材料导论(63) - 图文

Video 12: Synthetic Rubber

Today, we are going to talk about another important elastomer. It is synthetic rubber. 合成橡胶 译文：

今天，我们要聊一聊另外一类重要的弹性体，合成橡胶。

First, we have to know why synthetic rubber is developed. There are some problems for natural rubber, such as the limited sources. Even with the improved property obtained through vulcanization, natural rubber also has poor properties on aging resistance, chemical resistance, and oxidation resistance, due the reactive sites of carbon-carbon double bonds. 译文：

首先，我们需要知道为什么要发展合成橡胶。天然橡胶存在一些问题，例如有限的资源。尽管硫化可以提高其性能，但由于碳碳双键的反应位点，天然橡胶的耐老化型、耐化学品性和抗氧性等性能依然较弱。

Moreover, it is necessary to develop new elastomer to meet the special requirements in practical applications. For example, we have to consider the specific properties, price, and processibility of elastomers in practical applications. 译文：

并且，有必要开发新的弹性体来满足实际应用中的特殊要求。例如，我们需要考虑弹性体材料在实际应用中的特殊性能、价格和可加工性等。

Due to these shortcomings and specific requirements, the search for a substitute produced several synthetic rubbers in the early to middle part of the twentieth century. Firstly, based on knowledge about natural rubbers, scientist aimed to synthesize a polymer with the same molecular structure of natural rubbers, in order to copy their properties and overcome the shortcoming of limited sources. 译文：

由于这些缺点和特殊要求，在20世纪中叶的早期，作为天然橡胶的替代品，合成橡胶被生产出来。首先，基于对天然橡胶的了解，科学家们希望合成与天然橡胶具有相同分子结构的聚合物，从而复制天然橡胶的性能，并克服其资源短缺的弊端。 有缘学习更多驾卫星ｙｇｄ３０７６In 1909, a research group, working at the Bayer laboratory in Germany, succeeded in polymerizing isoprene. The first synthetic rubber was obtained. This is the chemical structure of polyisoprene. Synthetic polyisoprene is almost identical in properties to natural rubbers than any other rubber materials. Compared with natural rubber, the synthetic polyisoprene has greater stretching ability. Therefore, it can replace natural rubber in many applications, although it is relatively expensive. 译文：

在1909年，德国贝尔实验室的研究团队成功聚合了异戊二烯。第一个合成橡胶诞生了。这是聚异戊二烯的化学结构。与其它橡胶材料相比，合成聚异戊二烯与天然橡胶的性能几乎是一致的。与天然橡胶相比，人工合成的聚异戊二烯具有更好的拉伸性能。因此，在很多应用领域可以替代天然橡胶，虽然相对较贵。

Styrene-butadiene rubber is another important synthetic rubber. We name it as SBR. SBR is a random copolymer of butadiene and styrene. It is closer in properties to natural rubber and not expensive. 译文：

丁苯橡胶是另外一种重要的合成橡胶。我们把它简称为SBR。丁苯橡胶是丁二烯和苯乙烯的无规共聚物。它与天然橡胶的性能非常接近，而且还不贵。

It has a good abrasion resistance and good aging stability when protected by additives, such as black carbon. In 2012, more than 5.4 million tons ofSBR wereprocessed worldwide.And in 2017 in China, the output of SBR is over 2 million tons. More than 50% of car tires are made from various types of SBR. 译文：

当加入添加剂时，例如炭黑，丁苯橡胶具有优异的抗磨损性和老化稳定性。在2012年，全世界的丁苯橡胶产量超过540万吨。在2017年，中国的丁苯橡胶产量超过200万吨。超过50%的汽车轮胎是用各种型号的丁苯橡胶制成的。

Usually, SBR can be synthesized by two different methods, which are solution polymerization and emulsion polymerization. Solution SBR is synthesized by anionic polymerization. Emulsion SBR is synthesized by free radical polymerization. Now, emulsion SBR is more widely used. However, relative to emulsion SBR, solution SBR is increasingly favored because it offers improved wet grip and rolling resistance, which translate to greater safety and better fuel economy, respectively. 译文：

通常情况下，丁苯橡胶采用溶液聚合和乳液聚合两种方法合成。溶剂丁苯橡胶是采用阴离子聚合制备的。乳液丁苯橡胶是通过自由基聚合制备的。目前，乳液丁苯橡胶应用更广泛。然而，相对于乳液丁苯橡胶，溶剂丁苯橡胶所具有的湿附着力和抗滑性能够提高安全性和燃油经济性，逐渐受到青睐。

I think it is easy to find that a tire is made of different rubbers, such as tread rubber and sidewall rubber. Actually, a tire is made of both natural rubber and styrene-butadiene rubber. Why we use different rubbers to prepare a tire. The answer is to use their different properties. Elastic hysteresis is an important performance of rubber used in tire. 译文：

大家很容易发现轮胎是由不同的橡胶组成的，例如胎面胶和胎壁胶。实际上，轮胎是由天然橡胶和丁苯橡胶制备而成的。为什么我们要使用不同的橡胶来制备轮胎呢？答案是利用它们不同的性能。弹性滞后是橡胶在轮胎应用中的一项重要性能。

弹性滞后是橡胶作为轮胎材料使用时的一共重要的性质。It is an energy loss through heating in

elastomer. If you stretch a rubber band and hold it on your cheek, you can feel the release of heat from it. SBR has a high hysteresis, which is employed as tread rubber. When a tire is used on a car, the different position of tread will alternating contact with road. So there is a constant flexing at the tread of tire. It means that there is alternating stress at the tread of tire. 译文：

它是指弹性体材料通过生热而实现的能量损失。如果你拉伸一个橡胶样条，并把它放在你的脸颊上，你能够感觉到样条释放出的热量。丁苯橡胶具有高滞后性，被用作胎面胶。当轮胎在车辆上使用时，不同的部位会交替的与路面接触。所以，在胎面上会产生固定的挠曲。这意味着轮胎的胎面会出现交变的应力。

Alternating stress can generate enough heat at tread. Therefore, tread of tire is good in prevent slippage on a wet surface. Moreover, SBR has a better abrasion resistance than natural rubbers. Based on these advantages, SBR is widely used as tread rubber in tire. If a tire is made wholly of SBR, it would be quickly damaged. Therefore, for the sidewall rubber, natural rubber is a good choice. Because natural rubber can effectively convert stressing into elasticity and rebound with less heating. 译文：

交变应力能够在胎面上产生足够的热量。因此，轮胎的胎面具有在湿表面上防止打滑的特性。并且，丁苯橡胶与天然橡胶相比具有更好的抗磨损性。基于这些优点，丁苯橡胶被广泛用于轮胎的胎面胶。如果轮胎完全由丁苯橡胶制备，轮胎会很快的损坏掉。因此，对于胎壁胶，天然橡胶是更好的选择。因为天然橡胶能够在释放更低热量的情况下，有效的将应力转变为弹性和回弹。

Therefore, by using the different rubbers, such as SBR and natural rubber, we can prepare a good tire with multiple properties.

译文：

因此，使用不同的橡胶，例如丁苯橡胶和天然橡胶，我们能够制造出具有多功能的好轮胎。 Except for tire, rubber are also widely used in many other practical applications. Sometime, we need to use rubber and also require a good oil resistance for it. In this case, natural rubber and SBR cannot meet these requirements. So we have to develop a new synthetic rubber. Nitrile butadiene rubber, named as NBR, is another important synthetic rubber with a good oil resistance property, which has been widely used in oil resistant rubber products. 译文：

除了轮胎，橡胶还有很多其它应用。我们有时候使用橡胶时需要其具有很好的耐油性。在这种情况下，天然橡胶和丁苯橡胶都无法满足要求。所以，我们需要开发新的合成橡胶。丁腈橡胶的简称是NBR，是另外一种重要的合成橡胶，具有优异的耐油性，被广泛用于制备耐油橡胶制品。

丁腈橡胶具有极好的耐油性，广泛用于制各种耐油橡胶制品。NBR is a copolymer of acrylonitrile and butadiene, which is a family of unsaturated copolymers. Its physical and chemical properties vary depending on the polymer’s composition of nitrile. The more nitrile within the polymer would results in higher resistance to oils, but the lower flexibility of the material. It is widely used in the automotive and aeronautical industries to make fuel and oil hoses and self-sealing fuel tanks, since ordinary rubbers cannot be used. 译文：

丁腈橡胶是丙烯腈和丁二烯的共聚物，属于不饱和共聚物。丁腈橡胶的物理和化学性能会随聚合物中丙烯腈组份的含量而变化。高的丙烯腈含量可以得到更高的耐油性，但材料的柔韧性会下降。丁腈橡胶在汽车工业和航空工业中应用广泛，用于制造燃料和输油的管路、自密封油箱，然而普通橡胶无法用于制备这些制品。