Engineering Research Center of Polymer Green Recycling of Ministry of Education, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou 350007, China
Dr. Fubin Luo
Engineering Research Center of Polymer Green Recycling of Ministry of Education, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou 350007, China
High-power electronic architectures and devices require elastic thermally conductive materials. The use of epoxy resin in thermal management is limited due to its rigidity. Here, based on epoxy vitrimer, flexible polyethylene glycol (PEG) chains are introduced into covalent adaptable networks to construct covalent–noncovalent interpenetrating networks, enabling the elasticity of epoxy resins. Compared to traditional silicone-based thermal interface materials, the newly developed elastic epoxy resin shows the advantages of reprocessability, self-healing, and no small molecule release. Results show that, even after being filled with boron nitride and liquid metal, the material maintains its resilience, reprocessability and self-healing properties. Leveraging these characteristics, the composite can be further processed into thin films through a repeated pressing-rolling technique that facilitates the forced orientation of the fillers. Subsequently, the bulk composites are reconstructed using a film-stacking method. The results indicate that the thermal conductivity of the reconstructed bulk composite reaches 3.66 W m−1 K−1, achieving a 68% increase compared to the composite prepared through blending. Due to the existence of covalent adaptable networks, the inorganic and inorganic components of the composite prepared in this work can be completely separated under mild conditions, realizing closed-loop recycling.
Understanding the mechanisms of the coastal wetland ecosystem carbon sink function is crucial for adapting to, mitigating, and predicting global climate change. Landscape metrics and Carnegie Ames Stanford Approach (CASA) model were used to quantify the spatiotemporal patterns of soil organic carbon (SOC) and vegetation carbon sequestration (VCS) in the Yellow River Delta (YRD). GeoDetector model was used to explore the effects of various factors influencing VCS. The results showed that: (1) From 1999 to 2020, the area of natural wetlands and non-wetlands decreased, while the area of artificial wetlands increased. (2) The SOC stock in the 0 ~ 100 cm depth in 1999 and 2020 were about 7.8871 Tg C and 7.0521 Tg C, respectively. The amount of VCS increased from 0.2309 Tg C in 2000 to 0.3681 Tg C in 2020, with a significant annual increase of 6532 Mg C. In the past 21 years, the total carbon sink in the YRD was 6.0952 Tg C. The amount of VCS was equivalent to 2.93% of SOC stock in 1999, rising to 5.22% by 2020. (3) Vegetation cover has the greatest influence on the carbon sink function in the YRD, followed by precipitation and biodiversity. From 2000 to 2020, the effect of biodiversity on the carbon sinks of natural wetlands and artificial wetlands increased. The synergistic effect of wetland type and vegetation cover on carbon sink effect was replaced by the synergistic effect of biodiversity and vegetation cover. The identification of the primary factors that influence VCS in the YRD is significant to the understanding of the spatiotemporal evolution of carbon sink effect in coastal wetland ecosystems, and to the guidance of the rational development and protection of coastal wetlands and promote sustainable ecosystem development.
The increasing demand of thermal management materials consumes a large amount of petrochemical and inorganic mineral resources. It is essential to develop a kind of highly thermally conductive composite with realizable closed-loop recycling. Based on the covalent adaptable networks (CANs), which are filled with boron nitride (BN) and liquid metal (LM), recyclable biphenyl epoxy composites (LEP/BN/LM) with directional controllable thermal conductivity have been prepared in this study. The induced dual-aligned liquid metal and boron nitride in the preparative film composites is obtained using repeated pressing-rolling technique. The bulk composites are fabricated by film-stacking method, relying on self-healing via interesterification between each layer. By altering the stacking mode, high thermal conductivity can be obtained in the desired direction, which realizes the directional controllable high thermal conductivity. The result shows that a high thermal conductivity of 5.41 W m−1 K−1 can be achieved in the predominant direction of the LEP composite. The experiment indicates that the prepared composites have excellent thermal management ability. It also confirms that the filler and the organic compounds can be completely separated by mild chemical routes, which can be reused further.
5 January 2017 in Industrial & Engineering Chemistry Research