Abstract:The increasing demand for environmental protection has led to the rapid development of greener and biodegradable polymers, whose creation provided new challenges and opportunities for the advancement of nanomaterial science. Biodegradable polymer materials and even nanofillers (e.g., natural fibers) are important because of their application in greener industries. Polymers that can be degraded naturally play an important role in solving public hazards of polymer materials and maintaining ecological balance. The inherent shortcomings of some biodegradable polymers such as weak mechanical properties, narrow processing windows, and low electrical and thermal properties can be overcome by composites reinforced with various nanofillers. These biodegradable polymer composites have wide-ranging applications in different areas based on their large surface area and greater aspect ratio. Moreover, the polymer composites that exploit the synergistic effect between the nanofiller and the biodegradable polymer matrix can lead to enhanced properties while still meeting the environmental requirement. In this paper, a broad review on recent advances in the research and development of nanofiller reinforced biodegradable polymer composites that are used in various applications, including electronics, packing materials, and biomedical uses, is presented. We further present information about different kinds of nanofillers, biodegradable polymer matrixes, and their composites with specific concern to our daily applications.
High‐performance multilayer dielectric elastomer actuators (DEAs) are well‐positioned to overcome the insufficient output force and energy density as artificial muscles. However, due to the fabrication process, the multilayer DEAs with nonmodifiable structures often suffer from the limitation of short lifespans and scalable preparation. Herein, reusable multilayer DEAs with the detachable and reconfigurable structure are fabricated. This is achieved by realizing scalable compliant electrodes using the continuous spatial confining forced network assembly (CSNA) method and combining the vacuum lamination (VL) approach to have good attachability and detachability with the VHB dielectric elastomer. The flexible roller‐based CSNA method is used to prepare the large area compliant electrodes composed of α, ω‐dihydroxy polydimethylsiloxane and electrically conductive nanoparticles. The fabricated electrodes can continuously work over 10 000 cycles at 40% strained stretching and maintain smooth surfaces to construct multilayer DEAs. Moreover, owing to the detachable configuration of the DEAs, the electrodes can also be recovered and reused for building new actuators. The lower limb assistive device is demonstrated by detachable multilayer spring roll DEAs, achieving approximately 3.1 degrees of flexion and extension movement of knee models under a voltage of 7 kV. The detachable and reconfigurable multilayer DEAs shed new light on the applications of wearable assistive devices.
Efficiently estimating the aging status of rubber damping is indispensable in the transport system. Herein, we developed a facile approach to fabricate flexible capacitance sensors that can bear high loads, large deformations, and long cycle life. The sensor has a sandwich structure, including electrode layer, the dielectric layer, and encapsulation layer. In this approach, the spatial confining forced network assembly method was used to fabricate the electrode layer of the sensor and a novel injection mold process was used to form the encapsulation layer of the sensor. This flexible capacitive sensor can detect the cyclic loading of damping rubber springs as high as 0-60 kN under load frequency of 3 Hz with a sensitivity of 30 PF/KN, bear up to maximum 58% deformation and cycling stability over 50,000 cycle. Furthermore, a modified aging status prediction model for damping rubber springs based on the signal of sensor is proposed. The real-time working state and aging state of the rubber spring can be monitored through the measurement signal of the sensor.
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