Evaluation of Domain Size and Interfacial Thickness

HIS PS used in this experiment comprises SPS (M = 2.0 x lO g/mol, 2.8 x 10 g/mol, 4.5 X lO g/mol), PPO, elastomer, and compatibilizer. Elastomers are EPR (Mw = 3.0 X10 g/mol,= 2.2) and ethylene-propylene-diene rubber (EPDM) (Mooney viscosity at 100°C = 88), and compatibihzers MA-g-SEES (Thftec M1913), SEES (H-1081, 60% styrene), poly(styrene)-h/ocA -ethylenepropylene-h/oc -styrene (SEPS) (Septon 2105, 50% styrene), and 

The blend sample was compression molded into a thin film with 25-pm thickness at 300°C mold temperature and then was quickly quenched in ice water. The film specimen prepared in this procedure is amorphous. 

Styrene chains of MA-g-SEBS dissolved into the SPS matrix. This phase structure causes the reduction of interfacial tension, and hence the domain size becomes smaller (compatibilizer effect). 

Analyzing the LS curve at the Porod region where I q) obeys the power law of / the interfacial thickness can be evaluated. If the interface is assumed by the sigmoidal curve defined as Gaussian with standard deviation o, the scattering at the Porod region can be expressed as [16] 

The characteristic interfacial thickness t is calculated using t = (2jt) o [1]. Results are summarized in Table 18.6. The interfacial thickness and the surface area are found to increase with the addition of MA-g-SEBS. These results can be interpreted as the compatibilizer effect. However, this system does not indicate enough impact strength because the domain size is too large. Thus, it is necessary to make the domains much smaller by adjusting the primary structure of the polyolefin and the compatibilizer. 

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