聚乙烯与聚丙烯
聚合物是大分子，具有相同的结构单位重复。重复单元称为单体。这些单体与共价键相互键合，形成聚合物。它们的分子量很高，组成了10,000多个原子。在称为聚合的合成过程中，获得了更长的聚合物链。聚合物的主要类型取决于它们的合成方法。如果单体通过添加反应的碳之间具有双键，则可以合成聚合物。这些聚合物称为添加聚合物。在某些聚合反应中，当两个单体连接时，去除了一个小分子。这样的聚合物是冷凝聚合物。 Polymers have very different physical and chemical properties than their monomers. Moreover, according to the number of repeating units in the polymer, properties differ. There are a large number of polymers present in the natural environment, and they play very important roles. Synthetic polymers are also used widely for different purposes. Polyethylene, polypropylene, PVC, nylon, and Bakelite are some of the synthetic polymers. When producing synthetic polymers, the process should be highly controlled to get the desired product always. Polyethylene and polypropylene have become a very controversial issue at the present day, due to their incapability of degradation. They make up a considerable percentage in our garbage; therefore, they keep on increasing on the earth surface. This problem has caught the attention of researchers, and recycled plastics have been synthesized.
聚乙烯
这是当今世界上最常见的塑料。聚乙烯是由乙烯制成的聚合物。乙烯的两个碳原子与双键相互键合。将两个氢原子粘合到每个碳。当聚合时，双键会破裂，并在两个乙烯分子的两个碳之间进行新的Sigma键。换句话说，聚乙烯是通过单体乙烯的添加反应产生的。它的重复单元是–CH2-ch2-. Thus, this has a very simple structure with long chain carbon atoms. Depending on the way it is polymerized, the properties of the synthesized polyethylene change. Sometimes they can be straight chain, or sometimes they can be branched. Branched polyethylene is easy to make and lot cheaper. However, its strength is much lower than straight chain polyethylene. Polyethylene is used in making bottles, bags, toys, etc.
聚丙烯
聚丙烯也是塑料聚合物。它的单体是丙烯，它在两个碳原子之间具有三个碳和1个双键。聚丙烯是在催化剂（例如氯化钛）存在下用丙烯气体生产的。它易于生产，并且可以具有很高的纯度制造。聚丙烯的重量轻。它们对开裂，酸，有机溶剂和电解质具有很高的抗性。它们还具有高熔点和良好的介电特性，并且无毒。聚丙烯具有很高的经济价值。它们用于管道，容器，家具，包装和汽车零件。
聚乙烯和聚丙烯有什么区别？ •聚乙烯的单体是乙烯，聚丙烯的单体是丙烯。 •与聚丙烯的较高熔点相比，聚乙烯具有较低的熔点。 •聚丙烯不像聚乙烯那样坚固。 •与聚乙烯相比，聚丙烯对化学物质和有机溶剂具有耐药性。 •聚丙烯是纯净的，不伸直的，通常比聚乙烯更刚性。 |
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