Preparation and characterization of innovative cellulose diacetate/epoxy resin blends modified by isophorone diamine

A nonionic surfmer (MAA-EO 23 C 12 ) was prepared and reacted with acrylamide, acrylic acid, and a double tailed hydrophobic monomer (BTMAM) to synthesize a surface-active hydrophobically associating copolymer (SHAP) through photoinitiated free radical copolymerization in aqueous solution. Fourier transform infrared and 1 H-nuclear magnetic resonance spectroscopy were used to characterize the functional monomer and the SHAP. Several performance evaluations, such as viscosification property, temperature resistance, salt tolerance, and shear resistance, were also conducted. Experiment results demonstrated that the introduced nonionic surfmer and hydrophobic monomer could endow the copolymer with excellent temperature resistance, salt tolerance, and shear resistance capability at low concentration.

Synthesis, characterization, and solution properties of a surface‐active hydrophobically associating polymer

Ren

2018

Temperature effect on mechanical strength and frictional properties of polytetrafluoroethylene‐based core‐shell nanocomposites

Bian

Zhang

et al. 2020

Polytetrafluoroethylene (PTFE) has shown an outstanding lubricity as a solid lubricant, but its application is limited due to its low-mechanical strength and high-wear rate. In this study, core-shell nanoparticles were synthesized using PTFE as the core and polymethylmethacrylate (PMMA) as the shell. The formed core-shell nanocomposites by leveraging the core-shell nanoparticles as basic structural units exhibit remarkable enhancement on uniformity, tensile strength, and wear resistance, compared to mechanically mixed composites with the same composition. Our experiments demonstrated the following results: (1) Owing to the excellent uniformity, the maximum tensile strength of core-shell nanocomposites was 62 MPa, three times higher than that of mechanically mixed composites. (2) The composite matrix formed by PMMA shell had better reinforcement and protection effect on inner PTFE phase, resulting in a reduced wear rate of 0.3 × 10 −5 mm 3 /(N m), one order of magnitude lower than that of mechanically mixed composites. (3) The friction coefficient and interfacial mechanical properties of the core-shell nanocomposites at different temperatures have been systematically studied to get insights into lubrication mechanisms. It is proved that the temperature can decrease the modulus and increase the interfacial adhesion as well as the loss tangent of the core-shell nanocomposites, thus affecting the lubrication properties in multiple ways.

Molecular dynamics study on enhancement of mechanical and tribological properties of polytetrafluoroethylene composites by incorporating hexagonal boron nitride nanosheets

Yang

Zhao

Cui

et al. 2023

Molecular models and sandwiched friction models of pure PTFE and h-BN/ PTFE composite were respectively constructed to investigate the enhancement of mechanical and tribological performances of the polytetrafluoroethylene (PTFE) matrix by incorporating the hexagonal boron nitride (h-BN) nanosheets as reinforcements. The simulation results indicate that increases of 36.4% in the Young's modulus, 23.6% in the bulk modulus, and 37.3% in the shear modulus of the PTFE matrix are achieved respectively by the incorporation of h-BN nanosheets. Decreases of 3.48% and 10.27% in the Poisson's ratio and the ratio of bulk modulus to shear modulus of the PTFE matrix are also observed due to the incorporation of h-BN nanosheets, which shows that the ductility of the PTFE matrix could be somewhat decreased with the addition of h-BN nanosheets. Additionally, decreases of 69.23% and 69.06% in the coefficient of friction and friction stress of the PTFE matrix are obtained respectively with the introduction of h-BN nanosheets. To provide in-depth insight into the internal reason for these findings, the interaction energy between the PTFE matrix and h-BN nanosheets, the MSD and diffusion coefficient of PTFE chains, and the RDF of carbon and fluorine atoms in the PTFE backbone chains were evaluated and interpreted accordingly.