First, the aqueous solutions of PVP, PAA, and PVPh had maximum absorbance at 195, 195, and 190 nm, respectively.
In particular, PVPh with the most hydrophobic characteristics showed the most pronouncedly diminished release behavior.
Since PHBHHx could not crystallize with the PVPh content higher than 30%, only neat PHBHHx, 85/15, and 70/30 were studied in this work.
Figure 1 shows the DSC traces of the melt-quenched samples of neat PHBHHX, neat PVPh and their blends.
Figure 2 shows the variation of [Tsub.g] with the PVPh content for the PHBHHx/PVPh blends.
where [W.sub.1] and [W.sub.2] are the weight fractions of the two blend components, [T.sub.g1] and [T.sub.g2] are the [T.sub.g]s of pure PHBHHx and pure PVPh, respectively.
Glass Transition and Morphology of DDS-Cured Epoxy Blends With PVPh
Figure 1 shows thermograms of the 30 phr of PVPh in the cured DGEBA/PVPh/DDS samples with various contents of DDS.
2, we plotted the [T.sub.g] compositions of the DDS-cured DGEBA network system without and with 30 phr of PVPh, to determine the effect of the PVPh contents on the DDS-cured epoxy.
For PVPh, the 1014 [cm.sup.-1] aromatic C-H in-plane bending vibration was used for PMMA blends, and the 3031 [cm.sup.-1] aromatic C-H stretching vibration for PEO and PVME blends.
PVPh with the same molecular weight was used for PMMA and PEO blends, whereas a higher molecular weight was used for PVME.
However, when comparing to orientation of pure PVPh, for both parts of the data to join (as expressed by the dotted line), a change in slope is required, and may occur at a similar composition as that of the more strongly interacting blends.