Tensile strength threshold values

In air, PTFE has a damage threshold of 200—700 Gy (2 x 10 — 7 x 10 rad) and retains 50% of initial tensile strength after a dose of 10" Gy (1 Mrad), 40% of initial tensile strength after a dose of 10 Gy (10 lad), and ultimate elongation of 100% or more for doses up to 2—5 kGy (2 X 10 — 5 X 10 rad). During irradiation, resistivity decreases, whereas the dielectric constant and the dissipation factor increase. After irradiation, these properties tend to return to their preexposure values. Dielectric properties at high frequency are less sensitive to radiation than are properties at low frequency. Radiation has veryHtde effect on dielectric strength (86). 

Data are presented which illustrate that the tensile strength and elongation-at-break depend significantly on the extension rate even when the stress remains in equilibrium with the strain prior to fracture. A crude estimate was made of the threshold (lowest possible) values of the true stress-at-break and the elongation-at-break for the TIPA elastomer. The estimated quantities are about 26% less than those found at an extension rate of about 0.01 min-1 at 30°C. 

Attempts to totally remove all particulate matter (i. e. ultrafiltration) have not been completely successful in that the theoretical limit for water s tensile strength ( 1500 atm) has not been achieved. One of the largest experimental threshold values 200 atm) is that found by Greenspan [11]. 

The observed critical relative densities are understood as threshold values for the tensile strengths of the tablets. One practical consequence of these works is to avoid the manufacture of matrix tablets close to these critical densities. The formulation may not be robust in this critical range from the viewpoint of mechanical tablet stability. 

The tensile strength in other systems like TiO -polyethylene nanocomposite system increases with the increase in concentration of the nanoparticle up to a threshold value of 2 wt%, beyond which, the high surface energy and the high surface area lead to the formation of agglomerates, which reduce the strength [37]. 

A Energy corresponding to the threshold value of unknotted suture. B Energy corresponding to the maximum KHF of knotted suture. C Tensile strength of straight suture. 

Values of Mc calculated from the small-strain tensile modulus, i.e., using C- + C2 in equation 2 in place of Cj, were, of course, smaller than those obtained from Ci values. However, the general form of the dependence of threshold tear strength upon Mc and the relative values obtained for different polymers at the same Mc were not significantly affected by this alternate procedure for calculating the mean molecular weight of network strands. 

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