Investigation On Deformation Recovery Properties Of CF/EP Composite Modified By HNBR/MECNT

Shape memory epoxy resin and related composites are of emerging smart materials in different applications,especially in biomedical,aerospace,and architectural engineering fields,due to many useful properties like chemical resistance,environmental stability,processability,and relatively low cost.But EPs are brittle materials duo to their tightly cross-linked network,so toughening and reinforcing of epoxy become very important.In this paper,epoxy resin E-51,curing agent MeTHPA(methy tetrahydrophthalic anhydride),accelerator 2E4MZ(diethyl four methy imidazole)and the carbon fiber sheet were used for the preparation of the raw materials of the shape memory polymer.Nitrile butadiene rubber and Multi-walled carbon nanotubes were choosed to toughen the composite.The bending strength of the sample was obtained by universal testing machines.The section morphology characterization of the composite was examined by SEM(scanning electron microscopy).The thermal expansion coefficient and glass transition temperature of the composite were measured by Dilatometer.DMA(dynamic mechanical thermal analyzer)was used to measure storage modulus,loss modulus and loss factor of these samples.The shape fixity ratio,shape recovery ratio,recovery time and the relaxation fitting curve were also taken into account by self-made equipment.The following conclusions are drawn from the study: bending strength decreases with the increase of folding frequencies and the addition of rubber.However,when the MWCNT was added,bending strength increases with the decreasing thermal expansion coefficient of these samples.The storage modulus decrease with the addition of rubber while it shows an increase tendency when the MWCNT was added.The shape fixity ratio was up to 98%.The shape recovery ratio approached 100%.The recovery time increased with the increase of recovery temperature.The relaxation fitting curve was reverse "S"-graphemic and the activation energy decreased with the increase of bending temperature.And the activation is obviously decreased with the addition of rubber and MWCNT.