Study on viscoelastic materials at micro scale pondering supramolecular interaction impacts with <scp>DMA</scp> tests and fractional derivative modeling

Pre‐crosslinked gel particles, colloidal dispersion gels, and polymer microspheres are often used as profile‐controlling and flooding agents to displace residual crude oil from formations. The preparation process of these profile‐controlling and flooding agents is complicated. In order to simplify the preparation steps, a water‐soluble chain transfer (RAFT) agent, S,S′‐bis(2‐propionic acid) trithiocarbonate (PATTC), was synthesized, and then, hydrogel dispersions were prepared by one‐pot RAFT polymerization. The structure of PATTC was confirmed by infrared spectroscopy and nuclear magnetic resonance. The effects of reaction conditions on the viscosity and viscosity‐average molecular weight of hydrogel dispersions were explored, the rheology, viscoelasticity, particle size, temperature responsiveness, and salinity responsiveness of hydrogel dispersions were measured, and the seepage properties of hydrogel dispersions in porous medium were analyzed. The results show that at higher shear rates, the polyacrylamide gel dispersions exhibited Newtonian fluid characteristics. Viscoelasticity tests further confirmed that the polyacrylamide gel dispersions were successfully synthesized. The particle size of the hydrogel dispersions is 1–75 μm, its viscosity is less affected by temperature and salinity, and its residual resistance coefficient is higher than that of the polyacrylamide solution under similar apparent viscosity.

Section: Rheology and Viscoelasticity Of Gel Dispersionsmentioning

confidence: 64%

Synthesis of a water‐soluble chain transfer agent and its application in gel dispersions

Zhang,

Yang,

Liu

et al. 2024

“…The viscous flow activation energy describes the viscositytemperature dependence of a material. 28,29 The relationship between the zero-shear viscosity (η 0 ) and temperature (T) was analyzed using the Arrhenius equation (Equation 1) for the rheological behavior above the melting temperature. 30…”

Section: Activation Energy Of Viscous Flow Measurementsmentioning

confidence: 99%

Study on the synergistic effect of additives on the processing performance of UHMWPE/HDPE blends

Liu,

Jin,

Qin

et al. 2024

The challenging melt processing of ultrahigh‐molecular‐weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high‐density polyethylene (HDPE), this article studies the effects of CaSt2, polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt2 and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as‐spun filaments of UHMWPE/HDPE blends modified with CaSt2/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%.

“…Rubber has been widely used for its remarkable performance, which can withstand large deformation and maintain its original properties. That makes it ideal for applications required that rubber shows eligible durability as energy dissipation devices to control structural stability, 1,2 such as tires, seals, belts, dampers, and so forth. The fatigue performance of rubber applications is the main influence of service life and directly affects economic benefit and safety.…”

Section: Introductionmentioning

confidence: 99%

Coupling effect of non‐relaxing and high temperature on fatigue properties of carbon‐black filled isoprene rubber

Luo,

Song,

Guo

et al. 2024

This paper presents an extensive experimental investigation on fatigue properties of carbon‐black filled isoprene rubber under complex loadings. A basic life prediction model taking strain energy density as fatigue parameter is first proposed based on fatigue crack growth tests and uniaxial tension fatigue tests under relaxing loads at room temperature. A database of fatigue life including relaxing and non‐relaxing is established through a great number of fatigue tests under five temperatures. Based on the database, two empirical parameters, that is, temperature factor (NRT/NHT) and life reinforcement factor (Re), are introduced to quantitatively characterize the coupling effects of high temperature and non‐relaxing loads on fatigue life. The fatigue mechanisms under different conditions are compared via wide‐angle x‐ray diffraction tests and postmortem analysis. It reveals that the weakening of life reinforcement at high temperatures is closely related to the strain induced crystallization behavior of rubber.