Polyester resins strength retention

Figures 10 and 11 show the weight change and the retention of strength for iso-phthalic unsaturated polyester resin (iso-UP). These behaviors show almost the same tendency as MTHPA-EP, however, as shown in Figure 12 the concentration influences flexural strength and the strength becomes minimum at the concentration of 30wt%. This behavior is thought to depend on contradictory tendency of the wetability and the reactivity with the concentration.

The high-performance rayons overcome this disadvantage. The HWM fiber has cotton like mechanical properties and a caustic resistance that allows mercerization. It is compatible in blends with all grades of cotton where it adds strength, improved luster and appearance, and a softer hand. In blends with nylon, polyester, acrylics, and triacetate, it has good strength retention after resination, and the blended fabrics have superior wash-and-wear performance and resistance to pilling. 

Table 4.40 Influence of temperature on short term flexural strength retention of FRP laminates, fabricated from several types of polyester resin (typical).

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