Radiation elastic modulus

The importance of polymer composites arises largely from the fact that such low density materials can have unusually high elastic modulus and tensile strength. Polymers have extensive applications in various fields of industry and agriculture. They are used as constructional materials or protective coatings. Exploitation of polymers is of special importance for products that may be exposed to the radiation or temperature, since the use of polymers make it possible to decrease the consumption of expensive (and, sometimes, deficient) metals and alloys, and to extent the lifetime of the whole product. 

Mechanical properties, such as elastic modulus and yield point, that depend on crystallinity per se are not seriously affected by low to moderate doses of ionizing radiation. On the other hand, those mechanical properties that are sensitive to interlamellar activity are most dramatically affected by the low to moderate radiation doses. This is seen in the ultimate tensile strength and elongation at failure of the polyolefins. It is also reflected in the large change in melt index between 0 and 18 Mrad, which indicates formation of cross-links that increase with increasing... 

Figure 3. Variation of elastic modulus at 160°C. with ionizing radiation dose...

Recently Yamaoka and Miyata carried out the reactor irradiation at 20 K on two kinds of aromatic polyimides, Upilex-S and Upilex-R [51]. The stress-strain curves of irradiated Upilex-S films are depicted in Fig. 7. No essential changes in both elastic modulus and yield strength were observed for Upilex-S after irradiation up to 8 x 106 Gy, although a slight decrease of the ultimate elongation was detected. A similar tendency was found in the reactor irradiation of Upilex-R at 20 K, in spite of the fact that its structural unit of the main chain is different from that of Upilex-S. These results indicate that a homologue of aromatic polyimides exhibits the excellent radiation stability even at cryogenic temperatures as well as at ambient temperature. 

Oliver WC, McCallum JC, Chakoumakos BC, Boatner LA (1994) Hardness and elastic modulus of zircon as a function of heavy-particle irradiation dose II. Pb-ion implantation damage. Radiation Effects Defects in Solids 132 131-141... 

Fig. 42. Variation of elastic modulus, E, with temperature and radiation dose (dynamic values) [428].

Fig. 45. Influence of the radiation dose on the mechanical properties of polystyrene. Curve 1, tensile strength curve 2, elongation curve 3, elastic modulus curve 4, shear strength curve 5, impact strength.

The chemical and mechanical stability of poly(n-butyl acrylate)(PnBA) to weathering, especially to solar radiation, is of interest for possible use of this material as an encapsulant/ pottant for silicon cell solar energy arrays. This application requires that the material retain an acceptable level of its desirable properties, such as transparency, elastic modulus, etc., over several years of exposure to intermittent moisture, temperatures ranging from -10 to 50 C, solar radiation, and other norms and extremes of exposure conditions. Knowledge of the dependence of changes in properties and composition of the material on exposure conditions is a requisite for establishing reasonable estimates of its prospective performance lifetime characteristics. 

In addition to pore size, the mechanical strength of polymer substrates has an influence on the behaviour of cells, as cells sense their environment through the focal adhesions that attach the cytoskeleton to the scaffold.The mechanical properties of elastomeric poly(l,2-butadiene) (PB) honeycomb patterned films can be controlled by crosslinking the films under UV radiation.Crosslinking of the PB films resulted in a 15-fold increase in the elastic modulus but had no effect on the surface properties of the polymer. Murine fibroblasts exhibited stronger adhesions to the crosslinked PB films. When attached to a growth substrate, cells apply a traction force of 30 nN to the surface. Simulation of this force on the... 

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