Effects of bivalve shell particles of hyriopsis cumingii on the performances of epoxy resin studied by positron annihilation

Mussel shell particles sized in micrometer level have been prepared with a ball mill. The X-ray powder diffractrometer (XRD) and Fourier transform infrared (FTIR) results proved that the shell particles contained mainly CaCO₃ in the form of aragonite, together with small amount of organic phase. EP modified with shell particles showed a much rougher fracture surface than unfilled EP. The mechanical properties have been improved obviously by adding the shell particles in EP from 1% to 5%. The particle would occupy a number of free volume holes of the EP matrix. This would lead to a decrease in the total free volume concentration of the composites. The particles acted as a bridge to make more molecules interconnected for the good interfacial adhesion, resulting in a reduction of the free volume hole size in the interfacial layers. I₂ reached its highest value when 3% shell particles were added and then decreased as the shellparticles content increased.