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Title:: Weakening Mullins effect of coordination crosslinked nitrile rubber/copper sulfate/tetramethylthiuram disulfide vulcanizates

Author(s):: LI Jia-hao; LIN Yu-sheng; HUANG Ping; WANG Zhao-bo; College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

Keywords:: coordination crosslinking; nitrile rubber; tetramethylthiuram disulfide; mechanical property; weakening Mullins effect; synergistic effect

摘要:: 采用硫酸铜/二硫化四甲基秋兰姆（TMTD）配位交联制备了丁腈橡胶（NBR）硫化胶，对不同TMTD用量下混炼胶的硫化特性和硫化胶的力学性能及压缩模式下的弱化Mullins效应进行了研究。结果表明，二价铜离子和TMTD通过协同作用生成的[Cu（SnCNMe2）]·2+络合物与氰基配位交联形成了三维网络结构。随着TMTD用量的增加，NBR硫化胶的交联密度得到提高。在单轴循环压缩过程中，NBR硫化胶产生了明显的Mullins效应，且随TMTD用量增加而明显减弱。同一应变下的最大压缩应力随着循环次数的增加而下降，表现出应力软化现象，瞬时残余压缩形变随循环次数的增加而增大；随着应变的提高，最大压缩应力的下降幅度和瞬时残余压缩形变的增加幅度增大，Mullins效应更加明显；但是随着TMTD用量的增加，最大压缩应力的下降幅度和瞬时残余压缩形变的增加幅度减小，Mullins效应得以明显弱化。

Abstract:: The nitrile rubber （NBR） vulcanizates were prepared by coordination crosslinking of copper sulfate（CuSO4）/tetramethylthiuram disulfide（TMTD）. The vulcanization characteristics, mechanical properties and weakening Mullins effect under compression mode of the vulcanizates with different TMTD amounts were investigated the. The results showed that the [Cu（SnCNMe2）]·2+ complex formed by the synergistic effect of Cu2+ and TMTD was crosslinked with cyano group to form a three-dimensional network structure；the crosslinking density of NBR vulcanizates increased with increasing TMTD amounts；the Mullins effect of NBR vulcanizates was significantly obvious during the uniaxial cyclic compression, but could be weakened with increasing TMTD amount. Moreover, the maximum compressive stress under the same strain decreased with increasing the number of cycle times, which showed the stress softening phenomenon， and the instantaneous residual compression deformation increased with increasing the number of cycle times. The decrease range of maximum compressive stress and the increase range of instantaneous compression residual deformation were increased with increasing strain, and the Mullins effect was more remarkable. However, the decrease range of maximum compressive stress and the increase range of instantaneous compression residual deformation were weakened with increasing TMTD amount, and the Mullins effect was significantly weakened.