Preparation And Study Of LDHs/ENR/SBR Gas Barrier Material

LDHs(Layered Double Hydroxides)is a kind of inorganic lamellar material with large aspect-thickness ratio and adjustable structure.LDHs has broad application prospects in many fields,and the preparation of composite materials with polymers has attracted much attention.Epoxy natural rubber(ENR)has good air tightness and excellent mechanical properties,and can be used as ideal tire air tightness material.In this paper,LDHs,ENR and styrene-butadiene rubber(SBR)were blended to prepare high performance gas barrier materials by using the unique geometric effect of LDHs.The relationship between the content of each component(including modified LDHs)and the properties of composite materials was discussed in detail.Part ?:First of all,ENRs with different epoxy degrees were prepared,and the basic properties of ENRs with different epoxy degrees were compared.The results show that ENR with high epoxy content has good mechanical properties and air tightness.Then,30%epoxy ENR and SBR were selected for blending.It was found that when the ratio of SBR to ENR was 60:40,the SBR/ENR blend had the best performance.The compatibility of ENR and SBR was discussed.The results showed that the compatibility of composites was poor without compatibilizer,and the phase interface was obvious.The compatibility was improved by adding compatibilizer(phenolic resin SL1801),and the mechanical properties,air tightness and flexural resistance of composites were improved.In the second part,LDHs/ENR/SBR composites were prepared by using LDHs as filler.The results showed that the composites had excellent mechanical properties,flexural resistance and air tightness when 5 LDHs were added.LDHs was added in dry powder and dispersed nonuniformly and easily in the adhesive.Therefore,the influence of different processing methods on the dispersion of LDHs and the properties of composite materials was explored from three aspects,including:(1)mixing sequence of LDHs,ENR and SBR three;(2)comparing the LDHs/SBR master glue prepared by emulsion flocculation method and dry powder method;(3)the tiling orientation of LDHs layer in composite material.Because of the interaction between the polar function of ENR and the hydroxyl radicals on LDHs,it was found by atomic force that LDHs were mainly distributed in ENR and the agglomeration was not improved even if the mixing order of the three was changed.The emulsion flocculation method helps LDHs disperse evenly in the rubber matrix,and the composite has better performance.LDHs can be oriented along the calendering direction by means of thinning through the mill,which is conducive to improving the mechanical properties,air tightness and flexural resistance of composites.The third part:In order to further improve the air tightness of the composites,LDHs were calcined at 500? in this paper.After calcination,it can be seen by transmission electron microscopy that the size and thickness of LDHs lamellae become larger and thinner when the bound water and hydroxyl groups are removed from the lamellae.The results of TGA test show that LDHs remove water molecules to form metal oxide LDO and form spinel structure at high temperature.Modified LDHs/ENR/SBR composites were prepared by adding LDHs with different calcination time into ENR/SBR blends.Atomic force phase diagram shows that the size distribution of calcined LDHs in rubber matrix is uniform,and it is not easy to agglomerate.Physical and mechanical properties of the composites showed that the calcined LDHs had good reinforcing effect,improved the mechanical properties,air tightness and modulus of the composites,and reduced the energy loss.However,it should be noted that the LDHs sheet is hard and brittle,the calcination time is too long and the size is too large.It is easy to fracture and introduce too many interface defects in the rubber mixing process.Therefore,the LDHs/ENR/SBR prepared by calcining LDHs for 1 h has the best comprehensive performance.