Research On The Crack Growth Of Nanoparticles Reinforced Natural Rubber And Its Blends

The study of rubber crack growth is of vital theoretical and application importance for the improvement of rubber safety.In this work,nanoparticles filled rubber model system with different filler morphologies,volume fractions and interfacial interactions were constructed and the crack resistance of rubbers can be improved.Dynamic mechanical analyzer with crack growth detection function will be used to test the crack growth behavior.By the application of microscopic high speed video recording and other characterization approaches,we proposed the crack resistance mechanism.The first part of this thesis involves the research on the carbon nanotubes reinforced natural rubber and styrene-butadiene rubber,the crack growth mechanism was investigated.Silane coupling agent was used to modify carbon nanotubes,which reinforces natural rubber.The nanocomposites have stronger crack resistance.Compared with the natural rubber and styrene butadiene rubber reinforced by carbon nanotubes of the same amount,it was found that the strain induced crystallization of rubber plays an important role in the crack growth of the nanocomposites.The second part of the thesis studied the crack growth behaviors of graphene enhanced NR/SBR blends and natural rubber/styrene butadiene rubber blend with the ratio of 60/40.A best blending state and lowest crack growth rate of the rubber blend were achieved.By the crack tip morphology study on the graphene/NR/SBR nanocomposites,it was found that the addition of graphene changed the crack tip morphology of the rubber blend.Even tearing energy reached 1200J/m2,the crack tip of nanocomposites still represented a “layered peeling” morphology,which largely suppressed the stress concentration at the crack tip and increased the energy required for crack propagation.Then,the crack growth rate decreased.At lower tearing energies,the “layered peeling” morphology dominated.When the tearing energy was higher than 600J/m2,the crack tip of natural rubber showed “ligament broken” morphology.The ligaments were in homogeneously distributed and the crack growth rate was higher.It was revealed in this thesis that graphene nanosheets can regulate the crack tip morphology of rubber materials.Although tearing energy is higher,rubber crack tip morphology maintained the “layered peeling” morphology,which improved the crack resistance of the rubber materials.Finally,rubber products of longer service life can be obtained.