【作者】 孙晋；

【导师】 郑强； 宋义虎；

【作者基本信息】 浙江大学 ， 材料学， 2009， 博士

【摘要】 绿色轮胎胎面胶是由白炭黑（SiO₂）填充溶聚丁苯橡胶（SSBR）基体并配合适当的硅烷偶联剂而制得。本论文以SSBR／SiO₂复合体系为研究对象，研究SiO₂与偶联剂含量对体系流变学行为和力学性能的影响，探讨不同外界作用模式（稳态剪切、动态剪切和稳态拉伸）下体系的特征流变响应。首先以己酰氯与γ-巯丙基三乙氧基硅烷为原料，在低温和N₂保护下合成封端基硅烷偶联剂3-己酰基硫代-1-丙基三乙氧基硅烷（HXT），采用动态流变学方法表征了HXT在SSBR／SiO₂体系中的偶联效果，发现HXT可有效抑制SiO₂粒子在SSBR体系中的团聚。与双-（3-乙氧基硅基丙基）-二硫化物（TESPD）相比较，含HXT体系的Payne效应呈现较高的临界应变值（γ_c）。研究了120℃和150℃混炼温度下三种偶联剂（双-（3-乙氧基硅基丙基）-四硫化物TESPT、TESPD、3-辛酰基硫代-1-丙基三乙氧基硅烷NXT）对SiO₂粒子表面改性的影响。结果表面，SiO₂粒子在SSBR中的分散状态既与混炼温度有关，又与硅烷偶联剂分子结构有关。在150℃混炼时，不同偶联剂均对SiO₂粒子起表面改性作用，但同时引起混炼胶不同程度的焦烧，其中以TESPT最为显著。随NXT含量增加，SiO₂粒子表面改性程度逐渐提高，低应变（γ）下的模量降低，γ_c值增大。NXT含量高于4．2 phr时，偶联剂与SiO₂粒子的反应趋于完全，NXT含量不影响流变行为。研究了SiO₂含量对SSBR/SiO₂体系储能模量（G′），损耗模量（G″）和损耗角正切（tanδ）等黏弹参数的频率（ω）、应变和时间依赖性的影响。结果发现，Payne效应随SiO₂体积分数（（?））的增大而变得更加明显。对于不同（?）的体系，G′～γ与tanδ～γ曲线可平移形成叠加曲线，表明Payne效应主要取决于橡胶分子链解缠结。在触变实验中，填充橡胶的模量回复程度随（?）增大而降低，表明除了橡胶分子链的贡献外，填料团聚网络破坏和重建的贡献随（?）增加逐渐增大。在非线性松弛试验中，阻尼函数（h（γ））的衰减速度随（?）增加而愈加明显。。对于不同（?）的体系，通过平移h（γ）-γ关系可叠加到SSBR曲线上。首次将应变放大效应引入填充橡胶在剪切作用下的非线性流变行为。由于刚性粒子的存在，基体分子链的局部应变远大于宏观应变，导致填充体系的非线性黏弹行为随（?）增大而增强。研究了SSBR／SiO₂体系在简单剪切、振荡剪切和稳态拉伸等不同作用模式下的流变行为。发现填充SSBR的粘度（η）、应力(τ和模量（G）等流变学参数的应变速率（（?））和γ依赖性类似于未填充SSBR体系，表明基体分子链的缠结网络是流变行为的主导因素。在稳态剪切中，填充体系的屈服现象随（?）增加而逐渐减弱，这是由于填料粒子限制了分子链运动能力。同时，Cox-Merz规则可较好地描述未填充和填充SSBR的η～（?）与复数粘度η^*～（?）关系。在低应变下，未填充和低填充量（（?）（?）0．12）SSBR的拉伸粘度（η_E（t））符合η_E(t=3η（t）。在高应变（ε）下，试样发生不均匀拉伸和成颈，拉伸流变行为偏离该理论关系。η_E峰值η_m与应变速率（（?））呈指数关系递减，呈现“拉伸变稀”。填充SSBR在高ε下均呈现应力软化，说明聚合物分子链的解缠结过程起主要作用。相应的临界应变（ε_c）随（?）增大而减小，反映了SiO₂粒子的应变放大效应。此外，SiO₂粒子的加入改善了SSBR体系的抗蠕变性。研究了偶联剂和SiO₂含量对填充SSBR硫化胶力学性能的影响。结果表明NXT偶联剂显著提高硫化胶拉伸强度，其含量高于4．2 phr时，拉伸强度几乎保持不变，而断裂伸长率随仅略微下降。NXT可改善SiO₂粒子在橡胶基体中的分散，显著降低硫化胶磨耗量与滚动阻力。在动态力学试验中，tanδ曲线在-70℃和80℃附近出现的两个损耗峰，分别对应SSBR橡胶分子链的玻璃化转变和苯乙烯嵌段的玻璃化转变及填料网络的松弛。在SSBR的玻璃化温度（-80～-50℃）附近，填充SSBR体系硫化胶的动态力学行为遵循时温叠加（TTS）原理，频率平移因子（α_T）与温度间的关系满足WLF方程。更多还原

【Abstract】 Nowadays,great improvements are claimed for the“Green Tire”which isprepared by using commercial rubber filled with silica （SiO₂） with respect to lowerrolling resistance,better traction on water and snow,and lower heat build-upcompared with conventional tires filled with carbon black （CB）.However thedispersion of SiO₂ is worse than that of CB due to existence of hydrophilic silanolgroups in SiO₂ surface.Silane coupling agents are usually used to improve thefiller-rubber interaction and to prevent SiO₂ agglomeration.Addition of colloidalparticles affects the rheological behaviors of the rubbery matrix.In this thesis,solution-polymerized styrene butadiene rubber （SSBR）/SiO₂compounds have been investigated.Silane coupling agent 3-hexanoylthio-1-propyltriethoxysilane （HXT） was synthesized and used in SSBR/SiO₂ compounds.Dynamic rheological measurement reveals that incorporation of HXT into SSBR/SiO₂compounds inhibit SiO2 agglomeration and improve dispersion of the particles in theSSBR matrix.The characteristic strain （γc） for Payne effect of the compoundscontaining HXT appears higher than that of those containing bis-（triethoxysilylp-ropyl）-disulfide （TESPD）.The effect of different silane coupling agent （TESPT,TESPD and NXT） on thetheological properties for uncured SSBR/SiO₂ compounds mixed at two differenttemperatures （120℃and 150℃） were investigated.It is found that the dispersion stateof SiO₂ particles in the matrix is related to compounding temperature and themolecular structure of silane coupling agent.For 50 phr SiO₂ filled rubber,NXTcontent above 4.2 phr hardly influences theological behaviors because the reactionbetween SiO₂ and NXT almost approachs saturated.On the other hand,the effect of filler volume fraction （φ） on the nonlinearviscoelastic properties for uncured SSBR/SiO₂ compounds was examined.Resultsshow that the curves of dynamic storage modulus （G’）,loss tangent （tanδ） anddamping function （h（γ）） versus strain amplitude （γ） for the filled rubber can besuperposed on those for the unfilled SSBR respectively,suggesting that the primary mechanism for the Payne effect is mainly involved in the nature of the entanglementnetwork in rubbery matrix.Moreover,the modulus recovery degree of filled rubber inthe thixotropy experiment becomes worse with increasingφ,indicating that thebreakdown and reformation process of filler network plays an important role in thefilled rubber besides the contribution of macromolecular chain.The effect of strain mode （steady shear,oscillatory shear and steady extension） onrheological behaviors for SSBR/SiO₂ compounds was studied.γand strain rate （γ）dependences of steady and complex viscosities （ηandη*）,stress （τ） and modulus （G）for filled rubber are qualitatively similar to those for unfilled SSBR.Yielding-likebehavior is gradually weakened with increasingφin steady shear,indicating that themobility of polymer chain is restricted by addition of filler.On the other hand,Cox-Merz rule can be applied to examineηandη^* of SiO₂/SSBR compounds.Goodagreement between steady extensional viscosity （η_E） in the low strain （ε） amplitudeand the linear viscoelastic envelope prediction is observed.An overshoot in the tensilestress growth appears and the maximum valueη_m presents extension thinning with anasymptotic expression close toη_m～ε^-k.The corresponding characteristic strain value（ε_c） decreases with increasingφ,revealing the strain amplification effect of SiO₂particles.The effect of silane coupling agent and filler loading on the mechanical propertiesfor vulcanized SSBR/SiO₂ compounds was investigated.Compared with TESPT andTESPD,tensile strength of vulcanized rubber containing NXT becomes higher.Incase of NXT content above 4.2 phr,tensile strength remains constant and elongationat break only decreases slightly with increasing NXT content.Both tensile strengthand elongation at break increase with increasingφ,and the vulcanites perform best atφ=0.12.It is suggested that in the temperatures from -80℃to -50℃（around Tg ofSSBR）,dynamicωsweep curves at different temperatures obey time-temperaturesuperposition （TTS） principle,and WLF equation can be used to fit the shift factor （α_τ）as a function of temperature.更多还原