Irradiation tensile yield

Dose (kGy) Temperature of irradiation (°C) Tensile yield strength (psi) Tensile strength (psi) Ultimate elongation (%)... 

An obvious requirement for a pressure tube is that it must be able to withstand the required internal pressure without any risk of fracture or of undue deformation. Possible modes of failure to be considered are tensile yield or bursting, fast fracture from local defects after embrittlement by hydrldlng or Irradiation, excessive deformation or fracture by creep. 

Line Alloy Dose, fast neuti ons/cm Temp, of irradiation, °F Yield strength Tensile strength Uniform elongation, 7o... 

The effect of E-beam irradiation on the physical properties of these resins is summarized in Tables 1-4. Unsterilized samples are used as a control. E-beam irradiation does not induce any significant changes in physical properties. There appears to be a small increase in the tensile yield strength of the PET homopolymer and the various copolyester resins. These increases in yield stress are consistent with the effects of physical aging (2). The PET and copolyesters have glass transition... 

It can be concluded that it is very difficult to predict the result from a polymer macrostructure, but it is relatively easy to measure the secondary species generated on irradiation by using known analytical techniques, such as measuring swelling, tensile tests, analysis using nuclear magnetic resonance (NMR), etc. The yield is then expressed by the G value, which represents the number of cross-links, scissions, double bonds, etc., produced for every 100 eV (1.6 X 10 J) dissipated in the material. For example, G (cross-links), abbreviated G(X), = 3.5 means that 3.5 cross-links are formed in the polymer per 100 eV under certain irradiation conditions. Similarly, the number of scissions formed is denoted by G(S). In order to determine the number of crosslinks or G(X), the number of scissions or G(S), etc., it is necessary to know the dose or dose rate and the time of exposure for these irradiation conditions. From the product yields it is possible to estimate what ratio of monomer units in a polymer is affected by irradiation. ... 

The following polymer characteristics were obtained on the variously irradiated test specimens melt index (ASTM 1238-62T), Vicat softening temperature (modified ASTM 1525-58T) heat distortion (ASTM D 1220-63T) physical strength yield strength ultimate tensile strength percent elongation at break (ASTM D 412-64T) chemical resistance to boiling toluene. 

A 30 Mrad dose of electron irradiation enabled particles to remain intact after dissolution of source samples and recasting into final form. Tensile tests were conducted on several sets of spin cast samples before and after electron irradiation with a dose of 30 Mrad. It was determined that the irradiation increased the yield stress somewhat and decreased the elongation, but substantial amounts of plastic deformation still occurred, indicating the presence of significant levels of craze... 

The tension stress-strain curves of irradiated (100 kGy) HDPE, LLDPE, and their 50/50 blends with different amount of DCP, showed that the yield strength and tensile strength increased with DCP concentration, whereas the modulus and elongation at break decreased marginally. Whereas the abrasion loss of HDPE and LLDPE increased with irradiation and DCP content, the abrasion resistance of the blends increased with increase of the irradiation dose and the DCP content. 

Later, these workers investigated the effect of irradiation on the tensile properties of the LDPE/PP blends. For the non-irradiated blends, the mechanical behavior gradually changed with composition. The elongation at yield gradually increased from PP to LDPE, whereas the elongation at break showed a minimum at 75 wt% PP [Spadaro et al, 1984]. The results are shown in Table 11.14. 

Polycarbonates, although they tend to strongly discolor for unstabilized grades, are relatively resistant to irradiation showing retention of elongation at yield and tensile modulus after irradiation up to 1,000 kGy [198]. 

Tensile strength and yield strain of y-irradiated SBS block copolymers [13]... 

Fig. 3.1 -93 Irradiation effects on mechanical properties of a zircaloy [1.68], YS - yield stress UTS - ultimate tensile strength. Solid lines irradiation in the annealed state. Dashed lines irradiation in the 10% cold worked state...

Figure 4.18 Scheme for the transition from elasticity to brittle failure during tensile tests of irradiated metal (a, yield stress TT, transition temperature) [54]... 

Figure 11.19 Schematic representation of temperature dependence of ultimate tensile strength or yield strength before and after irradiation and uniform elongation after irradiation. Nb-lZr and Mo-Re were reproduced from Ref. [100] and V Cr-4Ti from Refs. [8] and [40].

The consequence of UV irradiation is the progressive decrease in the polyethylene viscosity [58]. This essential element must be correlated with the modification of diffusion property of polymer, by which the degradation is significantly accelerated. The type of nanofiller (multi-waUed carbon nanotubes, fumed silica, neat Cloisite and modified Cloisite) influences differently the behavior of pristine HDPE [59]. The increase order of tensile strength measured at Yield point places the contribution of studied nanoparticle phases for the first 100 h of UV exposure describes promotion of a crosslinking process involving the radicals formed by photolysis. 

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