The thermal and rheological properties of blends of poly(epsilon-caprolacto
ne) (PCL) and polystyrene (PS) have been investigated by differential scann
ing calorimetry (DSC), scanning electron microscopy, and Advanced Rheometri
c Expansion System. Two different molecular weights of PS 1 ((M) over bar(w
) = 1000) and PS 2 ((M) over bar(w), = 69,000) have been used in the PCL-PS
blend. In the thermal analysis of the PCL-PS 1 blend by DSC, the T-c of PC
L in the blend decreased by about 3-13 degrees with blend composition compa
red to the T-c of pure PCL. The decrease in T-c of PCL in the blend indicat
es that the crystallization of PCL in the PCL-PS 1 blend is deactivated by
PS 1. The T-m of PCL in the blend decreased by about 2-6 degrees with blend
composition compared to the T-m of pure PCL. From the results of T-c and T
-m of PCL, it is suggested that the PCL-PS 1 blend is partially miscible. T
he T-c of PCL in the PCL-PS 2 blend increased by about 2-5 degrees in the P
CL-rich compositions. The increase in T-c of PCL can be explained by the nu
cleating effect of PS 2 on the primary nucleation of PCL in the PCL-PS 2 bl
end. From the results of the rheological properties of the PCL-PS 2 blend,
the storage modulus of the blend at low frequencies has a larger value than
that of the simple mixing rule. The elasticity increase from the simple mi
xing rule is consistent with the emulsion model for a dispersed system. (C)
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