Preparation,structure And Properties Of Nitrile Butadiene Rubber/eucommia Ulmoides Gum Damping Composites

Damping material is a kind of high performance material which can absorb vibration mechanical energy and sound energy.The progress of society and the rapid development of science and technology require more and more stringent performance of damping materials.The ideal damping material should have a high damping coefficient at ambient temperature and a wide damping temperature range to adapt to temperature changes.Nitrile butadiene rubber(NBR)is one of the common damping rubber.But its damping performance is still not ideal at ambient temperature.Eucommia ulmoides gum(EUG)is a kind of bio-based rubber with rubber-plastic duality.Its damping property is controlled by the mechanism of vitrification and crystallization melting.This paper intends to develop a new damping material by blending NBR and EUG to realize complementary advantages.In this paper,the effects of NBR/EUG ratio,processing field,curing conditions and carbon nanotubes and graphene on the submicrostructure,curing properties,mechanical properties,crystallization properties and damping properties of the composites were studied.From the perspective of the relationship between the structure and properties of the composites,the influence and the mechanism of change were analyzed.The main achievements of this paper are as follows:(1)The effects of EUG content and processing field on the sub-microstructure and various properties of NBR/EUG composites were studied.In NBR/EUG composites,EUG is uniformly dispersed in NBR in the form of nanocrystallites,forming NBR/EUG nanocomposites.Through the physical interaction and surface cross-linking of EUG nanocrystals with NBR,not only the mechanical properties of the composites are improved,but also the overall damping strength of the composites is improved,and the damping temperature range is broadened.Both the EUG melting temperature and the melting peak area in the composites after vulcanization were significantly reduced compared with those before vulcanization.The external effects of processing such as parking and re-melting can further improve the dispersibility of EUG in the NBR/EUG composite,increase the thickness of the two-phase interface and the total interface area,and move the damping temperature region to the high temperature direction,which is closer to the ambient temperature.(2)The effect of vulcanization conditions on the properties of NBR/EUG composites was studied.The study found that the increase of vulcanization temperature,the increase of vulcanization time and the increase of vulcanization pressure will increase the crosslinking density in the composite material,so that the tensile strength of the composite material increases first and then decreases.The stress shows an increasing trend,the hardness increases first and then tends to be stable,and the elongation at break and tear strength show a decreasing trend.With the decrease of vulcanization temperature,the melting peak area of EUG crystals in the composites increases;meanwhile,the peak tends to move to high temperature.The glass transition peak of NBR,with the decrease of vulcanization temperature,has a tendency to move to the low temperature,but the change is small.For the damping properties of the composites,it can be found that with the decrease of vulcanization temperature and vulcanization time,the peak value of the glass transition peak of NBR increases,and the glass transition peak of NBR shifts to the high temperature direction.The decrease of the vulcanization temperature increases the melting transition peak of EUG in the composite material,and the coverage of the curve moves toward the high temperature direction,so it can be known that reducing the vulcanization temperature and the vulcanization time can further improve the damping effect of the composite material,and at the same time widen the composite material.damping temperature range.The vulcanization pressure has little effect on the damping properties of the composites.(3)The effects of carbon nanotubes and graphene on the submicrostructure and various properties of NBR/EUG composites were studied.Carbon nanotubes and graphene are uniformly dispersed in the composite matrix.With the increase of carbon nanotube and graphene fractions,MH,ML,MH-ML increased,and scorch time and positive vulcanization time were shortened.When only carbon nanotubes or only graphene were added,the tensile strength and elongation at break of the NBR/EUG composites gradually decreased.When carbon nanotubes and graphene are added at the same time,the elongation at break of the NBR/EUG composite decreases gradually with the increase of the fractions of carbon nanotubes and graphene,and the tensile strength does not change much.The 300% tensile stress,The hardness and tear strength gradually increased;the analysis showed that carbon nanotubes and graphene formed a "sheet-tube-sheet" micro-nanostructure,which promoted the dispersibility of the two and improved the mechanical properties.With the increase of the amount of carbon nanotubes and graphene,the melting peak area of EUG increases,the peak tends to move to high temperature,and the glass transition peak of NBR tends to move to low temperature.When only carbon nanotubes or carbon nanotubes and graphene are added at the same time,the peak value of tanδ of NBR decreases,and the loss factor value of composites increases with the increase of carbon nanotube content above 0°C,while only adding carbon nanotubes and graphene.Graphene has little effect on the loss factor value of the composite material.With the increase of the amount of graphene and carbon nanotubes,both the electrical and thermal conductivity of the composites are significantly improved,and the electrical conductivity is improved more greatly.