Compatibilizer Kraton rubber

Response surfaces showing the effects of composition on mechanical properties are compared with the compatibilized blend and the glass-fiber-reinforced composite in Fig. 5.7 and 5.8. Regression models for the compatibilized blends are shown below the response surface graphs (Fig. 5.7, a-e) versus reinforced (Fig. 5.8, a-e) blends shows a marked difference in the nature of the responses. Most notably, the curvature in the response observed in the compatibilized blends has vanished, and the response is a function of Kraton rubber only for the flexural modulus, notched Izod impact, and tensile strength. Similarly, the heat distortion temperature is now only a linear function of Kraton and HDPE levels. Finally, elongation at break has been reduced to a single value (3.43 0.45%), as more than 90% of the variability in the data was explained by the mean value. Thus,... 

Microfibrils in the blend compatibilized with Kraton G probably formed by drawing of the rubbery shell of the core-shell particle. Important factors would have been the amount of rubber in the shell, the strength of the rubber, and the strength of adhesion to LLDPE. All these factors may have contributed in some degree to the high fracture stress and strain of the blend with Kraton G. The amount of compatibilizer in the shell differed for the various Kratons the thicker coating was certainly one of the reasons Kraton G gave better properties to the compatibilized blend than the Kraton D compatibiliz-ers. 

The presence of the rubber can give rise to some worsening of the thermal resistance of the blends. To verify this behavior, tests for measuring the Vicat temperature have been carried out. In Figure 14, the Vicat temperature is reported as a function of the content of Kraton. As expected a reduction of the Vicat temperature of the non-compatibilized blend is observed but can be considered still reasonable with 5% of Kraton the Vicat temperature decreases by about 6-7°C for both blends. 

---