Tensile strength, retention

In order to achieve the desired fiber properties, the two monomers were copolymerized so the final product was a block copolymer of the ABA type, where A was pure polyglycoHde and B, a random copolymer of mostly poly (trimethylene carbonate). The selected composition was about 30—40% poly (trimethylene carbonate). This suture reportedly has exceUent flexibiHty and superior in vivo tensile strength retention compared to polyglycoHde. It has been absorbed without adverse reaction ia about seven months (43). MetaboHsm studies show that the route of excretion for the trimethylene carbonate moiety is somewhat different from the glycolate moiety. Most of the glycolate is excreted by urine whereas most of the carbonate is excreted by expired CO2 and uriae. 

Fig. 2. Tensile strength retention, continuous service, for fluorocarbon elastomers. Compound I (see Table 4).

Table 8-42 Percent tensile strength retention using welding techniques... 

Reagent Retention of tensile strength (%) Retention of FS (%) Retention of EBC (%) Appearance Performance Retention of tensile strength (%) Retention of FS (%) Retention of EBC (%) Appearance Performance... 

Figure 4.59 displays examples of tensile strength retention versus short-term temperature increase for neat, glass fibre (GF) and glass bead (GB) PA 12 grades. 

Figure 4.59. PA 12 examples of tensile strength retention (%) versus temperature (°C)...

The short-term modulus or tensile strength retention at 120°C as a percentage of the value at 20°C is roughly 30-50% for a few glass fibre reinforced grades. 

Figure 4.98 displays an example of tensile strength retention versus temperature for a neat polyethersulfone. Note the slow decay considering the high temperatures and the significant value of 35% for the retention at 200°C, that is, 30 MPa. 

The resistance to moisture and hot water is good without hydrolysis but the resistances of glass fibre reinforced compounds can decrease significantly because of polymer/fibre interface alterations. For example, after 1 year in water at 120°C, tensile strength retention is 50% for a given compound. However, special grades with improved hot-water resistance are marketed and are successfully used in hot-water pumps. 

Figure 4.105 displays two examples of tensile strength retention versus temperature for a neat and a carbon fibre reinforced polyetherketone, showing the rather fast decay up to 180°C followed by a stabilization. 

The resistance to gamma radiation is good without significant degradation after 500 Mrad tensile strength retention is 94%. 

Table 4.84 Polyetherimide examples of tensile strength retention and weight gain after 100-day immersion at room temperature...

Chemical Concentration (%) Tensile strength retention (%) Weight gain (%)... 

Figure 16.11. Tensile strength retention of various fibers as a function of aging time in circulating air at 205°C.

Figure 11.6. Tensile strength retention after exposure to y-radiation at 3.5 MRad. [Adapted, by permission, from Mcllvaine J, Antec 95. Volume III. Conference proceedings, Boston, Ma., 7th-llth May 1995, 3346-9.]...

AT S00 C Ultimate Tensile Strength Retention after 100-hr burner rig 60% 100% 100% ... 

The ultraviolet resistance of poly( 1,3,4-oxadiazole) fibers can be improved, by the addition of 4,4 -azodibenzoic acid [50]. The tensile strength retention of the oxadiazole fibers containing 4,4 -azodibenzoic acid is much higher than that of the fibers without the azo groups after accelerated irradiation by an iodine-gallium lamp. Also the fibers with 4,4 -azodibenzoic acid in the molecular chain by copolymerization show a better UV stability than the fibers simply blended with the same amount of 4,4 -azodibenzoic acid. 

However, the availability of some new synthetic long-lasting absorbable sutures pushes the tensile strength retention period beyond 2-3 months. Table 10.A.1 in the Appendix at the end of this chapter summarizes all commercial absorbable and nonabsorbable suture materials that are available in the United States, Europe and the Pacific, their generic and trade... 

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