Unmodified blends

Table 4 Cure Characteristics and Properties of Unmodified Blends...

The blends modified with MBS rubber (without compatibilizer) show substantial improvement over the unmodified blend if PC is the major component (Nos. 21 and 22 vs No. 19), but they show minimum improvement when PA is the major component (Nos. 6, 7, and 8 vs No. 1). The blends modified with MBS-MA rubber also show significant improvement if PC is the major component (Nos. 23 and 24 vs No. 19), but they fail to show improvement when PA is the major component (Nos. 9,10, and 11 vs No. 1). 

The different roles played by each interfacial modifier when located at the interphase are evident when we observe the two opposite effects caused by the a-PP-SF/SA in the 85/15 and the 15/85 PP/PA6 modified blends. For the former, where the polypropylene is the matrix, the presence of the lowest amount of a-PP-SF/SA is enough to increase the tensile strength values with respect to the unmodified blend, while both strength at yield and at break decrease if the a-PP-SF/SA amount continues to increase. 

When polyamide becomes the matrix in the blend, both tensile strength values improve with respect to the unmodified blend by the presence of a-PP-SF/SA and also with an increase in a-PP-SF/SA amount. 

The biodegradation of ehitosan modified PVA-stareh blends by eompost was reported and compared with unmodified film by Jayasekara et al. [151]. Within 45 days of composting, the starch and glycerol components were fully degraded, leaving the PVA component essentially intact for unmodified blends. The film characteristics were improved by surface modification with ehitosan. There was slight evidence that PVA biodegradation had been initiated in composted, surface modified starch-PVA blends. 

It should be noted that, although unmodified blends with 75% PE were prepared with certain ease, the blending and processing of modified counterparts of these samples were made even easier. In addition, the higher PVC containing blends with unmodified PE (i.e., 50 wt%) could not be processed into an acceptable film at all, while a modification of PE surfaces by plasma (or addition of VCO to the system) always produced an easy to process blend. 

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