chapter材料科学基础课件资料讲解.ppt

NETWORK POLYMERS 网络型 A polymer composed of trifunctional mer units that form three-dimensional molecules. Trifunctional mer units, FIGURE 4.7 (d) Schematic representations of network These materials have distinctive mechanical and thermal properties. Epoxies and phenol-formaldehyde belong to this group. 环氧的 苯甲醛 三功能链节 FIGURE 4.8 Classification scheme for the characteristics of polymer molecules. 同质异构 立体异构 几何异构 全同立构 间同立构 不同立构 独立体 贯穿结构 4.9 Thermoplastic and Thermosetting Polymers Thermoplasts (or thermoplastic polymers): A polymeric material that softens when heated and hardens upon cooling. While in the softened state, articles may be formed by molding or extrusion. processes are reversible and may be repeated. Most linear polymers and those having some branched structures with flexible chains are thermoplastic. 热塑性和热固性聚合物 可逆的 thermosets (or thermosetting polymers) A polymeric material that, once having cured (or hardened) by a chemical reaction, will not soften or melt when subsequently heated. 热固性塑料 Thermoset polymers are generally harder and stronger than thermoplastics, and have better dimensional stability. Most of the crosslinked and network polymers, are thermosetting. which include vulcanized rubbers, epoxies, and phenolic and some polyester resins, 硫化橡胶 环氧类 酚类 聚酯树脂 4.10 Copolymers Copolymer：A polymer that consists of two or more dissimilar mer units in combination along its molecular chains. FIGURE 4.9 Schematic representations of (a) random, (b) alternating, (c) block, and (d) graft copolymers. The two different mer types are designated by black and colored circles. 共聚物 Random copolymer. A polymer in which two different mer units are randomly distributed along the molecular chain. Alternating copolymer. A copolymer inwhich two different mer units alternate positions along the molecular chain. 随机共聚物 交替共聚物 Block copolymer. A linear copolymer in which identical mer units are clustered in blocks along the molecular chain. Graft copolymer. A copolymer wherei