level 12
USING carrots to create concrete, turning wood into plastic, or even compressing it into a “super wood” that is as light and strong as titanium might sound like a series of almost Frankensteinish experiments. Yet all three are among the latest examples of employing natural fibres from plants as eco-friendly additives or alternatives to man-made materials.
用胡萝卜拌制混凝土；把木头变成塑料；把木头压缩成和钛一样又轻又坚固的“超级木材”。这听起来像是科学怪人鼓捣的一连串疯狂实验。实际上，这是研究人员尝试把植物中的天然纤维用作环保添加剂或人造材料的替代品的最近三例。
Materials-science researchers are finding that plant fibres can add durability and strength to substances already used in the construction of buildings and in goods that range from toys and furniture to cars and aircraft. A big bonus is that, because plants lock up carbon in their structure, using their fibres to make things should mean less carbon dioxide is emitted. The production of concrete alone represents some 5% of man-made global CO2 emissions, and making 1kg of plastic from oil produces 6kg of the greenhouse gas.
材料科学研究人员发现，在建筑材料以及玩具、家具、汽车、飞机等各种商品的原材料中添加植物纤维，能让它们更耐久、更结实。而由于植物可将碳封存在其组织内，使用植物纤维应该还会带来一大好处——减少二氧化碳排放。单是混凝土生产就造成了全球大约5%的人为二氧化碳排放，而用石油生产1公斤塑料会产生6千克温室气体。
Start with the carrots. These are being investigated by Mohamed Saafi at Lancaster University, in England. Dr Saafi and his colleagues do not use whole carrots, but rather what they call “nanoplatelets” that have been extracted from carrots discarded by supermarkets or as waste from food-processing factories. Sugar-beet peelings are also a useful source of nanoplatelets. The researchers are working with CelluComp, a British firm that produces such platelets for industrial applications, including as an additive that helps toughen the surface of paint as it dries.
先来看胡萝卜的妙用。英国兰卡斯特大学的默罕默德·萨菲（Mohamed Saafi）正在探究这种植物的用处。萨菲和同事们用的并不是整根胡萝卜，而是所谓的“纳米薄片”，是从超市丢弃或被食品加工厂当作废料的胡萝卜中提取而来。甜菜皮也是制作纳米薄片的有用材料。研究人员正在和英国公司CelluComp合作。这家公司生产工业用途的纳米薄片，其中有一种可用作添加剂，能让干燥后的油漆表面更牢固。
Each platelet is only a few millionths of a metre across. It consists of a sheet of stiff cellulose fibres. Although the fibres are minute, they are strong. By combining platelets with other materials a powerful composite can be produced. Dr Saafi is mixing the platelets into cement, which is made by burning limestone and clay together at high temperature. (The chemical reaction between them releases carbon dioxide from the limestone.) To turn cement into concrete it is mixed with aggregates such as sand, stones and crushed rocks, which act as reinforcement, and with water, which reacts with the chemicals in the cement to form a substance called calcium silicate hydrate. This starts off as a thick gel, but then hardens into a solid matrix that binds the aggregates together.
每个薄片只有一米的几百万分之一宽，由一层硬的纤维素纤维构成。这种纤维虽然非常细小，却很结实。将薄片与其他材料结合，便能得到强大的复合材料。萨菲正在把薄片与水泥混合。水泥由石灰石与粘土高温烧制而成。（二者发生的化学反应会令石灰石释放二氧化碳。）要将水泥变成混凝土，需要将它与骨料和水混合，骨料包括砂石和碎石，起加固的作用；水会与水泥中的化学物质发生反应，形成一种叫作水化硅酸钙的物质。一开始它是一层厚厚的胶状物，但之后会硬化成一种固体基质，将骨料结合在一起。
2018年07月20日 01点07分
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