Nylons tensile strength data

Fig. 19.11A,B presents, as an example, data of drawing series of nylon 6 and polyester filaments (Van der Meer, 1970). The additional data for the polyester (polyethylene terephthalate) are given in Table 19.8 by stretching the Young modulus increases by a factor 8 and the tensile strength by a factor 5.5 (Fig. 19.13).

Table VI compares the key properties of these two types of thermotropic polymers category by category. The samples compared had the same melting ranges, but were very different in reduced viscosities and solubility characteristics. The data compared were those processed under the most favorable conditions. Interestingly enough, the as-spun fibers from the polyester-carbonate can be heat-treated more efficiently than those fibers (of same tenacity) spun from the polyester. Both of them gave fiber properties far superior to those of nylons and polyethylene terephthalate. These two classes of polymers also had comparative properties (such as tensile strength, tensile modulus, flex modulus, notched Izod impact strength) as plastics and their properties were far superior to most plastics without any reinforcement.

Results of some of these short-term tests are shown in Table II. A comparison is given between PPS and five other plastics nylon (Zytel 101), polycarbonate (Lexan 141), polysulfone (Bakelite Polysulfone), polyphenylene oxide (Noryl), and polyetherimide (Ultem 2300). The data presented are based upon retention of tensile strength for all plastics except the Ultem 2300, which is based upon retention of flexural strength. Unsuccessful attempts were made to injection mold ASTM Type IV tensile bars out of the Ultem compound, but flexural strength bars could be made. Experience has shown that chemical resistance tests monitored by flexural strength retention are comparable to those monitored by retention of tensile strength. 

For instance, heat aging tests, which are used to evaluate the effect of longterm exposure to elevated temperatures, can be used to show the change in a given property value, say tensile strength, as a function of time. The gr hs show sample data from different versions of nylon (Figure 5.8). 

The graph depicted in Fig. 8.3 illustrates this phenomenon. The upper curve indicates that the value at O F is 14,000 Ib/in. At 72°F, it has dropped to around 12,000 Ih/in. By the time it reaches 140°F, the tensile yield strength is approximately 7000 Ih/in. This data is for nylon, a polymer particularly affected by moisture. The lower curve illustrates the effect of 2.5% moisture. In the range of temperatures between 30 and 100°F, the tensile yield strength appears to be about 20% lower for the moist material. Note that the curves begin to nm together beyond 150° F as most of the water has been driven off by that point. 

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