Interphase design

The consequences of the interphase design on mechanical properties are shown in Fig. 18.23. In contrast to the PP case, the tensile strength is not increased much by... 

JM Felix, P Gatenhohn. Interphase design in cellulose fiber/PP composites. Polym Mater Sci Eng. ACS Fall Meeting Preprints, 1990, pp. 315-316. 

Experimental data for standard Charpy impact suength was analyzed for array of particulate-filled and rubber-modified polypropylene composites (90). Table 6.1 summarizes interphase design characteristics. 

Felix and Gatenholm (10) characterized the effects of compatibilizer molecular weight on the mechanical response of interphase design of cellulose fiber-rein-forced polypropylene composites. The cellulose fiber surface was treated with three different compatibilizers having a range of molecular weights alkyl succinic anhydride, Epolene 43, and Hercoprime G. The latter two compatibilizers are MA-g-PP. 

At sufficiently high concentrations of compatibilizer bonded to the glass fiber surface, there is severe crowding of molecular chains to cause them to assume a perpendicular arrangement and stretch away from the glass fiber surface to satisfy steric hindrance. The free molecular ends become miscible with the polypropylene matrix in an entangled polymer brush structure. An interphase design... 

Heat Capacity Jump for Given interphase Design... 

By using the DSC method to evaluate ACp for a series of short GFR polypropylene composites, the calorimetric response has been used to gauge the relative effectiveness for an array of interphase designs given in Table 12.4. 

The evaluation of interphase thickness of the immobilized polymer layer surrounding glass fibers provides quantitative means for gauging the relative effectiveness of given interphase design. After obtaining necessary input data from DSC measurements, the following sequence of calculations is followed ... 

Then for a given volume fraction of glass fiber loading, Eq. (12.5) was used to compute the interphase thickness Aq for each interphase design. 

Table 12.5 provides a summary of the combined results of DSC and tensile strength measurements that characterize a set of interphase designs. Folkes (27) stressed the need to do further research of this t)rpe to develop quantitative rela-... 

Material- interphase design Fiberglass content (wt%) Heat oapaoity jump AC J/g°c Interaction parameter X Interphase thickness Arj(pm) Ultimate tensile strength (MPa)... 

The entire set of tensile strength and interphase thickness values from Table 12.5 coalesce into a single master plot shown in Fig. 12.16. This is powerful evidence that the thermodynamic probe of the microstructure for various interphase designs appears to provide a fundamentally meaningful correlation between structure and properties. 

Effect of Interphase Design on Composite Strength and Stiffness... 

Table 12.7 provides typical mechanical properties for a set of 10-40 wt% GFRP composites having mega-coupled (P7) type interphase design. In particular, these... 

Table 12.6 Characterization of Interphase Designs for 10 wt % Fiberglass Loading...

The plots shown in Fig. 12.21 exhibit trends in regards to base polymer type, interphase design, and ambient temperature ... 

Interphase Design—The sequence of best to worst stiffness up to about 120° C is P7 > P6 > PA-66 > Minion 22C. 

---