Effect of liquid rubber on mechanical properties and gas barrier properties of butyl rubber composites
Different types of liquid rubber including liquid EPDM(LEPDM,Mr=30 000/50 000),liquid polyisobutene rubber(LPIB,Mr=680/2 400)and liquid nitrile butadiene rubber(LNBR,Mr=5 000)on mechanical properties,free volume and gas barrier properties of butyl rubber/liquid rubber composites were studied.The results showed that the crosslinking density of the composite decreased while the elongation at break and tensile strength strength increased significantly after the addition of liquid rubber.Compared with IIR,the tensile strength and tear strength of IIR/LNBR 5000 increased by 74.7％and 29.4％,respectively.Positron annihilation test showed that liquid rubber increased the free volume of the composite except LPIB 2400.The gas permeability tests confirmed that the molecular chain movement was the key factor to determine the nitrogen permeability coefficient of IIR/LR composites.The nitrogen permeability coefficients of IIR/LPIB 2400 and IIR/LNBR 5000 decreased by 13.0％and 14.3％,respectively,compared with that of IIR.
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