Guangkai Hu, Xiaorui Zhang, Lizhu Liu, Weng Ling and Weiwei Cui
The dispersity of graphene oxide (GO) has an important effect on the properties of epoxy resin (EP) composites. Many modification and dispersion methods require the use of inert…
Abstract
Purpose
The dispersity of graphene oxide (GO) has an important effect on the properties of epoxy resin (EP) composites. Many modification and dispersion methods require the use of inert solvents which do not participate in the modification reaction, although GO can be uniformly dispersed in water and alcohol solvents. Based on this requirement, several inert solvents were selected as dispersion solvents to find out the suitable inert solvent for GO dispersion into EP matrix.
Design/methodology/approach
Several inert solvents with different solubility parameters were selected as dispersion solvents to prepare GO/EP composite. The microstructure, mechanical properties, insulation properties, dielectric properties and thermal property of the composite were characterized, which was due to find suitable inert solvent for GO dispersion into EP matrix.
Findings
The dispersity of N, N-dimethylformamide (DMF) was the best stable suspension state when it was used as solvent instead of occurring sedimentation and agglomeration. Moreover, DMF was further confirmed as a suitable inert solvent for the dispersion of GO into EP according to the mechanical properties, insulation properties and thermal conductivity characterization.
Research limitations/implications
The dispersion of GO in solvents has already been researched, but the traditional solvents, such as alcohols and water, has shown their limitations with the increase of modification methods, which were not suitable for the modification environment such as cyanate graft modification. Therefore, it was very important to choose a kind of inert solvent for dissolving EP matrix and dispersing GO better.
Originality/value
Several inert solvents were used to disperse GO into EP, and the influence of different dispersing solvents on the adhesive was discussed through the analysis of the mechanical properties, insulation properties and thermal conductivity, which was due to explore the inert solvent suitable for GO dispersion.
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Keywords
Lizhu Liu, Guangkai Hu, Xiaorui Zhang, Weng Ling and Jiawen Zhang
The effects of ultrasonication on the epoxy resin and its emulsion were investigated to find out the changes in the Mη and molecular structure of epoxy, as well as its room…
Abstract
Purpose
The effects of ultrasonication on the epoxy resin and its emulsion were investigated to find out the changes in the Mη and molecular structure of epoxy, as well as its room temperature storage stability, centrifugal stability, particle size and its distribution and particle morphology more importantly with the influence of different ultrasonic irradiation time, power and temperature.
Design/methodology/approach
The emulsion was prepared using an emulsifier with epoxy resin and by using phase inversion after subjecting to ultrasound irradiation with a power of 200 W at 50°C for 60 min. The changes in the epoxy resin and its emulsion induced by ultrasound were characterized by Ubbelohde viscometer, FT-IR, 13C-NMR, high-speed desktop centrifuge, laser particle size analyzer and transmission electron microscope.
Findings
The molecular weight of the epoxy resin was initially decreased and then stabilized by the increasing of ultrasonic irradiation time. The mole rate of the epoxy groups in epoxy molecular were decreased by about 14 per cent, resulting from ultrasonic irradiation. The particle size of the emulsion was decreased, while the particle size distribution became uniform in a certain time. The narrow distribution, stable and uniform of waterborne epoxy resin emulsion with more than 60 days room temperature storage period, 80 per cent of the supernatant volume, about 220 nm average particle size was gained with a power of 200 W at 50°C for 60 min.
Research limitations/implications
To overcome the problems commonly encountered with an epoxy emulsion, for example, short storage period and wider particle size, which limit its practical application, the effects of ultrasonic irradiation on the epoxy resin and its emulsion, were investigated. As the stability of emulsion was improved with the introduction of ultrasonic irradiation, the application of epoxy emulsion was improved.
Originality/value
The room temperature storage stability and centrifugal stability of the emulsion were decreased by the mechanical method, and thus, the benefit of an in-depth understanding of the influence of ultrasonic treatment on epoxy resin and its emulsion could further promote the development of water-based coatings.
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Guangkai Sun, Yang Hu, Mingli Dong, Yanlin He, Mingxin Yu and Lianqing Zhu
Soft robotics is a burgeoning field owing to its high adaptability and safety in human–machine interaction and unstructured environments. However, the feedback control of soft…
Abstract
Purpose
Soft robotics is a burgeoning field owing to its high adaptability and safety in human–machine interaction and unstructured environments. However, the feedback control of soft actuators with flexible sensors is still a challenge.
Design/methodology/approach
To address this issue, this study proposes an optical fibre-based sensing membrane for the posture measurement of soft pneumatic bending actuators. The major contribution is the development of a flexible sensing membrane with a high sensitivity and repeatability for the feedback control of soft actuators. The characteristics of sensing membrane were analysed. The relationship between wavelength shift and bending curvature was derived. The curvatures of soft actuator were measured at four bending status, and the postures were reconstructed.
Findings
The results indicate that the measurement error is less than 2.1% of the actual bending curvature. The sensitivity is up to 212.8 pm/m−1, and the signal fluctuation in repeated measurements is negligible. This approach has broad application prospects in soft robotics, because it makes the optical fibre achieve more strength and compatible with soft actuators, thus improving the sensing accuracy, sensitivity and reliability of fibre sensors.
Originality/value
Different from previous approaches, an optical fibre with FBGs is embedded into a multilayered polyimide film to form a flexible sensing membrane, and the membrane is embedded into a soft pneumatic bending actuator as the smart strain limited layer which is able to measure the posture in real time. This approach makes the optical fibre stronger and compatible with the soft pneumatic bending actuator, and the sensing accuracy, sensitivity and reliability are improved. The proposed sensing configuration is effective for the feedback control of the soft pneumatic bending actuators.