Lesson 11 Plastics第十一课塑料课文讲授，主要以教师翻译讲解和学生的参与理解翻译为主，在文章的学习中，识记专业词汇。
授课时间为45’×2Plastic means pliable or impressionable. It is defined as the capability of being deformed continuously in any direction without breaking apart. Following this definition, plastics could include glass, metals, and wax. Thus, it is evident that the name plastics is misleading and not exactly correct. Today, however, the name plastics is identified with the products which are derived from synthetic resins. The synthetic resins are made by various chemical processes. Plastics manufacturing is of comparatively recent date. The discovery of ebonite, or hard rubber, by Charles Goodyear in 1839, and the development of celluloid (cellulose nitrate ) by Hyatt in 1869 marked the beginning of plastic products. It was not until 1909, however, that one of the most important materials, phenol formaldehyde resin, was developed by Dr. L. H. Baekeland and his associates. Today plastics are commonly found in homes, automobiles, numerous other products, and machines. Some machines which utilize electricity require plastic parts with electrical insulating properties. One of the largest plastic products ever built is a 2600-pound 28-foot-long boat hull which is made of fiber-glass matting impregnated with polyester resin and low-pressure laminated. The unusual properties of some plastic materials are used in many interesting applications. Advantage should be taken of these unusual properties wherever possible.译文所谓塑料是指该材料是可塑的。
根据定义，塑料具有在任何方向上连续变形而不引起断裂的能力。
依据这个定义，塑料包括玻璃、金属和蜡。
因此很明显塑料这个名称是令人费解的也不是完全准确的。
然而现在塑料这个名次定义为人造树脂提取物。
人造树脂是由各种各样的化学过程加工的。
塑料加工是比较来说是最近出现的。
1839年Charles Goodyear 发现硬橡胶或硬质胶，以及1869年Hyatt发现的明胶是塑料加工的开端。
然而没到1909年，Dr. L. H. Baekeland和他的同伴发现了最重要的材料之一，即酚醛树脂。
现在塑料在家庭用、汽车、大量其他产品和机器中非常普遍。
有些用电的机器需要具有绝缘性能的塑料件。
曾经建立的最大的塑料产品是用表面填充聚酯树脂和低压层的玻璃纤维生产的重2600磅长28英尺的船体。
一些塑料材料的特殊性能用于许多有趣的应用。
应该尽可能的利用这些特殊性能的优势。
分析wax蜡synthetic resin人造树脂ebonite硬橡胶celluloid 明胶phenol formaldehyde resin 酚醛树脂insulating 绝缘boat hull 船体polyester resin 聚酯树脂fiber-glass 玻璃纤维Thermosetting or Thermoplastic. Plastic materials, commonly called plastics, are known either as thermosetting or as thermoplastic. Upon the application of initial heat the thermosetting plastics soften and melt, and under pressure they will fill every crevice of a mold cavity. Upon continued application of heat they polymerize, or undergo a chemical change, which hardens them into a permanently hard, infusible, and insoluble state. After this they cannot again be softened or melted by further heating. The thermoplastic materials are those which soften with heating and solidify and harden with cooling. They can be remelted and cooled time after time without undergoing any appreciable chemical change.译文热固性或热塑性。
塑料材料，通常称为塑料，即具有热固性或热塑性。
基于初始热固性塑料软化加热热量的应用，在压力作用下会充满模具腔的每个缝隙。
基于连续热量应用会产生聚合或产生化学变化，这样会使其硬化产生永久变硬、难熔和不溶解状态。
之后再加热也不会变软或熔化。
热塑性材料是加热变软冷却固化变硬。
热塑性材料是可以再熔化，且可以一次次冷却而不会产生化学变化。
分析Thermosetting or Thermoplastic热固性或热塑性crevice缝隙polymerize聚合infusible难熔insoluble 不溶解solidify固化Fillers. Plastics often contain other added materials called fillers. Fillers are employed to increase bulk and to help impart desired properties. Plastics containing fillers will cure faster and hold closer to established finished dimensions, since the plastic shrinkage will be reduced. Wood flour is the general-purpose and most commonly used filler. Cotton frock, produced from cotton linters, increases mechanical strength. For higher strength and resistance to impact, cotton cloth chopped into sections about 1/2-inch square can be processed with the plastic. Asbestos fiber may be used as a filler for increased heat and fire resistance, and mica is used for molding plastic parts with superior dielectric characteristics. Glass fibers, silicon, cellulose, clay, or nutshell flour may also be used. Nutshell flour is used instead of wood flour where a better finish is desired. Plastic parts using short fiber fillers will result in lower costs, while those with long fiber fillers having greater impact strengths are more expensive. Other materials, not defined as fillers, such as dyes, pigments, lubricants, accelerators, and plasticizers may also be added. Plasticizers are added to soften and improve the moldability of plastics. Filler and modifying agents are added and mixed with the raw plastic before it is molded or formed.译文填充材料。
塑料通常包含称为填充物的附加材料。
填充材料用于增加密度和部分要求性能。
包含填充材料的塑料可以更快的处理并更接近建立完成尺寸，因此塑料收缩降低。
