Shape memory and mechanical properties of TPU/ABS blends: The role of pristine versus organo-modified carbon nanotubes

Some shape-memory materials were prepared based on TPU/ABS blends containing pristine and organo-modified multiwalled carbon nanotubes (MWCNTs). The shape memory and mechanical properties of the samples were investigated. Scanning electron microscopy (SEM) analysis performed on the morphological features of the developed samples showed the presence of pristine MWCNTs and decreased diameter of ABS droplets which were uniformly distributed within TPU matrix. Unexpectedly, the ABS droplets in nanocomposites with organo-modified MWCNTs were greater than ABS droplets in TPU/ABS/CNT nanocomposites. These differences were attributed to different degrees in interfacial interactions between the modified MWCNT and TPU matrix. The presence of modified MWCNT in TPU matrix could have increased the differences in surface energy and polarity of TPU and ABS and it has disturbed the compatibility of the blend fundamentally. Also, the mechanical and Izod impact properties of the shape memory samples containing pristine MWCNT are better than those samples containing MWCNT-OH and MWCNT-COOH. The results showed optimum tensile strength in all samples containing 2 wt% MWCNTs. The shape memory results showed that the shape recovery and fixity of TPU/ABS blend improved significantly with increases in MWCNTs. The pristine MWCNTs improved the shape recovery ratio from 93.88% for the neat TPU/ABS blend to 99.3% for TPU/ABS nanocomposite by just loading MWCNTs at 2 wt%. Surprisingly, the shape fixity changed from 92.98% for the neat blend to 100% by loading of 2 wt% of MWCNT-OH and 1 wt% of MWCNT-COOH. The results showed that the functionalized MWCNTs had better performance in shape fixity as compared to its pristine MWCNT counterpart. POLYM. COMPOS., 39:E984-E995, 2018. (c) 2017 Society of Plastics Engineers