Enhanced thermal and tensile behaviour of MWCNT reinforced palm oil polyol based shape memory polyurethane

Shape-Memory Polymers Based on Carbon Nanotube Composites

For the past two decades, researchers have been exploring the potential benefits of combining shape-memory polymers (SMP) with carbon nanotubes (CNT). By incorporating CNT as reinforcement in SMP, they have aimed to enhance the mechanical properties and improve shape fixity. However, the remarkable intrinsic properties of CNT have also opened up new paths for actuation mechanisms, including electro- and photo-thermal responses. This opens up possibilities for developing soft actuators that could lead to technological advancements in areas such as tissue engineering and soft robotics. SMP/CNT composites offer numerous advantages, including fast actuation, remote control, performance in challenging environments, complex shape deformations, and multifunctionality. This review provides an in-depth overview of the research conducted over the past few years on the production of SMP/CNT composites with both thermoset and thermoplastic matrices, with a focus on the unique contributions of CNT to the nanocomposite's response to external stimuli.

Synthesis and properties of bio-based thermoplastic poly(ether urethane) for soft actuators

In this study, bio-based thermoplastic polyurethane (TPU) for use in soft actuators is bio-based poly(ether-urethane) made using fermented corn, along with bio-derived compounds such as propane-1,3-diol (PDO) as a chain extender. Bio-based TPUs were obtained through a solvent-free one-shot synthesis method, and the effects of varying the [NCO]/[OH] molar ratio and type of isocyanates on chemical structure, thermal stability, and mechanical properties were investigated. The degree of phase separation (DPS) and state of hard segment (HS) / soft segment (SS) of TPU are important factors affecting the thermal and physical properties of the prepared film. These properties depend on the [NCO]/[OH] molar ratio and the type of isocyanates used for polymerization. The results showed that, when aromatic isocyanate was used, the degree of separation of the HS/SS was improved as the molar ratio increased. The average molecular weight and DPS as well as thermal and mechanical properties of 1-isocyanato-4-[(4-isocyanatophenyl)methyl]benzene (MDI)-based TPU samples are all higher than those of 1,1’-methylenebis(4-isocyanatocyclohexane) (H12MDI)-based TPU samples in spite of the lower HS content. These findings of this study are expected to contribute to the preparation of fused deposition modeling (FDM) 3D printing or 4D printing for shape memory polymer from bio-based TPU filaments for use in soft actuators with a shore hardness range of 59~84A.

Comparison of Carbon-Nanoparticle-Filled Poly(Butylene Succinate-co-Adipate) Nanocomposites for Electromagnetic Applications

Electrostatic dissipative (ESD), anti-static (AS), and electromagnetic interference (EMI) shielding materials are commonly based on commodity fossil-fuel-based plastics. This, in turn, contributes to ever-growing non-biodegradable plastic pollution. Graphene nanoplatelets (GN), multi-walled carbon nanotubes (MWCNT), nanostructured carbon black (NCB), and amorphous carbon black (CB) were utilized as nanofillers to prepare bio-based and biodegradable poly(butylene succinate-co-adipate) (PBSA) nanocomposites. Solvent-cast composites were prepared with 1.1 to 30.0 vol.% nanoparticle loading. The literature mainly focuses on relatively low loadings; therefore, for this research, filler loadings were increased up to 30 vol.% but the maximum loading for NCB and CB loadings only reached 17.4 vol.% due to a lack of dimensional stability at higher loadings. The composites were characterized using tensile testing, volumetric and surface conductivity measurements, thermal conductivity measurements, dielectric spectroscopy in the microwave region, and transmittance in the terahertz range. Tensile tests showed excellent carbon filler compatibility and enhanced tensile strength for loadings up to 5 vol.% (up to 20 vol.% for MWCNT). The highest thermal conductivity values were reached for the MWCNT filler, with the 30.0 vol.% filled composite reaching 0.756 W/mK (262% increase over PBSA). All fillers were able to produce composites that yielded volume conductivities above 10^-10 S/m. Composites with MWCNT, GN, and NCB inclusions above the percolation threshold are suitable for EMI applications in the microwave and THz frequency range.