Shape Memory Behavior of Natural Eucommia ulmoides Gum and Low-Density Polyethylene Blends with Two Response Temperatures

A Study of Molecular Dynamic Simulation and Experimental Performance of the Eucommia Ulmoides Gum-Modified Asphalt

In recent years, eucommia ulmoides gum (EUG), also known as gutta-percha, has been extensively researched. Molecular dynamic simulations and experiments were used together to look at how well gutta-percha and asphalt work together and how gutta-percha-modified asphalt works. To investigate the gutta-percha and asphalt blending systems, the molecular models of asphalt and various dosages of gutta-percha-modified asphalt were set up using Materials Studio (MS), and the solubility parameters, intermolecular interaction energy, diffusion coefficient, and mechanical properties (including elastic modulus, bulk modulus, and shear modulus) of each system were calculated using molecular dynamic simulations at various temperatures. The findings indicate that EUG and asphalt are compatible, and sulfurized eucommia ulmoides gum (SEUG) and asphalt are more compatible than EUG. However, SEUG-modified asphalt has better mechanical properties than EUG, and the best preparation conditions are 10 wt% doping and 1 h of 180 °C shearing. Primarily, physical modifications are required for gutta-percha-modified asphalt.

Intumescent flame retardancy and smoke suppression of Eucommia ulmoides gum/natural rubber blends based on synergistic g-C3N4@Fe3O4 nanocomposites

A flame retardant synergist (g-C3N4@Fe3O4) was designed through an in situ co-precipitation method by using graphitized carbon nitride (g-C3N4) and Fe3O4, and its structure was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). A series of different contents of g-C3N4@Fe3O4 and intumescent flame retardant (IFR) were simultaneously added into eucommia ulmoides gum/natural rubber (EUG/NR) blends to improve the flame retardancy and reduce the smoke release. The flame retardancy, smoke suppression performance, thermal degradation behaviors and thermal stability of EUG/NR blends were evaluated by the limiting oxygen index (LOI), UL-94, cone calorimetry test (CCT) and thermogravimetric analysis (TGA). The results showed that using g-C3N4@Fe3O4 as a flame retardant synergist, the LOI value of the 9 phr g-C3N4@Fe3O4 synergist (EUG/NR 5) blend was 29.5%, which was much higher than the 20.0% of the original composite. Moreover, the 6 phr g-C3N4@Fe3O4 synergist (EUG/NR 4) and EUG/NR 5 passed the UL-94 V-0 rating, while the pristine EUG/NR blends showed no rating. Moreover, the total heat release rate (THR), peak of heat release rate (PHRR) and total smoke production (TSP) of the EUG/NR blends in the CCT test were much lower than those of the pristine EUG/NR blends. In particular, PHRR, THR and TSP of EUG/NR 5 decreased by 37.1%, 16.2% and 18.0%, respectively. This indicated that the introduction of g-C3N4@Fe3O4 decreased the release of combustible gases. TGA results also showed that the addition of g-C3N4@Fe3O4 accelerated the thermal degradation of the EUG/NR blends and changed the thermal degradation mechanism of the EUG/NR blends, indicating the synergistic effect of g-C3N4@Fe3O4. Finally, a possible degradation mechanism of EUG/NR blend composites was proposed.

Development of novel TPI/HDPE/CNTs ternary hybrid shape memory nanocomposites

In order to make up for the defects of trans-1,4-polyisoprene (TPI) shape memory polymer, TPI/high density polyethylene (HDPE) hybrid shape memory matrix was prepared from the perspective of matrix composition. The carbon nanotubes (CNTs) with excellent mechanical properties were introduced into the hybrid shape memory matrix. Due to the difference of the inherent properties and geometry of nano-fillers, the change of the content of nano-fillers directly affects the bonding state within the composites. Therefore, it is very important to choose the appropriate content. In order to give full play to the potential of thermodynamics of nano-filler, the TPI/HDPE/CNTs ternary hybrid shape memory nanocomposites were prepared by mechanical melt blending technology combined with dynamic vulcanization and hot-pressing forming technology. The addition of CNTs promotes the formation of the crystal structure of TPI and HDPE, and facilitates the energy transfer between different interface, which greatly improves the thermal conductivity and mechanical properties of the nanocomposites at the same time. The effect of the changes of filler content on the thermodynamic properties of the composite materials were revealed by series of tests. The results show that the CNTs act as nucleating agents in the crystallization region of TPI and HDPE. However, the excessive addition of CNTs can inhibit the formation of HDPE crystal structure. Meanwhile, the crystallinity of nanocomposites is also an important factor affecting its thermal conductivity. The specimens with the CNTs content of 0.5 wt% have excellent tensile resistance and cyclic recovery ability, and it can improve the shape recovery properties. Therefore, the nanocomposite with the CNTs content of 0.5 wt% has the best thermodynamic and shape memory properties.

Natural Polymer Eucommia Ulmoides Rubber: A Novel Material

As the second natural rubber resource, Eucommia ulmoides rubber (EUR) from Eucommia ulmoides Oliver is mainly composed of trans-1,4-polyisoprene, which is the isomer of natural rubber cis-1,4-polyisoprene from Hevea brasiliensis. In the past few years, the great potential application of EUR has received increasing attention, and there is a growing awareness that the natural polymer EUR could become an emerging research topic in field of the novel materials due to its unique and excellent duality of both rubber and plastic. To gain insight into its further development, in this review, the extraction, structure, physicochemical properties, and modification of EUR are discussed in detail. More emphasis on the potential applications in the fields of the environment, agriculture, engineering, and biomedical engineering is summarized. Finally, some insights into the challenges and perspectives of EUR are also suggested.

Fully Biobased Shape Memory Thermoplastic Vulcanizates from Poly(Lactic Acid) and Modified Natural Eucommia Ulmoides Gum with Co-Continuous Structure and Super Toughness

Novel, fully biobased shape memory thermoplastic vulcanizates (TPVs) were prepared using two sustainable biopolymers, poly(lactic acid) (PLA), and modified natural Eucommia ulmoides gum (EUG-g-GMA), via a dynamic vulcanization technique. Simultaneously, in situ compatibilization was achieved in the TPVs to improve interfacial adhesion and the crosslinked modified Eucommia ulmoides gum (EUG) was in "netlike" continuous state in the PLA matrix to form "sea-sea" phase structure. The promoted interface and co-continuous structure played critical roles in enhancing shape memory capacity and toughness of the TPVs. The TPV with 40 wt % modified EUG displayed the highest toughness with an impact strength of 54.8 kJ/m2 and the most excellent shape memory performances with a shape fixity ratio (Rf) of 99.83% and a shape recovery ratio (Rr) of 93.74%. The prepared shape memory TPVs would open up great potential applications in biobased shape memory materials for smart medical devices.