Synthesis, Morphology, and Mechanical Properties

The fracture energy of the nanocomposite containing 5 vol% of clay was three times as high as its value for the pure UP. 

This effect was more significant in the case of polyester modified with less polar alkylammonium MMT. The authors compared the fiexural properties of cured UP-MMT nanocomposites with styrene and HPA monomers. In both cases, the fiexural modulus increased with clay content. The more marked enhancement of the modulus was observed in the case of styrene-based nanocomposites, which was interpreted as the result of more favorable diffusion of nonpolar styrene into the galleries of alkylammonium MMT than in the case of polar HPA. However, only a slight improvement in the tensile properties was observed for nanocomposites containing 1 wt% clay obtained at long mixing times. The addition of more organoclay resulted in no further increase or even a decrease in tensile modulus. 

Zhang and coworkers used for the modification of UP resin three MMT clays containing various cations, that is, sodium, alkylammonium, and methacryloxy-alkylammonium [8]. The thorough mixing of UP resin with clay fillers was applied, for over 24h at 50 °C. XRD patterns of the cured UP-clay hybrids indicated only partial intercalation of sodium-MMT by polyester, while the interlayer distances of organically modified clays expanded beyond the values detected by XRD (8.8 nm). 

TEM analysis showed that most of MMT was dispersed in the UP matrix as small aggregates part of them were dispersed into layers. 

MT type MMT content (wt%) Tensile strength (MPa) Impact strength (KJ rn ) Hardness (Barcol) Heat distortion temperature fC) 

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Dubois Ph, Yu Y S, Teyssie Ph and Jerome R (1997) New polybutadiene-based thermoplastic elastomers synthesis, morphology and mechanical properties. Rubber Chem Tech 70 714-726. 

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