unit2polymerandcomposites.docVIP

Unit 2 Polymer and Composites 2单元的聚合物和复合材 Polymers and polymer composites are used in many different forms, ranging from synthetics through to structural composites in the construction industry and to the high technology composites of the aerospace and space satellite industries①. 聚合物和聚合物复合材料的使用在许多不同的形式，从合成通过在建筑行业的结构复合材料到高科技的航空航天复合材料和太空卫星产业。 Plastics are generally considered to be a relatively recent development. In fact, they are members of the much larger family of polymers. 塑料通常被认为是一个相对较新的发展。事实上，他们是聚合物的大家庭成员。 Polymers are the products of combining a large number of small molecular units called monomers by the chemical process known as polymerization ( which is the process by which molecules or groups of atoms are joined together) to form iong-chain molecules. Natural materials such as bitumen，rubber and cellulose have this type of structure. There are two main types of polymerization. In the first type, a substance consisting of a series of long-chain polymerized molecules, called thermoplastics, is produced. All the chains of the molecules are separate and can slide over one another. In the second type, the chains become cross-linked so that a solid material is produced which cannot be softened and whicli will not flow. Such solids are called thermosetting polymers. These two groups classify polymer materials. 聚合物是结合大量的小分子单元的化学过程称为聚合的单体产品（这是分子或原子团的过程结合在一起，形成长链分子）。天然材料如沥青，橡胶和纤维素都有这种类型的结构。有两种主要类型的聚合。在第一种类型，一种物质由一系列长链聚合的分子，称为热塑性塑料，产生。所有的分子链是分开的，可以互相滑动。第二型，分子链交联，成为固体材料产生不可软化，其中不会流。这种固体称为热固性聚合物。这两组分聚合物材料Polymers are usually made in one of two polymerization processes. In condensation polymerization the linking of molecules creates by-products, usually water, nitrogen or hydrogen gas. In addition polymerization no by-products are created. 聚合物通常有两种聚合过程。在冷凝聚合链接的过程中分子产生的副产品，通常，水，氮气或氢气。此外聚合无副产物产生. The final property of the plastics material will be determined by the type of additive mixed with the pure polymer. Additives