaking stress, and ultimate elongation are obtained. The results of investigations of creep are also reported. It is found that the creep compliance (the total current compliance minus the elastic compliance) obeys the power law of creep.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 3, pp. 391–404, May–June, 2005. 相似文献
5.
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. 相似文献
6.
The present paper surveys the investigation results of gamma-irradiated blends of high-density polyethylene (PE) with thermotropic liquid-crystalline polymer (LCP). The LCP used was a liquid crystalline copolyester of 40% poly(ethyleneterephthalate) with 60% p-(hydroxybenzoic acid). The LCP content in the blends was 0,5, and 10 wt.%. The constituents were blended with the use of a single-screw extruder. The samples were prepared by compression molding and irradiated by a Co60 -radiation source in an inert atmosphere (argon) to relatively low absorbed doses (up to 200 kGy; 1 Mrad=10 kGy). Morphological, thermal, and mechanical properties in a wide temperature range were investigated for the irradiated and nonirradiated samples. The effects of gamma-irradiation and LCP addition on the thermomechanical behavior of PE are discussed. It was found that the LCP addition affected significantly the stress-strain behavior of PE at temperatures above the melting point. The features of thermorelaxation properties of the PE/LCP blends previously irradiated and oriented, particularly thermorelaxation and residual shrinkage stresses at isometric heating and cooling, were also established. The results obtained testify that the LCP addition makes it possible to improve considerably the thermosetting properties of irradiated PE.Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 1, pp. 124–139, January–February, 1998. 相似文献
7.
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. 相似文献
8.
V. Kalkis R. D. Maksimov M. Kalnins J. Zicans T. Bocoka O. Revjakin 《Mechanics of Composite Materials》2000,36(3):223-232
Gamma-irradiated blends of polyethylene (PE) with ethylene-propylene-diene copolymer (EPDM) and a thermotropic liquid-crystalline
polymer (LCP) are investigated at absorbed radiation doses not exceeding 150 kGy (10 kGy=1 Mrad). The temperature dependences
of elastic moduli, tension diagrams at a temperature above the melting point of the crystalline phase of PE, and long-term
strain recovery curves for oriented test specimens are presented. The kinetics of thermal relaxation and shrinkage stresses
in previously oriented composite specimens upon their heating and cooling is investigated. Data on the influence of LCP additions
on the adhesive interaction of the compositions with steel are obtained. The peculiarities of thermomechanical and adhesion
properties of these composites are discussed taking into account the morphologic and calorimetric data obtained.
Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 3, pp. 379–394, May–June, 2000. 相似文献
9.
I. Reinholds V. Kalkis R. D. Maksimov J. Zicans R. Merijs Meri 《Mechanics of Composite Materials》2011,47(5):497-504
An experimental study of radiation-modified blends of high-density polyethylene with a chlorinated polyethylene exposed to
a constant magnetic field with induction equal to 0.7, 1.0, 1.4, and 1.8 T is presented. A preliminary gamma irradiation has
been performed with absorbed doses equal to 50, 100, and 200 kGy. The main attention is devoted to the investigation of deformation
(elastic and viscoelastic) properties of the material. Data showing the effect of the absorbed dose of gamma irradiation and
the induction of magnetic field on the elastic modulus and creep of the material under a constant stress are obtained. 相似文献
10.
Environmental Effects on the Mechanical Properties of Glass-FRP and Aramid-FRP Rebars 总被引:1,自引:0,他引:1
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. 相似文献
11.
Di Tommaso A. Neubauer U. Pantuso A. Rostasy F. S. 《Mechanics of Composite Materials》2001,37(4):327-338
This paper presents an evaluation of the results obtained from an initial study carried out at the IBMB, Technical University of Braunschweig, on the influence of temperature on adhesively bonded plate-concrete joint systems. The results of a theoretical model are also presented. The type of specimen used in this study is a three-point bending beam. The concrete specimens were prismatic in form, 100 × 100 × 700 mm without an internal steel reinforcement, strengthened at the intradoss with two types of UD CFRP lamina 20 mm wide and 590 mm long of thickness 1.4 mm for the E = 300 GPa type and 1.24 mm for the E = 175 GPa type. The plate-bonded specimens were designed to produce bending failure under a load, by not bonding the lamina and the concrete around the midspan of the specimens. The specimens were tested to failure at –100°, –30°, and +40°C after an approximately homogeneous temperature distribution within the concrete specimen has been reached. For comparison only, specimens of the same type were tested to failure at room temperature. The results obtained showed varying behavior of the bonded plate-concrete joint depending on variations in temperature. Furthermore, they showed different failure mechanisms. Greater reductions in the ultimate bond force were recorded for the test specimens strengthened with lamina having a high elastic modulus. A reasonable correlation was found between the experimental and theoretical results. 相似文献
12.
13.
Conclusions A significant effect of the addition of LCP on the mechanical properties and their anisotropy has been established. Already, if one considers the shape of curves of the stress-strain relationship it can be seen that curves typical for semicrystalline polymers (pure polypropylene) with clearly visible yield point and significant cold drawing leading to an anisotropic stiffening are changing into curves without yielding and with a brittle failure (LC-rich blends). Generally, the tensile elasticity modulus increases with increasing LCP content for both MD and TD. The maximum value of anisotropy of elastic properties was noted for a rather low content of LCP (c = 5%). On the contrary, the stress at yield decreases with increasing LCP content. The same was observed for the strain at yield but in both cases an important increase of anisotropy has taken place. Consequently, the total elongation during drawing (strain at break) showed a drastic decrease for blends with higher LCP content (about 60–80 times). The addition of the LCP to polypropylene has led to a stiffness increase (higher elasticity modulus) but simultaneously to a considerable plasticity decrease. As a confirmation of these observations, there served also the creep test where a decrease of the creep compliance (by two times) for LC-rich blends as compared with pure PP was noted.It also should be emphasized that, generally, a smaller effect of LCP content on the elastic deformation was noted than that on the time dependent effects (nonelastic creep deformation).Published in Mekhanika Kompozitnykh Materialov, Vol. 30, No. 4, pp. 442–450, July–August, 1994. 相似文献
14.
Unfitted finite element methods for the heat conduction in composite media with contact resistance
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Haifeng Ji Feng Wang Jinru Chen 《Numerical Methods for Partial Differential Equations》2017,33(1):354-380
This article is concerned with the heat conduction problem in composite media. In practical applications, the composite materials often do not contact well and there exist gaps between the contacting materials. This leads to the thermal contact resistance effect which results in a discontinuity of the temperature across the interface. In this article, an unfitted finite element method is proposed to solve the problem. Different from the traditional finite element method, the proposed method uses structured meshes that allow the interface to cut through. To avoid integrating on curved domains and interfaces, the interface is approximated by a broken line/plane corresponding to the triangulation. In addition, a ghost‐penalty is added to recover the condition number of the stiffness matrix to with a hidden constant independent of the mesh‐interface geometry. A rigorous analysis is provided. Finally, numerical tests are presented to verify the theoretical findings. © 2016 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 33: 354–380, 2017 相似文献
15.
This is a summary of the most important results presented in the authors PhD thesis (Spanjaard 2003). This thesis, written in French, was defended on 16 December 2003 and supervised by Patrice Perny. A copy is available from the author upon request. This thesis deals with the search for preferred solutions in combinatorial optimization problems (and more particularly graph problems). It aims at conciliating preference modelling and algorithmic concerns for decision aiding.Received: March 2004, MSC classification:
91B06, 90C27, 90B40, 16Y60 相似文献
16.
We consider the Choquard-Pekar equation and focus on the case of periodic potential V. For a large class of even functions W we show existence and multiplicity of solutions. Essentially the conditions are that 0 is not in the spectrum of the linear part –+V and that W does not change sign. Our results carry over to more general nonlinear terms in arbitrary space dimension N2.Mathematics Subject Classification (2000):35Q55, 35Q40, 35J10, 35J20, 35J60, 46N50, 49J35, 81V70in final form: 14 November 2003 相似文献
17.
Roberto Montemanni 《4OR: A Quarterly Journal of Operations Research》2003,1(3):257-260
A survey of the results described in the authors PhD thesis (Montemanni 2001) is presented. The thesis, which was supervised by Prof. Derek H. Smith and Dr. Stuart M. Allen, has been defended in January 2002 at the University of Glamorgan (U.K.). The thesis proposes new heuristic algorithms, based on well-known meta-heuristic paradigms, and new lower bounding techniques, based on linear programming, for the fixed spectrum frequency assignment problem.Received: May 2003, Revised: May 2003, AMS classification:
90C27, 90C59,05C90, 90C05Roberto Montemanni: Present address: Istituto Dalle Molle di Studi sullIntelligenza Artificiale (IDSIA), Galleria 2, 6928 Manno-Lugano, Switzerland (e-mail: roberto@idsia.ch) 相似文献
18.
19.
D. Pizele V. Kalkis R. Merijs Meri T. Ivanova J. Zicans 《Mechanics of Composite Materials》2008,44(2):191-196
Blends of low-density polyethylene (LDPE) and ethylene-octene copolymer (EOC) were obtained. The effect of EOC content and
absorbed radiation dose on the mechanical and thermomechanical properties of LDPE/EOC blends are investigated. Particular
attention is given to a tensile stress-strain analysis and the “form-memory” effect of the blends. With growing LDPE content,
the elastic modulus, the yield stress, and the thermorelaxation and residual stresses of the blends increase, but the ultimate
elongation at break decreases, which is caused by the higher crystallinity of polyethylene. As a result of radiation-induced
cross-linking, the elastic modulus, the yield stress (at a 1% strain), the ultimate yield strength, and the thermorelaxation
and residual stresses increase, while the ultimate elongation at break and the melt flow-behavior index decrease, which is
confirmed by the growing gel fraction in the blend.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 279–286, March–April, 2008. 相似文献
20.
Robert D. Maksimov Tomasz Sterzynskii Jozef Garbarczyk 《Mechanics of Composite Materials》1996,32(5):473-482
Blends of a poly(butylene terephthalate) (PBT) and a liquid crystalline polymer (LCP) were prepared in a single screw extruder.
The LCP used was a liquid crystalline copolyester of 40% polyethylene terephthalate with 60% p-hydroxybenzoic acid (40 PET/60
PHB). Specimens for mechanical testing were prepared by injection molding. Rheological, morphological, microstructural, and
mechanical properties were investigated by capillary rheometry, polarized light microscopy, x-ray diffractometry, and a tensile
tester, respectively. For the LCP content higher than 5 wt. % a significant decrease of the viscosity was noted. The morphology
of the dispersed LCP phase varies between droplets and oriented fibrils. The degree of cystallinity of PBT and the crystal
sizes were found to be affected by LCP addition. The tensile mechanical behavior of the PBT + LCP blends was also found to
be affected by their compositions. The elasticity modulus and the parameter of elasticity anisotropy monotonically increase
with the LCP content. The strain at break shows a drastic decrease for the blends containing more than 10 wt. % LCP. The long-term
creep test shows that the creep compliance decreases noticeably when the LCP content increases.
Institute of Polymer Mechanics of the Latvian Academy of Science, Riga, LV-1006, Latvia. Ecole Europeénne de Chimie des Polymeres
et des Matériaux, Université Louis Pasteur, F-67000 Strasbourg, France. Poznan University of Technology, Laboratory of Crystallography
and Polymer Physics, PL-60-965 Poznan, Poland. Published in Mekhanika Kompozitnykh Materialov, Vol. 32, No. 5, pp. 676–689,
September–October, 1996. 相似文献