Effect of polyamide end groups

In a detailed investigation on the PA6/m-EPR (80/20) reactive blends. Mason et al. [17] showed that the notched Izod impact strength at all temperatures down to —30°C improved steadily with the addition of an amine terminated PA6, replacing the balanced end group PA6 (Fig. 8.9). 

Typical morphology of an ultra-tough, amine terminated PA6/maleated EPR (80/20) blend as examined by transmission electron microscopy (TEM) via selective staining of 

PA6 by phosphotungstic acid, showed an average particle size of 0.3 p, with many particles containing some occluded or penetrated polyamide, presumably graft-coupled to the rubber (Fig. 8.12). It is believed that such occlusions may actually facilitate the 

5 Toughening Efficiency of Maleated Styrene-Ethylene/ Butylene-Styrene (M-SEBS) Block Copolymer Rubbers 

The differences in the observed impact efficiency were attributed to the differences in the average rubber particle size between these systems. The rather small rubber particle size (0.05 p) obtained in the case PA6/m-SEES blends was considered to be too small to be effective for obtaining high fracture toughness. It was suggested that there may be not only an upper limit, but also a lower limit for the rubber particle size for optimum rubber toughening efficiency [32]. 

---