Transesterification Enhancement Of Vitrimer By Polypyrrole Wrapped Carbon Nanotube Doping And Its Application In Electromagnetic Shielding With Further Fe₃O₄ Doping

Traditional thermosetting and thermoplastic materials have their advantages respectively.Thermosetting resins,such as epoxy,are equipped with properties such as mechanical stability,low curing shrinkage ratio and excellent resistance to acid and base.However,its drawbacks are also obvious.As a result of cross-linked network,it was unable to reconstruct or mend once the curing process is completed.However,thermoplastics are lack of mechanical stability but have advantages in easy reprocessing.Vitrimers,a recently discovered material with cross-linked network,is able to self-mending or reconstruction through transesterification reaction.As a result,it has potential to be equipped with the merits of both thermosetting and thermoplastic materials for various applications.The main topics of this article are:?1?The improvement of vitrimer on mechanical response,electrical conductivity and mending strength?transesterification ratio?benefitting from CNT/PPy doping,and their corresponding possible mechanism;?2?The enhancement of vitrimer by doped with CNT/PPy and Fe₃O₄ in electromagnetic shielding,hence the advantages for application of such a material in the field of electromagnetic shielding?EMI?.The article can be concluded as followed:1 Dopants study:CNT/PPy with various CNT contentThe choice for dopant:According to SEM image,lwt%CNT CNT/PPy display a ball structure,5wt%CNT and 10wt%CNT demonstrate structures of mixed ball and tubule,15wt%CNT shows overwhelming tubule structure.In my study,15wt%CNT CNT/PPy was chosen as dopant.2 Enhancement by CNT/PPy dopping on vitrimerAfter doping with the above CNT/PPy composite,several parameters were taken into consideration,including:various weight percentage of CNT?CNT/PPy?,various COOH/epoxy moiety ratios,various temperature and time for imparting pressure in lap-shear tests.FTIR experiment indicated the full curing of epoxy and the existence of bonded and free COOH group.Lap-shear test showed that the best experiment conditions for self-bonding are 0.612 COOH/epoxy group ratio,0.5 wt%CNT content.DMTA experiment suggested the improvement on storage modulus and glass transition temperature?Tg?in the presence of CNT/PPy dopants.Stress relaxation analysis showed the accelerated stress relaxation resulting from the acceleration of transesterification,in the case of CNT/PPy doping.Direct Current conductivity?DCC?outcome that threshold of CNT/PPy doping is lower than that of CNT doping.Meanwhile,enhanced improvement on DCC by CNT/PPy doping compared with CNT doping.3 Improvement of vitrimer on electromagnetic shielding through PPy/CNT and Fe₃O₄ doping,and the resulting potential applicationReflection loss analysis showed that either CNT/PPy or Fe₃O₄ doping will promote electromagnetic shielding.However,it also showed that doped with coaxial cable structure CNT/PPy-Fe₃O₄,electromagnetic shielding promotes greatly.Fe₃O₄ doping endows the material with the ability for magnetic response.Thus magnetic force could be employed to take place of mechanical force for non-contact self-bonding or reconstruction.Due to mild viscosity change of vitrimer at evaluated temperature,there is no need for precious temperature control.Highly fitted electromagnetic shielding layer could be obtained by putting the material onto the facilitate surface for reconstruction at evaluated temperature followed by shape-fixing at room temperature.Moreover,a same self-bonding strength was obtained by magnetic force in a shorter time,compared with mechanical force.