Anisotropy of mechanical properties

Zhitaru R. P., Radautsan S. I., Tezlevan V. E., Buzhor V. P., 1978, Ob anizotropii mekhanicheskikh svoistv monokristallov Cd Cr2 Se4 v Kristallicheskie i stekloobra-znye poluprovodniki (On the Anisotropy of Mechanical Properties of CdCr2Se4 Monocrystals) Izd. Shtiintsa, Kishinev. 

Force extension curves have revealed an anisotropy of mechanical properties for compression-moulded samples but an isotropy for cast films122. ... 

Anisotropy of mechanical properties at the increase of filler concentration [70, 78] rises significantly in the items produced from mineral media-filled thermoplasts. When a mineral filler is replaced for a mineralorganic, the dfect of mechanical anisotropy increase fades considerably [18]. At the same time cp values, durability of cold seal moulded products, made of kerogenes is higher than in products of mineral materials-filled compositions [18]. 

Orientational order plays an important role in solid polymers. It is often induced by industrial processing, for example in fibers and injection- or compression-modulated parts. In polymers with liquid-crystalline properties of the melt or solution, the anisotropies generated by the flow pattern are particularly pronounced. In order to improve the mechanical properties of polymer fibers or films, the degree of orientation is intentionally enhanced by drawing. At the same time, anisotropy of mechanical properties can result in low tolerance to unfavourably directed loads. In many liquid-crystalline polymers, in the mesophase near the transition to the isotropic phase, electric or magnetic fields can induce macroscopic orientational order [1]. Natural polymers such as silk protein fibers, which are biosynthesized and spun under biological condition, also have good mechanical properties because of their ordered structure [2]. 

Because the stress unloading points to the valley, the open fissures go parallel to the river bank. This not only makes the weakening of mechanical properties of slope rock-mass, but also leads to strong anisotropy of mechanical properties and permeability. 

Amphiphilic liquid-crystalline phases, 233 Anisotropy of mechanical properties, control, 9-10 Aromatic copolyester, 2 Aromatic copolyester analysis using proton NMR spectrometry distribution of correlation times, 256-257... 

Studies on randomness of filler distribution in polymethylacrylate nanocomposite are interesting. In this experiment, siUca particles were formed both before and after matrix polymerization. The results indicated that the concentration of silica was a controlling factor in the stress-strain relationship rather than the uniformity of particle distribution. Also, there was no anisotropy of mechanical properties regardless of the sequence of filler formation. This outcome cannot be expected to be duplicated in all other systems. For example, when nickel coated fibers were used in an EMI shielding application." When compounded with polycarbonate resin, fibers had a much worse performance than when a diy blend was prepared first and then incorporated into the polymer (Figure 7.1). In this case, pre-blending protected the fiber from breakage. 

At temperatures around 1000°C the product is amorphous and up to 1200°C it is polycrystalline with little orientation. When prepared above 1800°C by this method the product is highly oriented with resultant obvious anisotropy of mechanical properties. This feature can affect the values of hardness found in the literature. All forms are chemically very inert, but... 

L.S. Zevin and I.M. Zevin, Asbestos cement orientation of fibres and anisotropy of mechanical properties , int.J. Cem. Comp. Ltwt. Concr. A, 1982,181-184. 

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