Thermal, mechanical, and shape‐memory properties of nanorubber‐toughened, epoxy‐based shape‐memory nanocomposites

Abstract

Epoxy-based shape-memory polymers (ESMPs) are a type of the most promising engineering smart polymers. However, their inherent brittleness limits their applications. Existing modification approaches are either based on complicated chemical reactions or done at the cost of the thermal properties of the ESMPs. In this study, a simple approach was used to fabricate ESMPs with the aim of improving their overall properties by introducing crosslinked carboxylic nitrile-butadiene nanorubber (CNBNR) into the ESMP network. The results show that the toughness of the CNBNR-ESMP nanocomposites greatly improved at both room temperature and the glass-transition temperature (T g ) over that of the pure ESMP. Meanwhile, the increase in the toughness did not negatively affect other macroscopic properties. The CNBNR-ESMP nanocomposites presented improved thermal properties with a T g in a stable range around 100 8C, enhanced thermal stabilities, and superior shape-memory performance in terms of the shape-fixing ratio, shape-recovery ratio, shape-recovery time, and repeatability of shape-memory cycles. The combined property improvements and the simplicity of the manufacturing process demonstrated that the CNBNR-ESMP nanocomposites are desirable candidates for largescale applications in the engineering field as smart structural materials.

Preparation of modified multi‐walled carbon nanotubes as a reinforcement for epoxy shape‐memory polymer composites

“…Shape-memory materials are often applied to complete the folding deformation process; therefore, toughness is a very important index for evaluating these materials. 10,26,27 In this article, a notched impact test was used to compare the performance changes of the materials through MWCNT modification, and toughness was characterized by the impact strength and absorbed energy. 27,28 As shown in Figure 5 In addition, SEM tests were also conducted to investigate the fractured surfaces of the samples after the notched impact tests.…”

“…design and structure of SMPs to enhance their mechanical properties and toughness, and to afford multiple responsiveness. [8][9][10][11] However, the natural brittleness of epoxy creates barriers to improving the mechanical strength and toughness of epoxy SMPs simultaneously. 12 Therefore, various types of reinforcing fillers have become the focus of research to enhance these properties while keeping other characteristics stable.…”

Carbon nanotubes array reinforced shape‐memory epoxy with fast responses to low‐power microwaves

“…For each material, more than three specimens were tested and the averages were used. Pure ESMP had a R f <90%, indicating its relatively weak ability to maintain the deformed configuration after the constraint was removed, as shown in Figure . The R f values of both random CNTs/ESMP composite and CNTs array/ESMP composite were higher than pure ESMP, indicating the constraint effect of CNTs on the movements of polymer chains.…”

Bio‐Inspired Multiple Cycle Healing and Damage Sensing in Elastomer–Magnet Nanocomposites

“…[23] Recovery of the original shape occurs during AMF heating. [24,25] In the present work, we demonstrate strain sensing and triggered healing in the highly industrially important material, NBR. We developed a multi-cycle damage-sensing and healing MNP-NBR nanocomposite, denoted as Magpol.…”

“…Damage of the material will usually result in mechanical strain . Recovery of the original shape occurs during AMF heating . In the present work, we demonstrate strain sensing and triggered healing in the highly industrially important material, NBR.…”