Starch-Filled Ternary Polymer Composites. I: Dynamic Mechanical Properties

摘要

The dynamic mechanical properties of starch-filled blends of polyethylene (PE) and poly (hydroxy ester ether) (PHEE) are strongly dependent on the properties and distribution of the minor component (PHEE). The effect of the minor component on the viscoelastic properties was investigated by modeling the storage moduls, G', using a step-wise homogenization process. A comparison of theoretical and experimental data indicates that the morphology changes as the total volume fraction of filler phi_t increases. At low phi_t, the PHEE encapsulates isolated starch granules. Above phi_t approx 0.2, the PHEE surface coating contributed to the formation of particle clusters. Evidnece of particle encapsulation was provided by a microscopic examination of fractured tnesile bars. At all filler contents, the decrease in the composite's moduls at the T_g of PHEE is larger than can be accounted for if this material is simply dispersed in the matrix. When the starch granules are clustered, the decrease is also too large to be accounted for by only considering particle encapsulation. The effect of particle clustering must be included in order for the model to correctly describe the temperature dependence of the torage modulus.