Electromagnetic shielding performance has been achieved for a polyimide (PI)-matrix composite by the strategy of self-metallization of its thermosetting PI matrix. Self-metallization of the thermosetting PI was realized by silver ion/poly(amic acid) (PAA) precursor ion exchange and thermal reduction. The factors influencing the self-metallization were investigated. The electrical conductivity and integrity for the surface of the PI were achieved by optimization of ion exchange/thermal reduction parameters. The fabricated PI-matrix composite exhibits a maximum electromagnetic interference shielding effectiveness value of 81 dB. Importantly, the electromagnetic shielding performance can be maintained even after heat condition of 300°C. Meanwhile, the surface-metallized PI composite exhibits mechanical property equivalent to the pristine composite, and an Ag/matrix interfacial strength higher than 19.6 MPa. Besides, self-metallization mechanism of the thermosetting PI was investigated.
Vinyl polymerization is an important path for in-situ polymerization of thermoplastic resins. BPO (Benzoyl peroxide) and DMT (dimethyl-p-toluidine) were chosen to initiate the radical polymerization of MMA (methyl methacrylate) in this work. Optimization of initiator concentration was studied through reaction rate of polymerization progress and properties of PMMA (polymethyl methacrylate). At first, the catalytic of DMT in MMA polymerization was studied through polymerization experiments and rheological experiments. Results showed that DMT could catalyze more than one molecular BPO in the whole reaction period. It can catalyze the decomposition of BPO after being connected to PMMA chains. Second, the BPO: DMT ratio was set to 2:1 to study the ideal content by comparing the mechanical properties of PMMA. Results showed that with the increase of initiator contents, T g, molecular weight, and residual monomer were all declining. Meanwhile, the mechanical properties of PMMA matrix first increased and then decreased. This phenomenon was analyzed by 1H-NMR and SEM. And the optimal BPO-DMT concentration was 1.0 mol%–0.5 mol%.
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