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

Abstract

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. © 2017 Society of Plastics Engineers

Effect of PEW and CS on the Thermal, Mechanical, and Shape Memory Properties of UHMWPE

“…It can be seen that the Rf remains basically constant at the same TSW, but increases with the temperature because of more movement of the chain segments in the amorphous region, such as 90% at 85 °C, 95% at 100 °C, and 100% at 115 °C, which is consistent with the research of Wu et al [50]. In particular, The shape recovery process is the process of releasing the energy stored during the deformation at T SW [51]. Compared with the maximum value (approximately 77%) of R r of UHMWPE at 100 • C, it can be seen from Figure 10b that the R r of each group sample ranges from 48% of 13PEW5CS at 115 • C to 79% of 13PEW at 100 • C, which indicates that the addition of PEW and CS does not significantly improve the R r of UHMWPE.…”

Thermo‐mechanical and shape memory behavior of TPU/ABS/MWCNTs nanocomposites compatibilized with ABS‐g‐MAH

“…In this stage, the shape recovery and chain relaxation are observed . In case of TPU/ABS blend, with incorporation of ABS the crystallinity of neat TPU increased , which shows the nucleating role of ABS in the blend . This increment in the degree of crystallization can enhance the shape fixity.…”

“…Nevertheless, it was also reported that addition of ABS to TPU may deteriorate its tensile strength, which placed stress on the use of carbon‐based nanofillers like MWCNTs . As mentioned in our previous works , TPU and ABS are immiscible because of differences in their chemical nature and polarity; therefore, their blends show a clear two‐phase morphology. The relatively large spherical droplets of ABS phase were dispersed in TPU matrix and there is not strong interfacial adhesion between these components, and as a result, the tensile strength of the TPU/ABS blend decreases with increasing ABS content .…”

“…The relatively large spherical droplets of ABS phase were dispersed in TPU matrix and there is not strong interfacial adhesion between these components, and as a result, the tensile strength of the TPU/ABS blend decreases with increasing ABS content . So, to improve interfacial adhesion and obtain higher ultimate tensile properties, an appropriate compatibilization process should be utilized . Branched, block, or graft copolymers, as a result of their interfacial activity can act as a suitable compatibilizer to overcome this issue to some extent .…”

“…In a series of publications, the role of pristine and functionalized multiwalled carbon nanotubes (MWCNT‐OH, MWCNT‐COOH) on shape memory behavior and mechanical properties of TPU/ABS blends was thoroughly studied . The shape memory results suggested that the shape recovery and fixity of TPU/ABS blend was improved significantly with incorporation of MWCNTs into the blend .…”