Southwest University of Science and Technology

About: Southwest University of Science and Technology is a education organization based out in Mianyang, China. It is known for research contribution in the topics: Adsorption & Graphene. The organization has 10017 authors who have published 8923 publications receiving 94850 citations. The organization is also known as: Xīnán Kējìdàxué.

Graphitic carbon nitride (g-C3N4) as a metal-free catalyst for thermal decomposition of ammonium perchlorate

Abstract: Development of metal-free and environmentally friendly catalysts is of great significance for thermal decomposition of ammonium perchlorate (AP). In the present study, graphitic carbon nitride (g-C3N4) has been demonstrated to possess intrinsic catalytic activity for thermal decomposition of AP. Adding 10 wt% g-C3N4 to AP decreases the decomposition temperature by 70 °C and the activation energy (Ea) by 119.8 kJ mol−1. Moreover, the apparent decomposition heat of AP in the presence of 10 wt% g-C3N4 reaches up to 1362.6 J g−1, which is much higher than that of the pure AP (574.2 J g−1). Furthermore, a possible catalytic mechanism for the thermal decomposition of AP with g-C3N4 has been proposed. The unique surface structure of g-C3N4 consisting of triazine units connected by planar amino groups can be favourable for the adsorption and diffusion of perchloric acid via Lewis acid–base interactions, which decreases the reaction activation energy of AP and facilitates the formation of superoxide radical anions (˙O2−) and holes (h+), leading to the oxidation reaction of ammonia more completely in the catalytic decomposition of AP.

Rapidly reprocessable, degradable epoxy vitrimer and recyclable carbon fiber reinforced thermoset composites relied on high contents of exchangeable aromatic disulfide crosslinks

Abstract: With large quantities of waste carbon fiber reinforced polymer (CFRP) composites generated, the development of recycling routes for CFRP composites have been driven by both environmental and economic factors. Vitrimer materials provide exciting opportunities to recycle thermosets and CFRP composites, since they can be thermally reprocessed without losing their permanently cross-linked networks. However, the poor mechanical properties, additional catalyst and time-consuming recycling process still limit their applications. Herein, the authors proposed an epoxy vitrimer with high contents of exchangeable aromatic disulfide crosslinks to overcome these limitations. This epoxy vitrimer exhibited outstanding properties with the glass transition temperature (Tg) of 147 °C and the tensile strength of 63.1 MPa. Upon heating, it released the stress from deformation more rapidly without any catalyst, resulting from the high contents of disulfide crosslinks in the network. Meanwhile, the networks exhibited excellent reprocessability and were more readily degraded by thiols. Moreover, this epoxy was applied as matrix to prepare recyclable CFRP composites. By dissolving the epoxy matrix efficiently, the carbon fibers embedded were recycled rapidly and they still exhibited outstanding mechanical properties when being reused to form CFRP composites. Results from this study may promote the wide development of cost-efficient recyclable composites in automotive, wind power and aeronautical industries.