Because there is a component in nylon material called amido-nhco-has polarity, its molecular formula: c24h20clno3 molecular weight: 405.87, the content of this component is directly related to the size of water absorption. When selecting materials, we should pay attention to the structure of nylon material to avoid the failure of product design due to high water absorption.
The main component of nylon is polyamide, whose amide group nhco has polarity, which makes nylon have double-sided properties of water absorption and dehydration. Nylon without water absorption is brittle and easy to break, but its physical properties will appear after water absorption. Nylon products will be brittle and fracture after long-term drying and dehydration in low temperature environment, which will shorten the service life of nylon. Therefore, it is necessary to know that nylon molding PA6 is the PA with the highest water absorption. In the experiment of polycondensation, the molecular weight of nylon is about 5000. The molecular weight of the polymer reached 10000-20000. Because nylon 6 has good fluidity, its molecular weight is less than nylon, so the intermolecular gap is large, so its water absorption is high
1. Analysis of the reasons for the water boiling of nylon parts: nylon is a kind of crystalline thermoplastic material, which is easy to absorb water and contains hydrophilic group (acylamino). For crystalline polymer, in the injection molding process, the rapid cooling makes the material unable to naturally crystallize and set, so that there is a strong internal stress in the material. For nylon material without "tempering" treatment, the In the interior, the macromolecules will still tend to move towards natural orientation and crystallization after finalization, which will further aggravate the internal stress of the material. Therefore, the nylon parts without water boiling process are very brittle, which is easy to collapse or fracture when subjected to external force. Then, if the formed nylon macromolecules are naturally oriented and crystallized, how about eliminating the internal stress as much as possible In fact, the boiling and boiling process of nylon is similar to the setting of our metal "tempering" process. That is to let nylon parts soak in a certain water temperature, so that the internal macromolecules tend to the natural orientation as much as possible and reach the balance of internal crystallization and crystallization, so as to eliminate the internal stress. On the outside, the toughness of nylon parts is greatly enhanced, and the brittleness is basically eliminated Why cooking with water? That's because nylon contains acylamino group, a hydrophilic group, which makes nylon easy to absorb water, but when nylon absorbs a certain amount of water, it helps its internal macromolecule orientation and crystallization movement. The best temperature and time for cooking nylon parts: 90-100 ℃, 2-3 hours. If it's lower than 90 degrees, the effect is not good. If it's more than 3 hours, there will be no better result. In terms of cost performance, The above process conditions are the best 。