Effect of sample thickness

Figure 8.8. Examples of nonexponential fluorescence decay curves 9,10-diphenyl-anthracene on alumina for chromatographic purposes (Uhl.Oelkrug, unpublished results) (unnumbered curves time profiles of the excitation pulse, 2 - 360 nm). Upper left effect of environment (1) high vacuum, (2) liquid n-hexane. c=3/tmol g"1,2 =440 nm. Upper right effect of fluorescence wavelength (1) 2 = 500 nm, (2) 440 nm, (3) 406 nm c=3 /tmol g 1. Lower left effect of surface loading (1) 3 /rmol g (2) 0.13 mol g , (3) 0.02/r mol g"1 2e=440. Lower right effect of sample thickness (l) d - . (2) d - 0 c - 3 /tmol g 1, 2 = 440 nm.

Effect of Sample Thickness. Sample thickness significantly affects the radiation-induced expansion of unstressed samples (Figure 14). The equilibrium asymptotic deflection values vary approximately as the square of the sample thickness for the 20- and 30-mil samples. The deflection values for all thicknesses above 0.010 follow the same curve at short times (—0.2 minute), where diffusion out of the sample has probably not yet become significant. 

Figure 14. Effect of sample thickness on expansion of polystyrene during irradiation in the absence of significant stress...

Table V. Effect of Sample Thickness on Creep Rate of Polystyrene during Irradiation "...

Figure 15. Effect of sample thickness on creep during irradiation 88% PVC-12% PV Ac copolymer...

To study the rate of reaction and obtain adequate weight percent gain (WPG), reaction periods varying from 1 to 8 hours were used. Effect of sample thickness on overall acetylation levels was examined on 7.5 cm long mango samples of different cross-sections (6x6 mm2, 12.5 x 12.5 mm2, 20 x 20 mm2, 25 x 25 mm2, and 30 x 30 mm2). These samples were acetylated in vapor phase for 3 and 6 hours. 

Fig. 2a. Effect of sample thickness on the stress-strain curve of notched PA 6 b fracture surfaces...

Fig. 10.5. The effect of sample thickness on oxygen permeation through calcia-stabilized zirconia at 1230°C. Solid lines are theoretical results calculated using Eq. (38). Reprinted fixMn Dou et al. [95J.

There was no effect of sample thickness on the thermal diffusivity when the thickness ranged from 1.5 to 3.0 mm. 

Figure 1 also indicates the percent weight loss as a function of time for samples under desiccation. The effect of sample thickness is less pronounced. Again, a period of 10 days appears to be sufficient to attain nearly complete equilibrium. Other studies on previously dried samples indicate that at least 4 h must elapse before a significant increase in H2O content is observed in desiccated samples exposed to room air. Since these specimens were desiccated until just before testing, we consider that no moisture was present. Results of Figure 1 can be summarized as follows normal samples contained /0.6% H.O, dried samples had /0% H2O, and saturated samples had 2.2% H2O. Analysis by gas chromAography indicated that a small amount of residual monomer (F 0.6%) was present in these specimens. The analysis also indicated that this monomer was not removed by... 

Figure 15.13. Effect of sample thickness on the notched impact strength of unmodified (I) vs. impact modified (II) polycarbonates P reitag et al., 1985].

To illustrate the effect of sample thickness, we can compare adhesives to sealants, which in many cases can be viewed as thick adhesives. As the sample thickness is increased, the benefit of the BTZ is clearly demonstrated. In Table 3 a SEBS/hydrogenated hydrocarbon tackifier sealant formulation was prepared as a hot melt and poured into shallow petri dishes. Although both of these polymers have good inherent stability, sealant applications may require extended exposure to UV radiation. The discoloration data show that the BTZ prevents yellowing of the sealant. However, examination of the sealant surface shows surface crazing and cracking when not protected by incorporation of the HALS. The combination of the two classes of light stabilizers provides the best overall performance. 

The only remaining variable of interest in the Kramer relations is the sample aspect ratio (h /R). To test this the sample thickness was varied at constant strain amplitude. As we saw in Figure 3 there appeared to be a dependence of the calculated loss modulus on sample thickness. Some portion of the effect of sample thickness is not being corrected for by the Kramer (8) relations. 

Fig. 19.19 Effect of sample thickness on the notched impact strength of unmodified...

Figure 3 Effect of sample thickness on degradation behaviour (a) TVA curves (vacuum, 10 Cmin" ) for 20 mg PVC,...

Uribe-Arocha P (2003), Effect of sample thickness on the mechanical properties of injection-molded polyamide-6 and polyamide-6 clay nanocomposites . Polymer 44 2441-2446. 

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