Tensile strength data, with

Confidence Interval for a Mean For the daily sample tensile-strength data with 4 df it is known that P[—2.132 samples exactly 16 do fall witmn the specified hmits (note that the binomial with n = 20 and p =. 90 would describe the likelihood of exactly none through 20 falling within the prescribed hmits—the sample of 20 is only a sample). 

The random nature of most physieal properties, sueh as dimensions, strength and loads, is well known to statistieians. Engineers too are familiar with the typieal appearanee of sets of tensile strength data in whieh most of the individuals eongregate around mid-range and fewer further out to either side. Statistieians use the mean to identify the loeation of a set of data on the seale of measurement and the variance (or standard deviation) to measure the dispersion about the mean. In a variable x , the symbols used to represent the mean are /i and i for a population and sample respeetively. The symbol for varianee is V. The symbols for standard deviation are cr and. V respeetively, although a is often used for both. In this book we will always use the notation /i for mean and cr for the standard deviation. 

The most commonly reported physical properties of radiation cross-linked natural rubber and compounds made from it are modulus and tensile strength, obtained from stress-strain measurements. Figure 5.6 illustrates some of the results obtained from gum rubber and from a natural rubber compound reinforced by HAF carbon black.143 In Figure 5.7, the tensile strength of radiation-cured gum is compared with vulca-nizates cured by sulfur and by peroxide.144 Selected tensile strength data from radiation-cured NR compounds are in Table 5.4. 

Tensile Strength of Explosives. Ref 2 contains tensile strength data obtained with the procedure outlined In ASTM D638 (27) (1968),... 

Tensile Strength. Tensile strength data (Figure 7) indicate that the highest value was obtained with milled glass fiber (20% loading) and the relatively low value obtained with chopped integral strands. This may be related to the aspect ratio of dispersed milled fiber in the composite compared to chopped... 

On irradiation, NR undergoes degradation, whereas EVAc crosslinking. This is consistent with the modulus and tensile strength data (see Table 11.53). The radiation resistance of the EVAc-rich blends is better. Of the blends cured by the three systems, those cured with the mixed system showed lower retention of tensile strength but higher retention of the modulus. 

The tensile strength data show comparable values for the two samples. Similar dry and wet tensile strength data (Ibs/in) are observed at the 0.25%, 0.50% and 0.75% levels of the two resins. In particular, the wet tensile strength of both resins increases after curing. Thus, enzymatic synthesis produces fully acceptable polymers with commercially viable properties. 

Merker, et. a1. (13) reported that block copolymers of TMPS-DMS segments exhibited elastomeric properties and considerable toughness because of the crystalline TMPS blocks. The tensile strengths increased with molar concentration and block lengths of TMPS. Examples of some mechanical property data are as follows ... 

Fig. 7A.5. Responses of the seven runs of the centroid simplex model fitted to the tensile strength data. Is something amiss with any replicate value ...

Stress-Strain Properties. Tensile strength improves with an Increase in styrene content (at least up to 50 styrene) as shown in Figure 6 or an increase in molecular weight (ll). The latter effect may not be evident at room temoerature but is more significant at elevated temperature or in compounded stocks as illustrated in Tables II and III. Data in Table II as well as reference (ll) also indicate that the high tensile observed at room temperature decreases as tanperature is raised thus limiting the maximum service tanperature of these polymers. 

Figure 10.25. Tensile strength data for Kraton 101 (SBS triblock polymer) ( ) compared with those for an SBR vulcanizate containing 25% by volume of 350-A polystyrene latex spheres (O) (Morton and Healy, 1968) and SBR vulcanizate reinforced with 30% by weight HAF carbon black filler ( ). (Morton and Healy, 1968 Smith, 1970.)...

Table 4.3 Processing parameters and tensile strength data for unfilled and filled Xydar. Reprinted with permission from [20], copyright 1986 Society of Plastics Engineers, Inc.

Experimental tensile strength data for a lot of fibers of same length, L, can not always be fitted with a single straight line. Such a situation usually corresponds to the occurrence of two populations of defects, for example, a population of internal flaws and a population of surface flaws. 

The tensile strength data for a specific lot of SiC based fibers show a considerable scatter, as could be expected from the brittle character of silicon carbide. This spreading is usually depicted with a unimodal, two parameter Weibull distribution... 

Figure 12. Weibuli plot of tensile strength data for Si-C-0 (Nicalon NL 202) fibers, with a unimodal Weibuli...

Compression flow stress (20% strain) and ultimate tensile strength data from Sokolov et al. (1971), Sokolov et al. (1969b) and Love (1959) for erbium are in reasonable agreement with one another but deviate substantially from the ultimate tensile strength data from Owen and Scott (1968), fig. 8.38. Again the... 

Similar results are shown in Fig. 3.35 The tensile strength data shown are for composites that contain smaller particle size micas. Both treated 200 NP and untreated 200 HK micas were evaluated. Again, the NP grade is treated with aminosilane. 

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