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白炭黑 — 性能分析
理解白炭黑的补强性能

总 述
很长时间以来,一些汽车制造商要求对那些似乎矛盾的轮胎性能同时得到改善, 这些性能包括: 滚动阻力 湿地抓地力 使用寿命,特别是 OE 胎 在最近十年的早期,通过对胎面橡胶的改善,适应了这些要求,这些改善包括: 特殊聚合物的使用和 高填充量白炭(配合使用硅烷)取代炭黑。 这类(胎面)胶的性能很大程度上取决于所使用的沉淀法白炭黑。最佳的比表面 积和 DBP 吸油值可以用来判定对橡胶性能的重要程度。硅烷醇基团的密度、粒 子尺寸分布和表面活性对一些橡胶性能的影响描述如下:

介 绍:
一个很好的轮胎必须达到如下要求: 很好的干路面和湿地牵引力 安全的制动性能 使用寿命长 低滚动阻力 符合这些期望性能要求的轮胎的发展已经实现,即使用高性能的、高分散性的白 炭黑同时配合使用硅烷和溶聚丁苯橡胶。 基于这些发展成果,1992 年出现了“绿色轮胎”,与使用炭黑填充橡胶的轮胎 相比, 绿色轮胎可降低滚动阻力约 20%, 并且在不影响胎面磨耗的情况下湿地牵 引力也有所提高。 白炭黑的无定形是一个很重要的概念。 白炭黑的这些分析性能已证明对橡胶物理 性能有很大的影响。

白炭黑的一些重要特性会影响粘度、硫化速度、模量和耐磨性: 硅烷醇含量 含水量 结构和比表面积

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白炭黑的比表面积反过来又关系到胶料的硫化速度和动态性能, 并且直接影响到 胶料粘度、压缩形变和补强效果。

结果&讨论
研究了一种胎面胶(80 份白炭黑和 12.8 份 X-50)的加工特性和动态性能: 未硫化胶的粘度必须比较低以保证加工性。达到 95%硫化的时间要短。300%模 量和 100%模量的比值叫做补强指数,指数高比较好。 滚动阻力与 60C 时的 Tanδ值有很好的相关性; 动态刚性(转弯性能),60C 时的复合模量 E*。

湿地牵引力与 0C 时的 Tanδ值有关。 绿色轮胎胎面橡胶在 60C 时的 Tanδ值越低,复合模量越高并且 0C 时的 Tanδ 越高,表示橡胶的动态性能越好。 BET比表面积/DBP吸收值对橡胶性能的影响: 白炭黑的 BET 比表面积和 DBP 吸收值关系到两项流变性能, 而这两项流变性能 又是胶料加工性好坏的一个量度: 门尼粘度 硫化速度 同样也关系到绿色轮胎胎面胶的下面 7 项硫化胶的性能参数: 100%定伸模量 300%定伸模量 邵尔 A 硬度 分散系数 60C 时的动态刚性 E* 60C 时的 Tanδ值 0C 时的 Tanδ值 BET 比表面积超过约 200m2/g 时会导致硫化速度慢。 白炭黑的比表面积高则表明硅烷醇基团的浓度高。在与相同数量的硅烷反应后, 仍会有相当数量的未反应的硅烷醇基团存在。然而,这些未反应的硅烷醇基团与 促进剂之前会发生强烈的界面反应,从而可能会降低硫化速度。 在多种情况下,如果白炭黑的 DBP 值低于 235g/100g,则硫化速度会比较快。 要使绿色轮胎胎面胶获得较快的硫化速度,就有必要选用 BET 表面积不超过 200m2/g 且 DBP 值低于 235g/100g 的白炭黑。 比表面积低且 DBP 值低于 235g/100g 时在多数情况下可使胶料具有较低的门尼粘度。 要使门尼粘度控制在 80 以下,则 BET 表面积应该低于 200m2/g. 白炭黑的填料填料间的强烈界面反应和结构可以很好的说明这种这种相关性。 因此, 低的 DBP 值和低 BET 表面积的共同影响下,则胶料的流变性能会较好。

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如果用 DBP 值高于 235g/100g 和更高比表面积的白炭黑,则 100%和 300%模量 会分别增加。 在 10%-50%的低应变下,填料-填料网络发挥主导作用。由于填料网络是随应变 而定的并且在高应变下会被破坏,在高应变下就是聚合物-填料占主导。 白炭黑的比表面积高且结构高,则聚合物-填料间的界面反应会增加,从而模量 也增加。邵尔 A 硬度也是同样道理。 分散系数主要取决于DBP吸收。DBP值高于 235g/100g时在多数情况下分散会比 较好。具有较高DBP吸收值的白炭黑可提高分散且生成更高空隙体积,这一特性 可解释如下: • 在混炼的开始阶段,聚合物渗透进入白炭黑的空隙(吃料过程)。如果空 隙的数量多,就会有更多的聚合物渗透进入白炭黑。 • 在接下来的解聚过程中,白炭黑聚集体发生降解(一部分是被聚合物渗 入)。渗透过程进行的越彻底,则白炭黑在聚合物中的分散就越好。 要获得高的动态刚性 (E*) 有必要使用高 BET 表面积和 DBP 值高于 235g/100g , 的白炭黑。 在低应变下的动态模量 E*取决于交联密度,同时也取决于填料-填料间的界面反 应。BET 比表面积的增大同样也伴随着硅烷醇基团总量的增加。因此,填料-填 料间的界面反应也会增加,因为形成氢键的可能性在增加。 另一方面来说,使用 DBP 值低于 235g/100g 且 BET 表面积低于 220m2/g 的白炭 黑时,60C 时的 Tanδ值会变低,且 0C 时的 Tanδ值会较高。 总得来说, 更高的 DBP 值和更高的 BET 表面积会带来多数情况下好的硫化胶性 能,除了 60C 和 0C 时的 Tanδ。 白炭黑对橡胶的内在重要性能具有有利影响的几个方面如下: BET 表面积低于 180m2/g 并且 DBP 值高于 235g/100g. 硅烷醇基团的分布密度越低,则 60C 时的动态刚性(E*)越高。 门尼粘度与硅烷醇基团的分布密度之关系: 要理解这层关系,需考虑两个因素: - 硅烷和硅烷醇基团之间的反应 - 第二,门尼粘度和疏水度之间的相关性 硅烷醇基团的分布密度越高,则门尼粘度越低。这意味着在硅烷醇基团分布密度 较高时疏水度也较高。如果白炭黑的疏水性越大,则填料-填料间的界面反应就 会下降。 门尼粘度越低,则补强效果越好,填料-填料间界面反应越少。因此,硅烷醇基 团分布密度低时,60C 时的动态刚性 E*就越高,但一个明显的缺点是补强指数 降低。

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另一方面来说, 降低硅烷醇基团的分布密度对于增加 60C时的动态刚性来说是一 个好方法。但是这对补强指数会有负面影响。因此,硅烷醇基团的分布密度需 要细微地调整以便这两个重要的性能之间达到最佳。 硫化速度是胶料性能中需要改善的一个更重要的性能。在 BET/DBP/硅烷醇基团 分布密度三者的比例一定时, 白炭黑的另一个物理性能, 即表面活性就非常重要。 白炭黑的表面化学和表面活性对硫化反应的影响巨大。总的硅烷醇基团数量越 高,则会有更多的促进剂会被吸附。 结论:这里讨论了 BET 表面积和 DBP 值对改善分散性能、动态刚性和硫化速 度的共同影响 (此外也讨论了其它重要参数: 硅烷醇基团分布密度, 表面活性) 。 这类认识有助于开发出新的高分散性白炭黑产品。

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...Study Guide: Final Exam Concentrate your studies in the following areas. Questions for the Final Exam will come principally from this material. Lutgens and Tarbuck Textbook: Earthquakes and Structures (Chapter 6) * Know the definition of an earthquake (pg. 190). --ground shaking caused by the sudden and rapid movement of one block of rock slipping past another along fractures in Earth’s crust called faults * Know the difference between the focus and epicenter of an earthquake. Which is located at the source of the earthquake? Which is located on the surface of the earth directly above the source? --Focus=Earthquakes tend to occur along preexisting faults where internal stresses have caused the crustal rocks to rupture or break into two or more units. The location where slippage begins is called the hypocenter, or focus. --Epicenter=The point on Earth’s surface directly above the hypocenter * Understand the concept of elastic rebound. What is it? How are earthquakes produced via elastic rebound? * --Elastic rebound=At some point, the stress along the fault overcomes the frictional resistance, and slip initiates. Slippage allows the deformed ( bent) rock to “ snap back” to its original, stress- free, shape; a series of earthquake waves radiate as it slides. Reid termed the “ spring-ing back” elastic rebound because the rock behaves ­elastically, much like a stretched rubber band does when it is released. * Know the three basic types of seismic waves...

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...Reference Manual on Best Management Practices for PM-10 and Fugitive Dust Control BEST MANAGEMENT PRACTICES For Maricopa County, Arizona Rule 310 Written by Zbigniew D. Czupak Dr. Edward Kavazanjian, P.E. Arizona State University Ira A. Fulton School of Engineering School of Sustainable Engineering and the Built Environment Sponsored by 1 ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support provided by the Arizona Pavements, Materials, and Transportation Conference steering committee for preparation of this Reference Manual. The authors would also like to thank Amanda McGennis of the Phoenix Chapter of the Association of General Contractors and Cameron Flowers of Kitchell Engineering for their technical assistance in manual preparation, including their review comments on the document and many of the pictures used in the document. 2 QUICK REFERENCE GUIDE Application Control Method Watering Paved Roads p. 19 Unpaved Roads p. 20 Construction Entrances p.21 As needed (excessive watering increases track out, requires catch basins) Staging Areas p.23 Storage Piles p.24 Disturbed Flat and Sloped Surfaces p.26-28 Water to form visible crust Weed Abatement p.29 Use prior and during weeding Demolition/Blasting p.30-32 Backfilling p.33 Stacking, Loading, Unloading p.34 Use prior and during Trenching, Excavating p.35 Pre-wet, maintain moisture content Expensive, Can mix with water Hauling p.36-37 - Periodic reapplication Polymer...

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