Preparation And Properties Of Montmorillonite/(Brominated) Butyl Rubber Nanocomposites With High Airtightness

Montmorillonite(MMT)is a layered silicate mineral found in nature and has realized a wide range of applications in drilling fluids,cosmetics and photosensitive catalysts.Due to high hydrophobicity of MMT,polymer/MMT nanocomposites with excellent properties are commonly prepared using organic montmorillonite(OMMT).Currently,the common pathway for the preparation of OMMT is solution intercalation method,which requires a large amount of solvent to disperse MMT.In order to achieve efficient and green organic modification of MMT,a wet grinding method was developed to modify montmorillonite using octadecyl trimethyl ammonium chloride(OTAC)in the paper.Furthermore,MMT/brominated butyl rubber(BIIR)and butyl rubber(IIR)nanocomposites with high airtightness were prepared by in-situ modification method.The specific work in this paper is as follows:(1)The wet grinding method on the modification effect of MMT was investigated.The liquid modifier,dodecyl pyrrolidone(NDP),was used to modify MMT by grinding method,and the results of XRD indicated that NDP was inserted into the interlayer of MMT.The solid modifier OTAC was directly used to modify MMT by dry grinding method.The results of XRD showed that dry grinding method could achieve the intercalation modification of MMT,but the increase in interlayer spacing was not significant.The wet grinding modification of sodium-based montmorillonite(Na-MMT)by OTAC was realized by adding small amount of water.The intercalation effect of wet grinding method was as good as that of solution intercalation.The effects of water dosage,OTAC dosage and experimental equipment on the modification effect via wet grinding method were investigated.The wet grinding method was highly universal,and the content of modifier in OMMT increased with the increase of OTAC dosage.When the water dosage was 100% of the mass of MMT,the modification effect of MMT was the best.(2)OMMT/BIIR nanocomposites were prepared by melt blending method.The effects of mixing time,OMMT dosage and OMMT type on the properties of nanocomposites were investigated.When OMMT was added during the rubber blending process,stearic acid(SA)could form a composite modifier with the quaternary ammonium salt between OMMT layers,which further expanded the layer spacing of OMMT.Compared with BIIR,the mechanical properties and gas barrier properties of OMMT/BIIR nanocomposites were significantly improved.When OMMT was mixed for 5min,the tensile strength of the nanocomposites reached 12.8 MPa and the airtightness was improved by 49%.The airtight performance of the nanocomposites employing domestic OMMT was improved by 24%.(3)MMT/BIIR nanocomposites with high airtightness were prepared by in-situ modification method.The effects of OTAC dosage,Na-MMT dosage and Na-MMT type on the properties of the nanocomposites were investigated.In sulfur vulcanization system,the mechanical properties of MMT/BIIR nanocomposites were equal to those of BIIR standard sample.The airtightness of the nanocomposites continuously improved with the increase of OTAC or Na-MMT dosage.The nanocomposite with 5 phr Na-MMT and OTAC dosage of 1.0 times ion exchange capacity(CEC)had the best airtightness,about 39%improvement as compared with BIIR sample.(4)In order to verify the generality of in-situ modification method,the effects of domestic and imported Na-MMT,domestic and imported OMMT,and self-made OMMT on the properties of MMT/IIR nanocomposites were investigated.The tensile strengths of MMT/IIR nanocomposites were all around 13.5 MPa,and the airtightness performances of MMT/IIR nanocomposites using imported and domestic OMMT were improved by about 40%.The airtightness performances of MMT/IIR nanocomposites with imported and domestic Na-MMT were improved by more than 47%.