尼龙是最常见的人造纤四川大学

1、尼龙 (Nylon)Polyamide    尼龙是最常见的人造纤维。1940年用尼龙织造的长统丝袜问世时大受欢迎，尼龙从此一举成名。此后在二战期间，尼龙被大量用于织造降落伞和绳索。不过尼龙最初的用途是制造牙刷的刷毛。尼龙属于聚氨酯，在它的主链上有氨基。氨基具有极性，会因氢键的作用而相互吸引。所以尼龙容易结晶，可以制成强度很高的纤维。      尼龙分尼龙6,6、尼龙6、尼龙1010等。其实尼龙6和尼龙6,6，区别不大。之所以两种都生产，只是因为杜邦公司发明尼龙6,6后申请了专利所以其它的公司为了生成尼龙，才发明出尼龙6来。

2、尼龙的优点与不足：Advantages and Limitations of NylonsMechanical Properties Good combination of mechanical properties- fatigue and creep strength, stiffness, toughness and resilience- only slightly inferior to polyacetals. Limitations are that all nylons absorb or give up moisture to achieve equilibrium with

3、 ambient conditions- moisture acts as a plasticizer and decreases tensile and creep strength and stiffness and increases impact strength and the dimensions of the component. The effect is most serious in thin-sectioned components. Because nylons depend upon moisture for impact performance, embrittle

4、ment can occur in desiccated air. WearGood abrasion resistance (ability to absorb foreign particles) and self lubricating properties are responsible for the widespread use in gears and bearings. Thermal PropertiesSuitable for prolonged service temperatures of 80-100C and this can be increased to 140

5、 C with heat stabilized grades. Limitation is that thermal expansion varies with temperature and moisture content. Electrical PropertiesGood commercial insulator but electrical properties are greatly influenced by moisture content and/or temperature increase. EnvironmentalAll nylons are resistant to

6、 fuels, oils, fats and most other technical solvents such as aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, esters, ketones and alcohols. All have good alkali resistance. Limitations are that all nylons are attacked by strong mineral acids, acetic acid and dissolved phenols. Some typ

7、es are dissolved by formic acid. UV attacks un-stabilized nylons causing embrittlement in a comparatively short period. Food and medicineCan be used in contact with most food stuffs at room temperature and sterilized by steam or infra-red radiation. Fillers- Wide range of fillers and additives to im

8、prove specific properties and reduce limitations of unmodified materials, e.g glass fibre filler greatly reduces effects of moisture on dimensions and properties compared with unfilled materials. ProcessingMost material types are available in grades suitable for injection, blow and rotational mouldi

9、ng and extrusion, with additional possibilities of fluid bed coatings, sintering and casting for special grades. The latter (casting for monomer) is particularly useful for producing large stress-free sections in small economical batches. Most nylons can be readily machined using techniques akin to those used for the light alloys. Nylons can be joined with adhesives, induction bonding and ultrasonic welding. Limitations are that nylons have a sharply defined melting point and high shrinkage values occur on moulding t