| Abstract: | Young's moduli of a series of quenched isotactic polypropylene/high‐density polyethylene blends were measured. The moduli of many of the blends exceeded the upper bound, calculated from the parallel model with the moduli of the two quenched homopolymers as those of the two components. In fact, both components crystallized at higher temperatures in the blends than they did on their own. It is argued that the higher crystallization temperatures of the components lead to higher component moduli and that this can explain the observation that the measured moduli of the blends apparently exceeded the upper bound. The implications of this work are discussed in light of other studies concerning the measurement and calculation of blend moduli. © 2001 John Wiley & Sons, Inc. J Polym Sci B Part B: Polym Phys 39: 1404–1414, 2001 |
