Thermoplastic polyurethane/organically-modified montmorillonite (TPU/OMMT) nanocomposites were synthesized by the pre-polymer polymerization method using Cloisite ® 30B organoclay, 1,6-hexamethylene diisocyanate (HDI), polycaprolactone diol (PCL diol, 2000 g/mol) and 1,4-butanediol (BDO). The hard segment content of the TPU was maintained at ~25.5% while the role of clay content was investigated at 1, 3 and 5 wt.% of clay concentration. The aim of this work was to obtain a high-performance polyurethane system while reaching a general microstructure-property relationship for TPU/OMMT nanocomposites. Clay exfoliation was achieved at 1 and 3 wt.% of clay loadings while some agglomerated clay sheets were observed in samples containing 5 wt.% OMMT. Significant hydrogen bonding occurred between the urethane linkages with unreacted -CH 2 CH 2 OH groups of the OMMT particles which resulted in strong matrix-filler interactions. Consequently, the values of tensile modulus were enhanced with clay content; namely a 177% improvement was observed for samples containing 5 wt.% OMMT. On the other hand, samples exhibited more thermoplastic behavior with the increase of clay content which resulted in lower deformability and lower values of tensile strength.
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Taheri et al. (2015) studied this question.