Effect of clay loading on the structural and mechanical properties of organoclay/HDI-based thermoplastic polyurethane nanocomposites

摘要

Thermoplastic polyurethane/organically-modi-fied montmorillonite (TPU/OMMT) nanocomposites were synthesized by the pre-polymer polymerization method using Cloisite? 30B organoclay, 1,6-hexamethylene diisocy-anate (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-CH2CH2OH 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.