When polymers are fabricated into useful articles they are referred to sa plastics,rubbers, and fibers. 那么多内容才10分,正好我熟悉这个专业,可放心采纳
当聚合物被制造成有用的物件时,它们被称为塑料、橡胶和纤维.
There is no agerrment as to the minimum molecular weight of a substance in order for it to be classified as apolymer, however, a practical figure would be about 1000 to 5000.
关于一种为归类为聚合物的物质的分子量没有一致的意见.不过实践中的数字大约是1000到5000.The physcial properties of polymer are the determining fators the design engineer must use in seleetinga ploymer with those properties which most nearly meet the requirements of a product.聚合物的物理性质是设计工程师在根据最接近于满足产品要求的性质选择一种聚合物时必须用到的决定性因素.Injection molding machines are manufactured in many sizes.There are two basic units an injection molding machine; on for injecting the heated palstic and one for injecting the heated plastic and one for opening and closing the mold.The reciprocating screw is the most commonly used plasticating unit.The mold is at the core of a plastic manufacturing process because its cavity gives apart its shape.Molds used in injection molding consist of two halves;one staionary and one movable.Mold [and die] parts that that are mass-produced and standardized in shape and dimension are referred to as standards[or standard parts]
注塑机制成很多规格.一台注塑机有两个基本的单元,一个用于注入加热的塑料,另一个用于打开和闭合模具.往复的螺杆是最常用的塑化装置.模具处于塑料制造过程的核心地位,因为它的腔体给予一个加工件以形状.用于注塑的模具由两半组成,一个固定,另一个活动.大量生产的、形状和尺寸标准化的模具零件被称之为标准件.