| Polymer materials have the advantages of light weight,low price,good toughness,easy mass production and controllable properties,so they are widely used in important fields such as medical treatment,construction,electronics and aerospace.However,due to insufficient sustainability of polymer materials,a large number of waste products are generated,and further accompanied by material degradation problems,which increase the burden on the ecological environment and threaten the health of human beings and other living organisms.Therefore,realizing the sustainable development of polymers is an inevitable requirement to solve the current environmental pollution problem.In order to solve the difficult problem in the sustainable development of polymer materials,in this work,two-dimensional layered double metal hydroxides(LDHs)were introduced into the polymer matrix to construct polymer matrix composites.By regulating the structure and composition of the inorganic layered material,the anti-aging and controllable degradation processes of the polymer are respectively realized,thereby realizing the sustainable development of the polymer-based composite material.It mainly includes the following two aspects of work.1 Thermal energy dissipation and polymer aging resistance based on the structural transformation for MgAls-LDHsMgAl-LDHs/LDPE composites were constructed with Two-dimensional layered MgAl-LDHs in Low-density polyethylene(LDPE),and then we heat-treated LDPE and 2% MgAl-LDHs/LDPE composites for 0-100 h,and explored the relationship between sample structure transformation and performance.During the heat treatment,the movement of the polymer chains intensified,rwhich makes MgAl-LDHs gradually intercalated and delaminated.;finally,the size and thickness of the MgAl-LDHs material decreased,the defects increased,and the fluorescent signal was generated.In this process,the thermal energy received by the composite material is continuously dissipated through the chemical delamination of MgAl-LDHs,thereby reducing the thermal radiation received by the polymer material.Therefore,compared with pure LDPE,the growth rate of the crystallinity and carbonyl index of the composites is slowed down,from which it can be seen that the addition of MgAl-LDHs significantly improves the thermal aging resistance of the composites.The mechanism proposed in this work is expected to provide new ideas for finding and designing anti-aging polymer composites.2 Controllable degradation of polymers based on structural changes of CoAl-LDHsFirstly,we constructed x% CoAl-LDHs/LDPE composites and x%nitrate/LDPE composites,and then discussed the relationship between the structural changes and properties of the composites at different aging time points.The characterization results by XRD found that during the heat treatment,the polymer chain motion was intensified,and the CoAl-LDHs were continuously peeled off,resulting in a large amount of Co exposure and direct contact with the polymer.Based on this,metal Co catalyzes the conversion of ROOH generated by polyolefin aging into RO·,thereby accelerating the aging of the polymer.Therefore,compared with pure LDPE,the carbonyl index and fluorescence intensity of CoAl-LDHs/LDPE composites were significantly improved;and the aging degradation process of the polymer was accelerated.It is worth noting that the structure of CoAl-LDHs is stable within the first 24 h,basically maintaining the stability of LDPE,and the carbonyl index increases slowly,which ensures the safe use of composite materials.In the later stage of aging,the degradation of polymer materials is accelerated due to the increase of active sites for CoAl-LDHs exfoliation.The above research results show that CoAl-LDHs can effectively regulate the degradation rate of polymers at different stages,thereby achieving controllable polymer lifetime.The above research mechanism provides a new research direction for the construction of polymer matrix composites with excellent stability and controllable degradability. |
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